Re-Invite / Upgrading Media

Does Asterisk support upgrading the media when a Re-Invite comes in? The flow is as follows:

  • INVITE comes in from a trunk with Audio only in the SDP
  • After the call is ANSWERED, the remote side sends a Re-INVITE with Audio & Video in the SDP.

Looking at the Wireshark, it seems like Asterisk responded to the RE-INVITE.

Following is the SDP that was in the RE-INVITE

o=inbcf 1936544892 2 IN IP4
c=IN IP4
t=0 0
m=audio 20076 RTP/AVP 0
a=rtpmap:0 PCMU/8000
m=video 20078 RTP/AVP 96
a=rtpmap:96 H264/90000
a=fmtp:96 profile-level-id=42801f

Following is the OK which Asterisk responded with

o=root 342471461 342471462 IN IP4
s=Asterisk PBX 17.8.1
c=IN IP4
t=0 0
m=audio 15504 RTP/AVP 0
a=rtpmap:0 PCMU/8000
m=video 0 RTP/AVP 96

Looks like there was a similar issue reported which seem to have been resolve. However, I’m experiencing the same behavior.


Which version? It certainly used to require all streams to be present in the initial INVITE, but it is just possible that has changed.

Which channel driver?

Using chan_sip (I know I should be upgrading to pjsip, hopefully will get there soon)
Asterisk version 17.8.1

I think you can safely say that chan_sip cannot add streams mid call.

So if I were to use pjsip, would it be able to handle adding streams mid call?

PJSIP allows adding/removing streams mid-call. However, you are using a security fix only version of Asterisk that may not have received fixes/changes in that area, and certainly will not in the future.

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