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  FAQ for isdn4linux
  Matthias Hessler (hessler@isdn4linux.de)
  v2.0.103, 15 January 2006

  If you are reading this FAQ online, you may consider downloading the
  whole thing, and reading it offline (much cheaper). To download the
  latest version of this FAQ in TXT/HTML/SGML format, go to the homepage
  of this FAQ: <http://www.mhessler.de/i4lfaq/>.  A German translation
  of the FAQ is available at: <http://www.wolf-b.de>.  This FAQ answers
  questions that were frequently asked in the newsgroup
  de.alt.comm.isdn4linux. It contains questions any user should know
  about ISDN under Linux using isdn4linux, as well as hints on how to
  best make use of all the features isdn4linux provides.  Version 2 of
  the FAQ is derived from an earlier version which had become outdated
  at the time of this writing. To obtain information on old versions of
  isdn4linux (1997 and earlier) please have a look at the FAQ version
  1.3.4.  About the format of this FAQ: The main basis of this FAQ is
  the i4l mailing list (see question ``docu_mailinglist''). I've treated
  the knowledge gained from reading as public domain, without quoting
  the author of the original mail. The FAQ is now written in SGML, as
  this format is flexible to convert into any other form of documenta-
  tion (though some restrictions apply). The FAQ is now maintained in
  English since German-speaking people can easily follow the mailing
  list/newsgroup (or search in the archives). Whoever wants to translate
  back to German is welcome to do so!  The countless links in this docu-
  ments are not always complete and I'm sure many are no longer correct.
  I do not have the time to check them all. If you discover a bad link,
  please let me know (I'll try to install some automatic checking when I
  have the time).  Additions, improvements and other suggestions are
  always welcome (also correction of typographical errors!), preferably
  send "diffs" from the SGML version. Thank you very much in advance!
  Send feedback about this FAQ to: i4lfaq@isdn4linux.de or:
  hessler@isdn4linux.de.  The newest version of this FAQ can be found
  at:
   <http://www.mhessler.de/i4lfaq/> or:
   <http://www.isdn4linux.de/faq/>.  This FAQ is protected by the GNU
  General Public License (GPL) Version 2; (C) 1999-2002 Matthias Hessler
  (for version 2.0) Distribution under the terms of the GPL is welcome.
  However, we offer NO GUARANTEES for the information herein. Please
  read the GNU General Public License for further details. A printed
  version is available from Free Software Foundation, Inc., 675 Mass
  Ave, Cambridge, MA 02139, USA.  An electronic version is available
  from the author.
  ______________________________________________________________________

  Table of Contents



  1. general: General information about isdn4linux
     1.1 general_i4l: What is isdn4linux?
     1.2 general_misdn: What is mISDN?
     1.3 general_hardware: What hardware is supported by isdn4linux?
     1.4 general_features: What features are supported by isdn4linux?
     1.5 general_countries: Which countries are supported by isdn4linux?
     1.6 general_docu: Where do I find more documentation, how-to's, helpful tips & tricks?
     1.7 general_getlatest: Where do I get the latest version of isdn4linux?
     1.8 general_contacts: How can I get in contact with the developers?

  2. distrib: Distribution
     2.1 distrib_getlatest: How can I get the latest isdn4linux?
     2.2 distrib_cvs: How can I access the source from the current development/what is the CVS tree all about?

  3. Features
     3.1 feature_not: Which ISDN features cannot be offered by isdn4linux?
     3.2 feature_data: Which ISDN data transmission modes are supported?
     3.3 feature_voice: Has isdn4linux voice support (e.g. answering machine, voice-over-ip gateway for H.323 clients)?
     3.4 feature_fax: Can I fax with isdn4linux?
     3.5 feature_modem: Can isdn4linux connect to/be called by an analog modem?
     3.6 feature_divert: Is it possible to initiate call forwarding with i4l?
     3.7 feature_ipx: Can I route ipx/spx over ISDN with Linux?
     3.8 feature_2channel: Does isdn4linux support channel bundling?
     3.9 feature_diald: Can I combine isdn4linux with diald?
     3.10 feature_dod: Does the driver support "dial on demand"?
     3.11 feature_sms: Can I send SMS (short messages) to my mobile phone via ISDN?
     3.12 feature_btx: Is the German videotex/Btx/Datex-J possible with isdn4linux?
     3.13 feature_clock: Can I set the clock of my computer with ISDN?
     3.14 feature_dosemu: Can I use isdn4linux under dosemu?
     3.15 feature_capi: Is there a CAPI interface available?
     3.16 feature_uus: Is UUS (user to user signaling) supported?
     3.17 feature_subaddressing: Is subaddressing supported?
     3.18 feature_gsmv110: Can I connect from my PDA via GMS cellular phone to isdn4linux?
     3.19 feature_reversedcard: Can isdn4linux log ALL actions happening on the ISDN bus (dual mode/reversed card/COLP/...)?
     3.20 feature_chargeint: Can isdn4linux hang up just before the ISDN provider would charge me for another unit?
     3.21 feature_eurofile: Can isdn4linux download or offer files via EFT (Eurofile transfer)?
     3.22 feature_leased: Can isdn4linux handle leased lines (e.g. D64S)?
     3.23 feature_pointtopoint: Can isdn4linux work in point-to-point mode as well as in multi-device mode?
     3.24 feature_ntmode: Does isdn4linux support running a card in NT mode?
     3.25 feature_crossedcable: Can isdn4linux directly connect two ISDN user devices (two ISDN cards) via a crossed cable?
     3.26 feature_lcr: Can isdn4linux do least cost routing (LCR)?
     3.27 feature_internetdialin: Can isdn4linux be setup such that it dials into the Internet, whenever I call it via telephone?
     3.28 feature_future: Which features are planned for the future?

  4. docu: Documentation, Howto's, Tips & Tricks, Mailing List/Newsgroup
     4.1 docu_first: What documents should I read first?
     4.2 docu_website: Where is the official website for isdn4linux?
     4.3 docu_abc: Where do I find documentation on the abc extensions?
     4.4 docu_newsgroup: Where is the newsgroup for isdn4linux?
     4.5 docu_mailinglist: Where is the mailing list for isdn4linux?
     4.6 docu_maillistdigest: How can I get a digest of the mailing list for isdn4linux (only one message per day)?
     4.7 docu_mailarchive: Is there an archive of the isdn4linux mailing list?
     4.8 docu_bugtracker: Is there a bug tracker available for isdn4linux?

  5. hardware: Supported hardware, its specialities, and hardware-related problems
     5.1 hardware_support: Which hardware is supported?
     5.2 hardware_activepassive: What is the difference between an active and a passive ISDN card?
     5.3 hardware_recommend: Which card is recommended by the developers?
     5.4 hardware_external: Does isdn4linux support external terminal adapters?
     5.5 hardware_cabeling: How should I wire my ISDN cables?
     5.6 hardware_irq: Why should I avoid IRQ 12 and 15 for my ISDN card?
     5.7 hardware_irqsharing: Can the isdn4linux driver work with shared interrupts?
     5.8 hardware_s2m: Which S2M cards are supported?
     5.9 hardware_pcmcia: Which PCMCIA cards are supported?
     5.10 hardware_smp: Can I run isdn4linux on my multi-CPU board?
     5.11 hardware_64bit: Can I run isdn4linux on 64bit hardware with Linux?
     5.12 hardware_alpha: Can I run isdn4linux on a DEC Alpha with Linux?
     5.13 hardware_sun: Can I run isdn4linux on a Sun workstation?
     5.14 hardware_ppc: Can I run isdn4linux on a PowerPC with Linux?
     5.15 hardware_maxcards: How many ISDN cards can I put into my computer?
     5.16 hardware_hfc: What is special about card with an HFC chip?
     5.17 hardware_elsa: What should I know about ISDN cards from ELSA?
     5.18 hardware_sedlbauer: What is special about the Sedlbauer card?
     5.19 hardware_teles: What should I know about before buying an ISDN card from Teles?
     5.20 hardware_fritz: What should I know when configuring a Fritz! card (also known as: AVM A1, Teledat 150, BT Speedway)?
     5.21 hardware_avmb1: What is special about the AVM B1 card?
     5.22 hardware_hypercope: What is special about the Hypercope cards?
     5.23 hardware_icn: What is special about the ICN card?
     5.24 hardware_isurf: What should I know about the Siemens I-Surf cards?
     5.25 hardware_diva: What should I know about the Eicon Diva cards?
     5.26 hardware_crossedcable1: If i4l uses one B-channel then the other one will be blocked (incoming as well as outgoing)...
     5.27 hardware_crossedcable2: How can I test whether a a/b cable pair has been crossed?
     5.28 hardware_pbx: i4l is connected to the internal bus of a PBX. Any problem?
     5.29 hardware_telestrouble: The PNP tools done work with my Teles 16.3 PNP card!
     5.30 hardware_elsacabletrouble: On my ELSA card, the LED for the loss of the TEI often blinks. My connections are also often disrupted...
     5.31 hardware_elsairq: My ELSA Quickstep 1000 ISA card produces very many interrupts with the HiSax driver. Is this normal or a problem with the HiSax driver?

  6. config: General information about Configuration
     6.1 config_msn: How should I set up isdn4linux with my MSNs?
     6.2 config_hardware: How should I configure my hardware? Is there something special I should know about my ISDN card?
     6.3 config_dialout: How should I configure dialout?
     6.4 config_dialin: How should I configure dialin?
     6.5 config_suse: I can not select my card in yast?
     6.6 config_pnp: How do I configure a PNP (Plug and Play) card?
     6.7 config_startstop: How can I start and stop the ISDN configuration?
     6.8 config_kerneld: Why shouldn't I use kerneld to load the ISDN modules in the kernel as needed?
     6.9 config_runlevel: How can I boot Linux sometimes with ISDN, and sometimes without?
     6.10 config_manycards: How do I configure more than 1 ISDN card?
     6.11 config_manychannels: How can I increase i4l's maximum number of channels?
     6.12 config_gsmv110: How do I connect my PalmPilot via GSM over V.110 to my computer?
     6.13 config_h323: How do I configure isdn4linux to act as a voice-over-ip gateway for H.323 clients?
     6.14 config_point2point: How do I configure a point-to-point connection?
     6.15 config_links: What helpful links are there about and around isdn4linux?
     6.16 config_misdn: How should I configure the new mISDN driver, and what is so special about it?
     6.17 config_kernel26: What has changed with the kernels 2.6.x?
     6.18 config_asterisk: How can I install asterisk with mISDN?

  7. trouble: Troubleshooting
     7.1 trouble_22memory: I can't start ISDN on my machine with kernel 2.2.x. I get the error messages "init_module: Device or resource busy" and "isdn: Could not allocate device-struct.".
     7.2 trouble_littlememory: How can I reduce isdn4linux's memory requirements?
     7.3 trouble_debug: How do I get maximum debug output?
     7.4 trouble_strategy: My isdn4linux doesn't work! How do I best go about finding the problem?
     7.5 trouble_boot: How can I tell whether my ISDN card has been correctly recognized?
     7.6 trouble_isdncause: I get an error message like "cause: E1234" (or similar)?
     7.7 trouble_e001b: I get an error message with "cause: E001B"?
     7.8 trouble_noprotocol: upon startup of HiSax I get the message "Warning - no protocol specified"?
     7.9 trouble_euronotsupported: upon startup of HiSax I get the error "kernel hisax: protocol euro not supported"?
     7.10 trouble_unknownprimitive: upon connection attempt I get the error "lldata_handler unknown primitive"?
     7.11 trouble_notelrings: Neither my telephone nor my fax machine ring when I call them with isdn4linux?
     7.12 trouble_guestaccess: Are there sites that offer guest access where I can test my isdn4linux setup?
     7.13 trouble_unload: I can't unload my ISDN modules ("isdn: Device or resource busy"), even so I closed all ISDN applications?
     7.14 trouble_tcpdump: Why does my tcpdump not work for ip packets going over ISDN ("truncated ip" or so)? How can I get a tcpdump patched for ISDN?
     7.15 trouble_locatecrash: My isdn driver crashes my machine! Since I've configured it as a module, the addresses change each time it's loaded. How can I find out where the driver is crashing?
     7.16 trouble_lotsdebug: My hard disk becomes very active when isdn4linux run. How can I turn this off?
     7.17 trouble_oldhardware: Maybe my hardware is too slow?
     7.18 trouble_outofbuffers: I get messages like "HSCX RME out of buffers", "HSCX RFP out of buffers", "HSCX B EXIR 10" in the syslog?
     7.19 trouble_noresetinit: After a soft reset, my card does not initialize correctly.
     7.20 trouble_noisdnctrl: When attempting to use isdnctrl, I get the error "/dev/isdnctrl: No such file or directory"?
     7.21 trouble_noisdnctrl2: When attempting to use isdnctrl, I get the error "/dev/isdnctrl: No such device"?
     7.22 trouble_xosview: xosview doesn't show any network activity since installing i4l.
     7.23 trouble_unknownhost: When I for example from a W95 box call up a page with Netscape, I only get the answer "unknown host".
     7.24 trouble_noroute: Addresses are now found, but now I get "no route to host".
     7.25 trouble_nolocalnet: After booting, my local network can no longer be reached. I use the network interface ippp0 with ifconfig 0.0.0.0; the default route points to ippp0.
     7.26 trouble_unauthorizedcodechange: When HiSax starts, I get the error messages 'Approval certification failed, unauthorized source code changes'?
     7.27 trouble_crcerror: How can I see the number of packets for HiSax with invalid CRC?
     7.28 trouble_amproglibtool: When compiling isdn4k-utils I get the error 'AM_PROG_LIBTOOL not found'?
     7.29 trouble_hisaxparams: HiSax does not work - how can I set the HiSax parameters for newer Linux kernels?

  8. msn: Configuration/MSNs
     8.1 msn_my1: What is my MSN? What if I don't have any?
     8.2 msn_my2: How can I find out how my telephone number is transmitted to the calling party?
     8.3 msn_config: How do I configure my MSN?
     8.4 msn_max: How many MSNs as a maximum can I use for an isdn card?
     8.5 msn_mindialin: How can I minimize usage of MSNs for digital data dialin?
     8.6 msn_onlyone: How can I use one MSN for everything?
     8.7 msn_buendel: Can I have several NTBAs, all with the same MSN?

  9. lan: ISDN4LINUX in a LAN
     9.1 lan_config: How can I set up Linux so that other computers in my LAN can access the internet via my Linux computer?
     9.2 lan_modemserver: How can forward ISDN data from a local computer in my LAN to the ISDN card(s) in my Linux PC (like a modem server)?
     9.3 lan_remotedialing: How can I allow the users in my LAN to trigger a dial out via   the ISDN card(s) in my Linux PC?

  10. dialout: Configuration of Dial-Out
     10.1 dialout_config: How do I configure dialout properly?
     10.2 dialout_dialmode: When an IP packet should go over the link (which usually triggers a dialout), all I see in the log is: "dial rejected: interface not in dialmode auto"?
     10.3 dialout_advanced: What special dialout features are available?
     10.4 dialout_permission: How can I allow a normal user to initiate dialouts?
     10.5 dialout_manycards: How do I configure dialout with more than 1 ISDN card?
     10.6 dialout_fixedchannel: How can I force HiSax to always dial out on a specific B channel?
     10.7 dialout_dynip: On dynamic ip assignment, how do I find out which ip address is being used for dialout?
     10.8 dialout_bind: A dns query causes bind to dial out. Why does it take about a minute before it is answered? How do I work around it?

  11. pap: Authenticate properly (especially with PAP)
     11.1 pap_optionauth: When dialing out, I get the message "pppd: peer authentication required but no authentication files accessible." What does this mean?
     11.2 pap_requestauth: I cannot establish a connection -  it's rejected by the other side. In the log file I find a message that's something like: "sent (0) (LCP ConfReq id=0x1 mru 1500 auth pap magic 0xcd12e9c4"
     11.3 pap_rejectauth: I cannot establish a connection -  it's rejected by the other side. In the log file I find a message that's something like: "sent (0) (LCP ConfRej id=0x1 auth pap"
     11.4 pap_checkpwd: How can I check which password is actually sent to the remote side?
     11.5 pap_passwd: I have problems with PAP or CHAP authentication. It does not work although I'm sure I entered passwords etc. correctly.

  12. syncppp: Sync PPP
     12.1 syncppp_whichppp: pppd, ipppd, syncPPP, asyncPPP .. what is they? Which should I use?
     12.2 syncppp_compile: How do I compile isdn4linux with syncPPP?
     12.3 syncppp_netinterface: How should I name my network interface?
     12.4 syncppp_config: How do I configure isdn4linux with syncPPP?
     12.5 syncppp_busy: How can I tell if a connection is unsuccessful (busy)?
     12.6 syncppp_logindelay: How can I reduce login delay?
     12.7 syncppp_2configs: I want to talk to remote machines which needs different configurations. The only way I found to do this is to kill the ipppd and start a new one with another config to connect to the second machine.
     12.8 syncppp_pppbind: How does the (little-documented) "pppbind" command in isdnctrl work?
     12.9 syncppp_dynip: I want to use dynamic IP address assignment. How must I configure the network device?
     12.10 syncppp_msgetdns: How do I configure ipppd to obtain or provide the nameserver address at dial in?
     12.11 syncppp_ipx: How can I do IPX over ipppd?
     12.12 syncppp_faster: How can I increase my PPP data transfer rates?
     12.13 syncppp_compression: Which compressions can I use with ipppd?
     12.14 syncppp_strategy: I can't get a connect. How can I find out where the problem is?
     12.15 syncppp_log: How can I get a log for ipppd?
     12.16 syncppp_nopppsupport: Starting ipppd I get the error message "this systems lacks ppp support" or "isdn driver is out of date. maybe ippp0 has no syncppp0 encapsulation".
     12.17 syncppp_nousabledevice: When I try to start ipppd it says "Can't find usable ippp device"
     12.18 syncppp_starterror: When I start ipppd, I only get error messages from the i4l driver.
     12.19 syncppp_framesdelayed: I get the message IP frames delayed - but no connection.
     12.20 syncppp_noroute: I cannot dial out with isdnctrl dial ippp0. It seems as if the route to ipppd is missing although I did set it (network unreachable). With my old kernel 2.0 everything works fine!
     12.21 syncppp_nodefaultroute: After ipppd dials out my default route is gone.
     12.22 syncppp_packettoolarge: I often get the error message hscx_empty_fifo: incoming packet too large
     12.23 syncppp_slow: The connection with ipppd seems to work, but eventually it crashes or is very slow.
     12.24 syncppp_loadproblem: I only have problems with ipppd when the connection is being heavily burdened. Then everything stops. What could be causing this?
     12.25 syncppp_mtu: My ipppd works, but I keep getting the message pppd(104): ioctl(SIOCSIFMTU): Invalid argument"?
     12.26 syncppp_1stpacket: The first IP packet gets lost on automatic dialout with dynamic IP address allocation.
     12.27 syncppp_droppacket: What does the message "No phone number, packet dropped" mean?
     12.28 syncppp_leadingzero: Why does my ipppd dial one too many zeros ("ippp0: dialing 0 089XXXXXX...")? I don't have any extensions!
     12.29 syncppp_ethfake: My ISDN device is shown with HWaddr and IRQ=0 and base address = 0 when I list it with ifconfig
     12.30 syncppp_lzsproblem: I get an error message like kernel check for lzs failed?

  13. asyncppp: Configuration Async PPP
     13.1 asyncppp_whichppp: pppd, ipppd, async PPP, sync PPP - what are they? Which should I use?
     13.2 asyncppp_config: How do I configure async PPP?
     13.3 asyncppp_logindelay: How can I reduce login delay?
     13.4 asyncppp_fast: How can I increase my transfer rates with PPP?
     13.5 asyncppp_log: How can I get a log for pppd?
     13.6 asyncppp_suddendeath: Establishing the connection works fine, but pppd crashes just after that (i.e. the first bytes gets through, but then everything stops)

  14. rawip: Raw IP
     14.1 rawip_whatis: What is Raw IP, when should I use it?
     14.2 rawip_capi: How can I use Raw IP with the new CAPI 2.0 interface (mISDN)?

  15. ttyI: Configuration of the ttyI* devices (`Modem emulation')
     15.1 ttyI_nomodem: Don't the ttyI* devices emulate an analog modem?
     15.2 ttyI_dev: Which devices should I use for calls out or calls in?
     15.3 ttyI_hdlc: How to I switch the modem emulation from X.75 to HDLC?
     15.4 ttyI_uucp: How can I poll with Taylor-UUCP using isdn4linux?
     15.5 ttyI_speed: What speed should I set for the ttyI* devices?
     15.6 ttyI_max: How many devices are the maximum supported number?
     15.7 ttyI_nocarrier: When I dial with "ATD....." I always get a "NO CARRIER".
     15.8 ttyI_noincall: My ttyI* device/pppd does not recognize an incoming call.
     15.9 ttyI_callphone: Why can't I dial my telephone or fax from the ttyI* devices?
     15.10 ttyI_noconnect: I can't get a connection to my ISDN mailbox/BBS.
     15.11 ttyI_forcehangup: My modem emulation hangs. How can I force my card to hang up?
     15.12 ttyI_channelclosed: During a tty connection, I get a message from the kernel: "teles_writebuf: channel not open". Then no more input is accepted for this connection.
     15.13 ttyI_x75uucp: When I use UUCP with X.75, I always get transfer errors!

  16. dod: Unwanted dialout on demand
     16.1 dod_how: How does dialout on demand work?
     16.2 dod_disaster: What is a charge unit disaster?
     16.3 dod_causes: What can cause a charge unit disaster?
     16.4 dod_off: How can I safely turn off dialout on demand?
     16.5 dod_strategy: How can I track down unexplainable dialouts?
     16.6 dod_winclient: Can it be that the Win95 machine on my LAN is causing automatic dialouts?
     16.7 dod_localdns: I have set up a local DNS name server. Why does it cause unwanted dialouts? How can I find the cause?
     16.8 dod_forwarddns: I have set up my name server in 'forward' mode, with one forward address. Now it dials out about every minute?
     16.9 dod_sendmail: How can I get sendmail to not initiate any connections without local mail being left undelivered?
     16.10 dod_samba: The samba package always triggers dialouts for me. How can I prevent this?
     16.11 dod_netscape: How can I get Netscape to quit initiating dialouts when starting?
     16.12 dod_rstprovoking: Why should I use the RST-provoking mode/patch?
     16.13 dod_closeipconnect: After closing the line, I discover with netstat -nt that IP connections are still open. How can I close these manually?
     16.14 dod_onlineoncrash: Is it possible that even with a crashed computer a ISDN connection remains open (and the charge units accumulate)?

  17. chargeint: Chargeint
     17.1 chargeint_whatis: What does Chargeint?
     17.2 chargeint_config: How should I configure Chargeint?
     17.3 chargeint_whennot: When does it not make sense to use the chargeint?
     17.4 chargeint_correcttime: How can I be sure that the chargeint patch is using the correct time?
     17.5 chargeint_nohangup: The connection doesn't end with timeout.

  18. 2channel: Channel bundling (MPPP, raw bundling)
     18.1 2channel_whatis: What is channel bundling and how can I use it?
     18.2 2channel_raw: What is raw bundling?
     18.3 2channel_rawconfig: How do I configure raw bundling?
     18.4 2channel_rawgoodbad: What are the advantages and disadvantages of raw bundling?
     18.5 2channel_mppp: What is MPPP?
     18.6 2channel_mpppgoodbad: What are the advantages and disadvantages of MPPP?
     18.7 2channel_mpppconfig: How do I configure MPPP?
     18.8 2channel_mpppcompile: I tried MPPP but it doesn't work. The ipppd writes in the debug log something like: " ...  rcvd (0)(proto=0x3d) c0 00 00 00 80 fd 01 01 00 0a ... sent (0)(LCP ProtRej id=0x2 00 3d c0 00 00 00 80 fd 01 ..."
     18.9 2channel_cantlocateippp1: When trying to use MPPP I get the error message "modprobe: Can't locate module ippp1" and "ipppd: ioctl(SIOCSIFMTU): No such device..."?
     18.10 2channel_multiplenumbers: How can I set up multiple number when using MPPP?
     18.11 2channel_freebchannel: How could I set up isdn4linux to free the second B-channel if a phone call comes in?

  19. remote: Pecularities of the remote ISDN device
     19.1 remote_win95: How do I configure Windows95 to dial successfully into my isdn4linux computer?
     19.2 remote_mac: I'd like to exchange data with a Macintosh (Leonardo card), what do I or the Mac user have to watch out for?
     19.3 remote_macpap: A Macintosh with a Leonardo card tries to call in, and wants to negotiate chap md5. How can I switch it to CHAP/PAP?
     19.4 remote_cisco: How does isdn4linux work with a Cisco (HDLC) on the other side?
     19.5 remote_ispa: What settings does ISPA etc. (DOS, Windows) need to work with the standard settings of isdn4linux?

  20. leased: Leased lines
     20.1 leased_flatrate: What's the difference between a leased line and a flat rate?
     20.2 leased_nosignal: How does establishing and ending a connection work with D64S without signaling?
     20.3 leased_hisaxconfig: With i4l, how do I configure my card on a D64 leased line?
     20.4 leased_x75: How do I configure X.75 on a D64 leased line?
     20.5 leased_splitline: With i4l, can I use one channel as a leased line and the other as a dialup line?

  21. dialin: Configuration of a Dial-In Server
     21.1 dialin_config: How can I enable others to login via ISDN?
     21.2 dialin_manyparallel: How can I allow several people to call in to me at the same time?
     21.3 dialin_manycards: When using several ISDN cards, how can I react upon on a call received via a specific ISDN card?
     21.4 dialin_analogditalsamettyi: Can I configure a ttyI* device to accept both digital and analog modem dialins?
     21.5 dialin_fixedip: How can I assign fixed ip addresses per user who dials in via ipppd?
     21.6 dialin_hdlc: Someone would like to dial in to my mgetty with HDLC. Is ttyI1 correct, or do I have to start with ttyI0?
     21.7 dialin_autoppp: Is it possible with mgetty to automatically start pppd when LCP frames are received?
     21.8 dialin_passwd: How can I have (i)pppd check passwords from /etc/passwd instead of /etc/ppp/pap-secrets when someone dials in?
     21.9 dialin_ignored: I keep getting the message "isdn_tty: call from XXX - YYY ignored". Why does isdn4linux (syncPPP) ignore this dialin attempt?
     21.10 dialin_async: A SunISDN tries to dial into my i4l system.

  22. callback: Callback
     22.1 callback_delay: An incoming call is rejected by i4l. i4l then calls back. The reject is not recognized by the other side which keeps on dialing to i4l.
     22.2 callback_cisco: Somehow i4l can not callback a Cisco?
     22.3 callback_ascend: Callback from an Ascend works only when I set "Active=Yes" in the Ascend menu; but then the Ascend keeps calling me, even when my machine is off.
     22.4 callback_banzai: How can I callback a Banzai!?
     22.5 callback_microsoft: Does isdn4linux support Microsoft Callback (CBCP)?

  23. isdnlog: Isdnlog
     23.1 isdnlog_rates: Where do I get the latest rate information?
     23.2 isdnlog_servicetype: Can I see the service type from an incoming call in the output from isdnrep?
     23.3 isdnlog_callerid1: Why don't I always receive from the German Telekom the number of a caller ("Caller ID")?
     23.4 isdnlog_callerid2: Do I receive the Caller ID from foreign calls (German Telekom)?
     23.5 isdnlog_spoofcallerid: I've heard that actually two Caller IDs are transmitted?
     23.6 isdnlog_betterlogging: Why doesn't isdnlog record the number dialed by my other ISDN devices, since it records the charges?
     23.7 isdnlog_reversedcard: How can I get isdnlog to also show the telephone numbers for other ISDN devices?
     23.8 isdnlog_rategraphic: How can I display the data transfer rates graphically?
     23.9 isdnlog_2callerid: Isdnlog (=2.52) shows for a caller two telephone numbers! Which one is correct?
     23.10 isdnlog_soundbusy: I've set up a script to play sound per cat on /dev/sound or some other device. When several events occur, then there is an error: Can't open output file '/dev/sound': Device or resource busy
     23.11 isdnlog_noshell: Isdnlog should call a program with redirected output (e.g. play anruf.au 2/dev/null). Why does ISDN tell me Can't start '/usr/local/bin/play anruf.au 2/dev/null' with execvp()?
     23.12 isdnlog_blankscreen: When dialing out, the screen goes momentarily black?
     23.13 isdnlog_nologging: Isdnlog does not log any incoming call for me?
     23.14 isdnlog_enoughdata: How can I check whether isdnlog receives enough information from the kernel drivers?
     23.15 isdnlog_database: How can I set up isdnlog with database support?

  24. audio: Handling Voice with ISDN
     24.1 audio_links: Where can I find helpful links regarding vbox?
     24.2 audio_format: What is the format of the audio messages (.msg) vbox plays when it answers a call?
     24.3 audio_recordmsg: How can I record my own messages for vboxgetty?
     24.4 audio_play: How can I play audio messages locally using /dev/audio?
     24.5 audio_convertto: How can I convert audio messages which where recorded by vbox to other formats (i.e. from uLaw to WAV)?
     24.6 audio_convertfrom: How can I format WAV for uLaw (for my vbox announcement message)?
     24.7 audio_dtmf: How can I improve the recognition of (DTMF) dial tones?
     24.8 audio_e0265: My vboxgetty gets a modem timeout, and reports error E0265.
     24.9 audio_noanswer: My vboxgetty does not answer any incoming calls.
     24.10 audio_nocat: If vboxgetty has recorded a message in a format which can not be played using "cat xxx/dev/audio" how can I still hear the message?
     24.11 audio_earlyrecording: At the beginning of a message recorded by vboxgetty, there's often a part of my own announcement?

  25. Supported Countries
     25.1 country_which: In which countries does isdn4linux work?
     25.2 country_certified: Is isdn4linux approved for use by the telecommunications authorities?
  26. 1tr6: German Pecularities for 1TR6
     26.1 1tr6_eaz: Which EAZ should I use for i4l?
     26.2 1tr6_extension: I use 1TR6 on an extension - the extension number has more than one digit (e.g. 206). What is my EAZ?
     26.3 1tr6_spv: What is a SPV?
     26.4 1tr6_spvdial: Does isdn4linux support SPVs? How?

  27. Other countries
     27.1 country_austria: Austria: We have neither an MSN nor an EAZ, only a normal plain telephone number. What do we have to use for i4l?
     27.2 country_brazil: Brazil: How does our MSN look like?
     27.3 country_france: France: How does our MSN look like?
     27.4 country_italy: Italy: What does our MSN look like?
     27.5 country_netherlands: Netherlands: What does our MSN look like?
     27.6 country_northamerica: North America: Can we use isdn4linux in North America?
     27.7 country_pakistan: Pakistan: What should we use as MSN?
     27.8 country_portugal: Portugal: What should we use as MSN?
     27.9 country_switzerland: Switzerland: We have neither an MSN nor an EAZ, just a plain telephone number. What do we have to use for i4l?
     27.10 country_uk: UK: What should we use as MSN?

  28. misc: Miscellaneous
     28.1 misc_standards: Which standards apply to the ISDN protocol layers?
     28.2 misc_nonullcable: Can I connect two ISDN devices directly with a kind of "null modem cable"?
     28.3 misc_uisdn: Can isdn4linux run in parallel to UISDN?

  29. glossary: ISDN specific words which are used in this FAQ


  ______________________________________________________________________

  1.  general: General information about isdn4linux

  1.1.  general_i4l: What is isdn4linux?

  isdn4linux is a set of kernel modules which are part of the Linux
  kernel. It consists of the main module isdn and the actual hardware
  driver that control some specific card.  In addition, the package
  isdn4k-utils contains utilities to make use of ISDN specific features.
  Please note that since kernel 2.6.0 isdn4linux is considered legacy.
  It has been superseded by the new mISDN drivers (see question
  ``general_misdn''.


  1.2.  general_misdn: What is mISDN?

  mISDN is the successor of isdn4linux, and also consists of kernel
  modules that are part of the Linux kernel. The mISDN modules have been
  rewritten from scratch since the old isdn4linux modules were difficult
  to maintain.

  The new mISDN modules are based on the CAPI interface (see question
  ``feature_capi'' for more details on the CAPI interface). Not all ISDN
  cards supported by isdn4linux have been/will be ported to mISDN.
  However, it is planned to create a compatibility layer to allow
  migration of the existing isdn4linux drivers. Also, ipppd would be
  replaced by the standard pppd once pppd works as well as ipppd
  currently does.  For the moment, isdn4linux can still be used in
  parallel with mISDN, but this may change in the future.

