H.323 Annex L Conference Call Announcement

[Dave Walker]

Thanks, Radhika.

I assume you've pointed Ben at this list as well as just forwarding his
question?
Comments/answers inline.

Regards,
Chris

"Roy, Radhika R, ALARC" wrote:
>
> Hi, Everyone:
>
> I am enclosing Ben's questions to the SG16 members for their answer because
> I believe that there are many members who might better insights for taking
> part in H.323 development.
>
> Best regards,
> Radhika R. Roy
> AT&T
> +1 732 420 1580
>
> > -----Original Message-----
> > From: ben-w at jlonline.com [SMTP:ben-w at jlonline.com]
> > Sent: Thursday, December 09, 1999 4:09 AM
> > To:   Roy, Radhika R, ALARC
> > Subject:      H.323 questiones
> >
> > Hi Mr.Radhika ,
> > I have some questiones about Ad Hoc Conference defined in ITU-T
> > Recommendation H.323.
> >
> > H.323 Section 8.4.3.1 states:
> >
> >     Endpoint 1 creates a conference with Endpoint 2 as follows:
> >     A1) Endpoint 1 sends a Setup message to Endpoint 2 containing a
> > globally unique CID ? N and conferenceGoal =
> >             create according to the procedure in 8.1.
> >     A2) Endpoint 2 has the following options:
> >             ....
> >     A2d) If Endpoint 2 is an MC(U) that hosts multiple conferences and
> > wishes to provide Endpoint 1 with a choice
> >             of  conferences to join, it can send a Facility message
> > indicating conferenceListChoice and a list of
> >             conferences that Endpoint 1 may choose from. The list of
> > conferences is sent as part of the Facility- UUIE.
> >             For backward compatibility, with version 1 endpoints,
> > conference lists are only provided if the
> >              protocolIdentifier in Endpoint 1's Setup message indicates
> > that it is version 2 or above.
> >
> >             Upon receipt of this conferenceListChoice Facility message,
> > Endpoint 1 may join a conference from the list
> >             of conferences by sending a new Setup message to the MC(U) on
> > the Call Signalling Channel which contains
> >             the selected CID and which has conferenceGoal = join.  If
> > Endpoint 1 chooses not to join any of the listed
> >             conferences, it shall send a Release Complete message to the
> > MC(U).
> >
> > 1.      When EndPoint 1 calling EndPoint 2(MCU),MCU "wishes to provide
> > Endpoint 1 ...",what
> >         does it  mean?Can't any endpoint get a list of conferences?What
> > decides it's wish?
This depends on local policy.  It is possible to have a local policy which
allows only certain people to create or join conferences.  Admittedly the
natural place for this to be administered is in a gatekeeper rather than
internal to the MCU, but this allows the MCU that freedom.  There may also be
private conferences going on within an MCU which will not be advertised.

> >          CUSeeMe Pro and NetMeeting get diferent list of conferences from
> > MeetingPoint(MCU),  I
> >          called MeetingPoint too,but I can't get a list of conferences,I
> > connected with it just like an
> >          endpoint.Why?Does it mean I have created a new conference in a
> > MCU?!
I don't know for certain.  I suggest you ask the providers of MeetingPoint.
There are a number of possibilities:
a) If I remember rightly, CUSeeMe and MeetingPoint come from the same stable.
If so, they may communicate by proprietary means.
b) NetMeeting was originally a T.120 application.  It may still use T.120
protocols to do its conferencing.
If both these guesses are right, and additionally MeetingPoint keeps separate
CUSeeMe conferences from T.120 conferences from H.323 conferences, then you may
indeed be creating a new conference.

> > 2.      If an EndPoint is a standard H.323 client,and MCU provide it with
> > a list conferences,then it
> >          has only two choices: join or release.It means the EndPoint can't
> > create a conference!How to
> >          create a conference in a MCU?Who is the initiator?
There's a bit of text which crept in when I wasn't looking!
I guess the idea is that one of the options that the MCU will give if it wants
to allow creation of a new conference is one with ConferenceID matching the one
in the setup originally sent, in which case this is just like any other join
(except that you're first to join).  But this is a bit of a kludge and should
be clarified.  In fact it's a complete misuse of the word "create" for
conferenceGoal that it can mean "join"!

> > 3.      If I want to learn details about MCU calling procedures,what other
> > protocols should I study?
Er...  Good luck.
If you mean H.323 MCUs, you've found about all there is on the call signalling
side.  There is a lot of stuff in H.245 as well on the connection control side,
which in turn references H.243 and H.230.

> > The questiones puzzle me,can you help me ?
Good luck!

Regards,
Chris
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