Thanks Samuel. Actually I have a constraint where my peer SIP phone doesn't support UPDATE method. I checked the Session Timer draft again and it does mention that for refresh request SDP may be included but to avoid SDP negotiation, 'origin' field can be kept same as previous SDP message to peer.(sect 7.4). Hence I can use it in this scenario. Hoping all SIP phones/gw comply to this SDP mechanism. Regards, -Manish
Samuel Osorio Calvo <[EMAIL PROTECTED]> wrote: Using UPDATE requests (which does not mandates to include SDP body) no media negotiation is required. Actually the SessionTimer draft/RFC recommends using UPDATE instead of INVITE. Regards, Samuel. Unclassified. >>> Manish 10/12/04 11:15AM >>> Hi All, I have a query about way session timer is implemented with call transfer: Lets say: Phone A - Transferor Phone B - Transferee Phone C - Transfer Target A SIP call is up between A and B with G.729, though preferred codec on Phone B is G.711. Phone A does'nt support G.711. Phone B is SIP session refresher and perodically sends a RE-INVITE to referesh session timer. At this point Phone A initiates a transfer by sending REFER to B, which sends an INVITE to Phone C with G.711 and hence switches internally to G.711 codec. While phone C is ringing, session refresh timer for original call fires on B and hence it has to send a REINVITE to A. Here is a doubt: - What are the media parameters phone B should send to A at this moment. It cant send G.729 and change internal codec setting since it has already sent G.711 to Phone C. And if it sends G.711 to A, that INVITE would be rejected may be with 488 which will cause first call to go down, which we dont want at this moment. - This leads me to think that Ideally for just session refreshing SDP should not be considered at all.. But AFAIK, SDP should be negotiated as part of INVITE transaction. Any info on how this or similar scenarios usually handled ? Is there a way of session timer refreshing without any media negotiation after call is UP ? Regards, M. --------------------------------- Do you Yahoo!? vote.yahoo.com - Register online to vote today! _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors --------------------------------- Do you Yahoo!? vote.yahoo.com - Register online to vote today! _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
