[Serusers] RE: Transfer and Conferencing - Please help!

[Bob Carlson]

I sent this earlier and got no responses.  Perhaps this is not the right
forum to ask this question.  Can any one suggest a better place to go for
this information?

Thanks, Bob

-----Original Message-----
From: Bob Carlson 
Sent: Wednesday, November 03, 2004 3:22 PM
To: 'SerUsers'
Subject: Transfer and Conferencing

Let me apologize in advance for my question, which is a little rudimentary.
We are just starting a project that will use SER and I am being forced to
document right now how transfer and conferencing will be handled.  I have
spent a lot of time looking for definitive information on the subject with
no luck.  Well, maybe too much luck.  There seem to be many proposals and
models and so on, but it is not clear to me what is actually being done in
practice.  I have downloaded all the RFCs and proposal papers on the
subject.  I am still reviewing them, but I think the folks on this forum can
help me a lot.

I need to know the SIP message sequences for performing a call transfer and
a blind call transfer and for constructing a conference.  I have found
information in proposals, but I need to know what actual, available SIP
phones can do.  We have some phones that we will test, but I do not know
what they do when you press their transfer and conference buttons.  Pardon
me again for my impatience in asking before I have tried this out.

The Transfer models are straightforward, but conferencing is more
complicated.  We must construct a simple conferencing model where the
conferencing is performed by a central server, a SIP IPX.  Only conferences
of 3 participants need to be supported.  We want it to look exactly like
3-way calling on your home phone.  During a call, put the call on hold with
a conference button, call another phone, hit conference button, the two
calls are joined in a 3-way conference.

The document draft-ietf-sipping-service-examples-07.txt seems to be very
helpful on the subject, but all examples are in the form of 3 or more UAs
and do not address any examples from the point of view of a PBX.  I can see
how to extend the examples to a PBX case, except for one aspect.  If the
IP-PBX is to perform the action as a proxy, what does the phone send the
IP-PBX to indicate the steps in the process.  Put more plainly, what happens
when the user hits the Transfer or Conference button on the phone?  What
message is sent to the IP-PBX?

Can anyone tell me where else I should be looking?  Is the service examples
draft the best base document to work from?

Thanks in advance, Bob Carlson