  For more technical and configuration information about the mISDN
  driver see question ``config_misdn''.


  1.3.  general_hardware: What hardware is supported by isdn4linux?

  Generally, isdn4linux can control ISDN cards that are connected to the
  PC's ISA or PCI bus. Also a few PCMCIA cards are supported. However,
  isdn4linux can not make use of any devices connected via a serial or
  parallel interface (which are called 'terminal adaptors'), with only a
  few exceptions: the Creatix/Teles S0 box for the parallel port, and
  the Gazel 128 USB.  For more details on which cards are supported see
  section ``hardware''.


  1.4.  general_features: What features are supported by isdn4linux?

  Basically, isdn4linux can receive and transmit data via ISDN in
  several ways (X.75, HDLC, raw ip, synchronous ppp, asynchronous ppp,
  V.110). Some of its utilities offer additional features. Two examples
  are isdnlog, which allows logging of and reaction to ISDN events
  (including calculating any charges); and vbox, which provides voice
  answering machine capabilities. For more details see the section
  ``feature''.


  1.5.  general_countries: Which countries are supported by isdn4linux?

  At least all countries which use Euro-ISDN are supported, however some
  pecularities apply. To find more about your country, check the section
  ``countries''.


  1.6.  general_docu: Where do I find more documentation, how-to's,
  helpful tips & tricks?

  Besides this FAQ, take a look at the various man pages and Readme's
  that come with the isdn4linux package. Then there is the isdn4linux
  website: <http://www.isdn4linux.de>. There is also a mailing list on
  isdn4linux which will give you the most up to date information. To
  find out more about these great information sources, see section
  ``docu''.  And: check out all the great links listed in question
  ``config_links''!  You may find information in your language, or
  information specific to your linux distribution.


  1.7.  general_getlatest: Where do I get the latest version of
  isdn4linux?

  The latest version of the kernel drivers should be found in the Linux
  kernel. However, sometimes the Linux kernel does not have the latest
  version or does not yet support your ISDN card. Additionally, you may
  need to use the isdn4k-util package. In those cases you could try to
  get the very latest version that is currently in development. See the
  section ``distrib''.


  1.8.  general_contacts: How can I get in contact with the developers?

  You can contact the isdn4linux developers through the
  www.isdn4linux.de website. Have a look at
  <http://www.isdn4linux.de/contacts.shtml>.



  2.  distrib: Distribution

  2.1.  distrib_getlatest: How can I get the latest isdn4linux?

  There are different ways, depending on your kernel. Unless you are an
  experienced user of Linux, you should use a recent kernel (=first
  option).


  o  You have a recent kernel (at least 2.0.36/2.2.11/2.3.14): Great
     choice, you have already the current kernel ISDN stuff.
     Additionally, you just need to get the current isdn4k-utils package
     from <ftp://ftp.isdn4linux.de/pub/isdn4linux/utils/> - unless it's
     already included in your distribution.

  o  You have an older kernel (before 2.0.36/2.2.11/2.3.14): An upgrade
     to a recent kernel is HIGHLY recommended. And it is MUCH easier to
     do a kernel upgrade than to get ISDN to work with your older
     kernel.  Ok, now if you still want to keep your old kernel, here is
     how to do it: First you have to identify the correct CVS extract
     for your kernel version (CVS is the version control system the ISDN
     developers use to develop ISDN4LINUX). Take a CVS snapshot that is
     dated with about the date when your kernel came out. You find the
     kernel patches and the old isdn4k-utils packages on
     <ftp://ftp.isdn4linux.de/pub/isdn4linux/> or on one of its mirrors
     (see  <http://www.isdn4linux.de/download.shtml> on how to find
     mirrors).

  o  As a developer: If you want to participate in the development of
     i4l, you can get the very latest stuff via CVS. For this, see the
     question about access to CVS: ``distrib_cvs''.


  2.2.  distrib_cvs: How can I access the source from the current devel-
  opment/what is the CVS tree all about?

  CVS - Concurrent Version System:

  This is a multiuser/server extension to RCS (Revision Control System).
  The I4L drivers are developed under CVS, and there is a server
  (cvs.isdn4linux.de) with a CVS tree to which all developers have
  access.  In addition, Fritz has configured anonymous read-only access
  to the CVS tree . If you must have the very latest versions, you can
  get them there, however they may contain more bugs than the released
  versions!!!

  Here is how to get the latest version:

  1. Create and go to the directory where you want to store i4l

     ___________________________________________________________________
     mkdir ~/cvs; cd ~/cvs
     cvs -d :pserver:guest@cvs.isdn4linux.de:/i4ldev login
     ___________________________________________________________________



  2. Log in (asks for a password, enter readonly)

  3. Get the isdn kernel driver stuff (same hierarchy as in the linux
     source)

     ___________________________________________________________________
     cvs -d :pserver:guest@cvs.isdn4linux.de:/i4ldev checkout isdn
     ___________________________________________________________________



  4. Get the utility package into the current directory

     ___________________________________________________________________
     cvs -d :pserver:guest@cvs.isdn4linux.de:/i4ldev checkout isdn4k-utils
     ___________________________________________________________________


  If you want to get the latest version for kernel 2.0.x rather than for
  the latest kernel, then you have to give the additional option `-r':

  ______________________________________________________________________
  cvs -d :pserver:guest@cvs.isdn4linux.de:/i4ldev checkout -r isdn4kernel_2_0 isdn
  ______________________________________________________________________



  5. After having checked out, further updates can be done by first
     changing into isdn or isdn4k-utils subdirectory and running

     ___________________________________________________________________
     cvs update -P -d
     ___________________________________________________________________


  Tip: since cvs stores the password on your first login, you don't need
  to login again when updating.

  WARNING!! THE NEWEST STUFF SOMETIMES IS VERY INSTABLE OR MAY NOT EVEN
  COMPILE WITHOUT PROGRAMMING KNOWLEDGE - No newbie questions on this
  PLEASE! Use the source, Luke!

  People who want to continuously help develop isdn4linux by writing new
  drivers etc. can get a real account for full access. In this case
  write an email to Fritz Elfert fritz@isdn4linux.de



  3.  Features

  3.1.  feature_not: Which ISDN features cannot be offered by
  isdn4linux?

  Some ISDN features are device-specific and cannot be activated by
  isdn4linux for other devices, unless isdn4linux were to falsify the
  TEI (which would probably confuse the other device).  Such device-
  specific ISDN features are, among others: rejection of a waiting call,
  caller id on/off, hold, conference calls, differing COLP/CLRP.


  3.2.  feature_data: Which ISDN data transmission modes are supported?

  These low-level formats are possible:

  o  56k asynchronous : no

  o  64k synchronous  : yes

  o  128k synchronous  : yes (channel bundling - see the question
     ``feature_2channel'')

     These level2 formats are possible:

  o  HDLC

  o  X.75

  o  transparent

  o  V.110

     These encapsulations are possible:

  o  rawip

  o  ethernet

  o  Sync PPP

  o  X.25 (requires 2.1 or newer)

  o  cisco and cisco-h

  o  cisco-hk (=cisco with keepalive; requires 2.1 or newer)

  o  plus a few specialities: have a look at the man pages.

  Please note that X.31a is supported as X.25 on top of ISDN, while
  X.31b is not supported (neither in the B channel, nor in the D channel
  variation).


  3.3.  feature_voice: Has isdn4linux voice support (e.g. answering
  machine, voice-over-ip gateway for H.323 clients)?

  Yes, voice support is included in the current version of isdn4linux.
  For an answering machine you can either use "vgetty" from Gert
  Doerings "mgetty+sendfax", or "vboxgetty" from Michael Herold, which
  is made especially for isdn4linux.  The latter is part of the isdn4k-
  utils package, which can be found on:
   <ftp://ftp.isdn4linux.de/pub/>

  Also, you can use isdn4linux as a voice-over-ip gateway to let H.323
  clients (like Voxilla, Netmeeting) call normal telephones, and/or the
  other way around. For configuration see question ``config_h323''.


  3.4.  feature_fax: Can I fax with isdn4linux?


  o  For passive cards: Yes. Since 2005 the GPL software ivcall is able
     to send and receive voice calls and faxes even via passive cards.
     It makes use of the spandsp library which is part of the Asterisk
     project.  You can find it on:
      <http://0pointer.de/lennart/projects/ivcall/> An alternative
     project working on this problem existed (i4lfax) but has not made
     any progress since 1999. For more info on its status have a look
     at:
      <http://user.cs.tu-berlin.de/~ulfi/osvisions/i4lsoftfax/i4lfax/>
     Also, an idea exists to extend the new modular mISDN with layer 2
     and layer 3 protocols for fax. Once this works (e.g. with the
     Sedlbauer Speedfax card) then the layer 1 protocol
     (modulation/demodulation) could be also be implemented via the
     spandsp library.

  o  For passive cards from AVM: Yes. AVM recently released a binary
     CAPI 2.0 driver which supports faxing. However, the setup is rather
     complicated. Get a start on:
     <http://www.avm.de/ftp/cardware/fritzcrd/linux/index.htm>.  Here is
     a German website which has some nice installation instructions:
      <http://ixi.thepenguin.de> or
      <http://capi4linux.thepenguin.de> or
      <http://www.thepenguin.de> Please also have a look on the mailing
     list for tips how to do it, and what the consequences/disadvantages
     are.

  o  For the active card AVM B1: Yes (its firmware has implemented fax
     as one of its features). Get the newest stuff from:
      <ftp://ftp.aeccom.com/pub/fax4i4l/howto/current/> However, it has
     been reported that setting it up properly is very tricky.  Another
     site which could be helpful is:
      <http://www.topf-sicret.de/help/capi20.html>

  o  For the active Hypercope PCI cards HYSDN Ergo2 and HYSDN Metro4:
     Yes, after upgrade with a special fax card.  The setup is similar
     to that of an AVM B1, but may require extra patches.

  o  For the active Eicon Diva Server cards (except Diva 2.0Pro): Yes.
     Have a look at README.fax and README.eicon in the
     isdn/Documentation/isdn directory, as well as:
      <http://www.melware.de/>. The Eicon Diva Server cards allow faxing
     with class 2 commands.

  o  For semiactive cards Sedlbauer Speedfax+ and Siemens I-SURF 1.0:
     Yes But currently this requires some manual work. Check the mailing
     list on how to do it (special patch needed). Only class 1 fax
     commands are supported.  You can obtain the patch from:
      <//ftp.isdn4linux.de/pub/isdn4linux/kernel/v2.2/testing/i4l_isar_fclass1.tar.gz>
     The patch is not needed if your kernel is 2.2.15 or later.  You
     have to enable the kernel option for FCLASS2
     (CONFIG_ISDN_TTY_FAX=Y).  Also, you need to load the firmware of
     the card (part of the isdn4k-utils) with

     ___________________________________________________________________
     hisaxctrl <driver_id> 9 ISAR.BIN
     ___________________________________________________________________


  Then initialize the ttyI* interface with:

  ______________________________________________________________________
  ATZ&E<your_msn>S0=1S13=1+FCLASS=1
  ______________________________________________________________________


  and use a normal Hylafax class 1 config file, where you've replaced
  non-supported commands (flow control,...) by dummies.  For the I-Surf
  1.0 also check question ``hardware_isurf''.

  If you do want to fax now, your best choice is to install an analog
  fax modem along with your ISDN card. For companies who want to set up
  a fax server servicing multiple connections you could also have a look
  at the active ISDN cards.

  More information for setting up a fax server with hylafax can be found
  on: on the web site for Hylafax:  <http://www.hylafax.org> or on
  <http://www.mnd.fh-wiesbaden.de/~dreymann/linux>.


  3.5.  feature_modem: Can isdn4linux connect to/be called by an analog
  modem?

  Generally: NO. It may only work for cards with which you can fax: see
  question ``feature_fax''.  For the Sedlbauer card, you can give the
  following command on the ttyI*:

  ______________________________________________________________________
  AT&FS14=10S15=0S18=1&E<your_msn>
  ______________________________________________________________________



  3.6.  feature_divert: Is it possible to initiate call forwarding with
  i4l?

  Call diversion features have been implemented recently. Use the new
  program divertctrl in conjunction with the HiSax driver.

  If you make use of capi4linux, then you find a similar program named
  capidivert at: <http://www.tp1.ruhr-uni-bochum.de/~kai/i4l/>.  For now
  this is something only for the more experienced user, as so far there
  is no howto and only little documentation, and it is not automatically
  included in most distributions. However, it can be used with active
  ISDN cards.

  In the Netherlands, the keypad protocol can be used as an alternative.
  To use it you just dial with the usual dial command from an ttyI
  device:

  ______________________________________________________________________
  atd*123*0123456789#
  ______________________________________________________________________



  3.7.  feature_ipx: Can I route ipx/spx over ISDN with Linux?

  Yes, set up an ISDN interface with encapsulation ethernet, and use IPX
  framing ETHERNET_II. mars_nwe can do the rest (e.g. routing).  Also,
  you can route ipx with ipppd, see question ``syncppp_ipx''.  To use
  pppd for ipx, you have to give it the compile option IPX_CHANGE.
  However, be careful when using dial out on demand (dod), since
  frequent ipx broadcasts may cause a dod disaster (see question
  ``dod_disaster'').


  3.8.  feature_2channel: Does isdn4linux support channel bundling?

  The current version of isdn4linux support 2 methods of channel
  bundling:

  o  MPPP (based on sync PPP)

  o  Raw bundling (configured by so-called slave channels)

     Both variants have their own advantages and disadvantages.  See
     section ``2channel''.  Bonding (16bit channel) is not supported,
     since it can not work reliably when the dialup connections have
     deviating latency.  Warning: Channel bundling saves time, but not
     telephone charges.  It is useful only if you really need the extra
     bandwidth.


  3.9.  feature_diald: Can I combine isdn4linux with diald?

  Yes, you can. You have to configure it to use the ttyI* devices to
  dial out. E.g. like this:

  ______________________________________________________________________
  /usr/sbin/diald /dev/ttyI4 -m ppp [...]
  ______________________________________________________________________


  where [...] stands for further dialout parameters.  The recent diald
  releases contain configuration files for ISDN. See
  <http://diald.sourceforge.net> for details.

  3.10.  feature_dod: Does the driver support "dial on demand"?

  Yes. If a network interface (e.g. "isdn0") is set up, the driver will
  dial the number. If in addition a hangup timeout (Idle Timeout) has
  been given (like: isdnctrl huptime <interface> <time>), then the
  driver will automatically hang up when no data was been transferred
  over the interface for >time< seconds. However, with syncPPP there are
  problems (see the syncPPP section).  Also look at the dialmode
  description (see question ``dialout_dialmode'').  You should
  definitely be very interested in the large section of this FAQ that
  talks about the dangers of unwanted dialouts: (``dod'').


  3.11.  feature_sms: Can I send SMS (short messages) to my mobile phone
  via ISDN?

  Yes, you can use the program yaps to do this. However, due to some
  pecularities in the SMS-callcenter's ISDN connection, you have to
  compile the kernel with the options Disable send complete and Disable
  sending llc. For the new CAPI 2.0 interface a patched version of yaps,
  capi4yaps, is available on
  <http://sourceforge.net/projects/capi4yaps/>.

  Please note that mainly German providers support sending SMS via ISDN
  connection, in other countries this might not work. Dutch as well as
  UK SMS callcenters seem to not support this feature. Please let me
  know if you have additional information on this.  A useful sample
  config for yaps you might find on: <http://www.tnt-
  computer.de/linux/yaps-suite1-1.tgz>

  Another program to send SMS is asterisk. Have a look at:
  <http://www.asterisk.org> and <http://www.voip-info.org/wiki-
  Asterisk+cmd+Sms>.  One advantage over yaps is that it can also
  receive SMS, for Germany (you have to register for this first by
  sending a specific SMS - otherwise the SMS will be communicated to you
  by an automated voice call).

  Yet another program to send SMS is smsclient. You can find it on:
  <http://www.smsclient.org>.


  3.12.  feature_btx: Is the German videotex/Btx/Datex-J possible with
  isdn4linux?

  Yes, it works with the modem emulation with the ttyI* devices. There
  is a special register to set for videotex (ATSx=y -  see the Readme's)
  Warning! XCept (formerly Xbtx) has an ISDN configuration option. This
  should NOT be used. XCept should be configured as if a normal modem
  were being used.


  3.13.  feature_clock: Can I set the clock of my computer with ISDN?

  Yes. Isdnlog offers this feature with option "-t". Unfortunately, the
  seconds are not transmitted via ISDN, and the transmitted time is not
  very accurate - depending on the ISDN equipment of your telephone
  company there may be a deviation of several minutes (!).  It's better
  to get a PC clock that is set by radio signals and check it with, for
  example, xntp. You can also use a time server in the Internet with
  "netdate" or "rdate".  Check out the following urls on information
  about using time servers:

  o  <http://www.eecis.udel.edu/~mills/ntp/servers.html>

  o  In German:  <http://www.ptb.de/deutsch/org/4/43/433/verb.htm>

  o  In German:  <http://www.ptb.de/deutsch/aktuell/pi/pi00/pi0100.htm>


  3.14.  feature_dosemu: Can I use isdn4linux under dosemu?

  Yes, you can! Steffan Henke henker@informatik.uni-bremen.de wrote on
  25 Oct 96:

       In dosemu.conf it is enough to enter a virtual com port,
       (for example com2) that can be used with e.g. Telix or Ter-
       minate: serial { com 2 device /dev/ttyI3 } Access with Fos-
       sil is possible if fossil.com (included with dosemu) is
       started.  Tested with the following configurations: - Kernel
       2.0.21, Teles driver incl. Karsten's patches - Kernel
       2.0.21, HiSax



  3.15.  feature_capi: Is there a CAPI interface available?

  Currently, these cards support the CAPI 2.0 interface:

  o  the active card AVM B1.

  o  the active DIVA Server cards from Eicon.

  o  the active cards from Hypercope (HYSDN Champ2, HYSDN Ergo2, HYSDN
     Metro4)

  o  the passive Fritz card from AVM. However, please note that you have
     to download and manually install the binary drivers for this from
     AVMs ftp server. See the following web site for a nice howto:
     <http://www.topf-sicret.de/help/capi20.html>. There was also lots
     of stuff written in the mailing list on this.  Here is a German
     website which has some nice installation instructions:
      <http://ixi.thepenguin.de> or
      <http://capi4linux.thepenguin.de> or
      <http://www.thepenguin.de> Please note that due to its binary
     nature, this driver will not work if your distribution is
     incompatible with it (e.g. based on 64 bit).

  This interface follows the official CAPI 2.0 standard that was
  established recently for Linux by the CAPI Association (see
  <http://www.capi.org>).  Since kernel 2.6.0 the CAPI interface has
  been used as the general interface, also for other cards. For passive
  cards, the new driver mISDN will replace the old hisax driver once it
  is fully functional.

  There are no plans to implement a CAPI 1.1 interface.


  3.16.  feature_uus: Is UUS (user to user signaling) supported?

  Yes, isdn4linux could support both sending and receiving, but the
  implementation is currently rather incomplete due to the unclear legal
  situation for using this facility. Receiving UUS is only possible
  through the debug interfaces. Sending is supported in connection with
  the diversion services (when rejecting a call or announcing a busy
  condition), but not on an ordinary call. It is recommended to use
  subaddressing (see question ``feature_subaddressing'') instead.
  Please note that sending UUS it is not a free service (receiving is
  free), at least with some German phone providers you have to pay extra
  for it (also have a close look on the usage conditions). Additionally,
  please note that if you are connected through a PBX, it may filter out
  all the UUS stuff.

  3.17.  feature_subaddressing: Is subaddressing supported?

  Yes, isdn4linux does support subaddressing (available in France).  To
  configure it, give HiSax the number in this format:
  <number>.<subaddress>. However, you may have to order it seperately
  and pay extra for receiving it (sending is free), depeding on your
  ISDN provider.  Additionally, please note that if you are connected
  through a PBX, it will most likely filter out all the subaddressing
  stuff.


  3.18.  feature_gsmv110: Can I connect from my PDA via GMS cellular
  phone to isdn4linux?

  Yes, if the provider of the cellular phone has a GSM to ISDN/V.110
  gateway.  This has been reported to work from a PalmPilot to
  isdn4linux with V.110.  See question ``config_gsmv110'' for details on
  how to configure it.


  3.19.  feature_reversedcard: Can isdn4linux log ALL actions happening
  on the ISDN bus (dual mode/reversed card/COLP/...)?

  Yes, isdn4linux offers several possibilities to do this. Have a look
  at question ``isdnlog_reversedcard''.

  Please note that you may also use the software ISDN Sniffer for this,
  see the German web site <http://krypt.cs.uni-
  sb.de/projects/isdnsniffer/>.


  3.20.  feature_chargeint: Can isdn4linux hang up just before the ISDN
  provider would charge me for another unit?

  Yes, isdn4linux can do this. Check out section ``chargeint''.


  3.21.  feature_eurofile: Can isdn4linux download or offer files via
  EFT (Eurofile transfer)?

  Yes, isdn4linux offers special tools for this which are part of the
  isdn4k-utils.


  3.22.  feature_leased: Can isdn4linux handle leased lines (e.g. D64S)?

  Yes, isdn4linux can handle leased lines (explained in the glossary:
  ``glossary_leased''). Have a look at section ``leased''.


  3.23.  feature_pointtopoint: Can isdn4linux work in point-to-point
  mode as well as in multi-device mode?

  Yes, isdn4linux supports both. Check the glossary to understand the
  difference: ``glossary_pointtopointmode'' and
  ``glossary_multidevicemode''.


  3.24.  feature_ntmode: Does isdn4linux support running a card in NT
  mode?

  Yes, isdn4linux does support it, but only for a few special cards.
  See question ``feature_crossedcable'' for details. In the glossary
  there is more information on what the NT mode is: ``glossary_ntmode''.


  3.25.  feature_crossedcable: Can isdn4linux directly connect two ISDN
  user devices (two ISDN cards) via a crossed cable?

  Yes, isdn4linux can do this. However, this requires that the ISDN card
  can run in NT mode (for details on this mode see the glossary:
  ``glossary_ntmode'').  Only very few cards (e.g. HFC chipset) are
  cable of doing this.  Use the following command to start the ISDN card
  in NT mode:

  ______________________________________________________________________
  hisaxctrl <id> 98 1
  ______________________________________________________________________


  Make sure that the crossed cable is terminated even if it is very
  short!  Nothing will work without termination, not even a 1m cable.
  Some HFC card already have jumpers for termination. Since TX as well
  as RX circuits must be terminated with its own resistor, two jumpers
  should be present, like this:

  > 3 RX+ 2a --[100 Ohm]----+     ---------- /      ----------
  > 4 TX+ 1a --[100 Ohm]--+ |    | 87654321 |      | 12345678 |
  > 5 TX- 1b ---oJ1o------+ |    |__      __|/     |/_      /_|
  > 6 RX- 2b ---oJ2o--------+       |____|            |/___|



  It has been reported that for proper functioning even on a short cable
  a termination is required at/near both ends (at the ISDN card as well
  as at the connecting ISDN device).

  However, this will only give you the physical connection. Up to now
  isdn4linux does not (yet?) implement the higher level ISDN protocol
  DSS1 (this means that isdn4linux can not pretend to an ISDN device
  that it is an ISDN exchange, and give it the proper ISDN commands). As
  a result, you can simulate a leased line, but not pretend to be the
  PBX with isdn4linux.

  With the newer mISDN modules the situation is better. A special user
  space module is available for the emulation of a PBX. Development of a
  kernel module is in progress. In any case the chipset has to support
  the NT mode.



  3.26.  feature_lcr: Can isdn4linux do least cost routing (LCR)?

  Yes, this feature is now being supported by isdnlog. What it does is
  that it allows isdnlog to choose your telephone provider when placing
  a call through your ISDN card, depending on the time of day and the
  current rate information. Since isdnlog 4.16 an external script is
  called (if configured) to change various ISP settings (e.g. DNS
  lookup, proxy setup,...).

  Note: the ABC-extensions (s. ``docu_abc'') must be installed. Also,
  isdnlog should always be running (otherwise your dialout will be
  delayed by 3 seconds). If the ABC-extensions are not installed,
  isdnlog prints hints to the log file, which provider would have been
  chosen.


  3.27.  feature_internetdialin: Can isdn4linux be setup such that it
  dials into the Internet, whenever I call it via telephone?

  Yes, this is possible with isdnlog. You have to configure isdnlog such
  that it can execute a script whenever someone dials in. In the script
  you can check for the correct telephone number, then trigger the
  dialin.  To access your computer then over the internet, you can then
  access it via its ip address. In case of dynamic ip address
  assignment, you probably want to store the new ip somehow. Storage in
  a html page or via dynamic DNS may be good possibilities.

  If you understand German, there was an article about exactly this
  setup in ct 18/2002, page 204 (Bei Anruf Internet - Handy-Anruf loest
  Internet-Einwahl aus). Also, the following German web site explains
  how to set up such a configuration:
   <http://www.staschke.de/linux/anwahl.html>



  3.28.  feature_future: Which features are planned for the future?

  Actually, most features have been implemented and are now being
  improved.  But, who knows what other interesting stuff the developers
  may come up.  We'll see...



  4.  docu: Documentation, Howto's, Tips & Tricks, Mailing List/News-
  group

  4.1.  docu_first: What documents should I read first?


  o  ISDN kernel subsystem: /usr/src/linux/Documentation/isdn/README

  o  ISDN cards: /usr/src/linux/Documentation/isdn/README.card E.g.:
     /usr/src/linux/Documentation/isdn/README.HiSax

  o  Synchronous PPP: /usr/src/linux/Documentation/isdn/README.syncppp
     /usr/src/linux/Documentation/isdn/README.syncPPP.FAQ

  o  Voice capability: /usr/src/linux/Documentation/isdn/README.audio

  o  ISDN Utilities: /usr/src/isdn4k-utils-version/README(.*)

     Many of the utilities also have man pages!

  To get a good technical overview over isdn4linux have a look at the
  great whitepaper 'ISDN4Linux, CAPI4Linux, CPI4Hisax and other cute
  acronyms: The ISDN subsystem in the Linux kernel', which can be found
  at:
   <http://www.linux-kongress.org/2002/papers/lk2002-germaschewski.pdf>

  For a Suse distribution the following information might be helpful:

  o  /usr/doc/packages/i4l* (for i4l in general)

  o  /usr/doc/faq/faq/PPP-FAQ (for synchronous PPP)

  o  /usr/doc/howto/mini/Mail-Queue.gz (for email configuration)

     Also, read the excellent manual!

  For a Debian distribution the following information might be helpful:
  /usr/share/doc/isdnutils/HOWTO.gz

  If you are reader of the German computer magazine ct, they had very
  helpful articles at least on these issues:

  o  ct 5/1998, page 224: Der erste Kontakt/Linux: Mit PPP ans Internet

  o  ct 21/1998, page 288: Reiseleiter/Internet-Anbindung fuer das LAN

  o  ct 25/1998, page 218: Bei Anruf Netz/Linux: Dial-In Server

  o  ct 7/2001, page 228: Des Surfers Bastelstunde: Mobilfunktechnik
     HSCSD ausschoepfen (also contains information on dial-in
     configuration without HSCSD).

  o  ct 15/2002, page 204: Bei Anruf Internet: Handy-Anruf loest
     Internet-Einwahl aus

  o  ct 3/2004, page 182: Heimserver im Eigenbau - Teil 4: ISDN-
     Grundlagen fuer Linux (also contains information about the new
     mISDN driver).  An online version is available on:
      <http://www.heise.de/ct/04/03/182/>

  o  ct 9/2004, page 100: Tux vermittelt - Linux als Telefonanlage mit
     VoIP (refers to software PBX4Linux)

  o  ct 12/2005, page 116: Guter Stern vom Amt - Asterisk: Linux als
     professionelle Telefonanlage (refers to PBX software asterisk)

  o  ct 13/2005, page 216: Ein Pinguin als Sparfuchs - Linux-PC senkt
     Handy-Gebuehren (refers to PBX software asterisk)

  Also have a look at question ``config_links'' for helpful links on how
  to configure i4l (e.g. special help for SuSE, Red Hat, or Mandrake
  users).


  4.2.  docu_website: Where is the official website for isdn4linux?

  The offical website can be found at: <http://www.isdn4linux.de>.


  4.3.  docu_abc: Where do I find documentation on the abc extensions?

  You can find it on: <http://i4l.mediatronix.de/>


  4.4.  docu_newsgroup: Where is the newsgroup for isdn4linux?

  The newsgroup was de.alt.comm.isdn4linux, however had been closed down
  some time ago due to spam issues. To get in contact with the
  developers your best choice is to use the mailing list
  ``docu_mailinglist''. Alternatively, you find some interesting stuff
  in de.comp.os.unix.linux.isdn.


  4.5.  docu_mailinglist: Where is the mailing list for isdn4linux?

  The address of the mailing list is isdn4linux@listserv.isdn4linux.de.
  Before posting a message there please make sure it is not answered in
  this FAQ, and that the question has not been answered numerous times
  in the past (search <http://www.deja.com/> with keywords like ISDN,
  Linux, i4l, isdn4linux,...). People on the mailing list get really
  annoyed when the question "can I fax with my card xxx" is asked yet
  another time (see question ``feature_fax'' for the answer).  To reduce
  spam, as of 25. Aug. 2003 the mailing list has been changed to permit
  posts from subscribed members only. To write, you must be subscribed
  first.

  When writing on the mailing list, please always provide:

  o  Your Kernel version

  o  Your i4l/hisax version

  o  Your card type

  Most isdn4linux developers are present on the mailing list, and many
  other knowledgeable people. English postings are very welcome, and
  will be answered in English!

  The mailing list contains the same messages as the newsgroup (see
  question ``docu_newsgroup''), so you can read any responses to your
  question with your news reader. A bidirectional gateway ensures that
  mailing list and news are in sync.

  To subscribe to the mailing list, go to the web frontend at
  https://www.isdn4linux.de/mailman/listinfo/isdn4linux and submit the
  filled form. After that, you will not be subscribed yet.  Instead, you
  will receive a confirmation at the mail address you entered in the
  above form. This is a security precaution to prevent subscription by
  other persons or subscription of mistyped mail addresses. When you
  receive the confirmation, just follow the instructions in that mail.
  (I.e.: simply reply). After having replied, you will be subscribed and
  receive a welcome mail. The welcome mail will contain your password,
  so you should probably keep it just in case you want to unsubscribe or
  change some options at the web frontend.  To unsubscribe, go to the
  web frontend again, use your password to login and then unsubscribe.
  Please note: there are about 20-50 messages per day on this mailing
  list.  To receive only one message per day, containing all postings,
  have a look at question ``docu_maillistdigest''.


  4.6.  docu_maillistdigest: How can I get a digest of the mailing list
  for isdn4linux (only one message per day)?

  While filling the form as described in question ``docu_mailinglist'',
  simply click "Yes" at the radio-button, named "Would you like to
  receive list mail batched in a daily digest". You can change this
  option later when logging in the web frontend.


  4.7.  docu_mailarchive: Is there an archive of the isdn4linux mailing
  list?

  To quickly search for keywords, you can use
   <http://www.deja.com>. Make sure to also select older archive to do a
  complete search.

  Messages are also saved (unsorted) at listserv.isdn4linux.de,
  collected by month. To access the archive, you can use
  <http://www.isdn4linux.de/listarch/>.

  Other archives are:

  o   <ftp://ftp.uni-
     oldenburg.de/pub/unix/linux/isdn/isdn4linux/Mailing-List>


  4.8.  docu_bugtracker: Is there a bug tracker available for
  isdn4linux?

  Yes, there is a bugtracker available under the following url:
  <https://www.isdn4linux.de/mantis>. You have to register yourself
  before you can search for known bugs and enter new issues.


  5.  hardware: Supported hardware, its specialities, and hardware-
  related problems

  5.1.  hardware_support: Which hardware is supported?

  Only internal cards that plug into an ISA or PCI slot are supported.
  ISA Plug&Play cards are also supported, but need some additional
  manual configuration by means of the isapnptools. For details on the
  configuration see question ``config_pnp''.

  Internal cards may be ``active'', ``semi-active'', or ``passive''.
  Unless you have paid big money, assume you have a passive card. More
  about the difference: see question ``hardware_activepassive''.

