FAQ for isdn4linux

Matthias Hessler, hessler@isdn4linux.de

1. general: General information about isdn4linux

• 1.1 general_i4l: What is isdn4linux?
• 1.2 general_hardware: What hardware is supported by isdn4linux?
• 1.3 general_features: What features are supported by isdn4linux?
• 1.4 general_countries: Which countries are supported by isdn4linux?
• 1.5 general_docu: Where do I find more documentation, howto's, helpful tips
• 1.6 general_getlatest: Where do I get the latest version of isdn4linux?

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

3. Features

• 3.1 feature_not: Which ISDN features can not be offered by isdn4linux?
• 3.2 feature_data: Which ISDN data transmission modes are supported?
• 3.3 feature_voice: Can I use isdn4linux as an answering machine?
• 3.4 feature_fax: Can I fax with isdn4linux?
• 3.5 feature_divert: Is it possible to initiate call forwarding with i4l?
• 3.6 feature_ipx: Can I route ipx/spx over ISDN with Linux?
• 3.7 feature_2channel: Does isdn4linux support channel bundling?
• 3.8 feature_diald: Can I combine isdn4linux with diald?
• 3.9 feature_dod: Does the driver support "dial on demand"?
• 3.10 feature_btx: Is the German videotex/Btx/Datex-J possible with isdn4linux?
• 3.11 feature_clock: How can I set the clock of my computer with ISDN?
• 3.12 feature_dosemu: Can I use isdn4linux under dosemu?
• 3.13 feature_rawip: What is Raw IP, when should I use it?

4. docu: Documentation, Howto's, Tips & Tricks, Mailing List/Newsgroup

• 4.1 docu_first: What documents should I read first?
• 4.2 docu_newsgroup: Where is the newsgroup for isdn4linux?
• 4.3 docu_mailinglist: Where is the mailing list for isdn4linux?
• 4.4 docu_mailarchive: Is there an archive of the isdn4linux mailing list?

5. hardware: Supported hardware, and its specialities

• 5.1 hardware_support: What 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 trouble: Why should I avoid IRQ 12 and 15 for my ISDN card?
• 5.6 hardware_alpha: Can I run isdn4linux on a DEC Alpha with Linux?
• 5.7 hardware_maxcards: How many ISDN cards can I put into my computer?
• 5.8 hardware_teles: What should I know about before buying an ISDN card from Teles?
• 5.9 hardware_icn: What is special about the ICN card?
• 5.10 trouble: How can I tell whether or not my passive ISDN card is recognized
• 5.11 trouble: If i4l uses one B-channel then the other one will be blocked
• 5.12 trouble: On my ELSA card, the LED for the loss of the TEI often blinks. My connections are also often disrupted...
• 5.13 trouble: In the instructions for my NTBA it says that a crossed a/b cable pair has no effect on the operation?
• 5.14 trouble: How can I test whether a a/b cable pair has been crossed?

6. cfg_general: Configuration/General

• 6.1 cfg_general_msn: How should I set up isdn4linux with my MSNs?
• 6.2 cfg_general_hardware: How should I configure my hardware? Is there something special I should
• 6.3 cfg_general_dialmode: When an IP packet should go over the link (which usually triggers a
• 6.4 cfg_general_pnp: How do I configure a PNP (Plug and Play) card?
• 6.5 cfg_general_permission: How can I set up user permissions for the use
• 6.6 cfg_general_kerneld: Why shouldn´t I use kerneld to load the ISDN
• 6.7 cfg_general_runlevel: How can I boot Linux sometimes with
• 6.8 cfg_general_links: What helpful links are there about isdn4linux?

7. cfg_msn: Configuration/MSNs

• 7.1 cfg_msn_my1: What is my MSN?
• 7.2 cfg_msn_my2: How can I find out how my telephone number is transmitted
• 7.3 cfg_msn_config: How do I configure my MSN?
• 7.4 cfg_msn_mindialin: How can I minimize usage of MSNs for digital data dialin?
• 7.5 cfg_msn_onlyone: How can I use one MSN for everything?
• 7.6 cfg_msn_buendel: Can I have several NTBAs, all with the same MSN?

