CA2108738C

CA2108738C - Multi-level conference management and notification

Info

Publication number: CA2108738C
Application number: CA002108738A
Authority: CA
Inventors: Bruce Merrill Bales; Robert Louis Crumpley; Stephen Max Thieler; Donald Dean Gallagher
Original assignee: American Telephone and Telegraph Co Inc
Current assignee: AT&T Corp
Priority date: 1992-12-23
Filing date: 1993-10-19
Publication date: 1997-09-16
Anticipated expiration: 2013-10-19
Also published as: DE69327033D1; JP2828888B2; EP0604053A1; DE69327033T2; US5373549A; CA2108738A1; ES2141139T3; EP0604053B1; JPH06237303A

Abstract

A multi-level conference in which an originator of telephone conference of the multi-level conference controls the parties that can be added to that conference and can terminate any party at any time. Further, if two existing telephone conferences are combined together to form the multi-level conference, the party that originated the combining of these two conference calls can control not only the parties on its conference call but can disconnect all of the parties on the second conference call. In addition, the control of the conference resides in the telephone terminals beingutilized by the participants, rather than in a centralized service computer.
Information concerning the conference and control of the conference is communicated between the telephone terminals utilizing the standard telecommunication communication control channel and does not require the establishment of a separate data call to a centralized service computer. In addition, the telephone terminals display the names and telephone numbers of parties on the multi-level conference and identifies parties controlling the individual conferences.
In addition, when two conferences are combined together, each originator of a conference maintains control over their subconference and can independently separate that subconference from the other conference in a multi-level conference.

Description

~ ~'3 ~ ~8 MULTI-LEVEL CON~ERE:NCE MANAGEMENT ANI) NOTIF~CATION
Technlcal Fleld This invention rclates to cont~lling a telecommunication switching system, and, in particutar, to telephone confercnce calls on such a switching system.
5 Back~round of the ~nvention In prior art business communication switching systems (also referred to as PBXs), a conference call can be set up ~etwcen a plurality of station sets by a station set conferencing other station sets into a conference, Indeed, it is possible to haYe two conferences set up between two different sets of station sets and to join 10 those two conferences. A station se~ on the first conference conferences a station set on the second conference into the first conference, which results in all of the station sets of the second conference becoming part of the first conference. The problemthat arises is that the two sets of station sets cannot be disen~aged fnom the resulting conference call without each station set hanging up, since no station set has control 15 of the resulting conference. In prior art business communication systems, conference calls result in many awkward and inefficient situations because one station set does not control the conference.
Within the AT&T long distance telephone network, a teleconferencing service known as the Alliance Dedicated Teleconferencing Service is available. An 20 Alliance system comprises a teleconferencing bridge connected to a 4ESS toll switch. The Alliance system can conference up to 56 telephone lines interconnected via the 4ESS toll switch to the teleconferencing bridge. Conference calls are setup and controlled by AT&T operators who can selectively add and drop people to a conference and who can obtain a visual display of the individuals OQ the conference 25 by name and telephone number.
~ In an attempt to improve upon the Alliance system, U.S. Patent No. 4,796,293 discloses interposing a service computer between a coordinator of a conference and the Alliance syslem. ~e service computer uses the same interface into the Alliance system as that of an operator terminal interconnected to the system.
30 llle service computer gives the coordinator an improved human interface to the Alliance system than that of an AT&T operator terrn nal. The service computer takes the place of the AT&T attendant. In order to establish communicadon with the service computer, the coordinator is required to use a separate packet data system to est~blish communication between the service computer and the coor~inator's 35 computer ternninal. Once this connrnunication has been established, the coordinator has the same capabilities as the AT~T operator. The selvice computer assumes that the first terminal to establish cornmunications with the service computer is the - 2 - '~ 7 3 ~

