Sorry to dredge this up again, but someone must have got this working on Asterisk. My equipment is all T.38 compliant and I can make it work if I don’t use Asterisk as the SIP proxy. I need fax in my applications as they are Small/Medium business that want fax off their DID which goes into Asterisk via SIP.
SpanDSP does not cut it. Too unreliable over SIP.
I know the problem is something to do with the way Asterisk negotiates the call setup.
I have seen people putting bounties up for Asterisk to do T.38 natively. All I want it to do is allow 2 SIP devices to bridge T.38 to get my fax machine on line.