8. cfg_remote: Config/remote ISDN device

• 8.1 cfg_remote_w95: What do I have to watch out for to connect to Windows95?
• 8.2 cfg_remote_mac: I'd like to exchange data with a Macintosh (Leonardo card),
• 8.3 cfg_remote_macpap: A Macintosh with a Leonardo card tries to call in,
• 8.4 cfg_remote_cisco: How does isdn4linux work with a Cisco (HDLC) on the other side?
• 8.5 cfg_remote_ispa: What settings does ISPA etc. (DOS, Windows) need to work with the standard settings of isdn4linux?

9. cfg_ttyI: Configuration of the ttyI* devices (`Modem emulation')

• 9.1 cfg_ttyI_nomodem: Don´t the ttyI* devices emulate an analog modem?
• 9.2 cfg_ttyI_dev: Which devices should I use for calls out or calls in?
• 9.3 cfg_ttyI_hdlc: How to I switch the modem emulation from X.75 to HDLC?
• 9.4 cfg_ttyI_uucp: How can I poll with Taylor-UUCP using isdn4linux?
• 9.5 cfg_ttyI_speed: What speed should I set for the ttyI* devices?

10. cfg_asyncppp: Configuration Async PPP

• 10.1 cfg_asyncppp_whichppp: pppd, ipppd, async PPP, sync PPP - what are they? Which should I use?
• 10.2 cfg_asyncppp_logindelay: How can I reduce login delay?
• 10.3 cfg_asyncppp_fast: How can I increase my transfer rates with PPP?
• 10.4 trouble: How can I get a log for pppd?
• 10.5 trouble: Establishing the connection works fine, but pppd crashes just after

11. cfg_syncppp: Sync PPP

• 11.1 cfg_syncppp_whichppp: pppd, ipppd, syncPPP, asyncPPP .. what is they? What should I use?
• 11.2 cfg_syncppp_compile: How do I compile isdn4linux with syncPPP?
• 11.3 cfg_syncppp: How should I name my network interface?
• 11.4 cfg_syncppp_config: How do I configure isdn4linux with syncPPP?
• 11.5 cfg_syncppp: How can I tell if a connection is unsuccessful (busy)?
• 11.6 cfg_syncppp_logindelay: How can I reduce login delay?
• 11.7 cfg_syncppp: I want to talk to remote machines which needs different
• 11.8 cfg_syncppp: How does the (little-documented) "pppbind"
• 11.9 cfg_syncppp: I want to use dynamic IP address assignment. How must I
• 11.10 cfg_syncppp: How can I do IPX over ipppd?
• 11.11 cfg_syncppp: How can I increase my PPP data transfer rates?
• 11.12 cfg_general_compression: Which compressions can I use with ipppd?

12. cfg_lan: ISDN4Linux in a LAN

• 12.1 cfg_lan: How can I set up Linux so that other computers in my LAN can
• 12.2 cfg_lan: How can I allow the users in my LAN to dial out via the ISDN

13. isdnlog: Isdnlog

• 13.1 isdnlog: Can I see the service type from an incoming call in the output
• 13.2 isdnlog: Why don't I always receive from the German Telekom the number of a caller ("Caller ID")?
• 13.3 isdnlog: Do I receive the Caller ID from foreign calls (German Telekom)?
• 13.4 isdnlog: I've heard that actually two Caller IDs are transmitted?
• 13.5 isdnlog: Why doesn't isdnlog record the number dialed by my other ISDN devices,
• 13.6 isdnlog: How can I get isdnlog to also show the telephone numbers for other
• 13.7 isdnlog: How can I display the data transfer rates graphically?

14. Audio

• 14.1 audio_format: What is the format of the audio messages (.msg) vbox plays when it
• 14.2 audio_recordmsg: How can I record my own messages for vboxgetty?
• 14.3 audio: How can I play audio messages locally using /dev/audio?
• 14.4 audio: If vboxgetty has recorded a message in a format which can not be
• 14.5 audio: How can I convert audio messages which where recorded by vbox to
• 14.6 audio: How can I format WAV for uLaw (for my vbox announcement message)?
• 14.7 audio: My vboxgetty does not answer any incoming calls.
• 14.8 audio: My vboxgetty answers at the first ring but the number of rings is set to 4.
• 14.9 audio: My vbox 1.1 does not work together with HiSax.
• 14.10 audio: If vboxgetty has recorded a message in a format which can not be played
• 14.11 audio: At the beginning of a message recorded by vboxgetty, there's often a

15. chargeint: Chargeint

• 15.1 chargeint_whatis: What does Chargeint?
• 15.2 chargeint_whennot: When does it not make sense to use the chargeint patch?
• 15.3 chargeint_config: How does the chargeint patch work?
• 15.4 chargeint_time: How can I be sure that the chargeint patch is using the correct time?
• 15.5 The connection doesn't end with timeout. Possible reason: my service
• 15.6 ipppd doesn't hang up.

