[Asterisk-Users] Verizon ISDN

[Steven Critchfield]

On Mon, 2005-03-28 at 12:48 -0700, Kevin P. Fleming wrote:
> Brian G wrote:
> > I'm looking to use Asterisk with Verizon ISDN centex service in the US. 
> > I'd be connecting to an NT1 so I'd need an S/T interface.  Users would
> > have SIP phones registered with Asterisk and sharing the ISDN lines.
> 
> ISDN BRI interfacing into a PC is hard to do in the US... there are just 
> not many (if any) cards available to do it. The few cards that are 
> available only have firmware for Euro-ISDN, not NI-2 (and US BRI is 
> _not_ the same as anywhere else in the world).
> 
> There are other options, though: Adtran (and others) make boxes that can 
> cross-convert multiple BRIs into a PRI, which could then be connected to 
> Asterisk via a T-1 card. Not an inexpensive way to go, though.

I looked at the Adit cards for that, and didn't see it as a simple
conversion. 

The ADIT cards support putting the 2b+1d into 3 B channels on a T1. Then
you have to deal with the signaling for the D channel speed differences.
In BRI the D channel is 16k and the B channel it gets stuck into on PRI
is 64k. 

There was another method of encoding that allowed multiple D channels to
be combined into a B channel to get better density, but again, it wasn't
a direct fit with the zapata libraries and didn't look easy to do. 

Does the Adtran way differ significantly enough to make this become
easy? 
-- 
Steven Critchfield <critch at basesys.com>