Please see my response in line below.. varun wrote: >Hi, >1> In the invite offer, lets say a list of codecs with >send/recv mode are send..! >So in 200 OK, the calle just picks one of these codecs >and replies back or it can also send a list of codecs >with a ordered preference?? > In 3261, the callee is supposed to honor the caller codec preference unless it has a compelling reason to choose its own preference. Therefore, in general case, the caller will response in 200 OK with the codec that is listed first in the caller's SDP >2> Also, after sending INVITE, the caller opens its >media port ( ready to receive media)...how does it >receive media from calle before 200 ok/or any >provisional reponse...i mean since 200 OK/provisional >response would specify the actual common media >format..! > Early dialog can have media flow before 200 OK. Early dialog can happen when the UAS sends 183 with SDP and there could be RTP after that, no need to wait for 200 OK. And again, the SDP in 183 message would honor the caller's codec preference. >3> Also, can send and receive media formats be >different in a SIP call ( like h.323)...! >This would require multiple offer-Answer ??? > In SIP, if one of the parties wants to change the media type, it will need to re-INVITE or UPDATE with SDP. The other party will accept with 200 OK. The media type should be the same for both send and receive though. I don't think you can have caller sends one type of media and the other sends another type and the call would work. >4> what abt update method..how does it modify he >negotiated media formats?? > UAC would send the UPDATE with its codec preference in SDP. The UAS will determine if it can honor the UAC's preference and respond with 200 OK that has its codec of choice in the SDP >5> if you send an options request, how does the other >side notify about its capabilities and which all of >them??( does it tell abt its media capabilities too). > >Would appreciate your response. > >Thanks >Naveen > >__________________________________________________ >Do You Yahoo!? >Tired of spam? Yahoo! Mail has the best spam protection around >http://mail.yahoo.com _______________________________________________ >Sip-implementors mailing list >[email protected] >https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > >
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