Hi, Your pictures were not received.
I assume that your CFNR examples are similar to RFC 5359's "Call Forwarding - No Answer" or "Call Forwarding Unconditional". Within both of your cases, the offer/answer rules apply. However be aware that the offer/answer rules don't work very well if devices (or their deployed configuration) don't support forking proxies or RFC 3262/3311. Concerning case a), your understanding sounds correct if the softswitch supplied an (answer or preliminary answer) SDP within 18x and it actually needs to change the SDP before receiving ACK. Concerning case b), I'll assume that the flow is similar to RFC 5359's "Call Forwarding - No Answer". As shown within the example, the proxy uses a dialog that it creates if generating 18x (instead of proxying 18x) during call setup. See 181 response within the example. > -----Original Message----- > From: sip-implementors-boun...@lists.cs.columbia.edu [mailto:sip- > implementors-boun...@lists.cs.columbia.edu] On Behalf Of > swaminathan.seethara...@wipro.com > Sent: Friday, April 18, 2014 6:16 AM > To: sip-implementors@lists.cs.columbia.edu > Subject: [Sip-implementors] Reg. CFNR > > Hi, > > We would like to know what would happen in the following cases > involving CFNR: > > > (a) SIP User A calls a ISDN User B connected to a Class 5 > softswitch. User B has CFNR to a SIP user C. The scenario is > illustrated below. Upon reception of message 10 (18x) with SDP_answer2, > we assume that the softswitch shall send the 18x (message 11) with a > different "To" tag, as compared to what was sent in message 5. > Otherwise, we don't see a way of transporting the "new" SDP answer > before the completion of INVITE transaction in the case of unreliable > 18x responses. Is our understanding correct? > > Note: In the case of reliable 18x responses, message 10 can be > interworked by the softswitch to an UPDATE message. > > > > [cid:image002.png@01CF5B1D.52FDD5E0] > > > (b) SIP User A calls SIP User B. SIP endpoint B has CFNR active to > another SIP User C. > > The scenario is illustrated below. Our understanding is, Proxy B sends > the 180 Ringing (message 12) with a different "To" tag, as compared to > the one in message 5, if reliable 18x response is not supported. Is > this correct? > > > > [cid:image001.png@01CF5B1B.D516F590] -- This email is intended solely for the person or entity to which it is addressed and may contain confidential and/or privileged information. If you are not the intended recipient and have received this email in error, please notify BroadSoft, Inc. immediately by replying to this message, and destroy all copies of this message, along with any attachment, prior to reading, distributing or copying it. _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
