Hi All, Need expert advice on below scenario, Consider the following call flow,
SIP Proxy P2 ---- (INVITE) ----> <----- (100) ------ <- (183;100Rel) - ---- (PRACK) ----> <-(200;PRACK) -- <- (183;100Rel) - (new TO Tag) <- (183;100Rel) - (new TO Tag) <- (183;100Rel) - (new TO Tag) <- (200;INVITE) - (new TO Tag; not matching to above) --- (ACK;200)----> Two questions, 1. In a ISUP to SIP interoperability scenario, does SIP proxy need to PRACK all the 183 received since the INVITE was forked by the next hope proxy P2? 2. Is it valid to send a 200|OK for INVITE with new To Tag, not matched to any sent 183? I go through the RFC3262, things and not much clear on this scenario. relevant section of RFC, 3 UAS Behavior ... After the first reliable provisional response for a request has been acknowledged, the UAS MAY send additional reliable provisional responses. The UAS MUST NOT send a second reliable provisional response until the first is acknowledged. After the first, it is RECOMMENDED that the UAS not send an additional reliable provisional response until the previous is acknowledged. The first reliable provisional response receives special treatment because it conveys the initial sequence number. If additional reliable provisional responses were sent before the first was acknowledged, the UAS could not be certain these were received in order. and 5 The Offer/Answer Model and PRACK ... If the UAS had placed a session description in any reliable provisional response that is unacknowledged when the INVITE is accepted, the UAS MUST delay sending the 2xx until the provisional response is acknowledged. Otherwise, the reliability of the 1xx cannot be guaranteed, and reliability is needed for proper operation of the offer/answer exchange. Thanks, Aman _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors