Hi,
The 180 Ringing is the provisional response. According to RFC 3262, Retransmission of 180 Ringing occurs till it receives PRACK. In this scenario, PRACK is not received; the 200 OK response of INVITE is generated before receiving PRACK and is buffered. As the 200 OK for INVITE is already sent. No further final response can be sent. After certain retransmissions of 180 Ringing, CANCEL is sent and 200 OK for CANCEL is received. How this INVITE transaction should be terminated. How should SIP stack respond? Also what happens when instead of CANCEL, BYE is sent? Regards, Madhuri ________________________________ From: Venkatesh [mailto:[EMAIL PROTECTED] Sent: Friday, May 26, 2006 11:34 AM To: Nataraju A B Cc: Madhuri Sakhare; [email protected] Subject: Re: [Sip-implementors] Query Regarding Collision case of CANCEL. Please check this thread. The CANCEL will get a 2xx response. https://lists.cs.columbia.edu/pipermail/sip-implementors/2006-May/012974 .html On 5/25/06, Nataraju A B <[EMAIL PROTECTED]> wrote: Thanks & Regards, Nataraju A.B. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Madhuri Sakhare Sent: Thursday, May 25, 2006 7:40 PM To: [email protected] Subject: [Sip-implementors] Query Regarding Collision case of CANCEL. Hi, Consider this call flow: UAC UAS | INVITE | |----------------------->| | 180 RINGING | |<-----------------------| | CANCEL | |----------------------->| | 200 OK CANCEL | |<-----------------------| | | This is a collision case of a reliable 180 response and a CANCEL Request. The application on the callee side has sent a 200 OK response, and the response is left pending in the SIP stack. Then the collision occurs and the CANCEL is indicated to the application, but since it has already sent a final response, it has no way of sending another one. The call is not freed. How should the SIP stack responds to this? [ABN] This scenario has been discussed in the list quite a few times... if the callee UA had already sent 200OK for INVITE then 200OK will not be sent for CANCEL. CANCEL would be rejected with 481 responses... The call will go through... The caller's SIP stack has to initiate the BYE request to terminate the call once the INV/200/ACK transaction is completed... if the user had hung up the call... Regards, Madhuri _______________________________________________ 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 _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
