[Asterisk-Dev] PRI/T1-Signaling

[Steven Critchfield]

On Fri, 2004-01-09 at 09:15, Alfred R. Nurnberger wrote:
> I started looking into * a coouple of weeks ago. I do work on T1/PRI
> interfaces - stacks etc. So I am a bit familiar with their
> capabilities.
>  
> 1.) I wonder if it is possible to use the quite extensive signalling
> features of ISDN / PRI with Asterisk.
>  
>     i.e. instead of  sending an inband Busy tone - send a DISCONNECT
> with CAUSE Subscriber busy.
>          or trigger USER-USER messages from * 
>  
> 2.)I haven't played with the T1 boards yet. 
>     Does the board support transmission of audio BEFORE answer ?
>     This way * could send call progress tones to the network.
>  
>     From the network side audio transmission before answer is
> available on most DID, T1 and PRI lines.
>     We use it here on all 3 trunk types.

It does support audio before answer. For your PRI questions, look to the
libpri library. Libpri implements all the q931 and q921(?) messages. 

Remember that since this is all open source, if you see ways of
improving what is done, you are welcome to make suggestions and/or code
it yourself and offer it back to the community.
-- 
Steven Critchfield  <critch at basesys.com>