  Right now there is a driver for all passive card with certain Siemens
  chipsets (HiSax driver). Have a look at the README.HiSax that comes
  with the driver for the most up to date information on supported cards
  and which parameter to pass to Hisax.  Here the status from 1st
  February 2002 (constantly improving):

  o  Teles 8.0/16.0/16.3 and compatible ones (like: Dr. Neuhaus Niccy
     1016, Creatix 16/S0)

  o  Teles 16.3c (can not be used as reversed card)

  o  Teles S0/PCMCIA (old hardware)

  o  Teles PCI

  o  Teles S0Box

  o  Creatix S0Box

  o  Creatix PnP S0

  o  Compaq ISDN S0 ISA card

  o  AVM A1 (Fritz, Teledat 150 ISA)

  o  AVM Fritz PCMCIA

  o  AVM Fritz PnP

  o  AVM Fritz PCI (Teledat 150 PCI)

  o  AVM Fritz PCI v2

  o  ELSA Microlink PCC-16, PCF, PCF-Pro, PCC-8

  o  ELSA Quickstep 1000

  o  ELSA Quickstep 1000PCI (new name: ELSA Microlink PCI)

  o  ELSA Quickstep 3000 (same settings as QS1000)

  o  ELSA Quickstep 3000PCI

  o  ELSA PCMCIA

  o  ITK ix1-micro Rev.2 (also: ITK colombus card)

  o  Eicon DIVA 2.0 ISA and PCI (S0 and U interface, no PRO version)

  o  Eicon.Diehl Diva 2.01 ISA and PCI, and Diva 2.02


  o  Eicon DIVA Piccola

  o  ASUSCOM NETWORK INC. ISDNLink 128K PC adapter (order code I-
     IN100-ST-D)

  o  Dynalink IS64PH (OEM version of ASUSCOM NETWORK INC. ISDNLink 128K
     adapter)

  o  All other ASUSCOM/Dynalink cards (includes OEM versions; in total
     more than 50 card versions)

  o  PCBIT-DP (OEM version of ASUSCOM NETWORK INC. ISDNLink)

  o  HFC-2BS0 based cards (TeleInt SA1)

  o  Sedlbauer Speed Card (Speed Win, Teledat 100, PCI, Fax+)

  o  Sedlbauer Speed Star/Speed Star2 (PCMCIA)

  o  Sedlbauer ISDN-Controller PC/104

  o  USR Sportster internal TA (compatible Stollmann tina-pp V3)

  o  ith Kommunikationstechnik GmbH MIC 16 ISA card

  o  Traverse Technologie NETjet PCI S0 card and NETspider U card

  o  Dr. Neuhaus Niccy PnP/PCI

  o  Siemens I-Surf 1.x (with ISAR =< try type 29)

  o  Siemens I-Surf 2.x (with IPAC => try type 12 asuscom)

  o  Trust PCI (only the old one with Siemens chip; the one called
     'Wisecom' in NL does not work)

  o  ACER P10

  o  HSR Saphir

  o  Berkom Telekom A4T

  o  Scitel Quadro

  o  Gazel ISDN cards

  o  HFC-PCI based cards

  o  PCI/Winbond W6692 based cards

  o  HFC-S+, HFC-SP/PCMCIA cards

  o  HFC-USB ISDN TAs

  o  ST5481 based USB ISDN adapters, e.g. BeWan Gazel 128 USB

     Note:

  o  AVM A1+ is not supported

  o  PCF, PCF-Pro: up to now, only the ISDN part is supported

  o  PCC-8: not tested yet

  o  Eicon Diva U interface not tested

  o  Some cards do not work when compiled into the kernel, only when
     loaded as modules.

  o  Asuscom card: please note that the ISA version is a different type
     (12) then the PCI version (35 for HFC chip or 36 for Winbond chip)!

  o  To distinguish between HFC-PCI and PCI/Winbond, have a look at the
     output of cat /proc/pci. You have HFC-PCI if you have a line saying
     "Master capable" for your card.

  o  DataFire Micro V PCI = HFC-based card (type 35)

  o  Xircom Cardbus Eth10/100+ (PCMCIA) is not supported by isdn4linux,
     but you can use it like an active external ISDN terminal adapter
     (requires the xircom and serial driver).

  o  Gazel 128 USB from BeWAN Systems is supported as hisax_st5481
     module.  For configuration hints have a look at:
     <http://www.posern.org/my-prjs/isdn/>.

  In Germany: every ISDN card which German Telekom distributed in the
  past is supported (the same is NOT true for the PBX they distributed).

  The following cards are definitely not supported and will probably
  never be supported, since the manufacturers have not released the
  specifications for their very proprietary hardware/protocols:

  o  Fritz!X

  o  Eumex 404

  As for the Eumex 404, there is an unofficial binary driver for
  isdn4linux with Suse 6.3, which may or may not help you. Use it at
  your own risk: <http://home.t-online.de/home/MetalMilitia/eumex.htm>


  5.2.  hardware_activepassive: What is the difference between an active
  and a passive ISDN card?

  An active ISDN card handles most of the ISDN connection protocols
  (dialing, accepting calls, etc.) itself. The card includes a kind of
  minicomputer with its own software (firmware). With a passive card,
  the computer in which the card is installed has to perform these
  functions.

  In principle, both types are supported by isdn4linux. However, since
  active cards have non-standard interfaces, a driver can only be made
  when the producer publishes the specifications for the interface.
  Also, the card's firmware needs to be made freely available. In
  contrast, many passive cards share the same chipset. Therefore many
  passive cards can be supported once a driver supports this one
  chipset.

  These active cards are currently supported by an individual driver:

  o  AVM B1

  o  AVM C4

  o  Eicon DIVA Server BRI PCI

  o  Eicon DIVA Server 4BRI

  o  IBM Active 2000 ISDN card


  o  ICN

  o  PCBIT-D


  5.3.  hardware_recommend: Which card is recommended by the developers?

  The developers suggest using ELSA cards. ELSA has made their
  specifications available to the developers, and provided a lot of
  support, resulting in an excellent driver. Also, their cards are
  certified for usage in Germany, see question ``country_certified''.

  If you want to buy an active card, then the developers would recommend
  the PCI Server from Eicon. The reason is that it can fax on both
  channels with AT class 2 commands, and includes a V.90 modem.  The AVM
  B1 works also very well, and is likewise recommended. Old versions (up
  to 3.0) could receive faxes only on one channel, but since AVM B1 PCI
  V4 all channels can be used simulateously for sending and receiving
  faxes.  See also question ``hardware_avmb1'' for more details about
  this card.  The Hypercope cards have also been reported to work very
  well, servicing all available channels for faxing. However, they
  require a hardware update for faxing and their linux driver is fairly
  new. See also question ``hardware_hypercope'' for more details about
  this card.

  If faxing is important for you, but you don't want to spent the money
  for an active card, then a card with ISAR chipset may work well for
  you, e.g.  Sedlbauer Speedfax+ (in Germany you may be able to buy it
  at Conrads).

  And if you want to buy a USB terminal adapter, then the Gazel 128 USB
  from BeWAN Systems  <http://www.bewan.com> has been reported to work
  fine with the hisax_st5481 module.


  5.4.  hardware_external: Does isdn4linux support external terminal
  adapters?

  Generally not, but it doesn't need to. Terminal adapters are designed
  to behave either like a modem or like a network card. Linux already
  supports both modems and network cards without isdn4linux - so no
  special ISDN driver is necessary (which usually greatly simplifies the
  configuration).  For example, have a look at the dialout program
  wvdial.

  However, there is (at least) one exception. The Gazel 128 USB from
  BeWAN System in France  <http://www.bewan.com> has been reported to
  work fine with the hisax_st5481 module. For configuration hints have a
  look at:  <http://www.posern.org/my-prjs/isdn/>.


  5.5.  hardware_cabeling: How should I wire my ISDN cables?

  For any details in this direction have a look at the excellent cable
  FAQ, which can be found at least in a German version at:
  <http://www.in-berlin.de/User/scorpio/faqkabel.html>.


  5.6.  hardware_irq: Why should I avoid IRQ 12 and 15 for my ISDN card?

  On many PCI boards, interrupt 12 is often used by a PS/2 mouse (even
  though you may not have any or the IRQ is not activated for it). It
  may be used even when you have no PS/2 port. Interrupt 15 is also
  often used by the second IDE bus (even when you are not using it or
  the IRQ is not activated for it).  Even though one thinks that some
  IRQs are available they are still somehow reserved by the BIOS. Good
  IRQs to try are always IRQ 5 and IRQ 9. Without mice or modems you
  could also try 4 and 3, which works even on very exotic boards.


  5.7.  hardware_irqsharing: Can the isdn4linux driver work with shared
  interrupts?

  Yes, the drivers have been written to work with shared interrupts.
  However, at least for the AVM Fritz!PCI card occasional problems have
  been reported for motherboards with a BIOS bug (DFI motherboards
  K6BV3+, P5BV3+ K6XV3).  Try to disable the BIOS option CPU to PCI
  WRITE Buffer in those cases as a workaround.


  5.8.  hardware_s2m: Which S2M cards are supported?

  At least these S2M cards have been reported to work:

  o  AVM T1

  o  Eicon S2M-ISA or DIVA Server PRI family (see
     <http://www.melware.de/>)


  5.9.  hardware_pcmcia: Which PCMCIA cards are supported?

  At least these PCMCIA cards have been reported to work:

  o  ELSA Microlink (NOT: ELSA Microlink/all)

  o  Sedlbauer

  o  AVM

  o  Teles PCMCIA (old hardware) - deprecated, since Teles often changes
     hardware, and does not support the developers (see question
     ``hardware_teles'').


  5.10.  hardware_smp: Can I run isdn4linux on my multi-CPU board?

  Yes, this works nicely. However, make sure to compile the kernel and
  all modules with option SMP. If you run into problems when both CPUs
  try to handle the same IRQ, try to boot with noapic.


  5.11.  hardware_64bit: Can I run isdn4linux on 64bit hardware with
  Linux?

  In principle yes, however your hardware choice is currently limited to
  active cards and external devices. Most desired are external devices
  using standard interfaces (network, USB) which do not require
  isdn4linux at all.  The drivers for passive cards are currently not
  working under 64bit.  Obviously you can also not make use of binary
  drivers, unless you find a binary compiled for 64bit.

  One external USB device based on the HFC-S chipset reported to work
  with isdn4linux is the Sitecom DC 104 with serial number greater than
  SN 46000202 (olders are ST chipset based, they have the same box).
  Also "tiny USB TA" from Billion, and "surf mini usb" from Acer have
  been reported to work.



  5.12.  hardware_alpha: Can I run isdn4linux on a DEC Alpha with Linux?

  Yes, most cards should run with isdn4linux on a DEC Alpha. Many cards
  have been reported to work with the HiSax driver. Also the active ICN
  card has been reported to work.


  5.13.  hardware_sun: Can I run isdn4linux on a Sun workstation?

  Probably not. There are three options for (internal) isdn in the SUN
  enviroment:

  1. SBUS ISDN adapter: Old SUN-workstations used to have a SBUS
     interface for additional peripheral boards.  There exists an ISDN
     sbus board sold as "X1012". As no information is available for
     these boards, they are NOT supported!

  2. Built-in ISDN adapter: Sparc-Station-LX, Sparc-Station-10 and
     Sparc-Server-10 have a motherboard with build-in isdn-adapter.
     These machines were supported by HISAX (kernel 2.3.0) but the code
     has been left unsupported for very long (over nine months).  All
     kinds of ancient hisax definitions are still left in these drivers.
     Much work is to be done to get it properly working again.  Note
     from the original developer, not to expect too much: the dbri chip
     is not capable of buffering (irq for each byte) and raw-hdlc has to
     be done in software instead of hardware...  The author of dbri.c
     has stopped active work on it, but made a copy of the DBRI data
     sheet available at: <http://www.freesoft.org/Linux/DBRI> for anyone
     who wants to fix the remaining glitches (status as of Jan 10,
     2000). Please be aware that the code of the latest developments can
     not be compiled for 32 bit machines like all sun-4m machines.

  3. PCI ISDN adapter: Modern SUN-workstations and servers have a
     different busstructure nowadays. The ULTRA series uses the PCI-bus.
     Allthough some pc boards seem to be working in a SUN, there are NO
     reports (yet) of properly functioning ISDN-PCI-boards in the SUN
     environment. Please write me if anyone ever succeeds.



  5.14.  hardware_ppc: Can I run isdn4linux on a PowerPC with Linux?

  Yes, in theory most cards should work. However some Endian format
  issues remain due to the bugs. I heard that the AVMFritz!PCIv2 card
  may work well with the old isdn4linux drivers (even with asterisk via
  chan_modem_i4l).  Also the Eicon Diva Server cards should work. You
  are welcome to report any bugs and fixes to the mailing list.

  In any case, you may also get a terminal adapter (= external ISDN
  "modem").  Since then you don't need isdn4linux (see question
  ``hardware_external''), this is not covered here any further.


  5.15.  hardware_maxcards: How many ISDN cards can I put into my com-
  puter?

  It depends on the availability of slots, interrupts/IO addresses in
  your computer as well as the possibilities of the ISDN card. Most
  passive cards are limited by the supported IO addresses (e.g.: Teles
  16.x: only 3 addresses are legally possible: 0xf80, 0xd80, 0xe80), and
  the total usage of interrupts (every card needs one).

  To use more cards, the ICN card may be your choice. It has no
  interrupts, a more flexible port configuration and the driver places
  the shared memory area of all ICN cards at the same address. The card
  memory is shown only as needed. Therefore, one can use as many cards
  are there are slots.

  If you really need a lot of ports, then eventuelly, a S2M card might
  be interesting for you, see question ``hardware_s2m''.

  See question ``config_manycards'' about the specialities for the
  configuration of more than one card.


  5.16.  hardware_hfc: What is special about card with an HFC chip?

  Cards with an HFC-PCI chip allow some specialities that are not
  possible with other ISDN cards. So it is possible to run the card in
  NT mode (requires crossing the ISDN connection and change by software)
  - this means you can simulate to another ISDN card that your card is
  an NTBA. Since isdn4linux does not implement the level 3 protocol used
  by the exchange, you can only use this mode like a leased line.

  However, some special software named PBX4Linux has been written for
  this.  You may want to have a look at the German article in ct 9/2004
  on how to use PBX4Linux. You can also check the web site
   <http://isdn.jolly.de>.  You may especially be interested in the
  information about card support for the NT mode with mISDN at:
  <http://isdn.jolly.de/cards.html>.

  Another alternative for emulation of a PBX is Asterisk, to be found
  on:
   <http://www.asterisk.org>.

  Also, it is possible to give up one B-channel in exchange for reading
  the complete D-channel protocol, which is great for isdnlog. The later
  can also be done with a reversed card (see question
  ``isdnlog_reversedcard'') but with HFC chips this works much more
  reliably and cleanly. You can activate this special echo mode by
  calling:

  ______________________________________________________________________
  hisaxctrl <driver_name> 10 1
  hisaxctrl <driver_name> 12 1
  ______________________________________________________________________


  You can deactivate it by calling:

  ______________________________________________________________________
  hisaxctrl <driver_name> 12 0
  hisaxctrl <driver_name> 10 2
  ______________________________________________________________________


  Parameter 10 changes the number of available channels, parameter 12
  switches the echo mode.

  Cards with HFC chips may be difficult to run on older mainboards.
  Ensure with lspci -v that an IRQ has been assigned to the card (if not
  check the PnP bios settings). Verify that the card is located in a
  slot with busmaster DMA capabilities. Verify whether the kernel is
  compiled such that it will run on your CPU (newer distributions may
  not run on CPUs like 486 or Pentium; Suse provides the kernel 'k_i386'
  to run with older hardware).


  5.17.  hardware_elsa: What should I know about ISDN cards from ELSA?

  Generally, ELSA supports the ISDN4LINUX developers quite well with
  documentation on how to access their cards. Thus, these cards are well
  supported and very recommendable for use under ISDN4LINUX. Also, the
  ELSA Quickstep 1000 PCI (new name Microlink PCI) is one of the only
  brands of cards that are officially certified for use in Germany, and
  therefore in EC (see question ``country_certified'' for more
  information on certification).

  However, there is a speciality with some non-PCI-conformal mainboards
  and the ELSA Quickstep 1000pro-PCI. These mainboards set the IO
  address to incorrect values (they need to be on 0x100 boundaries, and
  in a higher area). This may create an error message like "You may have
  the wrong PCI bios" and hang the system. The best fix is a Bios
  upgrade. If this is not feasible, you can get the module pcitest from
  Karsten Keil keil@isdn4linux.de. It will initialize the card
  correctly, then exit with an intentional error (thus not occupying any
  memory).

  To interface from ELSA's RJ11 plug to an RJ45 cable, use the following
  cabling scheme:

            RJ11   -   RJ45
  pins      1234       12345678
  Cable     abcd       --abcd--



  Regarding the Elsa Microlink ISDN USB: contrary to previous
  announcements it does NOT works like a serial terminal adapter with
  the USB communication class driver. Currently, it is not supported by
  isdn4linux.


  5.18.  hardware_sedlbauer: What is special about the Sedlbauer card?

  The Sedlbauer card comes in several versions:

  o  Sedlbauer Speedwin

  o  Sedlbauer Speedfax

  o  Sedlbauer Speedfax PCI

  The Speedwin is a normal passive card with no specialities.

  The Speedfax has a very special hardware: it is a semiactive card
  based on the ISAR chipset which supports sending/receiving faxes and
  an analog modem up to 14400. It is special in that you use it with
  HiSax which normally works only for passive cards.  As all active card
  you have to load its firmware (in this case after loading HiSax) from
  the file ISAR.BIN, which is part of the isdn4k-utils.

  Please note that compression (V42bis, MNP) are not implemented in
  firmware, and therefore not supported when using the analog modem. The
  ideal init string for the card to allow modem dialin is AT%C0\N0.

  If for some fax senders receiving by Hylafax does not work, then try
  to set the following configuration parameter for Hylafax:

  ______________________________________________________________________
  Class1SwitchingDelay:  75
  ______________________________________________________________________



  The Sedlbauer Speedfax PCI is special in that it was produced just for
  Linux - there is no driver for it under Windows.

  5.19.  hardware_teles: What should I know about before buying an ISDN
  card from Teles?

  First the latest news: according to the German magazine ct 02/2001,
  Teles has closed down its business activities in the ISDN area.
  Therefore, this FAQ does not really apply any more. However, I'll keep
  this FAQ for now to document Teles' attitude towards their customers.
  The author has had personal experience with Teles since 1994.

  One of the most frequently asked questions for Teles cards: The Teles
  card 16.3c has a crippled FIFO, therefore it is required to use
  AT&B1024 when using the ttyI* devices (if the remote side still send
  packets with more than 1024 bytes it will not work - unfortunately
  many CAPIs use 2048 bytes as default).  The latest Teles PCI card
  needs the netjet driver, the teles driver will NOT work (that card
  identifies itself as 'TigerJet Tiger300' when doing a cat /proc/pci).

  Now some comments about Teles in general (these are the personal
  opinions of the author of this FAQ, please blame nobody else than me):

  Teles' business practices are very customer- and developer-unfriendly
  when compared to those of other companies. Naturally, the developers
  give priority to cards for which support is available, and where the
  specifications are freely available.

  So far, Teles has had a very unfriendly attitude towards the i4l
  developers. No support has ever been received from them, and they
  don't publish any information about how to access their card. The
  developers have invested a lot of private effort into getting this
  card to work from the beginning without receiving any support. The
  driver has been a complete private effort. Yet, Teles has bragged on
  their web site that their cards run under Linux, without giving proper
  credit.

  Even companies that buy Teles cards and resell them under their own
  name have not been able to improve the support. This has lead to the
  situation where a re-branding company (!) itself had to go through the
  effort of obtaining approval to legally use i4l in Germany on a Teles
  card.

  From a customer point of view, check out the prices for their hotline
  before you buy any hardware from them! The author of the FAQ refuses
  to use any hotline that charges 216,- DM per hour. Reports about
  quality and waiting time have not always been favorable.

  And this company did not even give away drivers for other operating
  systems, like Windows, for free for many years (I know about
  1995-2000).  Only since about April 2000 you can download the drivers
  over the Internet.  Before you had to dial up a very expensive number
  (0190) where you had to pay about DM 1,20 per minute in Germany to
  download the driver. Not that it's advisable to use Windows anyway,
  but just to let you know...

  Warning: Teles has often changed their cards without notice, while
  still using the same name. When you buy a Teles card, you may find out
  that your brand-new card can not be supported by i4l! (As has happened
  many times in the past...)

  The developers will try to support new Teles cards when information
  about how to access it becomes available, and when they have no other
  priorities. Of course you can always send a patch.



  5.20.  hardware_fritz: What should I know when configuring a Fritz!
  card (also known as: AVM A1, Teledat 150, BT Speedway)?

  The Fritz! card comes in different variations. Since the PCI card and
  the ISA/PNP card have the same type (27), hisax will assume an ISA/PNP
  card if you pass an io address, and a PCI card if you do NOT pass an
  io address.  Make sure to give the parameters properly.

  The newest Fritz! PCI card (v2.0) is now supported by a new driver,
  however it has not yet been tested thoroughly. The card can be
  identified by lspci returning 0e00 as the card id.

  If the interrupt for the card is shared with other devices and your
  card does not work, then there could be an issue with the motherboard.
  See question ``hardware_irqsharing'' for this.

  One very interesting thing: the Fritz! card was the first card for
  which a capi driver existed which can be configured to fax. See
  question ``feature_capi'' and
  <http://www.avm.de/ftp/cardware/fritzcrd/linux/index.htm> for more
  information on this. Usage of the capi driver is completely optional,
  you might as well stay with the standard driver if you do not need
  capi support.

  In total three drivers exist: the old Hisax driver (part of
  isdn4linux), the new mISDN driver, and the binary AVM driver. Only the
  last one is prepared for sending faxes.


  5.21.  hardware_avmb1: What is special about the AVM B1 card?

  This card supports many special features in its firmware and is very
  well supported by its Linux driver. It's currently one of the only
  ISDN cards that you can use to fax under ISDN4LINUX, or which supports
  the CAPI 2.0 interface. You can get the newest driver from:
  <ftp://ftp.in-berlin.de/pub/capi4linux/>.  To get the firmware
  download the two perl scripts from: <ftp://ftp.in-
  berlin.de/pub/capi4linux/firmware/> They will download and extract the
  firmware from tar files on the avm ftp server on:
  <ftp://ftp.avm.de/cardware/b1/linux/>.

  To use the AVM on a point-to-point connection ("Anlagenanschluss") add
  "DSS1 P2P" to the load command for the firmware, like:

  ______________________________________________________________________
  avmcapictrl load /usr/lib/isdn/b1.t4 0 DSS1 P2P
  ______________________________________________________________________



  There is also a mailing list for problems with the AVM B1 available.
  Visit  <https://mlists.in-berlin.de/mailman/listinfo/linux-avmb1> for
  more details about it.


  5.22.  hardware_hypercope: What is special about the Hypercope cards?

  These cards support several special features in their firmware. They
  are newly supported by a Linux driver. They are currently one of the
  only ISDN cards that support the CAPI 2.0 interface. Also, you can use
  them very well for faxing under ISDN4LINUX (after upgrade with a fax
  card - possible for HYSDN Ergo2 and HYSDN Metro4).

  More information on company and hardware is available on:
  <http://www.hypercope.de> Configuration is similar to that of an AVM
  B1.
  5.23.  hardware_icn: What is special about the ICN card?

  This was the first active card supported by isdn4linux. The
  manufacturer has always supported i4l developers (
  <http://www.think.de/>).  The ICN does not need any interrupt
  (polling), therefore a PC can be equipped with many of them without
  any interrupt conflicts. The newest firmware should be available at
   <ftp://ftp.think.de/pub/isdn4linux/icn/firmware/>.  Unfortunately,
  the ICN is not produced any more.


  5.24.  hardware_isurf: What should I know about the Siemens I-Surf
  cards?

  There are several interesting things.

  o  Two Versions: There are two different versions (version 1.0 and
     version 2.0) with a different chipset. Both work fine, however you
     have to set the type properly (29 for version 1.0, 12 for version
     2.0).

  o  The USB version is currently not supported, there is no driver
     available.

  o  PnP bug: Due to a bug in the pnp chip it is very important for the
     I-Surf 1.0 to have the following PEEK and POKE lines in your isapnp
     file to properly initialize the PnP register:

     ___________________________________________________________________
     (MEM 0 (BASE 0x0c8000) (MODE bu) (UPPER 0x0c8400))
     # (MEM 0 (BASE 0x0c8000) (MODE br) (UPPER 0x000400))
     (REG 0x31 (PEEK))
     (REG 0x31 (POKE 0))
     (REG 0x31 (PEEK))
     (ACT Y)
     ))
     ___________________________________________________________________



  o  Memory mapping: Since the I-Surf 1.0 uses memory mapping for the
     ISA bus, ensure that the used memory area is not shadowed or cached
     (see BIOS setup).

  o  Firmware loading: Before usage you have to load the firmware:

     ___________________________________________________________________
     hisaxctrl <id> 9 ISAR.BIN
     ___________________________________________________________________


  (You find the file ISAR.BIN in the isdn4k-utils or on the I-SURF cd.)

  o  Fax: The I-Surf 1.0 can be setup to send and receive faxes (see
     question ``feature_fax'' for details).


  5.25.  hardware_diva: What should I know about the Eicon Diva cards?

  In general, a dedicated driver exists which supports the active Eicon
  Diva cards very well. The Pro series are not supported by isdn4linux
  since it is a semiactive card with a DSP as a B-channel controller.
  There is no code available in isdn4linux to dynamically load DSP
  programs into the card. However, check Eicon's website; maybe by now
  they provide pre-compiled driver for their cards not supported by
  isdn4linux.
  5.26.  hardware_crossedcable1: If i4l uses one B-channel then the
  other one will be blocked (incoming as well as outgoing)...

  This behavior is typical for a cable with confused a/b wiring. Some NT
  from Quante had a wrong labeling. They caused exactly the mentioned
  behavior if the PBX was connected to the plug of the NT and the ISDN
  card to the pins of the NT. As soon as some device activates the bus
  the other one can no longer get through.


  5.27.  hardware_crossedcable2: How can I test whether a a/b cable pair
  has been crossed?

  This question assumes that you are connected by an internal bus that
  you installed, attached directly to the NT (without using an RJ45
  cable).

  The easiest way to test it is to buy a little cable tester (the author
  of this FAQ got one from Conrad Electronics in Germany for 29,- DM -
  just follow the simple instructions).

  Otherwise you have a bit more work. Switch line a1 and b1. If it
  doesn't work, put them back and switch a2 and b2. If it still doesn't
  work, try switching them both. As long as {a|b}1 and {a|b}2 are kept,
  nothing can break. If you want to be sure, before plugging it in
  measure between pins 4 and 5 and between Pins 2 and 6 on the socket;
  there should be no current, but between 3 and 4 and between 6 and 5
  should be 40 V, 6 and 3 positive.

  With the Western plug this works similar. 4 lines are used:

  | | | |
  | | | |
  1 2 3 4


  Then you can try to switch (1 with 4) or (2 with 3) or both. Never
  switch the outer with the inner lines - this would cross the RX and TX
  lines and nothing will work.

  Check the Cable FAQ for more details on which line should be connected
  how.

  If both devices are attached via RJ45, then one of the cables has been
  twisted. That usually happens if one of the RJ45 plugs has been
  attached upside-down (a1/b1 are inside, a2/b2 are outside, so the
  order of the sending/receiving pairs is maintained), then you just
  need a new plug and of course pliers for the RJ45, old plug off, and
  new plug (in the right direction) on.


  5.28.  hardware_pbx: i4l is connected to the internal bus of a PBX.
  Any problem?

  Many PBX run non-standard ISDN protocolls on their internal bus.

  In old versions (before end of August 2003) this could cause i4l to
  print warnings like "Unexpected discriminator 0xZZ" (where ZZ is a
  hexadecimal number) when it encounters unexpected frames (some old
  versions even crash). This can increase your message file by as much
  as 1 MB in 3 days. The PBX Ackermann Euracom 181 (discriminator 0xaa)
  as well as Ascom (discriminator 0x44/0x47) seem to be notorious for
  this. You can avoid the warning by adjusting the switch/case code for
  isdnlog in function processctrl(...) in processor.c and recompiling
  isdnlog.  Since August 2003 ignoring these unknown packages has become
  the default, therefore the recompile is not necessary any more.
  Please note that isdnlog will not be able to log any incoming data
  packages, since the PBX has to forward the packages. To see
  everything, you have to bypass the PBX.

  Please be aware, that the PBX may hang if the ISDN card does not
  respond to the PBX requests - bypass the PBX in such a case.

  Also, a PBX may run 1TR6 protocoll on the internal bus by default,
  rather than Euro ISDN. You have to configure i4l (or the PBX)
  accordingly, best is you try to configure both on the same or similar
  protocolls.

  Also the MSN may be different than you expect. Check several versions,
  no digit (then use 0, which i4l will require in such a case), one
  digit, or two digits, or the whole MSN. Best is you call some device
  (e.g. ISDN telephone) on the internal bus and check what i4l writes
  into the log file.

  When you can not dial out, the most common problem is that you have
  not set the MSN properly for outgoing calls, which causes the PBX to
  refuse your request.

  For dial in be aware that some PBX add a leading 0 to any incoming
  telephone number, so adjust your configuration for the secure option
  accordingly.

  Last, remember that you may have to configure your PBX to 'route'
  incoming calls onto the internal ISDN bus.

  If you have a point-to-point configuration ('Anlagenanschluss') then
  you cannot connect your card directly to the S0 bus in parallel to the
  PBX (otherwise nothing will work). You have to connect to an internal
  ISDN bus.  Your MSN is usually the extension at the end of your
  telefon number.

  If your PBX is the Ackermann Euracom, then you may also check out this
  German site for the configuration software maKs:
  <http://www.ganzfix.de>


  5.29.  hardware_telestrouble: The PNP tools done work with my Teles
  16.3 PNP card!

  It's probably not a Plug 'n Play card at all - even though Teles now
  prints PNP on all their card and packaging. The difference is easy to
  recognize: a real Teles PNP card no longer has the (tiny) Dip switches
  on the card to set the IO addresses.


  5.30.  hardware_elsacabletrouble: On my ELSA card, the LED for the
  loss of the TEI often blinks. My connections are also often dis-
  rupted...

  These blinking LEDS are often caused by a bad cable or a too long or
  unterminated SO bus.


  5.31.  hardware_elsairq: My ELSA Quickstep 1000 ISA card produces very
  many interrupts with the HiSax driver. Is this normal or a problem
  with the HiSax driver?

  This is normal. The ELSA Quickstep 1000 ISA card has a hardware timer
  on the card which can not be disabled by software. You have to modify
  the card hardware to get rid of it. Check with Karsten Keil for this:
  keil@isdn4linux.de

  6.  config: General information about Configuration

  6.1.  config_msn: How should I set up isdn4linux with my MSNs?

  See section ``msn''.


  6.2.  config_hardware: How should I configure my hardware? Is there
  something special I should know about my ISDN card?

  Have a look in section ``hardware''.


  6.3.  config_dialout: How should I configure dialout?

  See section ``dialout''.


  6.4.  config_dialin: How should I configure dialin?

  See section ``dialin''.


  6.5.  config_suse: I can not select my card in yast?

  If you have a SuSE distribution, and you can not find your card in
  yast, then select card generic and enter the exact parameters in the
  special case line, like: type=27 protocol=2 for Fritz!PCI and Euro
  ISDN. Get a newer kernel if the desired type is not yet supported.


  6.6.  config_pnp: How do I configure a PNP (Plug and Play) card?

  For PCI cards Plug and Play works automatically, they don't need any
  manual configuration if the correct card type is provided. ISA PNP
  cards will require some manual configuration:

  1. With "make menuconfig" (or "make config") set the following kernel
     options:

     o  ISDN = "M" (as module - otherwise PNP doesn't work!)

     o  HiSax = "M" (as module - otherwise PNP doesn't work!)

     o  16.3/PNP support

     o  EURO support

  2. Compile and install kernel and modules, depmod. (Reboot!)

  3. Read the configuration of the PNP card with:

     ___________________________________________________________________
     pnpdump -c > /etc/isapnp.conf
     ___________________________________________________________________



  4. Verify whether pnpdump has prepared the configuration file
     /etc/isapnp.conf properly:

     o  INT0 - the interrupt used by the card (Default for Teles 16.3
        PNP: 10).  Make sure that interrupt 3 and 4 are not used, since
        they are reserved for the serial interface (which,
        unfortunately, the serial driver may have forgotten to reserve).

     o  IO0, IO1 - the IO ports used by the card (Default for Teles 16.3
        PNP: 0x580 and 0x180) (Attention: these values must be 64-bit
        aligned (ending with 0, 4, 8, or c)! Early versions of the PNP
        cards may suggest incorrect values!)

     o  Comment removed in front of ACT Y!