16. dialin: Configuration of a Dial-In Server

• 16.1 dialin: How can I enable others to login via ISDN?
• 16.2 dialin: How can I allow several people to call in to me at the same time?
• 16.3 dialin: Someone would like to dial in to my mgetty with HDLC. Is ttyI1 correct,
• 16.4 dialin: Is it possible with mgetty to automatically start pppd when LCP frames
• 16.5 dialin: How can I have (i)pppd check passwords from /etc/passwd instead of

17. leased: Leased lines

• 17.1 leased: How does establishing and ending a connection work with D64S without signaling?
• 17.2 leased: With i4l, how can I successfully use the Teles card on a D64 leased line?
• 17.3 leased: Can I connect two computers with ICN cards over a D64s leased line?
• 17.4 leased: With ISDN, can I use one channel as a leased line and other as a dialup line?

18. 2channel: Channel bundling (MPPP, raw bundling)

• 18.1 2channel: What is channel bundling and how can I use it?
• 18.2 2channel: What is raw bundling?
• 18.3 2channel: How do I use raw bundling?
• 18.4 2channel: What are the advantages and disadvantages of raw bundling?
• 18.5 2channel: What is MPPP?
• 18.6 2channel: How do I use MPPP?
• 18.7 2channel: What are the advantages and disadvantages of MPPP?
• 18.8 2channel: I tried MPPP but it doesn't work. The ipppd writes in the debug log

19. trouble: Troubleshooting

• 19.1 trouble: General
• 19.2 trouble: My isdn4linux doesn't work! How do I best go about finding the problem?
• 19.3 trouble: Neither my telephone nor my fax machine ring when I call them with isdn4linux?
• 19.4 trouble: Are there sites that offer guest access where I can test my isdn4linux setup?
• 19.5 trouble: My pppd or ipppd has problems with PAP/CHAP authentication.
• 19.6 trouble: I closed all ISDN applications. Why can't I unload my ISDN modules
• 19.7 trouble: i4l is working on the internal bus of a PBX. Any problem?
• 19.8 trouble: I get messages like "HSCX RME out of buffers",
• 19.9 trouble: My isdn driver crashes my machine! Since I've configured it as a module,
• 19.10 trouble: My hard disk becomes very active when isdn4linux run. How can
• 19.11 trouble: After a reset, my card does not initialize correctly.
• 19.12 trouble: How can I tell whether my ISDN card has been corrected recognized by
• 19.13 trouble: On bootup I get "HSCX version A:5 B:5" but I still have the impression that
• 19.14 trouble: My ELSA Quickstep 1000 ISA card produces very many interrupts
• 19.15 trouble: The PNP tools done work with my Teles 16.3 PNP card!

20. trouble: ttyI* devices (´Modem emulation´)

• 20.1 trouble: When I dial with "ATD....." I always get a "NO CARRIER".
• 20.2 trouble: My modem emulation/pppd does not recognize an incoming call.
• 20.3 trouble: Why can't I dial my telephone or fax with the modem emulation?
• 20.4 trouble: I can't get a connection to my ISDN mailbox/BBS.
• 20.5 trouble: My modem emulation hangs. How can I force my card to hang up?
• 20.6 trouble: During a tty connection, I get a message from the kernel
• 20.7 trouble: When I use UUCP with X.75, I always get transfer errors!

