Sourav, Please check RFC3891;
This specification defines a new Require/Supported header option tag "replaces". UAs which support the Replaces header MUST include the "replaces" option tag in a Supported header field. UAs that want explicit failure notification if Replaces is not supported MAY include the "replaces" option in a Require header field. About your question, both replaces and REFER can be implemented in different applications and together. Replaces can be used without REFER during call pickup scenario where dialog information is passed to UA using subscribe/notify mechanism. REFER can be used in blind transfer scenario where replaces header is not required. Ps: Although you won't see a Replaces header inside a REFER message, REFER in context to Replaces header is involved in a replaces call flow which is actually carried by INVITE message. Best Regards, Vivek Batra On Tue, Oct 28, 2014 at 4:35 PM, Sourav Dhar Chaudhuri < sourav_mi...@yahoo.co.in> wrote: > Hi, > Is this mandatory to have support for replaces parameter to support > REFER request? > > Means If Supported: replaces is not present in the User Agent side . > Then that user will not support REFER request. The REFER request is > containing Replaces-to header having Replaces parameter. So in this case > the Use Agent will not support that REFER request? is there any RFC > reference.. I have not got anything relevant in RFC 3515 for this. > > Thanks > > Sourav Dhar Chaudhuri > _______________________________________________ > Sip-implementors mailing list > Sip-implementors@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