  5. Activate the configuration with:

     ___________________________________________________________________
     isapnp /etc/isapnp.conf
     ___________________________________________________________________



  6. Now the HiSax module can be started for Euro-ISDN with:

     ___________________________________________________________________
     modprobe hisax io=4,2,INT,IO0,IO1
     ___________________________________________________________________


  (Replace INT, IO0, and IO1 with your values in isapnp.conf.)


  6.7.  config_startstop: How can I start and stop the ISDN configura-
  tion?

  There are several options:

  o  Reboot: rebooting your computer always works. If you compiled i4l
     into the kernel, then this is actually your only chance. The
     remaining options only work if you configure i4l using modules.

  o  Manual: Unload the modules used by i4l with rmmod, then reload them
     with modprobe.

  o  Runlevel: use telinit to switch to a runlevel which does not
     contain ISDN, then switch back to the original runlevel.

  o  Scripts: most distributions come with start/stop scripts.  For
     example, on a Suse 7.0 distribution, this will stop ISDN:

     ___________________________________________________________________
     rcroute stop
     rci4l stop
     rci4l_hardware stop
     ___________________________________________________________________


  This will restart ISDN:

  ______________________________________________________________________
  rci4l_hardware start
  rci4l start
  rcroute start
  ______________________________________________________________________



  6.8.  config_kerneld: Why shouldn't I use kerneld  to load the ISDN
  modules in the kernel as needed?

  kerneld does not work well with the ISDN modules, since the ISDN
  modules can not store their status, and could miss important messages
  on the D channel. Newer versions of i4l ensure that they won't be
  unloaded by kerneld, but you should not try to use kerneld with any
  version of i4l.


  6.9.  config_runlevel: How can I boot Linux sometimes with ISDN, and
  sometimes without?

  Yes, you can define two different run level for this (under SysVInit)
  in /etc/inittab. One run level includes the ISDN processes, where the
  other one does not.


  6.10.  config_manycards: How do I configure more than 1 ISDN card?

  There are some specialities for configuration of more than 1 card:

  o  You have to start a driver for every type of card you have, with
     the correct configuration arguments.

  o  To handle more than 1 card with the same driver (e.g. HiSax should
     handle an ELSA and an ASUS card), you have to pass the
     configuration arguments for all cards to this driver. Please note,
     that you'll have to use modules for more than two cards, to pass
     all arguments. As an example, you can load HiSax for two Sedlbauer
     cards with the following command:

     ___________________________________________________________________
     modprobe -v hisax protocol=2,2 type=28,28
     ___________________________________________________________________



  o  Driver ID: the HiSax driver uses 'HiSax' as the default for a
     driver id if you have only one card. For more cards you have to set
     the id explicitely, e.g. for two cards in the form of

     ___________________________________________________________________
     id="contr0%contr1"
     ___________________________________________________________________



  o  Dialin of many people at the same time: have a look at question
     ``dialin_manyparallel''.

  o  Dialout through several cards: have a look at question
     ``dialout_manycards''.


  6.11.  config_manychannels: How can I increase i4l's maximum number of
  channels?

  You can adjust the parameter ISDN_MAX_CHANNELS and the ISDN_MINOR*
  parameters in /usr/src/linux/include/linux/isdn.h and rebuild the isdn
  stuff.  It is unlikely you have more than 64 physical B channels
  available, therefore you probably want to leave ISDN_MINOR_B and
  ISDN_MINOR_BMAX as they are.

  Your bottleneck are probably the number of potential (logical) network
  connections (ipppX devices). The maximum number for this
  (ISDN_MAX_CHANNELS) is 127, since the minor devices start at 128 (see
  ISDN_MINOR_PPP) and have to end before 255 (ISDN_MINOR_STATUS).

  To further increase the maximum number of logical connections you
  either have the possibility to use an additional major (e.g. 44 - not
  used any more) - this requires some small changes to the driver and
  the installation of one ipppd instance per logical connection; or to
  use only one ipppd per physical B channel with external Radius
  authentication. In the first case you have to modify and recompile the
  driver, in the second case you have to modify and recompile ipppd
  (you'll find some preparations for this already in the source code).

  Don't forget to create the additional devices with makedev.sh (part of
  isdn4k-utils) or by hand.


  6.12.  config_gsmv110: How do I connect my PalmPilot via GSM over
  V.110 to my computer?

  A connection via GSM will first go to the GSM provider via a special
  air transmission protocol. To forwarding the data on to an analog or
  ISDN line, an adapter called IWF (interworking function) has to
  translate this into the analog or ISDN specific transmission protocol.
  Which analog or ISDN transmission protocol is being used depends on
  how the mobile phone requests its GSM connection.  An analog
  connection is not very attractive due to the lengthy modem handshaking
  on dialin. For ISDN, HDLC and X.75 are currently not supported by the
  IWF, so the choices are down to V.110 and V.120.  V.120 has better
  flow control and error correction, but currently isdn4linux only
  supports V.110.

  On the dialup server set up async PPP with a normal pppd on a ttyI*
  device (sync ppp will not work). Additionally to setting the msn, you
  have to set V.110 and the transmission rate to 9600 with AT&R9600
  (/usr/src/linux/Documentation/isdn/README gives more details on the
  V.110 bitrate adaption for this command).  Switch off autoanswer with
  ATS0=0 if you use mgetty.  pppd needs to be called with noccp and
  require-pap.

  On the GSM mobile phone side, request an ISDN V.110 connection with
  the command

  ______________________________________________________________________
  AT+CBST=71,0,1+CHSN=1,0,0,0
  ______________________________________________________________________


  For a Nokia 7110, you may have to use the undocumented command

  ______________________________________________________________________
  AT+CBST=75,0,1
  ______________________________________________________________________



  If the bearer capability is reported as "88 90 21 48 06 bb" by
  isdn4linux, then you have set it correctly (88 90 21 means V.110, 48
  means ASYNC 9.6kbit, 06 means flowcontrol RX/TX, bb means 8 bit 1 stop
  none parity).

  If the call is indicated with service indicator byte 2 = 0 and not
  accepted (happens with some wrongly configured PBX), then adjust with
  ATS19=0.

  A higher bandwidth of 19.2kbit (HSCSD) could be requested with the
  command

  ______________________________________________________________________
  AT+CBST=81,0,1+CHSN=3,0,0,0
  ______________________________________________________________________

  but you can not be sure that your GSM provider will really use this
  rate.  Configure your dialin server accordingly.

  For a mini-howto see:
  <http://www.oltom.com/Linux/Docs/GSM%20over%20V.110%20Mini-HOWTO.txt>



  6.13.  config_h323: How do I configure isdn4linux to act as a voice-
  over-ip gateway for H.323 clients?

  You have to install a gateway which handles the translation. Several
  versions exist which are all based on the OpenH323 and PWLib
  libraries.  The latest recommendation is to use isdngw at:
  <http://www.gnugk.org/h323-isdn-gw.html>. This is an updated version
  of the isdngw located at: <http://www.virtual-net.fr/h323/isdngw/>,
  which in turn is an updated version of the Linux H.323 - ISDN Gateway
  found on <http://www.telos.de/linux/H323/>.

  Please note that not all sound cards support full duplex audio.
  Depending on your hardware you may end up with uni-directional voice.


  6.14.  config_point2point: How do I configure a point-to-point connec-
  tion?

  First of all, the point-to-point connection will only work for one
  single device connected to it - therefore nothing else but your ISDN
  card may be attached to it. You can switch HiSax into point-to-point
  mode:

  ______________________________________________________________________
  hisaxctrl <driver_id> 7 1
  ______________________________________________________________________


  Additionally, you can use the "AT&Lxxx$dquot; command to configure the
  range of telephone numbers isdn4linux should be listening to on the
  ttyI* devices.

  If you really absolutely want to run your ISDN card for read-only
  purposes in parallel to your pbx on a point-to-point connection, then
  you have to disconnect the RX leads (pin 3 and 6 on western plug), so
  that the NTBA will not see the ISDN card. In this case configure HiSax
  normally, NOT in point-to-point mode.


  6.15.  config_links: What helpful links are there about and around
  isdn4linux?

  These are helpful links that are currently available on how to
  configure isdn4linux:

  o  English:  <http://www.wurtel.cistron.nl/i4l-howto-uk.html>

  o  Dutch:  <http://www.wurtel.cistron.nl/i4l-howto-nl.html>

  o  German:  <http://www.franken.de/users/klaus/>

  o  French:  <http://www.linux-france.org/article/connex/ISDN/> and
     <http://www.linux-france.org/prj/inetdoc/guides/rnis/>

  o  Suse Support database: <http://sdb.suse.de/sdb/en/html/index.html>;
     there is also an ISDN howto (isdn.html) and a ISDN quick-install
     guide (isdnquick.html).

  o  Tips to configure Suse (and about offline reading):
     <http://www.schlenn.de/isdn4linux/>

  o  Tips to configure Red Hat: <http://www.webideal.de/rh-isdn/>

  o  Tips to configure Debian with Fritz Card PCI and kernel 2.6 (in
     German): <http://www.plzk.de/archiv/files/docs/FritzCard.PCI.Linux-
     HOWTO.html>

  o  Tips to configure Mandrake:
     <http://www.mandrakeuser.org/connect/cisdn.html>

  o  Tips to configure Gentoo:
     <http://forums.gentoo.org/viewtopic.php?t=29991> <http://de.gentoo-
     wiki.com/ISDN>

  o  fli4l, a prepackaged Linux version to use an old PC as ISDN router:
     <http://www.fli4l.de> (great!)

  o  LR101 (a project which tries to create a hardware router based on
     Linux): <http://lr101.linux-it-solutions.de>

  o  Scripts and installation tips from several people:
      <http://www.rosat.mpe-garching.mpg.de/~web/ISDN.html>

  o  Documentation on abc extensions:
      <http://i4l.mediatronix.de/>

  o  Installation of CAPI4LINUX, CAPI4LINUX, and CAPI4Hylafax (in
     German):
      <http://ixi.thepenguin.de> or
      <http://capi4linux.thepenguin.de> or
      <http://www.thepenguin.de>

  o  Vbox development:
      <http://innominate.org/projects/vbox/index.php3>

  o  Michael Hipp's page (general informations):
      <http://www-ti.informatik.uni-tuebingen.de/~hippm/isdn.html>

  o  Chargeint tips:
      <http://www.auf-der-er.de/chargeint.html>

  o  Homepage of linecontrol (manage isdn dialing similar to kisdn):
      <http://linecontrol.sourceforge.net>

  o  (German) Homepage of ISDN Sniffer (read ISDN bus, e.g. via reversed
     card):  <http://krypt.cs.uni-sb.de/projects/isdnsniffer/>

  o  Homepage of Asterisk (Open Source Linux PBX):
      <http://www.asterisk.org>

  o  Homepage of ivcall (send and receive fax/voice calls):
      <http://0pointer.de/lennart/projects/ivcall/>

  o  Configuration software maKs for Ackermann Euracom (not isdn4linux
     related):
      <http://www.ganzfix.de>


  6.16.  config_misdn: How should I configure the new mISDN driver, and
  what is so special about it?

  The mISDN driver stands for modular ISDN. It is a complete rewrite of
  the old isdn drivers and now communicates via CAPI messages. The mISDN
  driver is retire the historical drivers once it is fully functional
  within the 2.6.x kernels. As a temporary work around the historical
  drivers have been ported into the early 2.6.x kernels to get isdn
  working, however, this will be fixed in later versions.

  To start mISDN, you have to load all the following modules:

  o  capi

  o  mISDN_core

  o  mISDN_l1

  o  mISDN_l2

  o  l3udss1

  o  mISDN_capi

  o  mISDN_isac (for isa card)

  o  Hardware specific driver (e.g. hfcpci, or avmfritz)

  Not all features are available. It is currently not planned to port
  1TR6 (the ancient ISDN protocoll in Germany) to the new driver.

  For more information on how to configure it have a look at the
  following website:  <http://rcum.uni-mb.si/~uvp00845b/>

  For a more general description on the mISDN driver and the future of
  isdn4linux you may also read the German article published in ct
  3/2004. An online version is available at:
  <http://www.heise.de/ct/04/03/182/>

  Please note that the current FAQ applies mainly to the old isdn4linux
  drivers.  mISDN may work differently than described in this FAQ.
  Please let me know about any amendmends for this FAQ.



  6.17.  config_kernel26: What has changed with the kernels 2.6.x?

  With the kernels 2.6.x the mISDN driver has been introduced (see
  question ``config_misdn''). It is planned that the mISDN drivers will
  replace the old isdn4linux drivers like HiSax, which have been ported
  to 2.6.x only since mISDN was not ready yet.

  Please note that the ported drivers have not been upgraded to make use
  of the new kernel features like devfs. You still have to create all
  the devices you need, either with makedev.sh (part of isdn4k-utils),
  or by hand. Some distributions will do that for you (e.g. Suse), for
  others you have to do this yourself (e.g. Mandrake 10).



  6.18.  config_asterisk: How can I install asterisk with mISDN?

  First you have to get mISDNuser and compile it. Then you have to
  compile chan_misdn (included with asterisk) so it works together with
  mISDNuser.  For this you have to modify the Makefile in
  asterisk/channels/misdn/ to configure the correct location of
  mISDNuser. A make in the same directory, followed by a 'make install'
  in the asterisk directory should be sufficient.

  The easiest way is to get the install script published at:
  <http://www.beronet.com/download/install-misdn.tar.gz>.

  7.  trouble: Troubleshooting

  7.1.  trouble_22memory: I can't start ISDN on my machine with kernel
  2.2.x. I get the error messages "init_module: Device or resource busy"
  and "isdn: Could not allocate device-struct.".

  This is a memory problem and means you don't have enough unfragmented
  memory. While 2.0.x kernels may work on low memory/slow hardware (the
  author's answering machine is a 386 and used to run with 4MB of RAM),
  you can run into the memory fragmentation problem even if you have as
  much as 32MB of RAM when running 2.2.x kernels. The problem has been
  eased since 2.2.14, when ISDN4LINUX's memory allocation has been
  changed to use vmalloc.

  You can try to reduce the memory requirements (see question
  ``trouble_littlememory''), compile ISDN4LINUX into the kernel, or
  start and then exit a large program to ease the memory fragmentation
  problems.


  7.2.  trouble_littlememory: How can I reduce isdn4linux's memory
  requirements?

  Try to do the following things:

  o  Stick with kernel 2.0.x if you have a 486 or lower.

  o  In /usr/src/linux/include/linux/isdn.h, change the line

     ___________________________________________________________________
     #ifdef CONFIG_COBALT_MICRO_SERVER
     ___________________________________________________________________


  into:

  ______________________________________________________________________
  #if 1
  ______________________________________________________________________


  and recompile kernel.

  o  Reduce ISDN_MAX_DRIVERS, ISDN_MAX_CHANNELS in include/linux/isdn.h,
     then recompile kernel.


  7.3.  trouble_debug: How do I get maximum debug output?

  Execute the following commands to get maximum debug output:

  ______________________________________________________________________
  hisaxctrl <id> 1 0x33ff
  hisaxctrl <id> 11 0xf4f
  killall isdnlog
  cat /dev/isdnctrl > /tmp/ilog
  ______________________________________________________________________


  Be careful: this will generate a lot of output!


  7.4.  trouble_strategy: My isdn4linux doesn't work! How do I best go
  about finding the problem?


  The following steps are recommended:

  1. Check everything is working when booting.  Are there unusual error
     messages in /var/log/messages?  Are all programs active that should
     be started at boot (check with ps, or fuser /dev/xxx)? HiSax won't
     start if something isn't right.  Check question ``trouble_boot''
     for what you can check.  The old Teles driver, on the other hand,
     will appear to start even if it is not working. See the questions
     under Troubleshooting Teles.

  2. Make sure you configured the ISDN driver either as modules, or you
     compiled them into the kernel - never both.

  3. Try calling your dialin number with a telephone. The number should
     be shown in /var/log/messages. Check for a line like this:

     ___________________________________________________________________
     Call from 0,1,2345 -> 6789
     ___________________________________________________________________


  This means that on channel 0 a call from 2345 with service indicator
  (SI) 1 (1 = voice; data would be 7) to MSN 6789 was received. Now at
  least you know that you have to configure your MSN to 6789 (or what-
  ever other number you find there), and that your isdn4linux kernel
  driver understand ISDN commands coming from your ISDN card properly.
  If instead of the number 2345 you find a 0, then your ISDN provider
  does not pass you the caller id.  If you don't find such a line: per-
  haps the driver was incorrectly started?!

  4. As a next step we'll try to get the telephone or fax to ring by
     dialing ourself using a ttyI device with minicom. First we have to
     change the service recognition with the ATS18=1 command to audio.
     Now you can get the telephone to ring by dialing ATDxxxxxx, where
     xxxxxx is your own MSN.

  5. Next we try to transmit data via ISDN. Open 2 different consoles as
     root, and on each run "minicom -s"... in the first set "Serial Port
     Setup Serial Device" to /dev/ttyI0, and the other to /dev/ttyI1.
     Then choose "Exit" and start the modem emulation with "ATZ" and
     "AT&Exxxxxx" (where xxxxxx is your own MSN without the area code).
     Then you can start. On the first console you can dial your own
     number with ATDxxxxxx. On the second console you should now see
     "CALLER NUMBER: xxxxxxx" and "RING". Accept the call on the second
     console with "ATA", and you should then see the message "CONNECT
     64000/X.75" on both consoles. You can then send characters to the
     other console by typing (to see the characters on your own console,
     turn on local echo).

  6. Next, try calling a known ISDN BBS. If you don't know of any, try
     Gernot (see "Are there sites that offer guest access where I can
     test my isdn4linux setup?"). If you have problems with the modem
     emulation, see "Troubleshooting Modem Emulation"

  7. Fifth, try configuring the network interface or ipppd. Experience
     shows that they cause beginners (and not only beginners!) the most
     problems.  To make things easier and you're happy with asyncPPP (to
     see what asyncPPP means, see the question "pppd, ipppd, syncPPP,
     asyncPPP - what is that? What should I use?"), you can use the
     normal pppd with modem emulation (i.e. /dev/ttyI*).

  8. Ensure that you set up your authentication configuration properly
     (see questions in section ``pap''.

     Otherwise, it is highly recommended that use an example script form
     the HowTo (see the question "Where can I find scripts and other
     information on configuring i4l?"). For testing you can try your own
     provider or of the guest accounts (see "Are there sites that offer
     guest access where I can test my isdn4linux setup?").  The latter
     have the advantage of being able to see the log files as well as a
     stable, working configuration. For example, if accessing via ipppd
     doesn't work, you can log in via modem or modem emulation to find
     out what happened on the other side. Not all providers are so
     cooperative.... :-)


  7.5.  trouble_boot: How can I tell whether my ISDN card has been cor-
  rectly recognized?


  1. Check for error messages in the boot messages (you can review them
     at any time with the command dmesg.

  2. For the HiSax driver: During booting a message kernel: HSCX version
     A:5 B:5 and kernel: channels 2 should appear. A:4 B:4 is also okay.
     Other values (in particular A:??? B:???) mean the card is not
     recognized correctly.  HiSax is only loaded if the hardware can be
     found and the appropriate interrupts can be generated. This means
     the card is installed correctly in the computer, and there are no
     hardware conflicts. It does not mean that everything will work
     (e.g. twisted cables, broken cables, terminators).

  3. Check that your card got an interrupt assigned, e.g. with

     ___________________________________________________________________
     lspci -v
     ___________________________________________________________________


  A common problem is that your BIOS did not assign an interrupt to your
  card. HiSax will then complain with "No IRQ for PCI card found".  To
  fix, set the BIOS option "PnP OS" to NO.

  4. Check that the interrupts are registered correctly. Check with

     ___________________________________________________________________
     cat /proc/interrupts
     ___________________________________________________________________


  The following entry indicates that the card is configured on interrupt
  11, and so far has received 3 interrupts:

  11:        3 + hisax


  When you call yourself, the number of received interrupts should
  increase.

  5. Check the io ports with

     ___________________________________________________________________
     cat /proc/ioports
     ___________________________________________________________________



  7.6.  trouble_isdncause: I get an error message like "cause: E1234"
  (or similar)?


  Just have a look at man isdn_cause to find out what the problem is.
  For the very popular cause "E001B" see question ``trouble_e001b''.


  7.7.  trouble_e001b: I get an error message with "cause: E001B"?

  This is a very popular error and means (see man isdn_cause): euro ISDN
  (E), location user (00), and out of order (1b).  Taken together means
  that the driver either can't get a layer 1 connect (cable problem,
  hardware error, hidden hardware conflict - see section ``hardware''),
  or it can't get a layer 2 connect (wrong configuration: no Euro ISDN,
  no automatic TEI supported, point-to-point BRI instead of multi-device
  - see section ``config'').


  7.8.  trouble_noprotocol: upon startup of HiSax I get the message
  "Warning - no protocol specified"?

  This means that you did not specify which D-channel protocol you want
  to use with HiSax. In most cases this is wrong, and you have to
  specify that you want to use the Euro Protocol ISDN DSS1. Only if you
  have a leased line you don't need to specify any D-channel protocol.


  7.9.  trouble_euronotsupported: upon startup of HiSax I get the error
  "kernel hisax: protocol euro not supported"?

  This means that you did not select the Euro Protocol ISDN DSS1 option
  when compiling your kernel. You have to switch this on and recompile
  your kernel to be able to use it.


  7.10.  trouble_unknownprimitive: upon connection attempt I get the
  error "lldata_handler unknown primitive"?

  This means that the link level protocols do not match (e.g. you tried
  to connect with X.75, whereas your provider answers with HDLC). Check
  and fix your connection parameters with:

  ______________________________________________________________________
  isdnctrl l2_prot <interface> <protocol>
  ______________________________________________________________________



  7.11.  trouble_notelrings: Neither my telephone nor my fax machine
  ring when I call them with isdn4linux?

  Isdn4linux sets "digital data" as it's own service when it calls out.
  The switching station does in fact route such calls to analog devices
  like a telephone or a fax machine. However, since the machine is
  analog, it will only answer analog call, and ignore the digital data
  call.


  7.12.  trouble_guestaccess: Are there sites that offer guest access
  where I can test my isdn4linux setup?

  The following information is quite old. Please tell me if you find out
  that the guest sites are not available any more:

  The following sites offer guest access for modem emulation or IP:

  o  Eberhard Moenkeberg emoenke@gwdg.de:

     o  Welcome to Linux at eberhard.moenkeberg.de (LAN, 192.168.99.1).
        Under ++49-551-7704103, ISDN NetCalls (HDLC-trans-rawip) for
        192.168.99.1 get accepted. You should come as 192.168.*.*
        because sometimes my "default" route is not your way.  /ftp is
        exported for NFS; try "showmount -e".  You can login as "guest"
        without password.  FTP as "gast" with password "gast" avoids the
        restricted shell.

     o  Under ++49-551-7704102, a 28800 bps modem and a Creatix ISDN
        card (HDLC only, not X.75) are listening for logins.

     o  With the net setup from
         <ftp://ftp.gwdg.de/pub/linux/isdn/isdn4linux-gwdg/rc.isdn-
        Beispiel> you can test NetCall at 551-7704103 (works as is
        within Germany, from outside Germany you just have to change the
        number).


  o  Gernot Zander hifi@scorpio.in-berlin.de:

       There's a "gast" at +49 30 67 19 81 01 (X.75, mgetty).
       There's the stones-html-page with pics in postscript to test
       downloading. Whoever needs a target to call can use it. At
       ...81 03 there's a getty with HDLC. As guest you enter a
       kind of BBS and can read some news.



  7.13.  trouble_unload: I can't unload my ISDN modules ("isdn: Device
  or resource busy"), even so I closed all ISDN applications?

  In this case "fuser -v /dev/isdn* /dev/ippp* /dev/cui* /dev/ttyI*" is
  very helpful. This helpful program shows, which processes are using
  those devices.

  o  Is some program still using an ISDN device?

  o  Did you remove all getty's? (They may have restarted automatically)

  o  Are isdnlog, imon, iprofd, etc., still running?

  o  Maybe there is still a route on your net interface and it's not yet
     deleted with "route del xxx"?

  o  Maybe the net interface wasn't put down. This can easily happen
     when killing ipppd. It does not react to signal 15 and has to be
     killed with "kill -9 ipppd pid". Then the net interface is left
     "up".

     Sporadic errors of this type can be fixed by inserting sleep
     commands between the unloading commands.  As a very, very last
     resort, there are two secret telesctrl commands to adjust the
     module counter:

     ___________________________________________________________________
     telesctrl id 3 1  --- dec module_count
     telesctrl id 4 1  --- inc module_count
     ___________________________________________________________________


  Please use with appropriate caution and on your own risk!



  7.14.  trouble_tcpdump: Why does my tcpdump not work for ip packets
  going over ISDN ("truncated ip" or so)? How can I get a tcpdump
  patched for ISDN?

  The reason is that tcpdump does not always understand the special
  encapsulations that are possible with isdn4linux, especially syncppp.
  To change this, you need to patch tcpdump.

  Michael Stiller michael@toyland.ping.de wrote on 23 Oct 1996:

  Tip for ftp:

   <ftp://ftp.gwdg.de/pub/misc/isdn/linux/isdn4linux-gwdg>

  There is the patch: "tcpdump-3.0.4-1-isdn.dif.gz"

  and the rest is at:

  /pub/linux/mirrors/funet/PEOPLE/Linus/net-
  source/tools/tcpdump-3.0.4-1.tar.gz

  You might need to hack some, depending on the name of your ISDN
  interface (mine is bri0). By default, it recognizes only isdn* and
  isdnY* as interface names.

  Henning Schmiedehausen henning@pong.iconsult.com further wrote on 30
  Oct 1996:

       After finding the patch from Eberhard Moenkeberg at
       ftp.gwdg.de cannot dump cisco HDLC, I made my own patch for
       tcpdump-3.0.4 that asks the interface which encapsulation it
       used and sets itself accordingly. The patch is against a
       tcpdump-3.0.4-1.tar.gz distribution, for example at


   <ftp://ftp.funet.fi/pub/Linux/PEOPLE/Linus/tools>

       This patch recognizes rawIP, ISDN-IP and CISCO-HDLC and can
       dump these packets.


  (The patch was attached to the message  - it should be easy to find in
  the mailing list archive - Ed.)

  Sascha Ottolski sascha@alzhimer.isdn.cs.tu-berlin.de gave the
  following tip on 5 Nov 1996:

       This is a isdn4k-utils-2.0/tcpdump-3.0.3-isdn.diff ! It
       work, if one makes some changes: In the file tcp-
       dump-3.0.3-isdn/libpcap-0.0/pcap-linux.c after patching you
       find the following: else if (strncmp("ppp", device, 3) == 0)
       Either you name your ppp devices pppX instead of ipppX, or
       change this line, e.g.  else if (strncmp("ippp", device, 4)
       == 0) ^^^^          ^^ Then tcpdump will also recognize
       syncPPP. At least it does for me.



  7.15.  trouble_locatecrash: My isdn driver crashes my machine! Since
  I've configured it as a module, the addresses change each time it's
  loaded. How can I find out where the driver is crashing?

  The driver should be loaded with the command "insmod -m". The output
  has to be transformed somewhat to be a form similar to System.map. You
  can do it like this:

  ______________________________________________________________________
  insmod -m isdn.o | sort | sed -e 's/   / T /g' |
                     egrep '.* T (a-z,A-Z,_)+'  /etc/isdn/isdn.map
  cat /System.map /etc/isdn/isdn.map  /iSystem.map
  ______________________________________________________________________


  (The line ending with "|" has to have the following text on the same
  line!) iSystem.map should then be used instead of System.map for find-
  ing the error.


  7.16.  trouble_lotsdebug: My hard disk becomes very active when
  isdn4linux run. How can I turn this off?

  Check whether the reason for the hard disk activity is caused by the
  amount of messages written into the logfile. If this is the case, you
  can reduce the output by:

  ______________________________________________________________________
  isdnctrl verbose 0
  ______________________________________________________________________


  and/or by removing the "debug" option for ipppd.


  7.17.  trouble_oldhardware: Maybe my hardware is too slow?

  Actually, properly configured, isdn4linux will on much smaller
  machines, than you might expect (still running an elder version on my
  386-25, which used to have only 4MB RAM). However, newer
  isdn4linux/kernel versions need more memory, and may require some
  tweaking before they run on very old hardware.  Have a look at
  question ``trouble_outofbuffers'' when running out of buffers.  See
  question ``trouble_littlememory'' on how to reduce the amount of
  memory needed.


  7.18.  trouble_outofbuffers: I get messages like "HSCX RME out of
  buffers", "HSCX RFP out of buffers", "HSCX B EXIR 10" in the syslog?

  These errors happen when i4l is not able to process its buffers fast
  enough. They are often caused by bad sound cards or their drivers when
  they disable the interrupts too long! It may also happen on old
  hardware (happened to the author of this FAQ when using vbox on an old
  386-25 with only 4MB RAM). You may be able to work around it by
  increasing the number and size of the buffers. Check the source code
  header files for definitions like:

  ______________________________________________________________________
  #define HSCX_RBUF_ORDER 1
  #define HSCX_RBUF_BPPS 2
  #define HSCX_RBUF_MAXPAGES 3
  ______________________________________________________________________


  The first two influence the size, the last one the maximum number of
  buffers.


  7.19.  trouble_noresetinit: After a soft reset, my card does not ini-
  tialize correctly.

  After you stopped your system with the reboot command or with Ctrl-
  Alt-Del, press the reset button (=hard reset). Sometimes the card
  needs to receive a hardware signal to reinitialize properly.



  7.20.  trouble_noisdnctrl: When attempting to use isdnctrl, I get the
  error "/dev/isdnctrl: No such file or directory"?

  First check whether there is a device /dev/isdnctrl0. If there is,
  just create a symbolic link by executing

  ______________________________________________________________________
  ln -s /dev/isdnctrl0 /dev/isdnctrl
  ______________________________________________________________________


  If the device is not there, run the script scripts/makedev.sh, which
  is part of the isdn4k-utils.



  7.21.  trouble_noisdnctrl2: When attempting to use isdnctrl, I get the
  error "/dev/isdnctrl: No such device"?

  In contrast to "/dev/isdnctrl: No such file or directory" the message
  "/dev/isdnctrl: No such device" indicates that the device
  /dev/isdnctrl exists, but no ISDN device driver is available.  To fix,
  load the ISDN modules (verify with "cat /proc/modules" that they are
  loaded) or compile the ISDN drivers into the kernel.



  7.22.  trouble_xosview: xosview doesn't show any network activity
  since installing i4l.

  Peter Hettkamp Peter.Hettkamp@kassel.netsurf.de wrote:

       xosview reacts, at least for me with version 1.4, to the IP
       accounting in the kernel. So, configure, if necessary build
       a new kernel, then couple with: ipfwadm -A -a -S your-ip-
       address-here -D 0.0.0.0/0 ipfwadm -A -a -D your-ip-address-
       here -S 0.0.0.0/0 (I don't know who it works with variable
       IP addresses. I have a fixed address.)



  7.23.  trouble_unknownhost: When I for example from a W95 box call up
  a page with Netscape, I only get the answer "unknown host".

  What is entered on the "Win95 box" for the name server? As long as the
  router has no name server of its own, then the provider's name server
  of course has to be entered on all computers on the LAN.


  7.24.  trouble_noroute: Addresses are now found, but now I get "no
  route to host".

  Please check:

  o  Is the Linux computer entered as the gateway? (Some 'operating
     systems' have to be restarted before changes to the networking take
     effect)?

  o  Does the router have a default route to the prepared interface to
     the provide (e.g. ippp0 with syncPPP or sl0 for diald (even when
     the real connection is over ppp0, diald uses a slip interface as a
     "doorknob")
  o  Does the provider require the use of proxies? Then the addresses of
     the proxies have to the entered in the appropriate clients on the
     LAN computers

  o  Maybe your route was removed when using syncppp? Check the
     questions ``syncppp_noroute'' and ``syncppp_nodefaultroute''.


  7.25.  trouble_nolocalnet: After booting, my local network can no
  longer be reached. I use the network interface ippp0 with ifconfig
  0.0.0.0; the default route points to ippp0.

  Wolfgang Barth wrote on 5 Jan 1997:

       I've noticed that after the first connection via ippp0 that
       the local network can again be reached. Then the address
       0.0.0.0 is no longer listed in ifconfig for ippp0, but
       instead the address assigned from the pool by the PPP part-
       ner.  This was already discussed in de.comp.os.linux.net-
       working, along this possible solution: Simply set ippp0 to a
       dummy IP number from the pool. Then the local network will
       have problems after booting, even with the default route,
       and the IP number in ifconfig will be overwritten anyway.



