> Is it allowed to change the order of media line in SDP > in case an UA sends a reINVITE?
No; however old slots can be reused. RFC 3264 section 8.1: "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. 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." > 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 > > > As seen above "image' line is added prior to "audio" line. They can send it; however it is invalid unless they can justify it by removing and replacing media at the same time. Since I think that it is common for fax, they might want to support it even if potentially not fully RFC 3264 compliant. _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
