[SR-Users] SDP in fifth 200 OK is not the same as in first four

[Henning Westerholt]

Am Montag, 8. Oktober 2018, 11:59:37 CEST schrieb Roman Romanchenko:
> I have an issue with SDP from Kamailio side in the following scenario:
> simple call from A to B. When B answers a call and sends '200 OK' to A, A
> delays ACK for a while, so '200 OK' re-transmission happens.
> 
> After the fourth try to re-send '200 OK' towards A, Kamailio changes SDP
> (specifically connection information 'c', IP address become address of A
> instead of proxy IP as it was in the previous attempts). At some point A
> sends ACK and call is established, but last received '200 OK' has invalid
> SDP and it prevents successful media establishment.
> 
> I wonder if there any re-transmission counter or whatever what can affect
> this scenario and change SDP?

Hello Roman,

Kamailio should not change your SDP - unless you use the sdpops module or use 
a similar transformation in the configuration on the SDP in the SIP message.

If the above is not the case, I can only think that this is a strange bug. We 
would need more information in this case.

Best regards,

Henning

-- 
Henning Westerholt - https://skalatan.de/blog/
Kamailio security assessment - https://skalatan.de/de/assessment