Extra c= line in media section

[camilleoudot]

Hi,
i'm testing a very simple call flow involving re-INVITE (call on hold). I'm using the interface-bridging branch:

• Alice is in the "internal" zone (127.0.0.1)
• Bob is in the "external" zone (10.193.x.x)
• Kamailio + rtpengine act as SIP and RTP relays

Alice invites Bob, Bob picks up, everything OK

Bob hits the "on hold" button

Bob's phone sends a re-INVITE to Alice with the following SDP

v=0
o=bob 1201 3427 IN IP4 10.193.13.216
s=Talk
c=IN IP4 0.0.0.0
t=0 0
m=audio 7078 RTP/AVP 111 110 0 8 101
c=IN IP4 10.193.13.216
a=rtpmap:111 speex/16000
(...)
a=sendonly

rtpengine rewrites the SDP

v=0
o=bob 1201 3427 IN IP4 10.193.13.216
s=Talk
c=IN IP4 0.0.0.0
t=0 0
a=ice-lite
m=audio 30114 RTP/AVP 111 110 0 8 101
c=IN IP4 127.0.0.1
a=rtpmap:111 speex/16000
(...)
a=sendonly
a=rtcp:30115
(... ice stuff)

there is now an extra c=line in the media section. Is this done intentionally? If yes, in what case is it added and in what case is it not? This re-INVITE message is the only one where i saw an extra c= line.

[rfuchs]

I see two c= lines in the original SDP and two c= lines in the rewritten SDP. Am I missing something?

[camilleoudot]

Hi Richard,
In fact It's me who missed something, everything is fine as you said.The client I'm using is sending 2 c= lines in the sendonly SDPs, and 1 c= line otherwise, and somehow I mixed these messages, sorry.
Thanks