One of our customers has fax/SIP gateways which send INVITE with t38 SDP directly, without previous audio SDP INVITE. I was able to modify PJSIP t38 module to work with this direct INVITE, receive fax on asterisk and also pass the direct t38 INVITE thru Dial between two PJSIP channels and transfer fax.
Now the customer asks to send the patch to the asterisk source, which is impossible because it is very use case specific ugly hack.
Is here anybody able and so kind to say if there is reasonable way to the correct solution, what would be correct approach and which parts of asterisk need to be changed?