scm-j@nuntius.com wrote:
I am facing some problems with sending fax calls. I am using G.711 codec. However, my service provider (Level-3) does not support T.38 fax relay.
According to Level-3 they “think” the problem lies in the “Media Description” field of the SDP message I am sending them. The problem is related to the “Media Format” sub-field (value 101) that I am sending, which according to them should be removed.
The SDP “Media Description” field I am sending, looks as follows:
“m=audio 20744 RTP/AVP 0 101”
which is decoded by Ethereal as follows:
Media Type: audio
Media Port: 20744
Media Proto: RTP/AVP
Media Format: ITU-T G.711 PCMU
Media Format: 101
My call is initiated by Asterisk which is sent to Level-3 via SER
Asterisk -à SER -à Level-3
The SIP call flow looks fine for the call. The sending fax sends the page and then gives an error. The receiving side gives me an error and prints a blank page.
My questions are as follows:
Could the “Media Format” 101 be the problem? If so, how do Iremove the 101? This change is probably in Asterisk, as it initiates the call, and not SER, or probably both.
I don't think that this will cause problem. If this is really the problem, than the L3 gateway su$%s.
If not, should I be looking elsewhere in SER/Asterisk to solvethis problem?
How is the fax generated? A PSTN fax machine connected to asterisk? span_dsp?
regards, klaus