  7.26.  trouble_unauthorizedcodechange: When HiSax starts, I get the
  error messages 'Approval certification failed, unauthorized source
  code changes'?

  Since the certification of the HiSax driver is only valid for
  unchanged source code, the source code is protected by a checksum.
  When you get this message, then either you have changed the source
  code yourself, or the author did not update the checksum when changing
  the source code (reason could be that the complete certification tests
  have not yet been run on the changed code).


  7.27.  trouble_crcerror: How can I see the number of packets for HiSax
  with invalid CRC?

  With HiSax you can view the accumulated number of hardware CRC errors
  with:

  ______________________________________________________________________
  hisaxctrl <id> 0 0
  ______________________________________________________________________


  and reset them with:

  ______________________________________________________________________
  hisaxctrl <id> 0 99
  ______________________________________________________________________


  It is ok if you have the occasional CRC error, but if you see a lot of
  errors then check your cable termination & connectivity.



  7.28.  trouble_amproglibtool: When compiling isdn4k-utils I get the
  error 'AM_PROG_LIBTOOL not found'?

  You have to regenerate the files from automake/autoconf with your
  version of automake/autoconf.  You can do it with the following shell
  script (assuming you stored the source code for the isdn4k-utils under
  /isdn/isdn4k-util):

  ______________________________________________________________________
  cd ~/isdn/isdn4k-utils
  for i in capi20 capiinfo capifax capiinit rcapid ; do
   cd $i
   rm -f lt*
   aclocal
   libtoolize --force --automake --copy
   automake --add-missing --copy
   autoconf
   cd ..
  done
  for i in eicon isdnlog ipppd ; do
   cd $i
   autoconf
   cd ..
  done
  ______________________________________________________________________



  7.29.  trouble_hisaxparams: HiSax does not work - how can I set the
  HiSax parameters for newer Linux kernels?

  Unfortunately the udev/hotplug mechanism of current kernels (written
  in November 2005) loads hisax without the needed parameters. To check
  whether this is the issue of missing parameters unload the hisax
  module with rmmod:

  ______________________________________________________________________
  rmmod hisax
  ______________________________________________________________________


  then insert the kernel module with the correct parameters again, e.g.:

  ______________________________________________________________________
  modprobe -v hisax type=35 protocol=2
  ______________________________________________________________________


  In case this solves the issue, you can permanently fix it by providing
  the needed parameters to the module loader, e.g. in /etc/mod-
  probe.d/hisax on a Suse distribution.



  8.  msn: Configuration/MSNs

  8.1.  msn_my1: What is my MSN? What if I don't have any?

  Your telephone company will tell you your MSN. It is your own
  telephone number. Please note that you have to provide i4l with at
  least one MSN. If you don't have any you can use `0', which is assumed
  if no MSN is transmitted from your telephone company. Check section
  ``countries'', together with the following questions, on how to
  configure your MSN(s).



  8.2.  msn_my2: How can I find out how my telephone number is transmit-
  ted to the calling party?

  The transmitted MSN can simply be determined by calling yourself (for
  example by telephone). In the log files you will find the entry that
  looks like: "isdn_tty: call from XXX - YYY ignored" (in order for this
  to work, you must of course already have the ISDN drivers in your
  kernel and active).


  8.3.  msn_config: How do I configure my MSN?

  If your telephone number were 56789, then it would be configured as
  follows:

  o  Modem emulation: "AT&e56789"

  o  Network interfaces: "isdnctrl msn interface 56789"

  o  For test calls to yourself add the area code (e.g. 01234):

     ___________________________________________________________________
     "isdnctrl addphone interface in 123456789" (without leading zero)
     "isdnctrl addphone interface out 0123456789" (with leading zero)
     ___________________________________________________________________



  You may find national differences here (check section ``countries'').



  8.4.  msn_max: How many MSNs as a maximum can I use for an isdn card?

  For outgoing calls, at maximum one MSN can be used. Only incoming
  calls may be configured to allow multiple MSNs.

  For ttyI* devices, at a maximum you can listen to EVERY incoming MSN
  by using the * as a wildcard:

  ______________________________________________________________________
  at&l*
  ______________________________________________________________________



  When you have a point-to-point connection you should rather specify
  the length of your number area with as many times "?" as you have
  digits, otherwise your number may be accepted too early on overlapping
  receiving. I.e. for 3 digits use:

  ______________________________________________________________________
  at&l???
  ______________________________________________________________________



  For network devices, you can also use a '*' as a wildcard at the end
  of the number for incoming calls (e.g. isdnctrl msn interface 123*).
  However, this will create problems for outgoing calls. To handle such
  a situation properly, please use the isdnctrl mapping feature (see
  question ``dialout_manycards'').



  8.5.  msn_mindialin: How can I minimize usage of MSNs for digital data
  dialin?

  i4l gives priority to net interfaces. Therefore, you can get away with
  only one MSN when you set it up like this:

  1. Set up net interfaces (sync ppp, rawip) for all users that will
     want to use them (ipppd or rawip), with their incoming phone number
     (precondition is that it is transmitted).

  2. Set up ttyI* for all other users (X.75, async ppp).

  3. Set option `secure on'.

     i4l gives priority to net interfaces. `secure on' ensures that only
     users that have been set up will be connected to a net interface.
     Users that want to choose between both will have to use different
     outgoing MSNs to call you.


  8.6.  msn_onlyone: How can I use one MSN for everything?


  In Germany, this is not much of an issue any more since you can get 10
  MSN for free with Deutsche Telekom ( <http://www.dtag.de/english/>).
  Other phone providers may offer less MSN for free. In general, you can
  get at least 3 MSN. However, minimizing MSN usage may still be very
  interesting for other countries or if you have a large demand for
  numbers. On a normal ISDN bus with MSNs, 10 MSN per bus are the
  maximum. To get more numbers, your only alternative would be to get a
  usually more expensive point-to-point ISDN connection.

  Digital data dialin can easily be distinguished from voice/analog
  modem dialin by the 'Service Recognition' code ("digital, data").

  For the differentiation between net interfaces (ipppd, rawip) and
  ttyI* (X.75) see last question.

  To get voice/analog modem to work in parallel, use mgetty for the
  analog modem. Mgetty can handle analog data calls, faxes, and even
  voice calls as answering machine if the modem supports it. Configure
  it for 10 rings. If you take the phone and hear a fax or modem, send
  mgetty a USR1 signal (kill -USR1 mgetty-pid). If your phone socket is
  correctly wired, the modem will take over the connection, cutting off
  the phone. If you have an ISDN PBX then you can forward the call to a
  different analog port when you picked up a fax/modem call.

  If your analog modem can not handle voice calls, then you have to
  choose since incoming voice calls can not be distinguished from analog
  fax/data calls. Use either VBOX to take your voice calls as an
  answering machine. Or forget about voice calls and set up your modem
  to handle only faxes and/or analog data calls.


  8.7.  msn_buendel: Can I have several NTBAs, all with the same MSN?

  Yes, but you need the cooperation of your telecommunication company.
  They can set up several BRIs in Point-to-point mode that have the same
  MSN. In Germany it is called a bundled line (`Buendelanschluss').

  Please note that in such a case the MSN may not be transmitted to you.
  Just use the default MSN 0 then.



  9.  lan: ISDN4LINUX in a LAN

  9.1.  lan_config: How can I set up Linux so that other computers in my
  LAN can access the internet via my Linux computer?

  There are several possibilities:

  1. Your LAN is an official Class C net with IP addresses valid on the
     Internet.  This case is the easiest of configure. You give each
     network card on your network one of these addresses and set a
     default route on the ISDN card that goes to your provider.

  2. You'd only like to do http in Internet from your LAN. In this case
     you can make up IP addresses for your LAN; the only official IP
     address is that for your ISDN card. Then install a proxy server on
     your Linux router, and enter it in all of your browsers. In this
     case you do not need a default route.

  3. From your LAN you only want to log in to your Linux ISDN router and
     FROM THERE do your work on the Internet. This is even simpler, then
     you don't even need a proxy server.

  4. Use ip masquerading. This is the most comfortable one to use, but
     more difficult to set up. The Linux computer acts as a gateway. The
     trick is that it hides the ip addresses of the LAN, by giving its
     own internet address as response address. When receiving the
     response, it will forward it to the correct computer on the LAN.
     You can also use masquerading with dynamic ip addresses. If you
     don't want to start the ISDN connection from the Linux computer to
     your internet provider manually, then you can set up dial on demand
     functionality (see section ``dod'').


  9.2.  lan_modemserver: How can forward ISDN data from a local computer
  in my LAN to the ISDN card(s) in my Linux PC (like a modem server)?

  On the Linux PC you have to install a forwarding server.  One option
  is to use modemd. This is a very short perl script (also see Linux
  Modem sharing mini-HOWTO at
   <http://www.linuxdoc.org/HOWTO/mini/Linux-Modem-Sharing.html>):

  ______________________________________________________________________
  #!/usr/bin/perl
  select((select(STDOUT), $| = 1)[$[]);
  select((select(STDIN), $| = 1)[$[]);
  exec "cu","-E","''", "-l", "$ARGV[0]";
  die "$0: Cannot exec cu: $!\n";
  ______________________________________________________________________


  It has to be started by inetd, therefore this has to be added to
  /etc/services:

  ______________________________________________________________________
  modem           20006/tcp       modemd  # Modem service via TCP
  isdn            20007/tcp       modemd  # ISDN  service via TCP
  ______________________________________________________________________


  And this has to be added to /etc/inet.conf:

  ______________________________________________________________________
  modemd stream tcp nowait root /usr/sbin/tcpd /usr/sbin/modemd ttyI5
  ______________________________________________________________________


  Instead of modemd you can also use the program mserver, which has some
  additional functionality (e.g. rights based on ip address):
   <ftp://ftp.innet.be/pub/staff/carl/>

  Additionally, you need some software on your non-ISDN computer which
  emulates a serial port, but redirects it via telnet to the Linux ISDN
  computer.  Some telnet clients allow this functionality (e.g. some
  uucicos).  If you generally want to offer all applications a kind of
  "remote COM port", then there is COMT for Windows (95), and
  "telser.device" for Amigas. Disadvantage of COMT: it is only visible
  to ancient 16bit Win applications, and not even working in the DOS
  box.  Another program is DialOut/IP, but it's fairly expensive ($70).

  COMT may be found on Simtel:
   <http://educom.sce.fct.unl.pt/ftp/pub/shareware/win-utils/comt2.zip>

  DialOut/IP can be found on:
   <http://tacticalsoftware.com>

  Those who just want to save their CrossPoint installation should be
  aware that it now offers tcp modem support, such that it will run
  without additional software. Check out:
   <http://www.openxp.de>


  9.3.  lan_remotedialing: How can I allow the users in my LAN to trig-
  ger a dial out via   the ISDN card(s) in my Linux PC?

  For this you need two pieces of software. At the computer where the
  ISDN-line is connected you need to install a dial daemon. The dial
  daemon will execute any dial commands given from a dial frontend
  located on a different computer on the LAN. You have several options
  to choose a dial daemon and dial frontend.

  1. At first you can use the free software smpppd (SuSE Meta PPP
     Daemon) from SuSE as the dial daemon. smpppd gets used in the SuSE
     distribution for all ISDN, Modem and DSL connections. You can
     connect to smpppd locally or over a LAN via different dial
     frontends and trigger dial-out, hang-up and so on. The most known
     dial frontend is kinternet a small applet for the KDE Kicker.
     Others are the qt-only qinternet and the command line tool
     cinternet.  Unfortunately there is no frontend for Windows or Mac
     OS available.

     Obviously this is the easiest way if you already have SuSE
     installed on the server, and all other involved computers are also
     based on Linux (installation of the dial frontend should not be too
     difficult with non-SuSE distributions).  Some more hints:

     o  The software is available in SuSE-Linux within the packages
        smpppd, kinternet and qinternet, see  <http://www.opensuse.org>

     o  In order to allow smpppd listening into the LAN change the
        following two options in /etc/smpppd.conf (see also "man
        smpppd.conf"):

        ________________________________________________________________
        open-inet-socket = yes # (default is no)
        bind-address = <IP> # IP of the LAN-network-card of the dial in server;
        # default is listening on all network cards (!)
        ________________________________________________________________



     o  On the client side you can either enter the dial server via GUI
        or via /etc/smpppd-c.conf (see also "man smpppd-c.conf").
  2. Another free software solution working the same way is LineControl.
     It has a dial daemon (linesrv) which you can configure dialing
     different connections (similar to smpppd) be it ISDN, Modem, DSL or
     another dial-out connection. Dial frontends are available for Linux
     (one for KDE and one for Gnome), Windows and Java.  Some more
     hints:

     o  The software and tutorials can be found at
        <http://linecontrol.srf.ch/>

     o  The config files is located at /etc/linesrv.conf (the relevant
        configuration options are similar to that of smpppd)

     o  Several dial and hang up scripts where you can define the system
        commands how to dial/hang up certain connections are below
        /etc/linesrv/

     o  In order to have the linesrv daemon running at system start of
        your server you also need to enter it in your system start
        configuration.

     o  On the client side you now can enter the dial server via GUI in
        one of the frontends and dial/hang up a connection configured at
        the server.



  10.  dialout: Configuration of Dial-Out

  10.1.  dialout_config: How do I configure dialout properly?

  First you have to decide on how you want to dial out. You will have to
  use whatever your counterpart requires. These are your main options:

  o  Sync PPP: This is what most Internet Service Provider expect from
     you. See section ``syncppp''.

  o  Async PPP: May also be handled by your Internet Service Provider.
     Use when Sync PPP does not work for you. See section ``asyncppp''.

  o  Raw IP: Most efficient for TCP/IP over ISDN. It has very quick
     dialouts, but is not as common. See section ``rawip''.

  o  X.75: This is what you need to dial into an ISDN mailbox. See
     section ``ttyI''.

  o  Leased line: For this special case, see section ``leased''.

  Have a look on section ``dod'' on how to configure dial on demand -
  and on the dangers attached to it.

  For more advanced dialout features see question ``dialout_advanced''.

  Also you may have a look at section ``remote'' when you try to connect
  to a special remote ISDN device.


  10.2.  dialout_dialmode: When an IP packet should go over the link
  (which usually triggers a dialout), all I see in the log is: "dial
  rejected: interface not in dialmode auto "?

  The new ISDN drivers in 2.0.36 defaults to manual dialmode, not
  autodial. This is done to prevent unexpected (and unnoticed) dialouts.
  (See the big section about those and their dangers: ``dod'').  To
  enable autodial for a given interface e.g. ippp0, use
  ______________________________________________________________________
  isdnctrl dialmode ippp0 auto
  ______________________________________________________________________



  The meaning of the values for dialmode is:

     off
        means that you (or the system) cannot make any connection
        (neither incoming nor outgoing connections are possible). Use
        this if you want to be sure that no connections will be made.


     auto
        means that the interface is in auto-dial mode, and will attempt
        to make a connection whenever a network data packet needs the
        interface's link. Note that this can cause unexpected dialouts,
        and lead to a high phone bill! Some daemons or other pc's that
        use this interface can cause this.  Incoming connections are
        also possible.


     manual
        (DEFAULT) is a dial mode created to prevent the unexpected
        dialouts.  In this mode, the interface will never make any
        connections on its own. You must explicitly initiate a
        connection with:

        ________________________________________________________________
        isdnctrl dial ippp0
        ________________________________________________________________


     To end the connection, use:

     ___________________________________________________________________
     isdnctrl hangup ippp0
     ___________________________________________________________________


     Please note that the huptimeout may still end the connection auto-
     matically! To ensure that you have to hang up manually, you have to
     switch this off:

     ___________________________________________________________________
     isdnctrl huptimeout ippp0 0
     ___________________________________________________________________



  To allow a normal user to initiate a dialout, have a look at question
  ``dialout_permission''.


  10.3.  dialout_advanced: What special dialout features are available?

  Check out these special dialout features:

  o  Save money by hanging up just before a charge unit: see section
     ``chargeint''.

  o  Dialout on more than 1 channel at the same time: see section
     ``2channel''.


  o  Dialout on one specific channel: see question
     ``dialout_fixedchannel''.

  o  Callback: see section ``callback''.


  10.4.  dialout_permission: How can I allow a normal user to initiate
  dialouts?

  ISDN usage depends on the permissions to the devices /dev/ttyI* and
  /dev/cui*. You have several choices to selectively allow users to do
  ISDN transactions.

  1. You can establish the group `isdn' in /etc/group, and do:

     ___________________________________________________________________
     chgrp isdn /dev/ttyI* /dev/cui*
     chmod o-rw /dev/ttyI* /dev/cui*
     ___________________________________________________________________


  It has been reported that you also may have to change group and per-
  missions on the programs ipppd and isdnctrl to 'isdn'.  Then all users
  not in the group 'isdn' have no reading or writing privileges for the
  ISDN ttys. Those allowed to use ISDN have to be explicitly added to
  the group 'isdn'.

  2. You can allow only root to log out, but set up exceptions for other
     users with the su1 functionality (see man su1). As root edit
     /etc/su1.priv. Add these lines if they (or similar ones) are not
     yet there, to allow users XXXX and YYYY to initiate
     dialups/hangups:

     ___________________________________________________________________
     # log all dialouts in syslog
     syslog all
     define PPPUSER XXXX YYYY
     alias dial /sbin/isdnctrl dial ippp0
     alias hangup /sbin/isdnctrl hangup ippp0
     ask never
     allow PPPUSER prefix dial
     allow PPPUSER prefix hangup
     ___________________________________________________________________


  Then create two links for dial and hangup:

  ______________________________________________________________________
  ln -s /usr/bin/su1 /usr/local/bin/dial
  ln -s /usr/bin/su1 /usr/local/bin/hangup
  ______________________________________________________________________


  Now the users XXXX and YYYY can dial out by typing dial, and hangup
  with hangup.

  3. isdnctrl can be set SETUID root. Please not that if it is called by
     a user different from root, isdnctrl will only allow you to
     dialin/hangup, and addlink/removelink/show. However, the
     setup/configuration data can only be modified by root.

  4. If you only have one user that you use for ISDN interactions, you
     can make him owner of the ISDN interface.



  10.5.  dialout_manycards: How do I configure dialout with more than 1
  ISDN card?

  There are several possibilities to configure dialout.

  o  Dialout anywhere (default: all available cards are a pool, dialout
     on one MSN): just configure your cards in the order in which you
     want them to be dialed out.  First all channels on the first card
     are used, then all on the second card, and so on. Please note that
     the net interface or ttyI device will try to dial out using the MSN
     it was configured for - on all cards. Even on those that do not
     have this MSN! In such a case, the telco will replace that invalid
     MSN with the correct one. Use isdnctrl mapping to configure the
     correct MSNs (see item 'dialout on one specific card').

  o  Dialout on one specific channel: Use the isdnctrl bind (not
     pppbind) command to specify which channel should be used.  Please
     use this command after all other configuration with isdnctrl has
     been done! Check with isdnctrl list that the binding actually
     works.

  o  Dialout with different MSN on each card: You can configure this by
     using the isdnctrl mappping functionality.  Just map MSNs on the
     letters 0 to 9, like this:

     ___________________________________________________________________
     isdnctrl mapping <carddriver1> 111,222,333,,
     isdnctrl mapping <carddriver2> 999,888,,777
     ___________________________________________________________________


  Now, you could configure for telephone number 0 when you really want
  to use MSN 111 on <carddriver1> or 999 on <carddriver2> (however,
  since 0 has a special meaning, try to avoid using number 0). Configure
  to use number 1 when you really want to use MSN 222 on <carddriver1>
  or 888 on <carddriver2>. Configure to use telephone number 2 when you
  really want to use only MSN 333 on <carddriver1> (<carddriver2> will
  use the default MSN when used). Configure to use telephone number 3
  when you really want to use only MSN 777 on <carddriver2> (<card-
  driver1> will use the default MSN when used).

  o  Dialout on one specific card: After installing a patch that was
     posted by Karsten Keil on the mailing list against 2.2.12, you can
     disallow calls on some cards by using the isdnctrl mapping
     functionality.

     ___________________________________________________________________
     isdnctrl mapping <carddriver1> 111,222,333,-,
     isdnctrl mapping <carddriver2> 999,888,-,777
     ___________________________________________________________________


  It works as discribed for "Dialout with different MSN on each card",
  except that the "-" means dialing is disallowed. Dialout on telephone
  number 2 will now only dial out with MSN 333 on <carddriver1>, while
  dialout on 3 will now only dial out with MSN 777 on <carddriver2>.


  10.6.  dialout_fixedchannel: How can I force HiSax to always dial out
  on a specific B channel?

  HiSax has an undocumented feature for this. Add 'P1' in front of the
  dialout phone number for the first B channel, or 'P2' for the second B
  channel, like this:


  ______________________________________________________________________
  isdnctrl addphone <device> out P1<your_out_number>
  ______________________________________________________________________


  This will indicate the preferred B channel in the outgoing SETUP mes-
  sage.  Please note that some PBX may not like this.  Obviously, a
  dialout will fail when another device already uses the second B chan-
  nel.


  10.7.  dialout_dynip: On dynamic ip assignment, how do I find out
  which ip address is being used for dialout?

  Create a script called ip-up. It will be called by the ipppd whenever
  the connection is established with several parameters.  The ip address
  is passed in as the fourth parameter (access it as $4).


  10.8.  dialout_bind: A dns query causes bind to dial out. Why does it
  take about a minute before it is answered? How do I work around it?

  You are probably using the name server in 'forward' mode, and your ISP
  works with dynamic ip addresses. The initial UDP query will be lost
  since it carries the wrong source address. Unfortunately, bind will
  wait a whole minute before retransmitting the query again if you have
  only one forwarder.

  As a workaround, you can enter 4 times the same forwarder in
  named.conf to adjust retransmission timing (in 'forward' mode, bind
  retransmits its queries after the following period of time: 60 seconds
  divided by the number of nameservers given in the section "forwarders"
  of named.conf).

  ______________________________________________________________________
  forwarders { 10.0.0.40; 10.0.0.40; 10.0.0.40; 10.0.0.40; }
  ______________________________________________________________________


  Bind will then retransmit the query every 15 seconds to your forwarder
  (here the forwarder is 10.0.0.40).  The same principle applies to two
  or more forwarders.

  Another option are the programs ip_resend and ip_resend_wakeup which
  you can find on: <http://www.baty.hanse.de/ip_resend/>



  11.  pap: Authenticate properly (especially with PAP)

  11.1.  pap_optionauth: When dialing out, I get the message "pppd: peer
  authentication required but no authentication files accessible." What
  does this mean?

  Most likely the option "auth" was set by mistake. Then the other side
  is required to be authorized.


  11.2.  pap_requestauth: I cannot establish a connection -  it's
  rejected by the other side. In the log file I find a message that's
  something like: "sent (0) (LCP ConfReq id=0x1 mru 1500 auth pap magic
  0xcd12e9c4"

  Like in the last question, an option has been set that requires the
  other side to be authorized. These options shouldn't be set.  Possible
  candidates are: "+pap" as well as "+chap".
  11.3.  pap_rejectauth: I cannot establish a connection -  it's
  rejected by the other side. In the log file I find a message that's
  something like: "sent (0) (LCP ConfRej id=0x1 auth pap"

  Your computer is refusing to identify itself with user name (e.g. XXX)
  and password (e.g. YYY). That only works with the authorization
  options "user XXX" and "remotename YYY" for ipppd or pppd together
  with a correct (!) /etc/ppp/pap-secrets. With a password of ZZZ it
  should ideally look like this:

  ______________________________________________________________________
  XXX YYY ZZZ *
  ______________________________________________________________________


  If you have special characters in XXX, YYY, or ZZZ, try to use quotes
  around them. If that doesn't work for getting XXX or YYY correct, you
  can use wild cards, something like:

  ______________________________________________________________________
  * * ZZZ *
  ______________________________________________________________________


  Then every partner has the password ZZZ. If chap is required for
  authorization, then /etc/ppp/chap-secrets must be set up correctly.
  Important: the format is different from that of pap-secrets!  One
  important point is to use only the tabulator instead of space to sepa-
  rate username, computer, password.  Make sure to consult the README's,
  or check out:
   <http://www.lrz-muenchen.de/~ui161ab/www/isdn/> Also have a look at
  the next question: ``pap_passwd''.


  11.4.  pap_checkpwd: How can I check which password is actually sent
  to the remote side?

  Use the options debug and +pwlog for ipppd or pppd. Then you can see
  your password in the log file.


  11.5.  pap_passwd: I have problems with PAP or CHAP authentication. It
  does not work although I'm sure I entered passwords etc. correctly.

  Stefan A. Muehlenweg Stefan.A.Muehlenweg@samhh.hanse.de wrote on 4 Oct
  1996:

       I had exactly the same problem/the same error message. The
       cause for it was that I had three entries in chap-
       secrets/pap-secrets (for client, server, secret), but not a
       fourth one (IP addresses). BUT: after the third entry were
       some BLANKs. After removing the trailing BLANKs and/or TABs
       (i)pppd is now very satisfied with my auth-files.


  A further source of problems can be the password itself. If it con-
  tains the "#" character, then everything after than is understood as a
  comment. Spaces or tabs can cause similar problems. Solution: put the
  password in quotes!



  12.  syncppp: Sync PPP

  12.1.  syncppp_whichppp: pppd, ipppd, syncPPP, asyncPPP .. what is
  they? Which should I use?

  See this question in the asnyc PPP; section: ``asyncppp_whichppp''.



  12.2.  syncppp_compile: How do I compile isdn4linux with syncPPP?

  To compile the kernel with syncPPP included in ISDN4Linux, you have to
  answer the appropriate questions with "yes". Don't forget to load the
  module slhc.o before isdn.o, if VJ compression is not compiled into
  the kernel e.g. if you have no PPP and no CSLIP in the kernel. (Note
  that the use of VJ is problematic for elder kernels and does not work
  reliably - however, the support should still be included in the
  kernel, since there can otherwise be side effects.)


  12.3.  syncppp_netinterface: How should I name my network interface?

  The name of the network interface should always begin with "ippp", not
  with "syncppp" or "isdn"; otherwise the communication with ipppd will
  not work correctly. Please note that at least one of the interfaces
  has to be "ippp0", otherwise ipppd will not start. Check your
  interfaces with the command ifconfig.


  12.4.  syncppp_config: How do I configure isdn4linux with syncPPP?

  Synchronous PPP is simply another encapsulation for ISDN4Linux. This
  encapsulation is called "syncppp". Here is an example to configure the
  link level device ippp0:

  ______________________________________________________________________
  /sbin/isdnctrl addif ippp0
  /sbin/isdnctrl encap ippp0 syncppp
  ______________________________________________________________________


  Please note that syncppp is very peculiar about the names of the
  device.  Only devices starting with "ippp" will work, at least one
  interface has to be named ippp0 (see question ``syncppp_netinterface''
  for details).  All ippp* devices in use must be configured separately.
  Each ippp* device should be assigned to its own IP address (routing!).
  Several ippp* devices can be assigned to a single MSN. Several callers
  can then simultaneously use this MSN.

  To use these devices you need the program ipppd, which you have to
  configure. You have to start ipppd once after the modules are
  installed. ipppd needs to be constantly running to allow
  dialout/dialin. It communicates with the isdn4linux link level devices
  through /dev/ippp0 to /dev/ippp63. A single ipppd can handle all
  devices at once. If you want two PPP connections at the same time, you
  need to bind ipppd to two devices, etc. As a result, ipppd provides
  the network device ippp0, which can be checked with ifconfig (even so
  it has the same name, the network device ippp0 is not to be confused
  with /dev/ippp0 which is used for communication between ipppd and link
  level.

  ipppd has an additional option: "useifip" uses the IP address of the
  connected network interface (if it is not 0.0.0.0). (Even then, ipppd
  tries to use the pointopoint address as the remote IP.) For the
  beginning, disable all compression (lzs/stac, bsd, van jacobson),
  later you can try to enable it (see question ``syncppp_compression'').
  It is very important to set up the authentication information
  properly. Improper authentication is probably the most frequently
  reported problem on the mailing list. Please, work through section
  ``pap'' completely yourself, before asking others for help.

  You can find an example configuration in the file etc/rc.isdn.syncppp
  in the isdn4kernel-util package.

  You can also run several ipppds to allow for different configurations,
  in such a case use the "isdnctrl pppbind" functionality. However,
  normally one ipppd is meant to handle all traffic, so it is highly
  recommended to only set up several ipppds if their configuration has
  to be different.


  12.5.  syncppp_busy: How can I tell if a connection is unsuccessful
  (busy)?

  When giving the option defaultroute, then you can wait a few seconds,
  then check whether the default route exists. Another way, when giving
  option useifip is to check whether you find entries like "Local IP:
  x.y.z.a" and/or "Remote IP: x.y.z.a" in syslog.  In either case, the
  connection is up.


  12.6.  syncppp_logindelay: How can I reduce login delay?

  You can write out a login session with ("Debug-Log"), and see which
  options the other computer is refusing. Next time, configure ipppd
  without these unused options. A further side effect is that such
  unused options increase the redundance (e.g. when the other computer
  has bugs and refuses the options incorrectly). To create a log file,
  see "How to I create a log for ipppd".


  12.7.  syncppp_2configs: I want to talk to remote machines which needs
  different configurations. The only way I found to do this is to kill
  the ipppd and start a new one with another config to connect to the
  second machine.

  You must bind a network interface explicitly to an ippp device, where
  you can connect a (for this interface) individually configured ipppd.
  With the (unfortunately poorly documented) command

  ______________________________________________________________________
  isdnctrl pppbind interface Number
  ______________________________________________________________________


  you can link the interface interface to the device ipppNummer. You can
  release the link with "pppunbind".


  12.8.  syncppp_pppbind: How does the (little-documented) "pppbind"
  command in isdnctrl work?

  You have to first know how ipppd gets its data. All data that come in
  over the ISDN line is received by the network devices (these are set
  up with isdnctrl). Then the data given to one of the /dev/ippp*
  devices - to one where a ipppd daemon is waiting for data.

  To the network interfaces, all ipppd's appear to be able to handle the
  just-received data - therefore it is normally impossible to predict
  which ipppd will receive data from which network interface.


  In practice, you usually install several ipppd's with differing
  configurations. Each of these should receive data exclusively from a
  certain network interface (that has also be specially configured).
  The "pppdbind" command serves just this purpose. With:

  ______________________________________________________________________
  "isdnctrl pppbind interface number"
  ______________________________________________________________________


  attaches the interface interface to the device /dev/ipppnumber.

  Example: To attach the interface "ippp5" to /dev/ippp2, the following
  configuration should be used:

  ______________________________________________________________________
  "isdnctrl pppbind ippp5 2"
  ______________________________________________________________________


  Similarly, the command "pppunbind" will undo this attachment.


  12.9.  syncppp_dynip: I want to use dynamic IP address assignment. How
  must I configure the network device?

  At least you must have a route, which forwards a packet to the ippp
  network interface to trigger dialing. A default route to the ippp
  interface will work. Now you must choose a dummy IP address for your
  interface. If for some reason you can't set the default route to the
  ippp interface, you may take any address of the subnet from which you
  expect your dynamic IP number and set a 'network route' for this
  subnet to the ippp interface. To allow overriding of the dummy address
  you must call the ipppd with the 'ipcp-accept-local' option. You must
  know how the ipppd gets the addresses it has to configure. If you
  don't give any option, the ipppd tries to negotiate the local host
  address!  With the option 'noipdefault' it requests an address from
  the remote machine. With 'useifip' it gets the addresses from the net
  interface. You also can set the addresses in the option line with the
  a.b.c.d:e.f.g.h option. Note: the IP address of the remote machine
  must be configured locally, or the remote machine must send it in an
  IPCP request. If your side doesn't know the IP address after
  negotiation, it will close the connection! You must allow overriding
  of addresses with the 'ipcp-accept-*' options, if you have set your
  own or the remote address explicitly. Try these options, e.g.:

  ______________________________________________________________________
  /sbin/ipppd :$REMOTE noipdefault /dev/ippp0
  ______________________________________________________________________


  where REMOTE must be the address of the remote machine (the machine
  giving your address to you)


  12.10.  syncppp_msgetdns: How do I configure ipppd to obtain or pro-
  vide the nameserver address at dial in?

  Use the configuration option ms-get-dns to obtain the nameserver ip
  address when you dial up your internet provider. Use ms-dns to publish
  the nameserver ip address when someone dials up your ipppd.



  12.11.  syncppp_ipx: How can I do IPX over ipppd?

