> According to your response as below. > "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" > > While Alice remains in the signaling path means it is some thing like > "Conference Call you are talking about" > Correct me if i am wrong.
The sentence was literally referring to RFC 3725 type stuff where Alice switches to act like a 3pcc device. However it might be more common for Alice's outbound device (instead Alice's device) to behave as the 3pcc device and remain in the signaling path after the transfer; for example, see RFC 3725 section 7. > On Wed, Aug 6, 2014 at 12:30 AM, Sourav Dhar Chaudhuri < > [email protected]> wrote: > > > 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 > > <[email protected]> > > 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 [email protected] https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
