Hi RFC3262 says the following about UAC:
"Note that the PRACK is like any other non-INVITE request within a dialog. In particular, a UAC SHOULD NOT retransmit the PRACK request when it receives a retransmission of the provisional response being acknowledged, although doing so does not create a protocol error. Once a reliable provisional response is received, retransmissions of that response MUST be discarded. A response is a retransmission when its dialog ID, CSeq, and RSeq match the original response. The UAC MUST maintain a sequence number that indicates the most recently received in-order reliable provisional response for the initial request. This sequence number MUST be maintained until a final response is received for the initial request. Its value MUST be initialized to the RSeq header field in the first reliable provisional response received for the initial request. Handling of subsequent reliable provisional responses for the same initial request follows the same rules as above, with the following difference: reliable provisional responses are guaranteed to be in order. As a result, if the UAC receives another reliable provisional response to the same request, and its RSeq value is not one higher than the value of the sequence number, that response MUST NOT be acknowledged with a PRACK, and MUST NOT be processed further by the UAC. An implementation MAY discard the response, or MAY cache the response in the hopes of receiving the missing responses. " I interpret this as if the UAC receives a retransmitted reliable response it should NOT send the PRACK again. If this is true, it means that if the first PRACK is lost, the UAS will never receive it? // Andreas _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
