> Considering UAC, it can judge from the 4xx to terminate > the session (such as 481), or send a new PRACK. The PRACK 481 should not automatically terminate the dialog usage. Since avoiding the sending of PRACK 481 (after sending PRACK 488 and similar failure responses) is an open issue within draft-ietf-sipping-sip-offeranswer-10 section 6.1, I thought that I'd mention the RFC 3262 text and potentially missing RFC 5057 text concerning PRACK 481. RFC 3262 section 3 indicates to send PRACK 481 similar to sending CANCEL 481. The 481 should not automatically terminate the usage since the UAS is not necessarily indicating that the dialog does not exist. "If a PRACK request is received by the UA core that does not match any unacknowledged reliable provisional response, the UAS MUST respond to the PRACK with a 481 response." Unfortunately RFC 5057 section 5.1 note 8 only appears to discuss the special consideration for CANCEL instead of also discussing PRACK. "The 481 response to a CANCEL request has to be treated differently. For CANCEL, a 481 means the UAS can't find a matching transaction. A 481 response to a CANCEL affects only the CANCEL transaction. The usage associated with the INVITE is not affected." _______________________________________________ Sipping mailing list https://www.ietf.org/mailman/listinfo/sipping This list is for NEW development of the application of SIP Use sip-implementors@xxxxxxxxxxxxxxx for questions on current sip Use sip@xxxxxxxx for new developments of core SIP
