The UAC after checking from the provisional response that the required extension is not supported, can - keep on waiting for a timeout on the server side to get a final error response from UAS, or - an application level timeout on UAC itself - or send a CANCEL
The last approach has the advantages - of avoiding unnecessary retransmissions over the wire and cleaning up the state from both the UAs without any unnecessary delays. Ajay -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dale R. Worley Sent: Thursday, April 06, 2006 3:38 PM To: Sip-Implementors Subject: Re: [Sip-implementors] Query on PRACK On Thu, 2006-04-06 at 13:56 -0400, Rajendra, Subbu wrote: > You mean that the original INVITE did not have Supported: 100rel? > [Subbu] Yes > In that case, the far end is in error when it sends a Require: 100rel. > [Subbu] The UAS is behaving incorrectly The right way is to send not > supported. One of the 4XX responses. > [Subbu] How can a UAC send 4xx response? As far as I know UAC can only > send CANCEL for the INVITE it had send. I think there have been some mis-statements in this discussion. What we are discussing is if the UAS incorrectly sends a provisional response with a "Require: 100rel" header, when the UAC does not understand 100rel (and thus did not include it in a Require or Supported header). (Previous discussion suggested that the "Require: 100rel" was on a PRACK request.) When the UAC receives the provisional response, it must ignore the response, as it knows that it does not know how to handle it. Since the ignored response was provisional, it knows that it can wait for a final response. (If the ignored response was final, it might have to pass an error indication up to its application.) Dale --- interop.pingtel.com -- the public SIP phone interoperability test server _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
