Hi, RFC 3261 and RFC 3262 attempted to be backward compatible with RFC 2543 devices. This includes ACK being the only request that does not generate responses and the potential for an intermediary to return 407 (or other responses) for an unknown request.
There is an open issue about if "PRACK is a normal SIP message, like BYE". Some vendors ignore that aspect of RFC 3262 and think that it would be inappropriate for a UAS to generate many of the non-2xx final responses caused by "the procedures of Sections 8.2 and 12.2.2 of RFC 3261" and shown within RFC 3262 tables 1 and 2. > -----Original Message----- > From: sip-implementors-boun...@lists.cs.columbia.edu [mailto:sip- > implementors-boun...@lists.cs.columbia.edu] On Behalf Of Vimal Tewari > Sent: Wednesday, January 04, 2017 7:46 AM > To: sip-implementors@lists.cs.columbia.edu > Subject: [Sip-implementors] PRACK and Proxy Servers Compliant to RFC 2543 > > RFC 3262 says (in the Introduction part): > > PRACK is a normal SIP message, like BYE. As such, its own > reliability is ensured hop-by-hop through each stateful proxy. Also > like BYE, but unlike ACK, PRACK has its own response. *If this were > not the case, the PRACK message could not traverse proxy servers > compliant to RFC 2543 <https://tools.ietf.org/html/rfc2543> [4 > <https://tools.ietf.org/html/rfc3262#ref-4>].* > > > I do not get the meaning of the last sentence. Can somebody please elaborate > this point? > > > Thanks, > > VChandra _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
