Hi Paul, Thanks a lot for your detailed response. You have answered all my doubts. I am really grateful for your email.
Thanks & Regards, Sourav Dhar Chaudhuri On Tuesday, 5 August 2014 8:11 PM, Paul Kyzivat <pkyzi...@alum.mit.edu> wrote: On 8/4/14 10:12 AM, Sourav Dhar Chaudhuri wrote: > Hi, > Is there any way when a answered call [ 200OK is already provided for >initial INVITE and ACK also sent] can be transferred without using REFER >method? > > If it is possible without REFER then please let me know required procedure. More detail is needed to answer this. Lets assume that Alice and Bob are in a call. You want a transfer, so let's assume the transfer target is Charlie. Further, assume it is Alice that wants to initiate the transfer, resulting ultimately in Bob talking to Charlie. A simple answer to your question is for Alice to initiate the call to Charlie, and then bridge the media between Bob and Charlie. It is also possible for Alice to use 3pcc O/A techniques to establish a direct *media* path between Bob and Charlie, while Alice remains in the signaling path between them. The reason for REFER is to get Alice out of the signaling path. If there is a middlebox in the signaling (e.g. a sip pbx or an SBC) then in principle Alice can ask that middlebox to handle the transfer. But Alice needs a way to convey the desire to do so. Often REFER is still used for that, but is intercepted by middlebox, which then uses mechanisms such as I described above. Some other mechanism, other than REFER, can be used for that but it will be a proprietary solution. Does that help? Paul _______________________________________________ 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