  Give the option +ipx-protocol to the ipppd.


  12.12.  syncppp_faster: How can I increase my PPP data transfer rates?

  You can establish more channels with MPPP (see the MPPP section).
  Another way is to use compression, see question
  ``syncppp_compression''.


  12.13.  syncppp_compression: Which compressions can I use with ipppd?

  Several compressions can now be used with ipppd. However, if in doubt
  and it does not work: disable it.

  o  Van Jacobson compression (header compression).  Should work fine
     now for current kernels (later than 2.2.14). To use it you have to
     compile it into the kernel. To get around some problems with
     automatic loading of the VJ module try to also compile SLIP and
     CSLIP into the kernel. Disable with options "-vj -vjccomp".

  o  BSD compression.  Seems to work quite well if your peer supports
     it. It is independent of Van Jacobson compression, so you can use
     them both together.

  o  LZS compression (sometimes also called Stac compression).  Also
     works quite well. To enable it, some manual work has to be done to
     add the code to the ipppd (see the isdn4k-util package).



  12.14.  syncppp_strategy: I can't get a connect. How can I find out
  where the problem is?

  The output of ipppd is very helpful... (see next question:
  ``syncppp_log'')

  o  Have a look at the error messages and see the following
     questions...

  o  Check whether you can find a few "LCP-conf-req SENT" messages (less
     than ten) and then a "TERM-REF".

  o  Check whether the ISDN card was configured properly. It seems the
     computer doesn't dial (IRQ, IO, protocol wrong?)

  o  At least a few "RECV" messages: good! The card is dialing and your
     dialin computer tries to communicate. Maybe the pap/chap
     authentication doesn't work (see question ``pap''). Check the ipppd
     configuration!

  o  The message that ipppd was exited for some reason: not so good!
     Check /var/log/messages, /var/log/debug, and /var/adm/daemon (if
     existing). Could be a bug in ipppd.

  o  The error/cause E0010 is NOT an error! It is just the informal
     message that the call has ended.


  12.15.  syncppp_log: How can I get a log for ipppd?

  Normally when giving the option "debug" to ipppd, the debbuging output
  may be logged in /var/log/messages, /var/log/debug, or /var/adm/daemon
  (depends on your distribution, look around).

  For debugging purposes you can redirect the PPP log into a separate
  file.  Just edit /etc/syslog.conf and add the following line (caution:
  do NOT use blanks or tabs - check "man syslog.conf(5)" for more
  details):

  ______________________________________________________________________
  daemon.*                      /var/log/ppp-log
  ______________________________________________________________________


  then every information from PPP demon will be logged to /var/log/ppp-
  log.  Emil Stephan ste@esqhen.su.eunet.de also wrote:

  Remove the comment sign in front of this line in /etc/syslog.conf:
  #*.=debug                       /tmp/debug
  After changing this file you can restart syslogd with "kill -1 pid of
  syslogd".
  The output in /tmp/debug can be used to optimize the handshaking of
  PPP options.



  12.16.  syncppp_nopppsupport: Starting ipppd I get the error message
  "this systems lacks ppp support" or "isdn driver is out of date. maybe
  ippp0 has no syncppp0 encapsulation".

  Check whether the device "ippp0" exists (i.e. with the program
  "ifconfig"). See question ``syncppp_netinterface'' for details on the
  naming conventions for net interfaces.  The ipppd *needs* this device
  with exactly *that* name and *syncppp* encapsulation. If it doesn't
  exist then you have to define it:

  ______________________________________________________________________
  isdnctrl addif ippp0
  isdnctrl encap ippp0 syncppp
  (see i4l documentation or question
  <ref id="syncppp_config" name="syncppp_config"> for more information...)
  ______________________________________________________________________


  Maybe you compiled ipppd with the source of another kernel that you
  are not using...


  12.17.  syncppp_nousabledevice: When I try to start ipppd it says
  "Can't find usable ippp device"

  This message occurs when the linklevel interface is told to dial out,
  but ipppd is not running, or not available.


  12.18.  syncppp_starterror: When I start ipppd, I only get error mes-
  sages from the i4l driver.

  When ipppd is started, it calls functions that can trigger a network
  packet (e.g. gethostbyname()). Without ipppd (since at this time,
  ipppd it has not been fully started), this network access cannot be
  processed, You should try to put the needed hostnames in the local
  /etc/hosts or in some way define the name so that it can be resolved
  without having the access the ISDN/ippp interface.



  12.19.  syncppp_framesdelayed: I get the message IP frames delayed  -
  but no connection.

  Have you really dialed out? Check question ``dialout_dialmode'' and
  your configuration on the different dialmodes.


  12.20.  syncppp_noroute: I cannot dial out with isdnctrl dial ippp0 .
  It seems as if the route to ipppd is missing although I did  set it (
  network unreachable ). With my old kernel 2.0 everything works fine!

  In the newer kernels you have to place route as the very last command
  before the dialout command. Otherwise the kernel will delete the
  route.


  12.21.  syncppp_nodefaultroute: After ipppd dials out my default route
  is gone.

  It's the kernel's fault. Newer kernels (= 2.0.x) have some changes in
  the routing. Workaround: install a script /etc/ppp/ip-up like this:

  ______________________________________________________________________
  #!/bin/sh
  /sbin/route add default ippp*
  ______________________________________________________________________


  Please note, that for 2.2.x kernel, you should NOT do this (routing
  has changed yet again). Instead, give the "defaultroute" option to
  ipppd.

  If you make your connections manually, can use something like this
  script:

  ______________________________________________________________________
  /sbin/isdn
  #! /bin/sh
  case $1 in
  on)
  /sbin/isdnctrl dial ippp0       #  build up connection
  sleep 5                         #  wait until line open
  /sbin/route add default ippp0   #  set route
  ;;
  off)
  /sbin/isdnctrl hangup ippp0     #  hangup connection
  /sbin/route del default         #  and delete route again
  ;;
  *)
  echo -e "\a Usage: 'isdn on' or 'isdn off'"
  ;;
  esac
  ______________________________________________________________________


  Please note, that for 2.2.x kernel, you should NOT use the route add
  default, and route del default commands.  Instead, give the "default-
  route" option to ipppd.


  12.22.  syncppp_packettoolarge: I often get the error message
  hscx_empty_fifo: incoming packet too large

  Probably one of the compressions is activated (i4l can't handle those
  very well). See also next question.  Another possible reason could be
  an IRQ problem - see question "Why should I avoid IRQ 12 and 15 for my
  ISDN card?".  Another problem can be `#' characters in your pap-
  secrets file. In this case you have to surround user name and/or
  password with quotation marks (depending on which one is affected).


  12.23.  syncppp_slow: The connection with ipppd seems to work, but
  eventually it crashes or is very slow.

  It could be that some compression is activated (that i4l can't handle
  properly). Common error: "-vj" has to be used *additionally* to
  "-vjccomp" (to completely switch off the VJ compression) - the example
  scripts coming with ipppd don't have that option included already.
  Other compression modes (bsd, pccomp) can cause trouble, too.
  Therefore, you should switch off all compression options (see also
  question ``syncppp_compression''). Also giving the option "noccp" can
  help.


  12.24.  syncppp_loadproblem: I only have problems with ipppd when the
  connection is being heavily burdened. Then everything stops. What
  could be causing this?

  Sven Engelhardt sven@sik.de wrote on 12 Dec 1996:

       We are an ISP here in Dresden and use Linux (among other
       systems) for our access (with I4L as well as with external
       terminal adapters).  We have this problem mostly with Win-
       dows 95 and NT customers who are using the "included" (modem
       network) software. It doesn't make any difference whether
       the customer is dialing with async or sync PPP.  It also
       doesn't matter which modem emulation he is using on his
       side.  What they have in common is that the connection is
       made with Microsoft modem adapter + Microsoft PPP (although
       a colleague recently told me about a similar problem with a
       Macintosh customer).  Since it doesn't matter to PPP who is
       the server and who is the client, ask your ISP what kind of
       hardware you are dialing into (we have had no problems with
       Linux customers and Trumpet Winsock users, therefore I sus-
       pect a bug in MS-PPP).  The following workaround usually
       works for us: (it's not a cure, but helps to reduce the
       pain...)  * Reduce the Max MTU to 576 or even (296) * Reduce
       the  DefaultRcvWindow to 2144 On the Windows 95 side these
       are 2 Registry entries; on the Linux side you can set "mtu
       576" and "mru 576" in the PPP options. (See also:
       <http://www.winfiles.com/connect/trouble.html>)


  Erik Corry ec@sign-tronic.dk added on 16 Dec 1996:

       For me, neither PPP compression option nor mru/mtu 296
       helped.  What did help was the AT command: AT&B512 that lim-
       its the sent packets to 512 bytes.



  12.25.  syncppp_mtu: My ipppd works, but I keep getting the message
  pppd(104): ioctl(SIOCSIFMTU): Invalid argument"?

  If mtu is not set, then a default value is assumed - possibly "0"
  (which of course cannot be correct). Add "mtu 1024" to your ipppd
  options (1500 could also be ok).



  12.26.  syncppp_1stpacket: The first IP packet gets lost on automatic
  dialout with dynamic IP address allocation.

  There are some dialout problems in connection with syncPPP and dynamic
  IP address allocation. In this case your IP address will change while
  packets are waiting to be sent. All packets that should be sent before
  the change in IP address have the wrong response ip address and will
  therefore never receive an answer. The problem is that this may cause
  multiple dialouts (see section ``dod''). Possible solutions:

  o  Dial out manually with "isdnctrl dial ippp*"

  o  Use diald to control when the connection goes up or down.

  o  Get a permanent IP address

  o  A workaround is included in the newest kernels, which can be
     activated like this:

     ___________________________________________________________________
     echo 7 > /proc/sys/net/ipv4/ip_dynaddr
     ___________________________________________________________________


  (use 5 instad of 7 to not get warnings into /var/log/messages) If you
  have a SuSE distribution, this workaround can also be configured by
  setting IP_DYNIP="yes" in /etc/rc.config.

  o  Increase the number of retries on your Windows machine for setting
     up the connection. Change the registry entry
     Hkey_Local_Machine\\System\\CurrentControlSet\\Services\\VxD\\MSTCP\\MaxConnectRetries
     from 3 to a larger value (e.g. 5 or 7).


  12.27.  syncppp_droppacket: What does the message "No phone number,
  packet dropped" mean?

  Michael Engert michi@bello.wor.de wrote in Nov/Dec 1996:

  That means that your computer has an IP packet from somewhat who was
  logged on a few seconds before, but has since broken the connection.
  Your computer tries to send this packet on and finds an appropriate
  route. But the interface isdn(0|1|...) can't reach the other computer,
  since it has no telephone number to dial.


  12.28.  syncppp_leadingzero: Why does my ipppd dial one too many zeros
  ( "ippp0: dialing 0 089XXXXXX..." )? I don't have any extensions!

  The first zero is not dialed. It only shows the retry counter, which
  is related to the isdnctrl dialmax parameter.


  12.29.  syncppp_ethfake: My ISDN device is shown with HWaddr and IRQ=0
  and base address = 0 when I list it with ifconfig

  The ISDN device fakes an Ethernet device. It ignores IRQ and baseaddr
  and just needs the HWaddr for the Ethernet encapsulation.


  12.30.  syncppp_lzsproblem: I get an error message like kernel check
  for lzs failed ?

  This means that ipppd tries to use lzs compression, but can't find a
  compiled module which contains the code. The error message is only
  cosmetic, since the system will still work fine. Either disable lzs
  compression by providing noccp as an option for ipppd, or compile and
  load the lzs module.



  13.  asyncppp: Configuration Async PPP

  13.1.  asyncppp_whichppp: pppd, ipppd, async PPP, sync PPP - what are
  they? Which should I use?

  async PPP is a character-based protocol which is usually used over
  analog serial lines (async = asynchronous). You have to use the
  program pppd for it, and use it with the ttyI* devices.

  In contrast, Sync PPP is a bit-oriented protocol (sync = synchronous),
  for which the original pppd cannot be used. Michael Hipp has written
  an adapted version called ipppd which will use ipppd* net devices.

  With i4l you can have both. It all depends on what your ISDN
  counterpart supports. If it immediately begins to send frames, then
  you've probably reached an sync PPP machine. If you can log in via
  same terminal screen, and then can start pppd, this can be an
  indication of async PPP.

  Usually using sync PPP works fine, and it is slightly more efficient.
  To take advantage of newer features of the pppd, use async PPP.


  13.2.  asyncppp_config: How do I configure async PPP?

  Just set up a normal pppd, but tell it to use one of the ttyI*
  devices, e.g. /dev/ttyI0. You can set up several pppd's with different
  configuration on different ttyI* devices.

  It is very important to set up the authentication information
  properly. Improper authentication is probably the most frequently
  reported problem on the mailing list. Please, work through section
  ``pap'' completely yourself, before asking others for help.

  On problems also check out the section about the syncppp problems,
  since many configuration problems are common for pppd (async PPP) and
  ipppd (sync PPP).


  13.3.  asyncppp_logindelay: How can I reduce login delay?

  You can write out a login session with ("Debug-Log"), and see which
  options the other computer is refusing. Next time, configure ipppd
  without these unused options. A further side effect is that such
  unused options increase the redundance (e.g. when the other computer
  has bugs and refuses the options incorrectly). To create a log file,
  see "How to I create a log for ipppd".


  13.4.  asyncppp_fast: How can I increase my transfer rates with PPP?

  You can add more channels with MPPP (see question ``2channel_mppp'').
  For everyone for whom that's to expensive and who use async PPP,
  there's a little trick. With the option "asyncmap 0" you can avoid
  escaping all control characters (ASCII32). If the other side goes
  along with this, you can increase the transfer rate by about 12%.



  13.5.  asyncppp_log: How can I get a log for pppd?

  See this question for Sync PPP, it works the same way for pppd.


  13.6.  asyncppp_suddendeath: Establishing the connection works fine,
  but pppd crashes just after that (i.e. the first bytes gets through,
  but then everything stops)

  This is probably due to an incorrect block size on your side.
  Initialize your ttyI* device with AT&B512 or even smaller block sizes.



  14.  rawip: Raw IP

  14.1.  rawip_whatis: What is Raw IP, when should I use it?

  Raw IP does without the use of a protocol such as X.75 or HDLC (for
  modem emulation, etc.) or PPP. TCP/IP packets are directly exchanged.
  Raw IP has both advantages and disadvantages.  Advantages:

  o  No handshaking (= faster connections)

  o  Authorization by Caller ID (= fast, safe, no password)

  o  Fixed IP address (= a broken connection can be continued by
     redialing)

  o  Higher data transfer rates

  o  Better stability (smaller driver = almost no bugs)

     Disadvantages:

  o  No handshaking => Configuration must occur beforehand (IP
     addresses,...)  => sensible to use for only for one provider at a
     time

  o  Authorization only by Caller ID => Dialin only possible from one's
     own number

  o  Fixed IP address => must be known ahead of time, more IP addresses
     required, no dynamic assignment of addresses possible.

     From this summary it should be clear under what conditions it makes
     sense to use raw IP.


  14.2.  rawip_capi: How can I use Raw IP with the new CAPI 2.0 inter-
  face (mISDN)?

  Raw IP can still be used with the new CAPI interface and drivers by
  using ItunD, the ISDN tunnel Daemon. ItunD (ISDN tunnel Daemon)
  provides a network tunnel over ISDN lines using the CAPI interface.
  The ISDN4Linux isdn-net (raw IP) devices are supported.

  You can find ItunD at: <http://sourceforge.net/projects/itund/>



  15.  ttyI: Configuration of the ttyI* devices (`Modem emulation')



  15.1.  ttyI_nomodem: Don't the ttyI* devices emulate an analog modem?

  No! The ttyI* devices just offer a similar communication interface,
  where all commands are started with AT. This makes it easy to reuse
  software that was written to communicate with a modem. Communication
  with a remote analog modem is not possible via the ttyI* devices! The
  real communication happens in digital, not analog form.


  15.2.  ttyI_dev: Which devices should I use for calls out or calls in?

  Only the ttyI* devices should be used. The cui* devices are created
  only for reasons of compatibility. Now that there is mgetty, there is
  not reason to use the cui* devices any longer. If they are used,
  locking will not work correctly (several programs could simultaneously
  attempt to use the same device).


  15.3.  ttyI_hdlc: How to I switch the modem emulation from X.75 to
  HDLC?

  With the option S14=3; for example "ATS14=3".


  15.4.  ttyI_uucp: How can I poll with Taylor-UUCP using isdn4linux?

  As usual, the same as with serial interfaces. Simply use /dev/ttyI* as
  the device, as the init string for the modem emulation you have to set
  the correct MSN or EAZ with "AT&Emsn/eaz".


  15.5.  ttyI_speed: What speed should I set for the ttyI* devices?

  It doesn't matter. The driver internally always uses the full speed
  that ISDN offers. This is also given in the connect string.


  15.6.  ttyI_max: How many devices are the maximum supported number?

  The maximum can be set by configuring ISDN_MAX at compile time.
  Currently, it is set to 64 by default, which means that up to 64 ttyI
  devices are supported.



  15.7.  ttyI_nocarrier: When I dial with "ATD....." I always get a "NO
  CARRIER".

  Before dialing, you have to enter "AT&E123456" (if 123456 is your own
  MSN; with 1TR6 give the one-digit EAZ).



  15.8.  ttyI_noincall: My ttyI* device/pppd does not recognize an
  incoming call.

  Probably you did not tell the modem emulation with AT&E which MSN to
  use. For example, use AT&E123456; if your MSN is 123456.

  Please also note that only one application using the ttyI* devices
  will receive a ring for a particular MSN. Which will ring is selected
  by a loop over all ttyI* devices. A device is selected based on
  whether its parameters match (protocol, MSN) and whether it is
  currently not involved with another call. Therefore it does not make
  sense for multiple applications to register for the same MSN via the
  ttyI* devices, unless you want to have load sharing between the
  applications.


  15.9.  ttyI_callphone: Why can't I dial my telephone or fax from the
  ttyI* devices?

  You can. However, ISDN differentiates different services. All outgoing
  calls with the ttyI* devices use the service "Digital Data", which is
  incompatible with telephone or fax, so the call never gets through.
  Change the service recognition with the ATS18=1 command to audio, then
  you can dial your telephone or fax.


  15.10.  ttyI_noconnect: I can't get a connection to my ISDN mail-
  box/BBS.

  There are several possible protocol parameters. There is HDLC, there
  is X.75 and there are several possible block sizes with X.75. You can
  tell the modem emulation about the block size with AT&. Mostly used is
  a block size of 2048 byte: AT&B2048.


  15.11.  ttyI_forcehangup: My modem emulation hangs. How can I force my
  card to hang up?

  If there is really no process using your modem emulation any more,
  try:

  ______________________________________________________________________
  cu -l /dev/ttyI0 dir
  +++
  ath0
  ~.
  ______________________________________________________________________


  Before and after "+++" you have to wait for a second, otherwise the
  modem emulation won't recognize it as the escape sequence (like a nor-
  mal modem).  Watch out for processes that (with "ps -ax") have some-
  thing like "I0" or "I1" in the second column, they have an ISDN termi-
  nal as their controlling terminal. You may have to kill them with
  kill.


  15.12.  ttyI_channelclosed: During a tty connection, I get a message
  from the kernel: "teles_writebuf: channel not open". Then no more
  input is accepted for this connection.

  Can happen when the partner cannot handle the large frames from i4l
  and simply closes the B channel during the transfer. Try making the
  frames smaller with AT&B512.


  15.13.  ttyI_x75uucp: When I use UUCP with X.75, I always get transfer
  errors!

  Andreas Gutzwiller andy@hippo.proxyon.imp.com wrote on 5 Dec 1996:

       I had to use the following settings, otherwise I only had
       errors.  # Prot protocol-parameter g packet-size 512 proto-
       col-parameter g short-packets y protocol-parameter g window
       7 protocol-parameter g remote-window 7 protocol-parameter v
       packet-size 512 Now with large packets I can get ca 7300
       cps.


  Holger Burbach holly@cthulhu.pfalz.de on 5 Feb 1997 had another solu-
  tion:

       I have several XP users who poll without any problems. I did
       the following: First I set the send packet size for ttyI?
       to 1024 ("AT&B1024") and then set the packet size for the g
       protocol in UUCP: protocol-parameter g packet-size 2048 pro-
       tocol-parameter g remote-packet-size 0 As I said, it works
       fine..



  16.  dod: Unwanted dialout on demand

  16.1.  dod_how: How does dialout on demand work?

  After you habe set up a network interface, and defined a route to it,
  then all ip packages will be routed to this interface. If the autodial
  mode has been enabled (see question ``dialout_dialmode'' on the
  dialmodes) then the interface will automatically trigger a dialout
  when it receives ip packages. (This means that any user can trigger a
  dialout.)

  Example: You open a browser with no or a local homepage. Nothing
  happens. You enter some url to connect to, this will send ip packages
  to the network interface - thereby triggering a dialout.

  Using dial on demand is a potentially dangerous (means expensive)
  feature: see question ``dod_disaster''.


  16.2.  dod_disaster: What is a charge unit disaster?

  The charge unit disaster can happen for many reasons (see question
  ``dod_causes'' for more details). However the results are identical:
  your computer dials out to your Internet Provider more often than you
  want, thereby increasing your telephone bill by a large amount
  (especially when you are not only charged for time online, but also a
  minimum amount/charge unit for every dialin). The term 'large amount'
  is rather flexible. Anything is possible:

  o  "Cheap": any DNS request opens the line, causing several dialouts
     per day (depending on your programs). If this happens 10 times a
     day, this makes up about 300 unneeded dialouts per month.

  o  "Not so cheap": Some Windows 95 computer in your LAN triggers a
     dialout every 15 minutes for one of its silly broadcasts (see
     question ``dod_win95''). Makes up 96 dialouts per day, or 2880 per
     month.

  o  "Medium": Your email client is configured to check every 5 minutes
     whether you have new emails at your Internet Service Provider.
     Makes up 288 dialouts per day, 8640 per month.

  o  "Expensive": Keep alive packets prevent that your line ever hangs
     up.  Your line is always on. Note: THIS IS NOT THE WORST CASE!

  o  "More Expensive": Something goes wrong with dynamic addresses,
     leaving sockets open when hanging up. The sockets trigger another
     dialout when they try to resolve this, but since now you have a new
     ip address, the issue can't be resolved. The line will eventually
     hang up (when depends on your timeouts), but then re-open - since
     the sockets trigger another dialout.  If you are unlucky, you never
     get the same ip address back, so this repeats continuously. Your
     line is almost always on, but on top of it you have to pay for many
     dialouts: if your timeout is 30 seconds, this makes up 2880
     dialouts per day, 86400 per month.

  o  "Most Expensive - Worst Case": You misconfigure dialout/callback,
     so that when your (the initiating) computer dials out to your
     Internet Provider, who then hangs up on you (e.g. authorization
     failed - maybe he also has some misconfiguration or unhooks despite
     being down), your computer immediately dials out again. This is
     only limited by the amount of time needed to dial out. If we assume
     2 seconds for each attempt (conservative estimate), this makes up
     43200 dialouts per day, or 1296000 per month!

  This is no joke, and all these things have actually happened, even to
  real isdn4linux experts! See question ``dod_off'' on how to avoid any
  risk of this happening to you.


  16.3.  dod_causes: What can cause a charge unit disaster?

  There are many possibilities. See question ``dod_strategy'' on how to
  track down what is happening to you. See question ``dod_disaster'' on
  how expensive that could be. Here a non-comprehensive list of causes:

  1. You compiled your kernel with the option Bridging by mistake.

  2. ARP requests or broadcasts? You should run ifconfig with the
     options -arp and -broadcast to keep from opening connections in
     this way. You can recognize this one when you have a dialout, but
     no data is transferred.

  3. Other Broadcasts from the interfaces were being forwarded by ISDN.

  4. If IP connections are still open with the line is disconnected and
     IP addresses are dynamically assigned, then the disaster is
     inevitable.  Then a new connection is started to bring down the
     open IP connections, which fails because the IP address is now
     different. The line is hung up, but the IP connections are still
     open, the line is dialed again, and so on... This can only be
     avoided with the RST-provoking mode (see question
     ``dod_rstprovoking''. A patch for it may be needed if it is not
     included in your distribution. The patch had found its way into the
     2.0.x kernels, but not into 2.1/2.2/2.3. However, you can get an
     adjusted patch for 2.2.x kernels and some background information
     about it from:  <http://www.another.de/linux/router/>. See also
     question ``syncppp_1stpacket''.  Also make sure to use ipppd's
     "defaultroute" option rather than route add/del default in ip-
     up/ip-down with it.

  5. TCP retries trigger dialout: when the kernel tries to send tcp
     packets and does not receive any answer, then it will retry to send
     them (usually every 120 seconds). Check out whether you want to
     adjust the following parameters:

     o  /proc/sys/net/ipv4/tcp_syn_retries

     o  /proc/sys/net/ipv4/tcp_retries1

     o  /proc/sys/net/ipv4/tcp_retries2

     Documentation can be found in /usr/src/linux/Documenta-
     tion/proc.txt.

  6. Requests from your local DNS trigger a dialout: see question
     ``dod_localdns''.

  7. Sendmail triggers the dialout: see question ``dod_sendmail''.

  8. Windows 95 clients trigger the dialout: see questions
     ``dod_win95'', ``dod_localdns'', and ``dod_win95b''.

  9. Samba triggers the dialout: see question ``dod_samba''.

  10.
     Netscape triggers a dialout when started: see question
     ``dod_netscape''.

  11.
     dhcpd triggers dialouts: switch it off, and verify your
     configuration...

  12.
     Manually close IP connections which are still open when the line
     goes down: see question ``dod_closeipconnect''.

  13.
     Your computer is crashed, but still processes interrupts: see
     question ``dod_onlineoncrash''.


  16.4.  dod_off: How can I safely turn off dialout on demand?


  1. To always dial out manually, set your dialmode to manual (see
     question ``dialout_dialmode'').  Then use isdnctrl dial <device> to
     dial out, and isdnctrl hangup <device> to hangup.

  2. Set your dialmode properly (see question ``dialout_dialmode''). For
     example, set dialmode to manual in ip-down. Then dialouts will only
     be possible once after setting dialmode to auto.

  3. Delete the telephone number of the interface, or set an invalid
     one.  Then you can see from the complaints in the syslog whether a
     process wants to send packets out to the world.

  4. Switch the system off.

  5. Delete your route to the ISDN device.  For example, to disable any
     automatic dialouts:

     ___________________________________________________________________
     /sbin/route del default
     /sbin/isdnctrl system off
     /sbin/ifconfig ippp0 down
     ___________________________________________________________________


  To get things running again:

  ______________________________________________________________________
  /sbin/isdnctrl system on
  /sbin/ifconfig ippp0 up
  /sbin/route add $GATE-IP dev ippp0
  /sbin/route add default ippp0
  ______________________________________________________________________


  The latter method has the disadvantage that dialin is then no longer
  possible.



  16.5.  dod_strategy: How can I track down unexplainable dialouts?

  Finding the reason of unexpected dialouts is the first step to
  stopping it.  However, finding is usually more difficult than fixing
  the problem. This is what you can do to track it down:

  o  First disconnect your dialout server from your LAN to find out who
     is responsible for the dialouts: the dialout server himself, or
     some clients in your LAN. For Windows clients, see question
     ``dod_winclient''.

  o  Try to find out which TCP/IP packet triggers the connection with
     "isdnctrl verbose 3". A message should appear in the kernel message
     queue (visible with dmesg), like: OPEN: 141.76.60.54 -
     193.171.67.253 TCP, port: 1686 - 540 In this example, our computer
     is trying to pick up mail on port 540 (UUCP over TCP/IP over ISDN)
     - the port number can be looked up in /etc/services. Please note:
     only the triggering packet will be logged.

  o  If you are using ipppd: get a tcpdump which can show data with the
     syncPPP encapsulation (this may require a patch - see question
     ``trouble_tcpdump'').

  o  Try to turn off one daemon after the other and see if things have
     finally quieted down. named, sendmail, and also smbd (Samba) are
     likely candidates to open connections (see questions
     ``dod_localdns'', ``dod_sendmail'', ``dod_samba'').

  o  If broadcasts are your problem, you can also redirect the broadcast
     address to the dummy0 interface. It's not clean, but it works.


  16.6.  dod_winclient: Can it be that the Win95 machine on my LAN is
  causing automatic dialouts?

  Yes. When Windows 3.11/95 is started, then it tries to talks to the
  name server of your provider (if known), trying to look up some
  domains (e.g. WORKGROUP.xxx). To avoid this, these are your options:

  o  Switch off the feature Use DNS for Windows Names Resolution on all
     Windows computers on your LAN.

  o  Set up a local DNS name server such that it will answer all
     requests.  See question ``dod_localdns''.


  16.7.  dod_localdns: I have set up a local DNS name server. Why does
  it cause unwanted dialouts? How can I find the cause?

  Turn on debug level 1 in named and look at the logfile in /var/tmp.
  Often, you can find regular DNS requests from Windows machines.  The
  problem is that names like "WORKGROUP.domain.de" are requested, i.e.
  names that the DNS could not know. Windows seems to be looking for its
  master browser or a domain controller (if you are fluent in German,
  see ct 12/99, page 224: "Schnitzeljagd - Netzwerkumgebung und
  Browserdienst im Windows-Netzwerk" for more details). To work around
  this problem, you can set up your domain name server with cname =
  "WORKGROUP.domain.de" (other domain names are also possible). Or set
  up a Primary Domain Controller within your LAN. You can also use diald
  to control dialouts for DNS request.


  16.8.  dod_forwarddns: I have set up my name server in 'forward' mode,
  with one forward address. Now it dials out about every minute?


  From time to time, the name server will query its forwarder, which
  will trigger a dialout. Since your ISP uses dynamic ip addresses, the
  request is sent out with the wrong ip address at startup of the dial-
  in connection.  Therefore, no answer will be received. Bind waits for
  one minute before resubmitting. If your line has come down in the mean
  time, this will trigger a new dialout, resulting in a different ip
  address, and so on...

  For a workaround to this problem you can shorten the retransmission
  time as described in question ``dialout_bind''.

  Alternatively, you can set the option "dialup yes;" in the options
  block of named.conf. This will cause named to do only one interaction
  with a forwarder (triggering a dod) at startup. After that it will
  wait for some very long interval (24h?) before another query with the
  forwarder. Only during actual lookup it will do negotiations with the
  forwarder (this is usually when you have already dialed out anyway).


  16.9.  dod_sendmail: How can I get sendmail to not initiate any con-
  nections without local mail being left undelivered?

  First you have to get sendmail to no long open any DNS connections.
  You need to activate the following features: "nodns", "nocanonify".

  If you have a smarthost, you need to make sure that this name does not
  call the name server. You can either set it directly as an IP address,
  or add the name to /etc/hosts (/etc/host.conf should then contain
  "order hosts bind")

  You should set all non-local mailers as "expensive"
  ("define(SMTP_MAILER_FLAGS, e)"), and then forbid sendmail with
  "define(`confCON_EXPENSIVE', `True')" from automatically connection to
  expensive mailers. The call to sendmail should no longer include a
  time for the "-q" option (e.g. only "-bd -os -q"). "-os" means that
  all mail will be queued (which won't prevent local mail from being
  delivered immediately). The only catch is that when booting, mail that
  might still be in the queue will be sent by sendmail, even though the
  network is not yet up. Therefore, when booting you should remove all
  mail from /var/mqueue before starting sendmail, and then return it
  once sendmail has been started.

  Mail to expensive mailers will now only be send with the explicit call
  "sendmail -q".


  16.10.  dod_samba: The samba package always triggers dialouts for me.
  How can I prevent this?

  When nmbd starts up it tries to bind to 0.0.0.0 or all interfaces,
  which is what triggers the ISDN dialup.  The best way to solve this is
  to set "bind interfaces only = yes" and "interfaces = eth0" in
  smb.conf (in case you want to use Samba only in your LAN).
  Alternatively, you can give the samba daemon an internal ip address
  upon startup. First find out which ip address samba is trying to
  connect to (e.g. with netstat or tcpdump). Then start samba with:

  ______________________________________________________________________
  nmdb -S -B 192.168.99.255 -I 192.168.99.99
  ______________________________________________________________________


  if your Linux computer has 192.168.99.99 as ip address, and all users
  are in the same subnet (192.168.99.255).


  See also the above question:  set -broadcast and possibly -arp when
  defining the interfaces!

  Check out the help pages for the Samba configuration file for further
  possibilities on preventing dialout (I was told there should be some
  explicit dialup parameter which prevents it to cause many dialouts).


