[Asterisk-Users] ISDN, BRI, PRI, voice over IP, and more...

[Steven Critchfield]

On Thu, 2003-11-27 at 16:19, Harry McGregor wrote:
> Hi,
> 
> I am thinking of starting a project at Work to pilot to use of Astrisk
> and VOIP, and would like to tie in several projects together.
> 
> Currently we are looking at purchasing an ISDN and H.323 based video
> conferencing system from Polycom.  It suggests the use of 3-4 BRI lines
> (ie 6-8 B channels, but in the form of individual BRIs).  We need ISDN
> for the video conferencing to communicate with the Department of
> Interior conferencing system.
> 
> Also we are looking at setting up a US Robotics Total Control V.90 modem
> rack for field users to be able to dial into the network.  We can feed
> it with a few analog lines and run it at V.34, but would prefer to use
> the PRI card and feed with a few channels.  We are only looking at using
> about 4 modems at once, at the absolute most.
> 
> I can bring in ISDN BRI lines from Qwest through University Telcom, or I
> can bring in a single PRI via any number of CLECs, and have the
> University transport it to us.  The PRI would be far cheaper in the long
> run.  The problem is finding a way to split the PRI, and Astrisk looks
> like it might be it.  I also want to start deploying VOIP phones in a
> pilot project, and need circuits for it.
> 
> >From reading the archives I have learned that a 4 port T-1 card can
> accept an incoming PRI and give an outgoing fractional PRI for a modem
> rack, but I have not been able to find any information about serving
> ISDN BRI circuits.  If the Polycom unit would accept a fractional PRI I
> would be set, but it does not appear to have that option.
> 
> Does anyone have any information they can share on this?

I noticed that some of those Polycom units supported V.35 connections.
You could possibly get a V.35 card for your asterisk computer and split
the channels off to the V.35 similar to how the ZapRas works. I don't
know if that will work though.

Another route would be to help hack up the libpri code to support the
3DSO or Brite signaling to support ISDN lines of T1. CAC has ISDN cards
for the ADIT600, and I'm sure there is an equivalent for Adtran.

As far as the breaking of a few channels to the Modem rack, that is
easy. Just pick a DID number for asterisk to route the call via and send
it down one of the second channels. You could ideally set it up to have
all channels active instead of a fractional PRI up. This would let you
surge up to whatever your demand needed. It is also probable that when
your mode needs where high that your office needs are low and it would
let you use the channels more effectively. Remember you only route on
the channel, it isn't like each channel is a phone number. Any of the
channels could be any of the numbers.

The VoIP would easily fit into that setup also. Not to mention that if
anyone wanted to loan you other equipment to test out, asterisk could
provide a PRI connection to it also. 
-- 
Steven Critchfield <critch at basesys.com>