Hi All!

My question about a=inactive attribute of SDP and re-INVITE.
We  have  implemented  re-INVITE for our UAC. Our re-INVITE changes media 
session and add video
codecs to SDP and it works and tested with some sip proxies.

But with Asterisk and Bria, we have strange behavior:
Assume, that Asterisk is UAS and Bria is UAC1, UAC2

1. UAC1 INVITE to UAS with audio codecs only in SDP, audio a=sendrecv

2.  UAS  INVITE  to  UAC2  with  audio  and video codecs in SDP, audio
a=sendrecv, video a=sendrecv

3.  UAC2  200  OK  to  UAS  with  audio and video codecs in SDP, audio
a=sendrecv, video a=inactive

4.  UAC1  re-INVITE  to  UAS  with  audio  codecs  and  video  codecs,
a=sendrecv, video a=sendrecv

5. UAS 200 OK to UAC1 with  audio  codecs  and  video  codecs,
a=sendrecv, video a=sendrecv

6. ACKs...

Then RTP audio+video conversation has been established.

But in this scenario, UAS does not transmit re-INVITE to UAC2 at all.
Is it rfc3261 violation?

UAC2 starts send  RTP video packets after packets received
from UAS.

Is  it  correct  implementation  or workaround? - to start sending RTP
packets after receiving packets from the far end? If it is not workaround.
What specification describes it?


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