[Asterisk-Users] Questions about PRI lines for modem banks and Asterisk

[Peter Svensson]

On Sat, 11 Sep 2004, Clif Jones wrote:

> I have a friend with a PRI coming into a modem bank that is receiving 
> 56K modem calls and some ISDN data calls.  He wants to dump his analog 
> office phone lines and use some of the capacity on the PRI. I have been 
> digging through the mail archives and Wiki site on this subject but the 
> information I found doesn't give me a high enough confidence to go buy a 
> few T1 cards and try it out.  There is talk of using Asterisk as the 
> termination of the PRI from the PSTN and then forward calls for the 
> modem bank via another T1 span and a cross-over cable.  Others talk of 
> splitting the calls off with specialized equipment before it reaches the 
> Asterisk box.  Does anyone actually have the same (or similar) scenario 
> and if so what was your solution?  If you are using Asterisk to do the 
> switching, I would be interested in seeing your relevant config files.  
> My primary concerns are:
> - The load on the Asterisk box if it is acting as a router for the 
> incoming ISDN calls.
> - Effect of 56K modem dialup connections or ISDN data calls passing 
> through an Asterisk box.

We have something like this set up. 
  pstn <-pri-> asterisk <-pri-> pbx <-bri-> isdn modems
                                    <-bri-> isdn modems
                                       ...

The isdn modems handle both isdn data and analog modem calls without 
problems. The call is bridged inside the TE405P card I think. There is no 
noticable load on the asterisk server.

Peter