  16.11.  dod_netscape: How can I get Netscape to quit initiating
  dialouts when starting?

  Most likely in the preferences a non-local home page has been listed.
  Only a home page that Netscape is able to load immediately (e.g.
  "file://localhost/xxx") won't cause an immediate dialout.
  Alternatively you can also set up a cache daemon that saves pages that
  are often needed.

  Second check your proxy settings. When giving a complete name instead
  of an ip address, Netscape may try to do a DNS lookup to resolve the
  name to an ip address on startup. In this case provide Netscape with
  an ip address.

  Another thing is that Netscape tries to contact its news server. If
  you don't want to use this feature then you can enter the name
  Netscape uses for lookup (probably 'news') in your local DNS or in
  your /etc/hosts, and let it point to localhost.


  16.12.  dod_rstprovoking: Why should I use the RST-provoking
  mode/patch?

  If on every dialup (in auto dialout mode) you get a different ip
  address (dynamic ip), and the dialup connection gets terminated (e.g
  due to inactivity) while some ip connections have not yet been closed,
  then the following problem will occur: when the program tries to close
  the connection this will trigger a new dialout.  Since this will yield
  in a new ip address, the closing attempt will fail.  After the timeout
  period another dialout will be attempted, with the same result,
  leading to a dial on demand disaster.  To prevent this problem the
  RST-provoking mode has been invented.  If on the closing attempt a new
  dialout is opened and the ip address changes, then the kernel will
  send a ip packet with the reset flag on. This will close down the open
  connection, preventing the dial on demand disaster.  To activate the
  RST-provoking mode use the command

  ______________________________________________________________________
  echo 7 > /proc/sys/net/ipv4/ip_dynaddr
  ______________________________________________________________________


  Use 5 instead of 7 to prevent syslog warnings. Check the current sta-
  tus with:

  ______________________________________________________________________
  cat /proc/sys/net/ipv4/ip_dynaddr
  ______________________________________________________________________


  Your distribution may or may not have the patch for this rst-provoking
  mode included, it was not liked in the kernel code for kernels newer
  than 2.0.x.



  16.13.  dod_closeipconnect: After closing the line, I discover with
  netstat -nt  that IP connections are still open. How can I close these
  manually?

  This may only work with the RST-provoking mode (mentioned in question
  ``dod_causes''): You can bring the interface "down" then back "up".
  When you do this, it will try to dial out. But if you have removed the
  outgoing telephone number, then "no outgoing number..." appears in the
  syslog, and as soon as the interface is "up", all connections will be
  closed.

  You can prevent those open IP connections to trigger new dialouts if
  you add a special firewall rule in /etc/ppp/ip-down, and remove it in
  /etc/ppp/ip-up. This firewall rule drops all tcp packets which are not
  in SYNSENT state. Add this in /etc/ppp/ip-down for a 2.2.x kernel:

  ______________________________________________________________________
  ipchains -A output -j DENY -p tcp -i <interface> ! -y
  ______________________________________________________________________


  Add this in /etc/ppp/ip-up:

  ______________________________________________________________________
  ipchains -A output -j DENY -p tcp -i <interface> ! -y
  ______________________________________________________________________


  (As is the case for all firewall rules: it is best to put this into a
  separate script which is called with either a start or a stop parame-
  ter.)  Please note that this firewall rule only matches whole packets,
  no fragments.  A fragment will always bypass the firewall and trigger
  a dialout.


  16.14.  dod_onlineoncrash: Is it possible that even with a crashed
  computer a ISDN connection remains open (and the charge units accumu-
  late)?

  The ISAC chipset, which is in use on many ISDN cards, can be run in
  either auto mode, or in non-auto mode. When run in auto mode, the
  connection could be up when the computer is crashed (the card keeps it
  up and running).  Since the HiSax driver uses nonauto mode, this
  should not happen with ISDN4LINUX. Once no interrupt is processed on
  your machine, the connection will stop at maximum half a minute later.
  Only in the unlikely event that your machine is crashed, while
  interrupts are still processed normally, this could happen.



  17.  chargeint: Chargeint

  17.1.  chargeint_whatis: What does Chargeint?

  Chargeint is a way to reduce your costs when you have charges based on
  your time online, and the interval between two charges (the Charge
  Interval) is relatively large (e.g. per minute).

  Chargeint only hangs up two seconds before the end of a charge unit.
  isdnlog can be used to set the length of the charge unit (i.e. Charge
  Interval) according to the time of day and the date.



  17.2.  chargeint_config: How should I configure Chargeint?

  You can set the length of a charge unit manually via the isdnctrl
  parameter chargeset, or set up isdnlog to do this automatically for
  you:

  1. Set up isdnlog, so that it has all the information about your
     location and your telephone company (so that it knows your rates).

  2. Start isdnlog with the options -h0 and -w.

  3. Set your huptimeout as you like (idle time needed before i4l will
     consider a hangup). E.g.:

     ___________________________________________________________________
     /sbin/isdnctrl huptimeout ippp0 5
     ___________________________________________________________________


  Then i4l will hang up 2 seconds before the end of your charge unit, if
  the 5 seconds before (huptimeout) no activity has happened on the
  line.


  17.3.  chargeint_whennot: When does it not  make sense to use the
  chargeint?


  1. It does not make sense to use Chargeint when you are charged per
     data volume, or per flat fee. Chargeint can only reduce your costs
     when you are charged per time online.

  2. Also it makes no sense if you are charged in small units (e.g. per
     second rather than per minute).

  3. Chargeint may or may not make sense when every new dialup costs you
     fixed amount on top of the variable charges (depending on the
     rates).

  4. There are problems when the ip address is assigned dynamically. A
     broken connection cannot simply be restarted (since the IP address
     has changed). The interrupted FTP, telnet or WWW connection must
     then be newly established.


  17.4.  chargeint_correcttime: How can I be sure that the chargeint
  patch is using the correct time?

  It's best to synchronize the clock in your own computer with that of
  the switching station by calling isdnlog with option -t2.


  17.5.  chargeint_nohangup: The connection doesn't end with timeout.

  Chargeint will only hangup if there was no activity on the line.
  Possibly your service provider uses a router (e.g. Cisco) which sends
  a "keep alive" packets every ten seconds. If the Cisco doesn't get an
  answer for its keep alive packets then it will stop routing. This
  normally happens after the 4. or 5. keep alive packet. Very recently
  (begin of 2001), support for Cisco's keep alive packages has been
  corrected, so you can either use it, or tell the provider not to use
  keep alive packets ("no keepalive" in the Cisco configuration).

  It could also be that it's not the keep alive packets that are keeping
  the connection open, but rather OSPF routing updates. The sending of
  these updates can only be switched off on the Cisco. You can configure
  "snapshot server" on the BRI interface. That means it will send out
  routing updates only when they are received through this interface.

  However, nowadays the most likely cause for open connection is that
  connection requests looking for a backdoor or a file sharing
  application cause issues like this. You can use the active-filter
  option of ipppd to indicate which packets should be regarded as link
  activity.  See the man page for more details. A configuration could be
  like this:

  ______________________________________________________________________
  active-filter 'outbound and not icmp[0] == 3 and not tcp[13] & 4 != 0'
  ______________________________________________________________________



  18.  2channel: Channel bundling (MPPP, raw bundling)

  18.1.  2channel_whatis: What is channel bundling and how can I use it?

  Channel bundling is currently supported by isdn4Linux in two
  variations:

  o  Raw Bundling (configuration of so-called slave channels)

  o  MPPP (based on syncPPP)

     Both variations have their own advantages and disadvantages. See
     the following questions. Dynamic adjustment is supported for MPPP
     by the program ibod - see question ``2channel_mpppconfig'' for more
     details.


  18.2.  2channel_raw: What is raw bundling?

  Raw bundling works similarly to raw IP, only with several channels.
  Therefore, it has the theoretical advantages and disadvantages of raw
  IP. Raw bundling requires a network interface for each channel that is
  used. One network interface, the so-called master interface, controls
  the establishment and breaking of connections. For each further
  channel, an additional so-called slave interface is configured, that
  is automatically switched on by the master interface.


  18.3.  2channel_rawconfig: How do I configure raw bundling?

  The master interface is created as usual with

  ______________________________________________________________________
  isdnctrl addif master interface
  ______________________________________________________________________


  and configured. For all required slave channels, slave interfaces are
  created with the command:

  ______________________________________________________________________
  isdnctrl addslave master interface slave interface
  ______________________________________________________________________


  and configured as usual (e.g. "isdnctrl sdelay slave interface
  delay").

  18.4.  2channel_rawgoodbad: What are the advantages and disadvantages
  of raw bundling?

  Raw bundling has all the advantages and disadvantages of raw IP.
  Compared to MPPP, raw bundling has the advantage that isdn4linux
  itself can open and close the needed slave channels. Unfortunately raw
  bundling still has problems with transfer rates. See the further
  questions below.


  18.5.  2channel_mppp: What is MPPP?

  MPPP or MP or MPP (Warning: MP is also an acronym for 'Multi
  Processor') stands for Multi Point to Point and means bundling of
  several channels to one logical stream. It's a variation of the normal
  syncPPP. Accordingly, it inherits all its advantages and
  disadvantages. Just for your information: ipppd does MPPP according to
  RFC 1717, instead of the newer RFC 1990 (MLP).

  In contrast to raw bundling only one net interface is needed as
  interface to the ipppd, since the ipppd handles all its channels by
  itself. Incoming data is distributed round-robin by the ipppd on all
  available channels.  These channels do not necessarily have to be ISDN
  channels. In theory, modem connections could be mixed with ISDN
  channels. However, here we only cover ISDN channels.


  18.6.  2channel_mpppgoodbad: What are the advantages and disadvantages
  of MPPP?

  A disadvantage is that the slave channel has to be activated
  "manually". ipppd cannot by itself turn the slave channel on and off
  as it needs to. The normal automatic functions of ipppd are either
  unreliable (auto hangup) don't work at all (auto dial).  This is not
  true for the other encapsulations. The transfers rates are very good
  (ca. 30 KB/s with 4 channels).


  18.7.  2channel_mpppconfig: How do I configure MPPP?

  First ensure that support for MPPP has been switched on for
  compilation of your ISDN modules. Then define a (normal) interface for
  ipppd (e.g.  "isdnctrl addif ippp0", etc). This interface will be used
  as your master interface.  Then you must configure a slave device for
  every additional channel (e.g.  "isdnctrl addslave ippp0
  <slave_interface>", configure slave_interface, etc - see the i4l
  manual for more).  To enable MPPP negotiation, ipppd must be called
  with the "+mp" option and both devices have to be given to ipppd.
  Please note that the name of both devices has to start with "ippp".

  To use channel bundling you must first activate the 'master' or
  initial call. Now you can add the slave channels with the command:

  ______________________________________________________________________
  isdnctrl addlink device
  ______________________________________________________________________


  and close them with the command:

  ______________________________________________________________________
  isdnctrl removelink device
  ______________________________________________________________________



  This is different to other encapsulations of isdn4linux!  If addlink
  gives you error -2, then this means that there are no slave devices
  configured. Error -5 means that ippp0 is not connected.

  Please also note, that the slave device has to be in dialmode auto for
  this to work. For manual control, use

  ______________________________________________________________________
  isdnctrl dial slave
  ______________________________________________________________________


  and

  ______________________________________________________________________
  isdnctrl hangup slave
  ______________________________________________________________________


  When using manual control please ensure that the slave device is shut
  down before the master device. Currently (August 2002) there is a
  hard-to-fix bug in the MPPP code which will cause a crash on the next
  dialout. A patch exists which cures the symptoms to prevent the crash
  (see mailing list). However, since the dialout will fail in any case
  it is best to avoid this situation altogether by using the proper
  shutdown sequence.

  With syncPPP, there is no automatic activation of slave devices, they
  have to be added and removed. However, there is the program ibod
  available, which can do this automatically. Have a look at:
  <http://www.compound.se/ibod.html> or (for a version extended by
  Karsten Keil): <http://www.suse.de/~kkeil/xibod/>

  In the file etc/rc.isdn.syncppp.MPPP in the isdn4k-utils package you
  can find a sample script (unfortunately missing in some i4l versions).

  Please note that your Internet Provider has to allow you to make use
  of these features. Also, there may be a limit on how many channels you
  are allowed to open at the same time. It could be that all links are
  dropped when you exceed this limit.


  18.8.  2channel_mpppcompile: I tried MPPP but it doesn't work. The
  ipppd writes in the debug log something like: " ...  rcvd
  (0)(proto=0x3d) c0 00 00 00 80 fd 01 01 00 0a ... sent (0)(LCP ProtRej
  id=0x2 00 3d c0 00 00 00 80 fd 01 ..."

  You forgot to compile MPPP/RFC1717 support into the ISDN Subsystem.
  Recompile with this option enabled.


  18.9.  2channel_cantlocateippp1: When trying to use MPPP I get the
  error message "modprobe: Can't locate module ippp1" and "ipppd:
  ioctl(SIOCSIFMTU): No such device..."?

  This is a pecularity of ipppd. It tries to set MTU even for slave
  devices, and the kernel can not find a corresponding network device.
  You can safely ignore this information message, MPPP should work
  nevertheless.


  18.10.  2channel_multiplenumbers: How can I set up multiple number
  when using MPPP?

  Master and slave device are fully independent of each other, except
  for using the same network device to deliver packets. Setting up
  multiple number for master and slave devices will result in
  synchronized dialout (to the same number). Therefore it is best to
  give the slave device no number by default and set up the slave with
  the same number as the master in some ip-up script.


  18.11.  2channel_freebchannel: How could I set up isdn4linux to free
  the second B-channel if a phone call comes in?

  Well, this is a tough one, due to technical limits. Even if isdn4linux
  freed a B-channel, the exchange would not repeat the setup call.
  Therefore, the phone would not ring. The phone only signals a second
  incoming phone call if you are on the phone with another call that
  could be suspended.

  One option would be that isdn4linux frees one B-channel, then takes
  the call, and transfers it to the phone via ECT (explicit call
  transfer); however, this feature requires proprietary (unknown)
  protocol extensions, and is usually only available behind large
  private exchanges - therefore not implemented in isdn4linux.  Another
  option is that isdn4linux frees one B-channel, takes the call, then
  suspends it. However, the user would have to know to resume it without
  any phone ringing.  The most sensible option is that you handle it
  will a phone application making use of isdn4linux. Possibly ant-phone
  could be used for such a purpose:
   <http://www.antcom.de/>



  19.  remote: Pecularities of the remote ISDN device

  19.1.  remote_win95: How do I configure Windows95 to dial successfully
  into my isdn4linux computer?

  Configure your dialout network like this:

  o  Type of server: PPP:Windows 95, Windows NT 3.5, Internet

  o  Extended options: unselect all options

  o  Network protocolls: only select TCP/IP

  o  Standard gateway

  o  Switch off IP header compression for the beginning (for more
     details on compression with ipppd see question
     ``syncppp_compression'').

  o  Remainder of TCP/IP stuff (ip address, nameserver,...) as applies
     to you.


  19.2.  remote_mac: I'd like to exchange data with a Macintosh
  (Leonardo card), what do I or the Mac user have to watch out for?

  Currently, the Leonardo protocol is not supported by i4l. When you
  call the Mac, he should set the protocol to X.75 or HDLC. When he
  calls you, he must explicitly set the protocol (e.g. by inserting an
  "X" for X.75) in the called number.


  19.3.  remote_macpap: A Macintosh with a Leonardo card tries to call
  in, and wants to negotiate chap md5. How can I switch it to CHAP/PAP?


  You can't. The user should use LeoPort (always included with the card)
  and switch the CTB port to the ISDN card. Then with FreePPP 2.5v2
   <http://www.rockstar.com> set the Leo as the modem and configure
  FreePPP as usual. Then PAP/CHAP can be set.


  19.4.  remote_cisco: How does isdn4linux work with a Cisco (HDLC) on
  the other side?

  On the Cisco router the "keep alive" packets have to be turned off.
  isdn4linux has to be configured with HDLC, transparent, with Cisco
  encapsulation:

  ______________________________________________________________________
  isdnctrl l2_prot <interface> hdlc
  isdnctrl l3_prot <interface> trans
  isdnctrl encap <interface> cisco-h
  ______________________________________________________________________



  19.5.  remote_ispa: What settings does ISPA etc. (DOS, Windows) need
  to work with the standard settings of isdn4linux?

  The following configurations are possible (these also apply to the
  other drivers from H. Hanewinkel, i.e. CINDI, CANDI, WISPA...)  that
  can be found via
   <http://www.informatik.uni-bremen.de/~henker/dank>

  i4l side                             ISPA side
  ====================================================
  isdnctrl l2_prot isdn0 hdlc           \
  isdnctrl l3_prot isdn0 trans              -h0
  isdnctrl encap   isdn0 rawip          /
  ----------------------------------------------------
  isdnctrl l2_prot isdn0 hdlc           \
  isdnctrl l3_prot isdn0 trans              -h1
  isdnctrl encap   isdn0 uihdlc         /
  ----------------------------------------------------
  isdnctrl l2_prot isdn0 x75i           \
  isdnctrl l3_prot isdn0 trans              -l0
  isdnctrl encap   isdn0 rawip          /
  ----------------------------------------------------
  isdnctrl l2_prot isdn0 x75i           \
  isdnctrl l3_prot isdn0 trans              -l1
  isdnctrl encap   isdn0 uihdlc         /
  ----------------------------------------------------


  The parameter with the least problems is -h0.



  20.  leased: Leased lines

  20.1.  leased_flatrate: What's the difference between a leased line
  and a flat rate?

  A leased line requires a special setup of your S0 interface. After
  that, you can not reach any other destination than the one the leased
  line is set up for. It's also rather expensive.

  A flat rate is still a normal dialup, therefore the setup should be
  done like any dialup connection. The only difference from a normal
  dialup is the pricing. See section ``dialout''. Also please note that
  the connection on a flat rate will usually be stopped by your internet
  provider if you stay on for too long - so you can not rely on being
  online all the time, if this is what you desire.


  20.2.  leased_nosignal: How does establishing and ending a connection
  work with D64S without signaling?

  The data is simply sent out! Other than a ping, there is no way to
  find out whether the D64S or 2MB line is up or not. Only S01 or S02
  lines have a D channel and have something to use with signaling,
  however the best known solutions also use this 16kb for data transfers
  to get 144kb instead of 128kb (i4l can only to 128kb).


  20.3.  leased_hisaxconfig: With i4l, how do I configure my card on a
  D64 leased line?

  A later version of the new HiSax driver supports D64. Configuration is
  normal with the following specialities. HiSax has to be run in leased
  mode:

  ______________________________________________________________________
  /sbin/hisaxctrl HiSax 5 <channel>
  ______________________________________________________________________


  in case HiSax was loaded with "id=HiSax", where <channel> can be 0 or
  1. Additionally to the normal configuration, the following commands
  are important:

  ______________________________________________________________________
  /sbin/isdnctrl bind HiSax,<channel>/sbin/isdnctrl eaz isdn0 1
  /sbin/isdnctrl addphone isdn0 out 2
  /sbin/isdnctrl addphone isdn0 in  3
  ______________________________________________________________________


  if "isdn0" was used as interface name. The interface has to be set to
  "up" and a route associated with it. See the Readme's in the HiSax
  package.


  20.4.  leased_x75: How do I configure X.75 on a D64 leased line?

  Use a later HiSax version. First initialize the ttyI* device you want
  to use with "AT&E0" (set usage of first B-channel) and "ATS0=1"
  (autoanswer on first ring). Then set HiSax in leased mode:

  ______________________________________________________________________
  /sbin/hisaxctrl HiSax 5 <channel>
  ______________________________________________________________________


  This will simulate a call for MSN1 on the configured channel (0 or 1)
  (incoming number = LEASED0).


  20.5.  leased_splitline: With i4l, can I use one channel as a leased
  line and the other as a dialup line?

  Yes and no. You can configure HiSax for both at the same time, however
  you can only use one of them at any point in time (you have to switch
  off the leased line before dialing out). It may work occasionally
  simultaneously, however the driver has not been written for it so the
  results are not deterministic.  Also make sure that you use the
  correct channel.



  21.  dialin: Configuration of a Dial-In Server

  21.1.  dialin_config: How can I enable others to login via ISDN?

  Some configuration examples can be found at: <http://www.rosat.mpe-
  garching.mpg.de/~web/ISDN.html>.  If you have trouble setting it up,
  try to obtain the latest packages for isdn4linux (see question
  ``distrib_getlatest'').  As usual, you can also ask in the mailing
  list.  In general, there are several ways to configure dialin,
  depending on how you want others to dial in.

  o  Set up networking devices for dialin via syncppp, or rawip. Set
     option secure off to allow everybody to dial in, or set option
     secure on to only allow dialin by the isdn numbers you configure,
     which you set up with isdnctrl addphone <device> in <phonenumber>.
     It has been reported that you need to set option ms-dns for ipppd
     to have successful IPCP negotion.

  o  Use the ttyI* devices for asyncppp or X.75.

     Here some more details for setting up the ttyI* devices. The setup
     is like for a serial port.  Start a getty (mgetty from Gert Doering
     is highly recommended) on one of the ISDN devices (/dev/ttyI*). The
     entry in /etc/inittab looks like this:

     ___________________________________________________________________
     I0:56:respawn:/usr/local/sbin/mgetty ttyI0
     I1:56:respawn:/usr/local/sbin/mgetty ttyI1
     ___________________________________________________________________


  The init string needs to be entered in the mgetty.config, since mgetty
  needs to know which MSN or EAZ to listen to. For example, if your MSN
  is 123456:

  ______________________________________________________________________
  port ttyI0
  modem-type data
  speed 38400
  init-chat "" ATZ OK AT&E123456 OK AT&B512 OK
  ______________________________________________________________________


  For X.75 the block size was set to 512 bytes.  Alternatively you can
  enter the entire configuration onto a single line in /etc/inittab
  (here printed on two lines!):

  ______________________________________________________________________
  i0:45:respawn:/sbin/mgetty -D -m '"" ATZ OK AT&E123456 OK
  AT&B512 OK' -s 38400 ttyI0
  ______________________________________________________________________


  The most elegant way is to use iprofd. This daemon takes advantage of
  the AT&W0 command in the i4l modem emulation. You start iprofd with a
  path as parameter, e.g. "iprofd /etc/i4lprofile" Then with minicom or
  another terminal program, open an ISDN tty device and enter the neces-
  sary AT command by hand.  When finished, enter the command AT&W0, then
  the kernel notifies iprofd to write the current configuration to the
  file. From now on it is enough to start iprofd in you isdn init
  script, and to initialize the appropriate ISDN tty devices with ATZ.
  21.2.  dialin_manyparallel: How can I allow several people to call in
  to me at the same time?

  You have to configure exactly as many gettys or network interfaces as
  the number of people allowed to call in at one time. These gettys or
  network interfaces can be set to the same MSN, since several people
  can be connected to a MSN at the same time (as long as there are B
  channels free).  However, not more than one getty can be assigned to a
  single ttyI* device.


  21.3.  dialin_manycards: When using several ISDN cards, how can I
  react upon on a call received via a specific ISDN card?

  You can use the EAZ mapping feature for this to map incoming MSN
  numbers to new internal MSN numbers, in the same way as described for
  question ``dialout_manycards''. Usage of a card can be prevented by
  using the dash during the mapping. Please note that it is not possible
  to have any limitations based upon the B channel, since channel
  assignment is normally done by the exchange.


  21.4.  dialin_analogditalsamettyi: Can I configure a ttyI* device to
  accept both digital and analog modem dialins?

  Since the digital mode requires different register settings than the
  analog mode, this is not possible. Therefore you have to set up a two
  dedicated devices for this purpose. Please note that analog modem
  dialins are only possible if card and isdn4linux driver support it,
  which is only the case for a few cards.


  21.5.  dialin_fixedip: How can I assign fixed ip addresses per user
  who dials in via ipppd?

  Just specify the fixed ip address with the user name and password in
  the pap/chap-secrets file (see man ipppd).


  21.6.  dialin_hdlc: Someone would like to dial in to my mgetty with
  HDLC. Is ttyI1 correct, or do I have to start with ttyI0?

  No, it doesn't matter. It also has nothing to do with the number of
  the B channel (0 or 1). You just have to activate HDLC in the init
  string (ATS14=3).


  21.7.  dialin_autoppp: Is it possible with mgetty to automatically
  start pppd when LCP frames are received?

  Yes, it is. This feature is called `AutoPPP'. See the configuration
  for mgetty.


  21.8.  dialin_passwd: How can I have (i)pppd check passwords from
  /etc/passwd instead of /etc/ppp/pap-secrets when someone dials in?

  ipppd needs to be started with the options "login" and "auth". In
  /etc/ppp/pap-secrets, each user must have the following line to allow
  only certain users:

  ______________________________________________________________________
  login-name * "" *
  ______________________________________________________________________


  To allow all users simply:

  ______________________________________________________________________
  * * "" *
  ______________________________________________________________________


  The latter can also be achieved when the file pap-secrets does not
  exist.


  21.9.  dialin_ignored: I keep getting the message "isdn_tty: call from
  XXX - YYY ignored". Why does isdn4linux (syncPPP) ignore this dialin
  attempt?

  There are two possible explanations. Either your own MSN (here: YYY)
  is not correctly set with "isdnctrl eaz interface YYY". Or "isdnctrl
  secure interface on" was set, without allowing calls from the incoming
  number (here: XXX) with "isdnctrl addphone interface in XXX".


  21.10.  dialin_async: A SunISDN tries to dial into my i4l system.

  The Sun tries to communicate with asyncPPP. ipppd can't handle this,
  you have to use the ttyI* devices and the standard pppd.



  22.  callback: Callback

  22.1.  callback_delay: An incoming call is rejected by i4l. i4l then
  calls back. The reject is not recognized by the other side which keeps
  on dialing to i4l.

  Most problems with callback can be solved by adjusting the callback
  delay with isdnctrl cbdelay. One second on the triggering side A (set
  callback mode to out) and two seconds on the triggered side B (set
  callback mode to in) has been successful in most cases.

  The reason for the problem is a design bug in the link level driver.
  A calls B to trigger a callback. B rejects the call and calls back to
  A, establishing a working connection within less than 4 seconds.
  However, the triggering call from A to B will need 4 seconds to be
  terminated by the ISDN provider (giving other devices on B's side a
  chance to take the call). When it is finally terminated, the working
  connection from B to A is unfortunately also terminated.


  22.2.  callback_cisco: Somehow i4l can not callback a Cisco?

  Torsten Hentschel Torsten.Hentschel@DInet.de wrote on 3 Oct 1996:

       A Cisco may dial so heavily that the ipppd has no chance to
       callback.  That's how they are programmed (firm statement of
       a Cisco developer): If a Cisco receives a packet that should
       be routed through a "dial on demand" telephone connection,
       and there is a D-channel available for dialing out, it dials
       out immediately.  If in such a situation (which has be the
       case with Delta Internet for half a year now) a Cisco with 8
       D-channels is on the other side and somebody does a simple
       "ping RemoteIP" then the Cisco will use (worst case) all 8
       D-channels to dial out. Of course it can't dial the same
       telephone number with two D-channels in parallel (would be
       immediately busy). Its programming is not so stupid, but it
  sets up the next D-channel for dialout before it assumes the
  previous D-channel as failed. Such a Cisco works like a
  machine gun in respect to dialout. And i4l won't get a free
  D-channel for dialin if the Cisco doesn't want.  The bad
  thing: a Cisco always expects (even when configured on
  "callback client" = i4l dials back) that the other side
  unhooks the line, then both hang up and then comes the call-
  back. Username and password always have to be exchanged
  before the callback is allowed when using PPP, to be sure
  that the person requesting callback is allowed to do so.
  (Cisco seems to obey the rules of the (German) Telekom that
  no information are to be ex- changed without a B-channel
  connection. A callback request just by caller id could in
  doubt be considered as a transmission of information).


  Torsten Hentschel Torsten.Hentschel@DInet.de additionally wrote on 20.
  Nov 1996:

       I've often tried callback over PPP with two CISCOs. From my
       experience, trials in the combination CISCO - Linux will not
       be successful.  A CISCO always handshakes a callback request
       via PPP. To do this, the other side has to first unhook and
       then do all the handshaking (authentication,...). Then both
       hang up and the callback is placed.  isdnctrl commands of
       Linux influence only the kernels net devices and have no or
       hardly any influence on how the ipppd handles callbacks.  He
       does not recognize that he is supposed to expect that the
       remote side calls back.  Accordingly he rejects the offer of
       the CISCO via PPP, that the CISCO is ready to call back.
       Then the CISCO assumes that it should not call back (it
       wants to see an explicit callback request during the PPP
       handshaking).  The CISCO will confirm this when you log onto
       it and check with these commands: deb ppp chap deb ppp nego-
       tiotion deb ppp error term mon its debug messages about the
       dial in trials of your Linux computer.  You have to do this
       via telnet instead of on the console - otherwise the CISCO
       won't be able to handle the logging via the serial inter-
       face.



  22.3.  callback_ascend: Callback from an Ascend works only when I set
  "Active=Yes" in the Ascend menu; but then the Ascend keeps calling me,
  even when my machine is off.

  Ulrich Klein ulik@hprc.tandem.com wrote on 14 Dec 1996:

  Somewhere in the Ascend menus you can set "dial broadcast" to "no" or
  "off". Otherwise the thing will dial with every broadcast. At least
  that helped me. In case anyone from the network on which the Ascend is
  attached really wants to establish a connection, then you have to use
  the strange filters. I believe there's one that will dial out only for
  callback.


  22.4.  callback_banzai: How can I callback a Banzai!?

  Jan-Olaf Droese jano@layla.RoBIN.de wrote on 31 Jan 1997:

  On the Banzai side, a "c" should be added to the outgoing number, so
  it will be ready for the return call. Just to be safe, you can the
  dialout attempts on the Banzai to 1, so there won't be any call
  collisions.  On the i4l I've set the following:


  ______________________________________________________________________
  isdnctrl callback isdn0 in
  isdnctrl cbdelay isdn0 1
  ______________________________________________________________________



  22.5.  callback_microsoft: Does isdn4linux support Microsoft Callback
  (CBCP)?

  Yes, this is implemented in ipppd. To enable it you have to set the
  parameter "callback 6" as an ipppd option on the client side for an
  admin managed callback. This means the server will call back on the
  number it has been configured for.  More interesting is a user managed
  callback, since the number to be called back can be provided by the
  user. Set the paramter "callback 123456" if you want to be dialed back
  on number 123456.  To start the callback trigger it from the client
  via:

  ______________________________________________________________________
  isdnctrl cbdelay <device> 5
  isdnctrl callback <device> out
  ______________________________________________________________________


  Please remember that using the CBCP callback always requires both par-
  ties to connect and exchange data, so telephone charges will be
  incurred.  Please note that the man page may be confusing about the
  callback parameter for ipppd. Please note these hints from
  NOTES.IPPPD:

  - 'callback type[,message]' enables the callback feature
    also UNTESTED!
    ie: 'callback 0'       -> simple callback (info via auth. etc.)
        'callback 3,12346' -> us E.164 (tel) number 123456 for callback
        'callback 6' is different. This value means, that the whole negotiation
    is done with a seperate protocol after the authentification phase. Currently
    it's not possible to set any options in this case. The ipppd accepts
    everything from the remote side.


  The server side is not tested so far - please let me know if you have
  some feedback on using CBCP as a server).

  If you have a Red Hat distribution, setting the following parameters
  in ifcfg-ippp0 might do the trick for an admin managed callback:

  ______________________________________________________________________
  CALLBACK=out
  CBDELAY=5
  CBCP=on
  ______________________________________________________________________


  For user managed callback please follow the hints on:
  <https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=125710>.



  23.  isdnlog: Isdnlog



  23.1.  isdnlog_rates: Where do I get the latest rate information?

  This is the homepage of the rate data crew:
   <http://sourceforge.net/projects/rates4linux>. There you can download
  the latest rate files (which change very frequently), or have a look
  at the latest rate news.

  There is also a mailing list available for this kind of stuff.
  Subscribe by sending an email with subject "subscribe" to:
  rates4linux-users-request@lists.sourceforge.net (send "help" in your
  subject to get instructions).  To write to the mailing list, send an
  email to: rates4linux-users@lists.sourceforge.net.


  23.2.  isdnlog_servicetype: Can I see the service type from an incom-
  ing call in the output from isdnrep?

  Andreas Kool akool@Kool.f.EUnet.de wrote on 3 Dec 1996:

  Indirectly in isdnrep, yes -- as soon as you enter an alias for the
  decoded service types in your "isdnlog.conf" ...


