[reSIProcate-users] Media change between 183 Session Progress and 200 OK

[Emmanuel BUU <emmanuel.buu@xxxxxxx>]

Hello,

This is a theoritical question about SIP. When the following call flow 
occurs:


INVITE ---------------->

<----- 183 Session Progress ( media )

======= RTP =====>

<------- 200 OK ----------

<====== RTP =====>

ACK --------------------->


Is forbidden to change have a different media answer in the 183 Session 
Progress and the 200 OK provided that both answers are compatible with 
the offer?

I checked the RFCs (SIP, SDP offer/answer model and some various 
outdated draft) and could not find any definite answer.

Emmanuel
http://www.ives.fr/