21. trouble: Sync PPP

• 21.1 trouble: How can I get a log for ipppd?
• 21.2 trouble: Starting ipppd I get the error message "this systems lacks ppp support".
• 21.3 trouble: When I start ipppd, I only get error messages from the i4l driver.
• 21.4 trouble: When I try to start ipppd it says "Can't find usable
• 21.5 trouble: I can't get a connect. How can I find out where the problem is?
• 21.6 trouble: I get the message "IP frames delayed" - and I don't get a connection.
• 21.7 trouble: I cannot dial out with "isdnctrl dial ippp0". It seems as if the route to
• 21.8 trouble: After ipppd dials out my default route is gone.
• 21.9 trouble: When dialing out, I get the message "pppd: peer
• 21.10 trouble: I cannot establish a connection - it's rejected by the other side.
• 21.11 trouble_pap: I cannot establish a connection - it's rejected by the
• 21.12 trouble_pap2: I have problems with PAP or CHAP authentication. It does not
• 21.13 trouble: I often get the error message "hscx_empty_fifo: incoming
• 21.14 trouble: The connection with ipppd seems to work, but eventually it
• 21.15 trouble: I only have problems with ipppd when the connection is being heavily burdened. Then everything stops. What could be causing this?
• 21.16 trouble: My ipppd works, but I keep getting the message pppd(104): ioctl(SIOCSIFMTU): Invalid argument"?
• 21.17 trouble: The first IP packet gets lost on automatic dialout with dynamic IP address allocation.
• 21.18 trouble: What does the message "No phone number, packet
• 21.19 trouble_leadingzero: Why does my ipppd dial one too many zeros
• 21.20 trouble: My ISDN device is shown with HWaddr and IRQ=0 and base address = 0 when I
• 21.21 trouble: xosview doesn't show any network activity since installing i4l.
• 21.22 trouble: When I for example from a W95 box call up a page with Netscape,
• 21.23 trouble: Addresses are now found, but now I get "no route to host".
• 21.24 trouble: After booting, my local network can no longer be reached. I use the

22. Isdnlog

• 22.1 Isdnlog (=2.52) shows for a caller two telephone numbers!
• 22.2 I've set up a script to play sound per cat on /dev/sound or some
• 22.3 Isdnlog should call a program with redirected output (e.g.
• 22.4 When dialing out, the screen goes momentarily black?

23. dod: Unwanted dialout on demand

• 23.1 What can cause a charge unit disaster?
• 23.2 Ever since I installed a new kernel, my computer constantly open ISDN
• 23.3 My router wants to constantly dial out (and does it too) but NO
• 23.4 After closing the line, I discover with "netstat -nt" that IP connections
• 23.5 How can I safely turn off dialout on demand?
• 23.6 How else can I prevent the charge unit disaster?
• 23.7 Is it possible that even with a crashed computer a ISDN connection
• 23.8 How can I track down unexplainable dialouts?
• 23.9 Can it be that the Win95 machine on my LAN is causing automatic
• 23.10 I have set up a local DNS name server. Why does it cause unwanted dialouts? How can I find the cause?
• 23.11 How can I turn off the DNS requests for WORKGROUP.xxx from my
• 23.12 How can I get sendmail to not initiate any connections without local
• 23.13 The samba package always triggers dialouts for me. How can I prevent
• 23.14 How can I get Netscape to quit initiating dialouts when starting?
• 23.15 trouble_tcpdump: Why does my tcpdump not work for ip packets going over

24. Dialin

• 24.1 I keep getting the message "isdn_tty: call from XXX - YYY
• 24.2 With "isdnctl pppbind" I've established an exclusive connection.
• 24.3 A SunISDN tries to dial into my i4l system.

25. Callback

• 25.1 An incoming call is rejected by i4l. i4l then calls back. The
• 25.2 Callback isn't working. How many ippp* devices do I need (at a
• 25.3 Somehow i4l can not callback a Cisco?
• 25.4 Callback from an Ascend works only when I set "Active=Yes" in the
• 25.5 How can I callback a Banzai!?

26. Supported Countries

• 26.1 In which countries does isdn4linux work?
• 26.2 country_certified: Is isdn4linux approved for use by the
• 26.3 German Pecularities (1TR6)
• 26.4 Which EAZ should I use for i4l?
• 26.5 I use 1TR6 on an extension - the extension number has more than one
• 26.6 What is a SPV?
• 26.7 How long will there still be SPVs?
• 26.8 Does isdn4linux support SPVs? How?

27. Other countries

• 27.1 Italy: What does our MSN look like?
• 27.2 Netherlands: What does our MSN look like?
• 27.3 Austria: We have neither an MSN nor an EAZ, only a normal plain
• 27.4 Switzerland: We have neither an MSN nor an EAZ, just a plain telephone
• 27.5 Portugal: What should we use as MSN?
• 27.6 North America: Can we use isdn4linux in North America?

28. Miscellaneous

• 28.1 Where can I find information on the dip switches of my NTBA?
• 28.2 Can I connect two ISDN devices directly with a kind of "null modem cable"?
• 28.3 Can isdn4linux run in parallel to UISDN?

29. Glossary