> If retransmitted INVITE is received after exchanging > PRACK-200 OK (but before 200 OK of INVITE), what > should be the behavior?
The UAS knows the 180 was received because 100rel was used. To the UAS, the INVITE just looks like a late retry. Thus it has 3 options depending upon vendors interpretation of RFCs and interpretation of reason for the late retry. My interpretation of rfc3262 section 3 is that the UAS should/must consume the retry instead of resending 180 per rfc3261. However some vendors interpreting that rfc3261 takes precedent might resend the 180. And yet another option is to use the really late retry as excuse to trigger the periodic 18x with higher rseq for interactions with timer C. Note per rfc3262 section 3 if the UAS resends the 180, the UAC must discard it without triggering PRACK unless rseq is exactly 1 higher. <snip> > As per me, User B should send 180 provisional response even > if PRACK and 200 OK of PRACK is exchanged. See above. > Some of the SIP vendors are using retransmitted INVITE like > above as the tools to keep alive the signaling pinhole. I > need to know whether this retransmitted INVITE shall be > rejected by 500 or not. The scenario should not trigger a 500 response. However the 500 could be generated for other reasons. INVITE retries during call setup is an interesting choice for keeping the pinhole open. It sounds like everyone will continue to be creative until the outbound draft is finalized and implemented. _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
