T.38 passthrough error

Asterisk Asterisk Support
1

Having trouble with Asterisk 11.7.0 and T.38 passthrough to a Grandstream HT502 ATA. Both Asterisk and the ATA are behind NAT. The Grandstream is set to receive T.38. SIP trunk carrier is Flowroute.

Some fax messages get through, some don’t. I seem to get the following error no matter what:

[Jan 20 04:09:47] WARNING[980][C-00000022]: chan_sip.c:10353 process_sdp: Failed to initialize UDPTL, declining image stream [Jan 20 04:09:47] WARNING[980][C-00000022]: chan_sip.c:10506 process_sdp: Failing due to no acceptable offer found

Anyone know what this error means?

2

The remote system isn’t compatible. You will need to provide the complete SDP exchange (use sip set debug on) to find out why.