[asterisk-dev] gr303

[Rich Adamson]

> I have a siemens ewsd switch, it supports gr303 links. What i want to do is have one 
asterisk server connected to
> the switch(gr-303) passing calls . Then use asterisk servers at customer locations to 
handle voice and data either
> over a data t1 or voice and data t1. Can asterisk be used as a concentrator? If so 
how is best used? Using data
> t1s and everything go into the asterisk server as voip and get passed to gr303 then 
to the switch, or channelizing a
> t1 using some for data, some for voice into the asterisk back out the gr303? 
> 

I've been researching the exact same thing in the last several months.

Asterisk has gr303 support, but only enough to support its interaction
with a remote concentrator/channel bank via a T1.

One of the digium employees set up a configuration recently to loop two
T1's together using gr303; one as a concentrator and one port as a network
switch. He was able to complete calls through the loop mechanism, however
that test does _not_ suggest there is a sufficient amount of gr303
actually implemented to allow it to be connected to an ewsd central office
switch.

There is no doubt the maintenance channel that normally exists between the
ewsd switch and the remote concentrator does not exist in any form within
asterisk, but maybe its not required either. That implies someone would need
to configure asterisk separately from the ewsd, mapping entries one-for-one
on both ends of the T1.

We're getting close to attempting our first T1 connection between asterisk
and the ewsd switch and hope it actually works. Everything is currently
in place, but no attempt has been made to communicate as yet.

For those that aren't familiar with gr303, it is a standards-based protocol
for central office switches to interface to remote line units. It is supported
by a large number of manufacturers in the central office switching
enironment, but has basically gone unnoticed in asterisk (with the exception
of Mark implementing base functionality for show/booth demonstrations). The
protocol supports up to something like 1024 logical connections, but is
obviously limited to 24 simultanous g711 conversations per T1 at any moment 
in time.