Hans,
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.
Regards, Karl
------------------------------------------------ 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@vs.siemens.de
-----Ursprüngliche Nachricht----- Von: Hans Andersson E (ERA) (by way of Sakae OKUBO) [SMTP:Hans.E.Andersson@ERA.ERICSSON.SE] Gesendet am: Mittwoch, 3. März 1999 17:08 An: ITU-SG16@mailbag.cps.intel.com 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 8.4.3.5) 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 SystemsTel: +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@era.ericsson.se