Hi River, It depends on whether 180 contains Require header with vaule "100rel".
If 180 includes Require with 100rel, which means 180 is sent reliably, SDP in the 200 OK is not mandatory. Otherwise, the same SDP as one in 180 must be included in 200 OK to INVITE, because UAS doesn't know whether 180 has reached UAC. > Hello All, > > I have a question about 200 OK for INVITE. > Let's suppose an UAC sends out an INVITE/SDP, then the UAS replys with > 180/SDP and 200 OK for the INVITE. > Is it compulsory that the 200 OK for the INVITE also contain SDP (where the > 180 Ringing already has SDP)? > Thank you very much! > > > Best Regards, > River > _______________________________________________ > 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
