Hi all,

Polycom has suggested that we make use of their centralized conference
feature.  

A Polycom configured with a conference bridge URI will start conferences
on that bridge, instead of locally, when the user presses the
'Conference' button/softkey.  One advantage of centralized over local
conferences is that the number of participants is not limited by the
Polycom's resources.  (Currently 3 or 4 total participants, depending on
the Polycom model.)


Here's a user story: User A is in a call with User B, and they decide an
ad-hoc conference is in order.  User A calls User C, then joins the two
calls with the 'Conference' button.  All users are then connected to
User A's conference bridge.  User A can then pull in more participants
by dialing them directly, and joining then after consultation.  (Some
users would prefer this to the user portal invite, see
http://list.sipfoundry.org/archive/sipx-dev/msg17880.html.)  A's user
portal can of course also be used to control the conference.


We could implement a very basic version of this with relatively little
work in sipXecs (see XX-6576):

1. When a user is the owner of a conference bridge, then profiles of all
Polycoms assigned to that user will automatically have
'voIpProt.SIP.conference.address' set to the bridge URI.

2. The Contact header in INVITE responses from the conference bridge
will need to have the "isfocus" tag.


I refer to this as a basic version, because the usability suffers when
the conference bridge is protected with a PIN.  All participants
entering the conference will need the PIN.  But you would expect
participants pulled in by the conference owner to be joined directly,
without being prompted for the PIN.


This could be solved I'm sure, but it would be challenging.  Here's why.
A Polycom with two established calls starts the Conference by sending an
INVITE to the bridge.  That call is established when the bridge returns
an OK.  The Polycom then Blind Transfers (REFER without Replaces) the
two other parties to the Contact from the bridge OK.

We want the two REFER'd parties to enter the conference without a PIN.
It may be helpful if the bridge OK uses an obfusticated Contact in lieu
of a PIN.  But the main challenge is that the owner is prompted for the
PIN only after the call has been established.  That is, the other
participants are REFER'd (and will surely have sent their INVITEs)
before the conference owner has been authenticated.

The two non-owner INVITEs will need to become established calls before
the conference starts.  They should be "held" (with MOH) and then put
into the conference only after the owner has entered the PIN.


Thoughts?


-Paul
[email protected]







-Paul
[email protected]

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