  23.3.  isdnlog_callerid1: Why don't I always receive from the German
  Telekom the number of a caller ("Caller ID")?

  For data privacy reasons, telephone numbers from the analog network
  are not transmitted unless the caller has explicitly allowed the
  Telekom to do so (costs nothing).

  Those with an ISDN connection, on the other hand, must explicitly deny
  permission for the Telekom to transmit the number, or apply to be able
  to do this on a call-by-call basis (CLIR). Call-by-call denial is
  free; call-by-call transmission costs extra. However, it seems to be
  very difficult for the Telekom to configure this correctly on the
  first try.  If you depend on the transmission of Caller ID, you should
  check closely that everything is configured correctly.


  23.4.  isdnlog_callerid2: Do I receive the Caller ID from foreign
  calls (German Telekom)?

  Yes, with calls from countries that don't view Caller ID quite as
  strictly as does Germany (e.g. USA, Canada).


  23.5.  isdnlog_spoofcallerid: I've heard that actually two Caller IDs
  are transmitted?

  That's right, there's one that is "User-Provided, not screened", and
  the other is "Network-Provided" (from the telephone company). As the
  name says, the first one is provided by the user, whereas the second
  one is transmitted by the network.  Providing a caller ID is only
  possible for a PBX connected in Point-to-point configuration with the
  feature "CLIP no screening".


  23.6.  isdnlog_betterlogging: Why doesn't isdnlog record the number
  dialed by my other ISDN devices, since it records the charges?

  Because the ISDN card, like all ISDN device, has separate lines for
  sending and receiving (RX and TX lines). Isdnlog has to read data from
  the receiving line to learn the number dialed. This isn't possible, at
  least for the Teles cards, as Karsten Keil keil@isdn4linux.de wrote on
  12 Feb 1997:

  This is the case for all cards with 1 Siemens ISAX; it has
  (and needs) only 1 sender and 1 receiver.  Theoretically,
  it's possible to read the entire D channel with just one
  receiver (even with the ISAC); the D bits from the RX line
  are copied (somewhat delayed) to the TX line, over which the
  access control (collision recognition) of the SO bus takes
  place.  Unfortunately with the ISAC it's not possible to
  read the echo bits in TA mode from a register.


  See the next questions for a possible solution.


  23.7.  isdnlog_reversedcard: How can I get isdnlog to also show the
  telephone numbers for other ISDN devices?

  There are several possibilities.

  o  COLP: First, the German Telekom offers the service COLP (Connected
     Line Identification Presentation, ca. DM 10 per month per basic
     line) that returns all data sent. This can then be read by isdnlog
     (=2.52) from the TX line.

  o  Reversed card/dual mode: Alternatively, isdnlog offers the
     possibility to work with a second "re-poled" ISDN card. "re-poled"
     means that the RX line is connected to the TX connection of the
     card; the RX line of the card should not be connected to any line!
     (even if other documents might tell you something else).  Because
     of this setup, this ISDN card cannot be used for anything else.
     This is called a reversed card, or the dual mode. The whole thing
     looks something like this:

           3 -- RX+ 2a ---------------\
     ISDN  4 -- TX+ 1a -- open         ------------  ISDN
     bus   5 -- TX- 1b -- open         ------------  card
           6 -- RX- 2b ---------------/


  Please note that this only works when the second card is an ISAC based
  cards (e.g. old Teles cards, Fritz! classic), since it requires a spe-
  cial bug/feature of that chip. All other cards, like IPAC based cards
  (e.g. ELSA QS1000pro) will not work in the role of a re-poled card.
  Please note that this will only work on the standard BRI interface,
  since for the more expensive PRI interface no card is available which
  can be used (PRI is a point-to-point connection anyway).

  o  HFC cards: some HFC-PCI based cards allow a special feature where
     one of the B channels can be sacrificed in exchange for reading the
     complete D channel protocol - with just one single card. This is
     also supported by isdn4linux. Set the HFC card in the following
     way:

     ___________________________________________________________________
     hisaxctrl <driver_id> 1 4
     hisaxctrl <driver_id> 10 1
     hisaxctrl <driver_id> 12 1
     ___________________________________________________________________


  You have to give isdnlog the command line option '-1' so that it makes
  use of the HFC option.

  Please note that a plain HFC-S does not work for hardware reasons, it
  has to be a newer one. If your card works with Hisax type 35 or 37,
  then it should work.

  Please also note that there is no known card for logging on a PRI
  interface in this way (also, the PRI interface is point-to-point,
  therefore only one device can be connected).


  o  PBX: A third (theoretical) possibility exists for those who have
     their own PBX to which the other devices are connected. If the PBX
     can protocol all outgoing calls, this can be read (usually over a
     serial port).  There is a reason why isdnlog has not support for
     this until now. To evaluate this data, isdnlog has to be able to
     access the date immediately after the RELEASE COMPLETE, before any
     new data is sent on the D channel. The PBXs tested up to now have
     all been too slow (in particular the widely used ISTEC). The only
     possibility is to combine the data afterwards. But then there are
     problems with synchronizing the different times. Whoever want to
     attempt to do this is very welcome.


  23.8.  isdnlog_rategraphic: How can I display the data transfer rates
  graphically?

  You can use "xisdnload". Clemens Perz listperz@gwsnet.ttt.de on 6 Feb
  1997 knew of another possibility:

  On Sunsite I found a little tool for the console called netload, and
  apapted it for the ISDN interfaces. With it you can quite easily see
  the current traffic on the line. It can be found at:

   <ftp://ftp.region.trier.de/pub/unix/linux/sources/network/isdn/netload-0.92.isdn.tar.gz>

  Simply start with netload isdnxx.


  23.9.  isdnlog_2callerid: Isdnlog (=2.52) shows for a caller two
  telephone numbers! Which one is correct?

  The caller has most likely activated the (costly) feature CLIP (=
  Calling Line Identification Presentation, no screening), which means
  any telephone number can be transmitted. See the question "I've heard
  that actually two Caller IDs are transmitted?".

  Andreas Kool akool@Kool.f.EUnet.de wrote on 26 Jan 1997:

  In any case, you can only fool software/PBXs that do not evaluate the
  screening indicator - isdnlog with version 2.52 shows both the correct
  *and* the faked telephone number. 'CLIP, no screening' was actually
  designed for transmitting internal company numbers in the public
  network.


  23.10.  isdnlog_soundbusy: I've set up a script to play sound per cat
  on /dev/sound or some other device. When several events occur, then
  there is an error: Can't open output file '/dev/sound': Device or
  resource busy

  Only one process at a time can access the sound device. You need an
  upper instance that coordinates access to the sound device. NAS
  (network audio system), and rplay can be used for this.


  23.11.  isdnlog_noshell: Isdnlog should call a program with redirected
  output (e.g. play anruf.au 2/dev/null ). Why does ISDN tell me Can't
  start '/usr/local/bin/play anruf.au 2/dev/null' with execvp() ?

  Because isdnlog is not a (Bourne) shell ;-) Isdnlog can only start
  real programs. Just write a little script for it and make it
  executable (chmod +x):

  ______________________________________________________________________
  #!/bin/sh
  /usr/local/bin/play anruf.au 2/dev/null
  ______________________________________________________________________



  23.12.  isdnlog_blankscreen: When dialing out, the screen goes momen-
  tarily black?

  This may happen when you start isdnlog with the options -t1 or -t2,
  then the time is synchronized with the digital switching station. The
  screen saver thinks that more than x minutes have passed, which causes
  a short blackout of the screen.


  23.13.  isdnlog_nologging: Isdnlog does not log any incoming call for
  me?

  Please verify whether your setup complies with the restrictions given
  in the isdnlog man page:

  Isdnlog only works with the HiSax isdn driver. Other cards with their
  own driver are not supported. Additionally you need to enable d-
  channel logging (you can use "hisaxctrl <DriverId> 1 4" to do that,
  e.g.  "hisaxctrl line0  1  4").  Isdnlog can only log outgoing calls
  that originate from your isdn card, and incoming calls. To get
  information about outgoing calls from other isdn devices (e.g.
  telephones), you need a second Teles isdn card, with crossed lines.
  Such a card is not usable for communicating, but can log outgoing
  calls from any device.

  See also question ``isdnlog_reversedcard'' for using two ISDN cards
  for logging.


  23.14.  isdnlog_enoughdata: How can I check whether isdnlog receives
  enough information from the kernel drivers?

  First stop isdnlog (e.g. "killall isdnlog"), then run "cat
  /dev/isdnctrl0".  When you trigger some activity on the isdn line
  (e.g. by initiating an incoming call) you should see lines starting
  with "HEX:" or "D2:" in the output of the cat command. If these lines
  are missing then check your configuration of the kernel drivers.


  23.15.  isdnlog_database: How can I set up isdnlog with database sup-
  port?

  You have to rebuild isdnlog for this. You can find some instructions
  (in German) on: <http://lists.suse.com/archive/suse-
  isdn/2005-May/0043.html>.



  24.  audio: Handling Voice with ISDN

  (Most of the answers you will find here are taken from the - now
  unfortunately outdated - vbox manual by Matthias Hessler
  hessler@isdn4linux.de and Bernhard Hailer dl4mhk@lrz.uni-muenchen.de;
  you can get the manual at:

   <http://www.lrz-muenchen.de/~ui161ab/www/isdn/>

  - click on "Audio!" (still in German we're afraid - sorry...)  They
  are currently very outdated, but may give you a few hints?

  A newer place has now come up as a place for further vbox development.
  Please check it out:
   <http://innominate.org/projects/vbox/index.php3>


  24.1.  audio_links: Where can I find helpful links regarding vbox?

  There are several scripts available to be used in connection to vbox,
  but the author is not up to date. Here is the latest one I received
  information about:
   <http://innominate.org/projects/vbox/index.php3> Please send me
  information if you know more helpful links, or howtos, or whatever
  useful...

  Also please note the documentation in the kernel source package:
  /usr/src/linux/Documentation/isdn/README.audio


  24.2.  audio_format: What is the format of the audio messages (.msg)
  vbox plays when it answers a call?

  You can get the format from the messages with rmdgetheader. The
  samples messages in the packages are recorded using format 4 (the
  latest Zyxel-Compression)



  24.3.  audio_recordmsg: How can I record my own messages for
  vboxgetty?

  First call yourself on the number you configured vboxgetty to answer
  and leave a message. Then rename the message to *.msg (standard.msg
  for the main answering message) and copy it to the directory where all
  the messages are kept (usually /var/spool/vbox/user/messages where
  user is the user for which vboxgetty is configured).  You can also
  record a message using a microphone and the soundcard.


  24.4.  audio_play: How can I play audio messages locally using
  /dev/audio?

  This is best achieved with vbox using format 6 (uLaw - must be
  compiled in). You can then easily play the messages using:

  ______________________________________________________________________
  cat xxx  /dev/audio
  ______________________________________________________________________


  where xxx is the message-file.


  24.5.  audio_convertto: How can I convert audio messages which where
  recorded by vbox to other formats (i.e. from uLaw to WAV)?

  The standard tool for converting all sound formats is SOX. SOX is
  available as source code for both UNIX and DOS. You can get it at:

   <http://www.powerweb.de/mpeg/util/msdos/sox10c.zip>


  (including sources that compile under Linux).


  24.6.  audio_convertfrom: How can I format WAV for uLaw (for my vbox
  announcement message)?

  We receive the following tip form Christian Stueble
  stueble@ls6.informatik.uni-dortmund.de on 15 Jan 1997:

  For me, the following (somewhat indirect) method works:

  ______________________________________________________________________
  sox file.wav -r 8000 file.ul rate
  rmdcatheader -u file.ul  file.msg
  cat file.ul  file.msg
  ______________________________________________________________________


  It could be that you have to give different parameters to sox.  As a
  first test you can try file.msg  /dev/audio, you should be able to
  hear something.


  24.7.  audio_dtmf: How can I improve the recognition of (DTMF) dial
  tones?

  You can adjust the parameters DTMF_TRESH, SILENCE_TRESH, and H2_TRESH
  in file linux/drivers/isdn/isdn_audio.c. A DTMF tone is recognized if
  the amplitude of the correct frequency is larger than DTMF_TRESH and
  the amplitude of the second harmonian frequency is smaller than
  H2_TRESH.  If a dial tone is recognized when no dialing took place,
  try to increase DTMF_TRESH and/or decrease H2_TRESH. However, test
  with many telephones - the current parameters were already set after
  some tuning.



  24.8.  audio_e0265: My vboxgetty gets a modem timeout, and reports
  error E0265.

  Probably you need a patch that has been posted recently (8th December
  1999) on the mailing list.


  24.9.  audio_noanswer: My vboxgetty does not answer any incoming
  calls.

  vboxgetty needs ".vboxrc" in the home directory of the user for which
  vboxgetty is configured. The number of rings is taken from this file.


  24.10.  audio_nocat: If vboxgetty has recorded a message in a format
  which can not be played using "cat xxx/dev/audio" how can I still hear
  the message?

  Vboxgetty can play all formats. You can copy the message as the
  standard message (standard.msg in the messages directory) and call
  yourself, the message will be played then. (Don't forget to copy back
  the original message when you are done :-) ). See question
  ``audio_recordmsg''.



  24.11.  audio_earlyrecording: At the beginning of a message recorded
  by vboxgetty, there's often a part of my own announcement?

  This is a known bug that occurs when switching between the playing of
  the announcement and recording the message. Up to now there is no
  known workaround.



  25.  Supported Countries

  25.1.  country_which: In which countries does isdn4linux work?

  We are aware of at least the following countries:

  o  Austria (see question ``country_austria'')

  o  Australia

  o  Brazil (see question ``country_brazil'')

  o  Belgium

  o  Denmark

  o  Finland

  o  France (see question ``country_france'')

  o  Germany

  o  Hungary

  o  India

  o  Ireland

  o  Israel

  o  Italy (see question ``country_italy'')

  o  Japan

  o  Luxemburg

  o  Norway

  o  Pakistan (see question ``country_pakistan'')

  o  Peru

  o  Poland

  o  Portugal (see question ``country_portugal'')

  o  Singapore

  o  Spain

  o  Sweden

  o  Switzerland (see question ``country_switzerland'')

  o  The Netherlands (see question ``country_netherlands'')

  o  United Arab Emirates

  o  United Kingdom (see question ``country_uk'')

  o  USA (see question ``country_northamerica'')

     If your country is not on this list does not mean it is not
     supported. It just means we have not seen a confirmation about its
     usage there. Check the mailing list for other users from your
     country.


  25.2.  country_certified: Is isdn4linux approved for use by the
  telecommunications authorities?

  That depends on the driver used, and your country. We only have
  information about Germany (send me information if you have information
  about other countries). However, that covers most other European
  countries as well, since a certification in one EC country has to be
  accepted in all others.  These drivers are certified for use in
  Germany:

  o  Active cards: the approval covers the entire card including its
     firmware. Thus the approval also covers the use of these cards with
     isdn4linux.

  o  Elsa Quickstep series cards (new name Microlink PCI)

  o  Eicon Diva 2.01 PCI

  o  Teles 16.3 ISA (with Siemens chipset)

  o  Sedlbauer Speedfax+ PCI

  o  Passive cards: all cards based on the HFC-S chipset.

     Actually, since April 2000 the rules for certification have
     changed. Now the producer of an ISDN card has to do only hardware
     tests, the driver is not part of the certification anymore. This
     applies to the whole European Community.


  26.  1tr6: German Pecularities for 1TR6

  26.1.  1tr6_eaz: Which EAZ should I use for i4l?

  You can use all available EAZ. However, two EAZ have a special meaning
  and can cause problems:

  EAZ 0: global call (all telephones ring)
  EAZ 9: global call (no telephone rings)


  Gernot Zander hifi@scorpio.in-berlin.de wrote about this on 6. Jan
  1997:

       I would not use 0, for my taste it is too likely that i4l
       will steal all voice connections.



  26.2.  1tr6_extension: I use 1TR6 on an extension - the extension num-
  ber has more than one digit (e.g. 206). What is my EAZ?

  Jens Ey jens@jeyhh.shnet.org wrote on 10 Jan 1997:

  The EAZ for extensions is usuAlly the last digit of the extension
  number.  As EAZ for the Linux computer you should then enter a '6'.


  26.3.  1tr6_spv: What is a SPV?

  SPV stands for "semipermanente Verbindung" (semipermanent connection)
  and is a (soon to be obsolete) speciality of the German Telekom. Like
  a leased line, the calling partner is fixed, however the connection is
  only established as needed (which occurs very quickly, much quicker
  that a dial connection). Since the Telekom can use the line for other
  things when it's not needed, the SPV is cheaper than a leased line.

  This SPV is not to be confused with the Austrian understanding of SPV.
  The Austrian `SPV' has one channel leased line, and one channel for
  dialing.


  26.4.  1tr6_spvdial: Does isdn4linux support SPVs? How?

  To switch on the support for SPVs, add an "S" before the number to be
  dialed. This works (quite well) for modem emulations as well as for
  defined network interfaces.



  27.  Other countries

  27.1.  country_austria: Austria: We have neither an MSN nor an EAZ,
  only a normal plain telephone number. What do we have to use for i4l?

  In Austria ISDN lines are by standard installed without MSN (which is
  different from Germany). That means when somebody calls the installed
  ISDN number the called party gets signalled a "global call". i4l then
  says "incoming call without CPN" - "CPN" means called party number.
  Solution: Set the incoming "MSN" (in reality: none) to "0", then i4l
  responds to the global call. Otherwise it waits for the signalling of
  the number you told i4l, and that won't happen (happens only for
  *additional* MSN). The same applies to the setup of your getty.

  On the other hand you should set the outgoing MSN correctly (without
  area code) -- however, a wrong MSN will be replaced with the correct
  one by your telecommunications provider.


  27.2.  country_brazil: Brazil: How does our MSN look like?

  For use with Telemar you have to configure your MSN as your phone
  number without the leading area code.

  Brazil is using EuroISDN. The ISDN service DVI which was launched by
  Telemar is based on a hardware solution from Teles (BRI PCI card),
  which has to be configured as NETjet card. However, since this card is
  very incompatible to the motherboards sold in Brazil, Telemar also
  offers the option of a Teles 16.3c ISA. You may be able to find some
  configuration help on <http://www.olinux.com.br> for this card.


  27.3.  country_france: France: How does our MSN look like?

  If you don't have MSN, you need to specify as local number only the
  last 4 digits of you phone number. A good thing is that you can also
  use sub-addressing. If your phone number is 01 41 33 67 87, and you
  want to use sub-address 02, then configure the local phone number of
  the HiSax driver as 6787.02 .

  27.4.  country_italy: Italy: What does our MSN look like?

  isdn4linux also works in Italy (ICN card). The MSN must be the phone
  number with the Italian area code, and since middle of 2001 includes
  the leading 0.  For example, if my phone number is 72004681 and my
  area code is 045, my MSN is 04572004681.  Now with the setting
  AT&E04572004681 isdn4linux works fine.


  27.5.  country_netherlands: Netherlands: What does our MSN look like?

  In The Netherlands the MSN includes (as opposed to the German Telekom)
  also the area code - but without the leading zero.


  27.6.  country_northamerica: North America: Can we use isdn4linux in
  North America?

  Yes, you can use isdn4linux in North America. However, some
  specialties apply.

  In North America the telephone company will only provide a U instead
  of an S interface. This means that the customer rather than the
  telephone company has to supply the network terminator (NT-1). Your
  easiest solution is a card which has an integrated NT-1 and supports
  the U interface.  Alternatively buy an external NT which translates
  between U and S interface, and connect your ISDN card with S interface
  (without NT-1) to it.

  In North America the channel protocol NI-1 is being used. NI-1 is
  related to DSS1 (both are Q.931 Protocols), but both have totally
  different groups of functions. Support for NI-1 has recently been
  added to HiSax, the driver for passive cards, with great help from
  Traverse Technologies:
   <http://www.ttcomms.com>.  Since they helped to implement and verify
  NI-1 usability, we would recommend you buy their card NETspider-U
  (with integrated NT-1), as a thank-you for their contribution to
  isdn4linux open source development.

  See Documentation/isdn/README.HiSax for details on how to set up your
  system with HiSax (protocol type is 4, give SPID together with your
  own number in the form of <OWNNUMBER>:<SPID>).

  Quite some time ago, the firm "Spellcaster" has written their own
  isdn4linux driver for their (active) cards. Both BRI and PRI cards are
  available. More information is available on:
   <http://www.spellcast.com>

  Also, the active Eicon DIVA cards work fine in North America and have
  5ESS and NI drivers, which are currently ported to UltraSparc.



  27.7.  country_pakistan: Pakistan: What should we use as MSN?

  It seems that no MSN functionality is supported. Therefore the MSN
  should be set to "0".


  27.8.  country_portugal: Portugal: What should we use as MSN?

  As long as only one telephone number or MSN was applied for, the
  telephone company sends no caller ID. Therefore the MSN should be set
  to "0".  If more than one MSNs was applied for, then these should be
  set as usual.

  27.9.  country_switzerland: Switzerland: We have neither an MSN nor an
  EAZ, just a plain telephone number. What do we have to use for i4l?

  In Switzerland usually you have to use the telephone number without
  area code. For old ISDN numbers where you have been assigned ten
  numbers in a row this may be different; in that case use the last
  digit of your telephone number as your MSN/EAZ ("6" if you have the
  telephone number "123456").


  27.10.  country_uk: UK: What should we use as MSN?

  It depends on your ISDN option.

  o  ISDN: Does not allow normal MSNs in UK. Each MSN is actually a
     single digit, 0 - 9, corresponding to the last digit of the actual
     phone number.  You either have *no* MSNs (then configure isdn4linux
     to use '0' as MSN, e.g. with AT&E0), or 10 MSNs; you then always
     get a block of 10 sequential telephone numbers (xxx0-xxx9), of
     which the last digit (0-9) is your MSN (0 is used in case you use
     an invalid number).

  o  ISDN2e: Seems to be normal EuroISDN. You are assigned MSNs which
     you can use and configure for isdn4linux. The MSN is reported to
     consist of the last 6 digits of your telephone number (try to add
     digits from your area code, if the local number part is shorter
     than 6 digits).

  o  BTHH (BT HomeHighway): additionally to 2 ISDN ports it includes two
     analog lines with separate telephone number - but calls to and fro
     for those won't be signalled on the ISDN line, even so they use up
     a B-channel.  Additional MSN are NOT available (therefore use '0'
     as MSN to configure isdn4linux). Charge info is possible for extra
     cost. Configure isdn4linux only with your 'digital number' as MSN.

  o  BTBH (BT BusinessHighway): The additional paperwork including a
     credit-check enables you to get MSNs and other extras for extra
     cost.  Otherwise pretty much like BTHH. Configure isdn4linux to use
     your 'digital number' and/or your MSNs.

     Please note that BT offers an unexpected special "feature" on
     international calls. For international data calls you have to dial
     000<country_code> (three zeros), rather than the 00<country_code>
     (two zeros) for international voice calls.

  By the way: for a BT Speedway card try to select AVM Fritz card
  (either ISA or PCI - depends on what you got; see question
  ``hardware_fritz'').

  Since about November 2001, all BT home highway and possibly Business
  Highway NTE boxes come with a built in USB terminal adapter. This
  terminal adapter is based on the ST-5481 chipset. Load the module
  st5481 for this device, then set up your isdn configuration with
  isdnctrl.

  Also, check out  <http://www.wurtel.cistron.nl/i4l-howto-uk.html>.


  28.  misc: Miscellaneous

  28.1.  misc_standards: Which standards apply to the ISDN protocol lay-
  ers?

  These are the main standards:


  o  Layer 1: ITU I.430 and ETSI 300 012-1

  o  Layer 2: ITU Q.921 and ETSI 300 125-1

  o  Layer 3: ITU Q.931 and ETSI 300 102-1 (plus some changes and
     clarifications in ETSI 300 403)

     All layers are also described in TBR3. For study, the standards are
     freely available from  <http://www.etsi.org>.


  28.2.  misc_nonullcable: Can I connect two ISDN devices directly with
  a kind of "null modem cable"?

  This is only possible if one of the cable can run in NT mode (see
  glossary on what this is: ``glossary_ntmode''). Only a few cards allow
  it, all others need an NTBA or PBX with an internal bus to communicate
  with each other. See question ``feature_crossedcable''.


  28.3.  misc_uisdn: Can isdn4linux run in parallel to UISDN?

  Yes. Both ISDN packages load the module isdn.o, otherwise the naming
  conventions are different. Tip: rename Urlichs isdn.o to uisdn.o, and
  change lib/modules/modules.isdn (or whatever the file is called that
  lists the modules and is read by the script) accordingly. Happily the
  default names of the ISDN devices are also different.



  29.  glossary: ISDN specific words which are used in this FAQ


     active card

        Cards can come in different versions: passive, semi-active,
        active.  Active cards handle the D-channel and B-channel
        protocol in their hardware.  The extra hardware makes them more
        expensive, but better suited to use where a low CPU usage is
        needed (e.g. when having many ISDN cards in one computer).
        Because of their special hardware, a special driver is required.
        Depending on the hardware/driver, special tasks like
        sending/receiving analog G3 faxes may be very easy to implement
        - if you need these features, get one of them.


     AOC-D
        "Advice Of Charge During the Call".


     AOC-E
        "Advice of Charge at the End of the Call". In Germany, this
        service is included in the "Komfort" connection.


     BRI
        BRI means basic rate interface and is the most commonly used
        interface.  In Europe, a BRI includes 2 B-channels for data
        communication, and 1 D-channel for administration of the data
        communication. The alternative is a PRI interface.


     CLIP
        CLIP (Calling Line Identification Presentation) can be offered
        by the ISDN provider. When you call somebody, then your
        telephone number will be transmitted to the other phone.  The
        opposite of CLIP is CLIR.  In Germany, CLIP is the default.


     CLIR
        CLIR (Calling Line Identification Restriction) can be offered by
        the ISDN provider: one can (from call to call) restrict the
        identification of one's own caller ID to the other party.  The
        opposite of CLIR is CLIP.  In Germany, this must be applied for
        but is without charge (however call by call transmission of the
        caller ID costs extra).


     COLP
        COLP (Connected Line Identification Presentation) can also be
        offered by the ISDN provider. If you've applied for COLP, you
        get an extended dialing protocol. You will receive feedback from
        your telecommunication company who picked up your outgoing call.
        Normally, you will get the same number as you dialed beforehand;
        however, with call diversion this could also be a different
        number.  In Germany, it must be applied for, and costs extra.
        More information than COLP can be obtained with the help of a
        reverse-connected ISDN card.


     CVS Tree
        The i4l developers have formed a team. The tool CVS allows the
        members to easily make patches. The history of the project is
        also thereby documented, and it is also not difficult to
        reproduce older versions.


     EAZ
        This is a German name for an MSN. In Germany, EAZ and MSN are
        used as synonyms, though in theory one ought to differentiate
        according to the protocol used. That which is called MSN in the
        Euro-ISDN protocol was called EAZ in the German 1TR6-ISDN
        protocol (a German predecessor to Euro-ISDN).


     HDLC
        A widely used low-level protocol, usually used to connect your
        computer with your internet provider. To connect to a computer
        mailbox, usually X.75 is being used.


     HSCX
        A Siemens chip which is, similar to ISAC, on many passive cards.
        It takes over the serial bus from ISAC and demultiplexes when
        receiving or multiplexes (i.e. inserts the bits in the correct
        position) the B channels.


     ISAC
        A Siemens chip which is, similar to HSCX, on many passive cards.
        It is responsible for Level 1, so it sits (almost) directly on
        the line. It handles the D channel protocol and sends the S0
        data to a special serial bus (IOM). When sending it does the
        opposite.


     leased line

        Your telecommunication company can hardwire the connection
        between two of their ISDN users. Then these users are always
        connected to each other without dialing and can not dial out to
        someone else any more.


     MSN
        Unlike a normal telephone connection, an ISDN connection can
        have more than one telephone number - each of these is called an
        MSN (Multiple Subscriber Number).


     NT NT is the abbreviation of network terminator. This is the
        interface between an ISDN user and the ISDN provider. It is a
        small hardware box to which the user has to connect his ISDN
        devices via a so called S0 interface.  In most European
        countries, the ISDN provider supplies the NT. A user in North
        America usually has to buy one, therefore the NT is often
        integrated into the ISDN card there.


     NT mode

        When multiple devices are connected to the ISDN connection, then
        all user device behave as slaves, where the network terminator
        (NT) behaves as master and synchronizes the communication on the
        S0 bus. The special behavior of the network terminator is called
        NT mode. User devices are normally not capable of running in NT
        mode.  As a result, user devices can not communicate with each
        other even when they are connected via a crossed cable.  Only
        some special ISDN cards (HFC chipset) are capable of running in
        NT mode, and can directly communicate with other ISDN user
        devices via a crossed cable.


     multi-device mode

        Your ISDN interface can be configured either in multi-device
        mode (in German: Mehrgeraeteanschluss), or in point-to-point
        mode (in German: Anlagenanschluss).  The multi-device mode is
        the normal connection mode for private ISDN users or very small
        business users. The user can attach multiple devices to the ISDN
        connection. The ISDN provider will assign a small number of
        fixed telephone numbers (usually up to 10 MSN), if any, to the
        ISDN connection.


     passive card

        Cards can come in different versions: passive, semi-active,
        active.  Passive cards handle the D-channel and B-channel
        protocol in software.  This makes them least expensive, but only
        suitable where the CPU is able to do the additional work (for
        normal data communication any computer starting from a 486 or
        even a 386 should be able to handle one or two cards).  Since
        only a few hardware chips are in wide usage, a generic driver,
        HiSax, can handle almost all passive cards.


     PBX
        A PBX (Private Branch eXchange) is used to connect different
        internal devices to the ISDN network. This is usually for analog
        devices that cannot be directly connected to an ISDN network.
        The PBX can also make an internal digital S0 bus available, on
        which ISDN devices can be connected. This allows for local calls
        without using the switching station (thereby avoiding the
        charges from your telephone company).

     point-to-point mode

        Your ISDN interface can be configured either in multi-device
        mode (in German: Mehrgeraeteanschluss), or in point-to-point
        mode (in German: Anlagenanschluss).  The point-to-point mode is
        the normal connection mode for business ISDN users. The user can
        attach only one single devices to the ISDN connection which will
        have to handle all calls (typically a PBX will be used). The
        ISDN provider will assign a range of numbers to the ISDN
        connection.  Any call within this number range will be sent to
        the user. The ISDN provider will leave assignment of the last
        digits of the telephone number to the ISDN user.  This setup
        usually allows for additional features, but is also more
        expensive.


     PRI
        PRI means primary rate interface and is the used when a single
        or multiple BRI are not sufficient in bandwidth. In Europe, a
        PRI includes 30 B-channels for data communication, and 1 D-
        channel for administration of the data communication.


     semi-active card

        Cards can come in different versions: passive, semi-active,
        active.  For semi-active cards there is no fixed definition, so
        here is what we think: semi-active cards handle the B-channel
        protocol in their hardware with special DSP (digital signal
        processor) support, but they leave the D-channel protocol to the
        software. This makes them better suitable to special tasks like
        sending/receiving analog G3 faxes. Because of their special
        hardware, a special driver is required. Be aware, that for
        marketing reasons some cards are called semi-active when in fact
        they are passive (e.g.: Teleint).


     subaddressing
        When dialing, it is possible to provide an additional number,
        the subaddresss.  The subaddress is transmitted to the remote
        side, and allows it to react on it.  This feature may not be
        available, at least not for free (with the exception of France).


     TEI
        TEI stands for Terminal End Identifier. The local switching
        station, or with an internal S0 the PBX, automatically or
        permanently assigns each end device a TEI. This simply allows
        the addressing of the D channels. TEIs have the following
        values: 0-63 = permanent TEIs (e.g. 0 is used for point to point
        connections) 64-126 = automatically assigned 127 = broadcast to
        all devices (e.g. an incoming call)


     UUS
        UUS is user to user signalling. It means, that when placing a
        call, a few bytes of user-specific data can be transmitted along
        with the call setup frame. This feature has been abused in the
        past in Germany, causing the local exchanges to run out of
        available channels (the call setup causes them to reserve a B-
        channel). Since then, this feature usually costs extra and there
        is a data limit on it (depends on your ISDN provider). Have a
        look at the usage condition, in short it's only allowed to use
        this feature, if indeed you want to setup a call. Please note
        that it has been reported that some buggy PBX (like ISTEC 1003)
        may refuse a connection when support of UUS is signalled to
        them.


     X.75
        A widely used low-level protocol, usually used to connect your
        computer with a computer mailbox. For connections to the
        internet, HDLC is usually used.




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