Please check
https://datatracker.ietf.org/doc/html/rfc7345
You will find example
v=0
o=- 4423478999 5424222292 IN IP4
ua2.example.com
s=-
c=IN IP4
ua2.example.com
t=0 0
m=audio 0 UDP/TLS/RTP/SAVP 0
m=image 32000 UDP/TLS/UDPTL t38
a=setup:active
a=fingerprint: SHA-1 \
FF:FF:FF:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB
a=T38FaxRateManagement:transferredTCF
In my opinion, this example equal to your case.
Probable this need to be reported on RTPengine bug tracker.
Sergey Safarov
On Mon, 2024-09-23 at 08:27 +0000, Thomas Baumgartner via sr-users
wrote:
Hi,
we have a problem with a device trying to send T.38 fax. During the
T.38 ReInvite Kamailio fails to parse the SDP (via rtpengine_manage),
and subsequently rtpengine is failing to do it’s job.
The problem seems to be that Kamailio is trying to find a media
address, since there is no session-wide c= line present it goes to
the media c= lines, but since the first media stream which was an
audio stream is being removed (port 0) and can therefore omit all
attributes (as per RFC 3264 8.2, or am i understanding this wrong?),
the Kamailio SDP parser is failing, even if there is another c= line
in the T.38 media stream.
Here is the offending SDP from the ReInvite (IP changed):
v=0
o=xmserver 1726638425 1726638427 IN IP4 169.254.1.1
s=xmserver
t=0 0
m=audio 0 RTP/AVP 8
m=image 56002 udptl t38
c=IN IP4 169.254.1.1
a=sendrecv
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:200
a=T38FaxMaxDatagram:72
a=T38FaxUdpEC:t38UDPRedundancy
And here is the corresponding log entry:
<core> [core/parser/sdp/sdp.c:523]: parse_sdp_session(): can't find
media IP in the message
Can anyone confirm my findings? Is it possible to adjust the SDP
parser for these kind of scenarios?
Mit kommunikativen Grüßen I Best regards
Thomas
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