asterisk users - Aug 2009 - T.38 and reinvite

I have a setup with a number of customer Asterisks with T.38 enabled.
This works quite well for each customer sending faxes between branch
offices. 

They all have a SIP trunk to a central Asterisk, which connects them to
the PSTN through various providers on dedicated lines. I cannot enable
reinvite on those SIP trunks, because that would allow calls from the
customer's phones to get reinvited and talk directly to the central
Asterisk -- and there are firewall rules forbidding that.

Is there a way to get ONLY T.38 reinvite without Asterisk trying to get
out of the media path?


/Benny

On Sun, Aug 2, 2009 at 3:30 PM, Benny Amorsen<benny+usenet at amorsen.dk>
wrote:
> Is there a way to get ONLY T.38 reinvite without Asterisk trying to get
> out of the media path?
That's an excellent question. As you've realized, T.38 works by
initializing the SIP connection as audio over a chosen codec, and then
if T.38 is offered there's a reinvite to initiate the T.38 session.

Because of this behavior, and because you want to disable the reinvite
for normal audio calls, I think you will have a to use a separate SIP
trunk for faxing. I can't think of any other way to do it. So a second
parallel SIP trunk for each location sounds like the your way out of
this problem.