Documentation on writing a custom socket

Hans Petter Selasky hselasky at
Sun Mar 9 09:16:12 UTC 2008

On Saturday 08 March 2008, Max Laier wrote:
> Am Sa, 8.03.2008, 11:33, schrieb Hans Petter Selasky:
> > I'm planning to create a new socket type in FreeBSD called AF_Q921, which
> > is
> > to be used for ISDN telephony. Where do I find documentation on how to
> interesting ... can you share more information on this project?

Hi Max,

I'm currently working on some redesign of my ISDN4BSD stack in cooperation 
with the FreeSwitch project. One of things that I want to do is to have all 
ISDN adapters appear like network devices. The ISDN protocols usually use 
something called Q.921 which is similar to TCP, only very simplified.

The Q.931 part will either be in userland or in the kernel, and is used to do 
the telephony signalling like SETUP, CONNECT and RELEASE_COMPLETE. The idea 
is that once you use a socket you can easily change the layer2 to TCP, SCTP, 
UDP or whatever to be able to run Q.931 accross ethernet.


Current I4B homepage:

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