I see what you mean. This was discussed quiet recently on the SIPPING Group. Please refer to
http://www1.ietf.org/mail-archive/web/sipping/current/msg12363.html http://www1.ietf.org/mail-archive/web/sipping/current/msg12359.html I'm not sure whether a consensus was reached over it or not. Regards, Gaurav _____ From: Ritesh Tiwari [mailto:[EMAIL PROTECTED] Sent: Thursday, December 21, 2006 1:04 PM To: Gaurav Kheterpal Cc: [email protected] Subject: Re: [Sip-implementors] Use of 181--Call is being forwarded Hi Gaurav, I dont understand why proxy will generate 181 response when this is an end-to-end response? Then what and how proxy will fill as a To-Tag in 181? thanks Ritesh On 12/21/06, Gaurav Kheterpal <[EMAIL PROTECTED]> wrote: GK>> One of the uses of 181 is the scenario of 'Call Forwarding no No Answer'. The proxy sends back a 181 response to the caller to indicate that the original call is being forwarded to a new destination (URI) & subsequently sends an INVITE to the new callee. The difference between 181 and 3xx level forwarding is that 181 indicates proxy level forwarding while 3xx response is mostly used in UA level forwarding. Refer the call flow at http://www.tech-invite.com/Ti-sip-service-9.html. And rfc 3261 also says all provisional messages except 100 trying must have "To" tag in the section 8.2.6.2. GK>> The 'To' tag is of relevance in case of forking as there might be multiple responses returned by UAS. The 'To' tag helps a UAC distinguish between these final responses. I hope this helps. Regards, Gaurav -----Original Message----- From: [EMAIL PROTECTED] [mailto: <mailto:[EMAIL PROTECTED]> [EMAIL PROTECTED] On Behalf Of Ritesh Tiwari Sent: Thursday, December 21, 2006 1:43 AM To: [email protected] Subject: [Sip-implementors] Use of 181--Call is being forwarded Hi, I don't understand the use of SIP response 181 "Call is being forwarded". 181 is a end-to-end response. And rfc 3261 also says all provisional messages except 100 trying must have "To" tag in the section 8.2.6.2. thanks _______________________________________________ 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
