You can check the offer/answer RFC 3264. See inline.
> -----Original Message----- > From: Kumar, Puneet (Puneet) [mailto:[email protected]] > Sent: Monday, July 15, 2013 12:45 PM > To: [email protected] > Subject: [Sip-implementors] SDP media line reordering in reINVITE. > > Hi All, > > Is it allowed to change the order of media line in SDP in case an UA sends a > reINVITE? > > Consider a case where call is up with audio. > > m=audio 38646 RTP/AVP 18 > > Now can any UA send following in the SDP: > > m=image 38648 udptl t38 > ... > m=audio 38646 RTP/AVP 8 0 97 [Neel] This is moving media stream slots. One reason the endpoint trying to do is to provide a priority for image over audio. Alternatively if the goal is to do image and stop audio, the endpoint can be RFC compliant, by making port to 0 for m=audio. [Neel] >From RFC 3264. 8.1 Adding a Media Stream New media streams are created by new additional media descriptions below the existing ones, or by reusing the "slot" used by an old media stream which had been disabled by setting its port to zero. Rosenberg & Schulzrinne Standards Track [Page 13] RFC 3264 An Offer/Answer Model Session Description Protocol June 2002 Reusing its slot means that the new media description replaces the old one, but retains its positioning relative to other media descriptions in the SDP. New media descriptions MUST appear below any existing media sections. The rules for formatting these media descriptions are identical to those described in Section 5. > > > As seen above "image' line is added prior to "audio" line. > > Thanks, > Puneet > > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
