[OpenSIPS-Users] OpenSIPS sending 200 OK with SDP

[Andreas Sikkema]

Hi,

I know what I'm trying to do is very much frowned upon, but I'm
hitting walls everywhere to make this work.

We have this platform that is using what seems to be RFC3311 UPDATE
messages as part of a call transfer. A calls B, B answers, A calls C
and during the ringing phase A transfers C to B. During the transfer A
sends an UPDATE message to C to signal that it should send RTP to B
instead of A. B is notified using re-INVITE messages. B and C are both
behind an OpenSIPS install built especially for this sceanrio.

Most free software products have a hard time supporting this. Some
have bugs (see the bugfix for OpenSIPS where we reported the initial
problem) and others just don't support it at all. Since we're running
quite a lot of those products I'd rather have something handle the
UPDATE but don't bother other clients with it.

So, is there a way for OpenSIPS to receive the UPDATE, handle the SDP
change using either one of the media proxies and respond back to A
with a 200 OK containing the (perhaps) newly updated SDP?

We're already running an older installation of OpenSIPS that we can't
(yet) upgrade so we're introducing a new one (I'm hoping temporarily).
We found this issue while trying to connect our existing OpenSIPS
based platform to our hosted PBX platform using a SIP connection.

Thanks!

-- 
Andreas Sikkema