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This page describes how to connect to the internet or send and receive faxes using ISDN.

ISDN and Linux

What is isdn4linux?

isdn4linux is a set of kernel modules. It consists of the main module "isdn" and a set of hardware drivers (mainly "HiSax") that control specific ISDN cards. In addition, the package "isdn4k-utils" contains utilities to make use of ISDN-specific features.

What is mISDN?

mISDN is the successor of isdn4linux following the adoption of the CAPI interface with Linux kernel 2.6. Like isdn4linux, it consists of kernel modules (it has been rewritten from scratch).

The following diagram offers an overview of the differences between the older kernel module architecture based on isdn4linux and Terminal-emulation (ochre), and the newer mISDN architecture (blue) based on mISDN and the CAPI interface.

  • http://www.heise.de/ct/04/03/182/bild.gif

What ISDN cards are supported?

isdn4linux supports both "active" (built-in firmware) and "passive" cards that plug into a desktop PC's PCI slot as well as PCMCIA cards (for laptops) and USB adapters.

mISDN currently supports AVM Fritz!Cards and most HFC-PCI based cards via its hardware drivers.

For a comprehensive list of supported ISDN cards, see the Hardware Support wiki page.

Can I use my ISDN card to send and receive faxes?

At present, fax support for most passive ISDN cards is only available in conjunction with the older isdn4linux kernel module package. The GPL-licensed ivcall software is able to send and receive voice calls and faxes via passive cards (using isdn4linux, not mISDN). It makes use of the spandsp library which is part of the Asterisk project.

Users of (passive) AVM cards are somewhat luckier: they can take advantage of a binary CAPI 2.0 driver that supports faxing in tandem with the mISDN modules.

mISDN does not offer fax support for passive ISDN cards (other than AVM). There are plans to extend 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 also be implemented via the spandsp library.

See this section of the isdn4linux FAQ for details.

Connecting to the Internet using ISDN

IconsPage/apt.png Ubuntu 6.06 LTS (Dapper Drake)

  • To be added.

IconsPage/note.png For all Hardware configurations:

  • Once the ISDN card is configured properly, we can use both graphical interfaces and command line tools to configure the network connection to our internet service provider.
  • For more on how to use the Networking control panel to set up your internet connection, see the Ubuntu Desktop Guide's Connecting to the Internet section.

  • For more on how to set up and control your connection using command line tools, see Configuring the Dial-up connection to your provider on the DialupModemHowto wiki page.


To be added:

  • Tutorials for Dapper
  • capiutils tutorial
  • more on capi configuration and hardware initialization
  • troubleshooting section or subpage: using dmesg, modprob, modconf, modutils, lsmod, lspci to handle kernel modules

For More Information

Linux and ISDN

  • The ISDN4Linux page is home to isdn4linux and its successor, mISDN. A very comprehensive FAQ on the site offers answers to the most commonly asked questions.

  • This excellent article (in German) charts the history of ISDN support for Linux, explains the fundamental technical issues and details a range of possible applications. Highly recommended.

  • Dan Kegel's ISDN page, with lots of information on ISDN

  • See the Hardware Support wiki page for a list of supported ISDN cards with isdn4linux and mISDN

ISDN card manufacturers

Standards Bodies, Working Groups


Other Tutorials

man pages


IsdnHowto (last edited 2013-12-14 10:29:59 by knome)