AW: H.323 multipoint conference with consultation calls?

Klaghofer Karl ICN IB NL IP 7 Karl.Klaghofer at VS.SIEMENS.DE
Wed Mar 3 12:53:53 EST 1999


To make use of the conference "invite" approach, you always have to have
"created" (conference create) a two party conference before.

Here is my understanding of the proposal of the TD-26 Monterey how to make
use of the conference invite function (H.323 clause 8.4.3) for Conference
out of Consultation:
Precondition: A has put B on hold (call #1)  and consults to C (call #2).
Upon conference request by user A while being in consultation,  endpoint A
has now to send a new SETUP (call #3) with conference "create" to an MCU.
Afterwards endpoint A sends a further SETUP (#4) with conference "invite" to
the MCU (causing the MCU to call B). Furthermore A has to send another SETUP
(#5) to the MCU causing the MCU to call C. Finally you end up having calls
between the MCU and the endpoints A, B and C.

However, with the current draft H.450.8 approach, the SETUP#3 sent from A to
the MCU includes all the information (h450 operation) the MCU needs to
complete the conference. If the MCU does not understand this optimized
procedure, a fallback to H.225.0 procedures is defined.

Your question on adding further users D, E, ...:
Once the multipoint conference is in place, draft H.450.8 defines to make
use of existing conference "invite" function to add further parties. This
proposal was made to re-use existing H.225.0 functions as far as possible at
this stage.
According to your suggestion, a H.450 operation could be defined very easily
(to be sent from a conferee (A, B or C) to the MCU in a FACILITY causing the
MCU to call user D). This would especially make sense if the user A decides
to add a couple of users (D, E, F and G) to an existing multipoint
conference in one step (this is very likely at a PC based H.323 client where
the user A may select 4 additional users and clicks the "add to conference"
button. It would save 4 SETUPs compared to the current description.


Karl Klaghofer, Siemens AG, Dpmt. ICN IB NL IP7
Hofmannstr. 51, D-81359 Munich, Germany
Tel.: +49 89 722 31488, Fax.: +49 89 722 37629
e-mail: karl.klaghofer at

> -----Ursprüngliche Nachricht-----
> Von:  Hans Andersson E (ERA) (by way of Sakae OKUBO)
> [SMTP:Hans.E.Andersson at ERA.ERICSSON.SE]
> Gesendet am:  Mittwoch, 3. März 1999 17:08
> An:   ITU-SG16 at
> Betreff:      H.323 multipoint conference with consultation calls?
> Hello!
> I have a question regarding multipoint conferences in H.323.
> In the H.323 standard, it seems as if the "Conference Invite"
> functionality
> (see requires that calling party (Endpoint 1) already before
> making
> the call set-up to Endpoint 2 (E2) must have decided that E2 shall be
> brought into the conference as a new member. So it is not possible for E1
> to
> make an enquiry (consultation) call to see if E2 has the time to
> participate, has the required competence or whatever the criterion for
> participation might be.
> But, when I look at the Draft new recommendation H.450.8 "Conference out
> of
> Consultation Supplementary Service for H.323 (SS-CoC)" (February 8, 1999),
> it seems to have what I am looking for.
> According to this recommendation, it is possible to make a call, put the
> called (or calling of course) party on hold, make a consultation call and
> at
> that moment (after talking to the E2 party) decide to create a conference.
> But how do I do if I want to expand this to yet another party in the same
> way? According to H.450.8 (7.4.1), I shall use the H.323 "conference
> invite".
> That would mean that I have to use different principles when I go from a
> 2-party to a 3-party call, than when I go from an N-party to an
> (N+1)-party
> call. Does it have to be like that? I really think that it would be nice
> if
> the H.450.8 recommendation can be expanded to cover also cases when the
> held
> call is a conference. Currently, it only covers the case where the held
> call
> is to to a remote user.
> I would be glad to get your opinion regarding this.
> Best regards
> Hans Andersson
> _____________________________________________________________________
>         Hans Andersson
>         System Design
>         GSM Systems
> Tel:
> +46 8 757 22 38
>         Ericsson Radio Systems AB                               Fax: +46 8
> 404 95 30
>         F $B3SSH (Batan 6, Kista
> Mob:
> +46 70 533 91 12
>         S-164 80 STOCKHOLM
> Hans.E.Andersson at
> _____________________________________________________________________

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