In this call flow I don't think it is correct to send session description in 180. As per the two statements below **reliable non-failure message** 183 completed the offer/answer exchange, so resending answer is incorrect.
RFC 3261, section 13.2.1: If the initial offer is in an INVITE, the answer MUST be in a **reliable non-failure message** from UAS back to UAC which is correlated to that INVITE. For this specification, that is only the final 2xx response to that INVITE. That same exact answer MAY also be placed in any provisional responses sent **prior to the answer**. RFC 3262, section 5: All user agents that support this extension MUST support all offer/answer exchanges that are possible based on the rules in Section 13.2 of RFC 3261, based on the existence of INVITE and PRACK as requests, and 2xx and **reliable 1xx as non-failure reliable responses**. As per the statement below from RFC3261, section 13.2.1, sending an offer is incorrect. "Once the UAS has sent or received an answer to the initial offer, it MUST NOT generate subsequent offers in any responses to the initial INVITE." -Ramakrishna ________________________________ From: [EMAIL PROTECTED] on behalf of Neeraj Jain Sent: Sat 10/1/2005 10:49 AM To: 'Sip-Implementors' Subject: RE: [Sip-implementors] Query regarding 183 provisional response. Please see inline comments. Neeraj Jain BayPackets Technologies -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of jay prakash dubey Sent: Friday, September 30, 2005 12:26 PM To: Sip-Implementors Subject: [Sip-implementors] Query regarding 183 provisional response. Hi all, I am having one basic doubt in Prvisional response.If 180 ringing and 183 session progress both came from UAS to UAC. -----------INVITE+SDP-------------------> <----------183 Session progress(SDP)--------- ------------PRACK-----------------------> <------------180 Ringing(SDP)---------------- <------------200 Ok (for PRACK)--------------- <------------200 Ok (for INVITE)-------------- -------------------- --------------ACK( for Invite)----------> 1. what happen if 200 Ok for PRACK doesn"t recieve.call droped or not? [NEERAJ] UAS in this flow is violating RFC3262 which says that a UAS must not respond with final response to INVITE until there is an outstanding provisional response containing SDP (which is 180 Ringing in this case). Hence 200 Ok (for INVITE) must not be sent before the PRACK is received for 180 Ringing. 2. if 183 and 180 both has SDP than when final SDP negotiation can be done in 200 OK (PRACK)? [NEERAJ] Again as per RFC3262, SDP in 180 must be same as that in 183 unless PRACK (183) contains additional offer from UAC. In later case, 180 must have the same SDP as 200 OK (PRACK). can any body clarify this call flow as in my application Early media is must.... Thanks and regards Jay _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors Confidentiality Notice The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain confidential or privileged information. If you are not the intended recipient, please notify the sender at Wipro or [EMAIL PROTECTED] immediately and destroy all copies of this message and any attachments. _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
