[Asterisk-Users] GR303 with *

[Kevin P. Fleming]

Matt Darnell wrote:

> Do you have an recomendations for the GR-303 concentrator?

There are a number of them; Digium has an Adtran unit (IIRC) that they 
demonstrate in their trade show booth.

> I was read that the GR-303 protocol is very similar to ISDN-PRI & NFAS.

Yes it is.

> I don't understand what there is to support a GR-303 concentrator, it
> appears it presents a standard T1 to the end device.

It is an entirely different protocol from T1 RBS and PRI, so there is 
software support needed for it.

> Do you have any idea how hard it would be to plug the GR-303 circuit
> directly into *?

It's very easy; plug it into the T-1 card of your choice. The issue is 
what is on the other end: if it's a switch expecting to talk to an 
access concentrator, then it won't work. If it's an access concentrator, 
then it can be made to work using the proper configuration.

At this time, Asterisk can only use GR-303 for supporting analog devices 
hung off of channel banks that are themselves connected to a GR-303 
access concentrator. The purpose of this is to only require a smaller 
number of channels between the devices and Asterisk (only what is 
required for simultaneous use).

For example, if you have 96 analog desk sets (FXS devices), under normal 
circumstances those would be connected to 4 T-1 channel banks, each of 
which would connect to a T-1 port on the Asterisk server.

However, if it's rare that more than 24 of those phones would be in use 
at one time, it's possible to connect the channel banks to a GR-303 
concentrator, and run only a single T-1 between it and Asterisk. This 
saves money for hardware on the Asterisk end, and if the T-1 between 
Asterisk and the concentrator is between buildings (or across town), may 
say a lot of money because only one circuit is needed instead of four.

This is essentially the same idea as an SLC or DLC system, but using a 
newer protocol.