- coordinator's tcrminal. Othcr conferees can Intcrconncct thcir computer terminals to thc servicc computer via the packet network if cach has a login ID and a password.
Each conferec who acccsses the servicc computer via their own computer terminal also has displayed for them thc names and telcphone numbers of the people on thc5 conference. The coordinator has the capability to sub-conferences. All conferees converse using regular telephones. Once suWivided, the coordinator can also re-combine the two sub-conferences.
The problems of the prior art are thc lack of control and identificadon in business communication switching systems and the need in the system disclosed by10 U.S. Patent 4,796,293 for a separate service computer which requires interconnection via a separate packet network. Further, in the case of U.S. Patent 4,796,293 theconference call must begin on a dedicated conference bridge. What is needed is aunified conferencing system whereby users can, during the course of a two party conversation, convert that two party conversation into a conference call with the 15 originator of the conference call controlling the conference call with respect to adding and dropping individuals. Further, each user has displayed for them the participants in the conference calls on the telephone terrnlnal of the user.
Summary of the Invention The foregoing problems are solved, and a technical advance is achieved 20 by a switching system and method in which the originator of a telephone conference controls the parties that can be added to that conference and can terrninate any party at any time Further, if two existing telephone conferences are joined together, the party that originated the joining of these two conference calls can control not only the parties on its conference call but can disconnect all of the parties on the second 25 conference call. In addition, the control of the conference resides in the telephone terminals being utilized by the participants rather than in a centralized service computer. Information concerning the conference and control of the conference iscommunicated between the telephone terminals utilizing the standard telecommunication communication control channel and does not require the 30 establishment of a separate data call to a centralized service computer. In addition, the telephone terminals display the names and telephone numbers of parties on a multi-level conference and identify the parties controlling the conferences. In addition, when two conferences are combined together, each originator of a conference maintains control over their subconference and can independently 35 separate that subconference from the other conference in a multi-level conference.
Also, the telephone terrninal of the originator transmits party identification to the other telephone terminals in its conferencc.

-~ 2 ~ ~ 8 7 3 8 Advantageously, the telephone terminals communicate utilizing ISDN messages. Advantageously, the standard notify message of the ISDN
protocol has been expanded, to carry conference information and allows for the conference information to be communicated in the D channel (control channel) 5 of the ISDN protocol rather than requiring the use of another B channel (voice or data channel) to setup a data call.
In accordance with one aspect of the present invention there is provided an apparatus for establishing and controlling a multi-level telecommunication conference between a plurality of telecommunication 10 terminals interconnected by a telecommunication switching system, comprising: means, in a first telecommunication terminal, for establishing a first telecommunication conference among a first subset of the telecommunication terminals including the first telecommunication terminal, via the telecommunication switching system and for controlling removal of any one of 15 the telecommunication terminals from the first telecommunication conference;
means, in a second telecommunication terminal, for establishing a second telecommunication conference among a second subset of the telecommunication terminals including the second telecommunication terminal, via the telecommunication switching system, and for controlling removal of any one of 20 the telecommunication terminals from the second telecommunication conference;means, in the first telecommunication terminal, by communicating with the second telecommunication terminal, for forming a multi-level telecommunication conference to combine the second telecommunication conference and the first telecommunication conference via the telecommunication switching system;
25 means, in the first telecommunication terminal, for notifying each of the first subset of the telecommunication terminals of identities of users of the other ones of the first subset of the telecommunication terminals; means, in the second telecommunication terminal, for notifying each of the second subset of the telecommunication terminals of identities of users of the other ones of the second 30 subset of the telecommunication terminals; the notifying means, in the secondtelecommunication terminal, further notifying the first telecommunication terminal of the identities of users of the second telecommunication conference;

,~,.....
' A

~ a~o8738 -3a-and the notifying means, in first telecommunication terminal, further notifying the other ones of the first subset of the telecommunication terminals of the identities of users of the second telecommunication conference.
In accordance with another aspect of the present invention there is 5 provided a method for establishing and controlling a multi-level telecommunication conference between a plurality of telecommunication terminals interconnected by a telecommunication switching system, the method comprising the steps of: establishing, by a first telecommunication terminal, a first telecommunication conference among a first subset of the telecommunication10 terminals including the first telecommunication terminal, via the telecommunication switching system, and controlling removal of any one of the telecommunication terminals of the first subset of the telecommunication terminals; establishing, by a second telecommunication terminal, a second telecommunication conference among a second subset of the telecommunication 15 terminals including the second telecommunication terminal, via the telecommunication switching system, and controlling removal of any one of the telecommunication terminals of the second subset of the telecommunication terminals; forming, by the first telecommunica-tion terminal, by communicating with the second telecommunication terminal, a multi-level telecommunication 20 conference to combine the second telecommunication conference and the first telecommunication conference via the telecommunication switching system;
notifying, by the first telecommunication terminal, each of the first subset of the telecommunication terminals of identities of users of the other ones of the first subset of the telecommunication terminals; notifying, by the second 25 telecommunication terminal, each of the second subset of the telecommunication terminals of identities of users of the other ones of the second subset of the telecommunication terminals; the notifying step, by the second telecommunication terminal, further notifies the first telecommunication terminal of the identities of users of the second telecommunication conference; and the 30 notifying step, by the first telecommunication terminal, further notifies the other ones of the first subset of the telecommunication terminals of the identities ofusers of the second telecommunication conference.

f~ 8 7 3 ~
-3b-BRIEF DESCRIPTION OF THE DR~WING
FIG. I shows a telecommunication switching system in accordance with the invention;
FIG. 2 shows the message flow for a station set to set up a three 5 way conference call;
FIG. 3 illustrates the records which are maintained for a three way conference call;
FIG. 4 illustrates the records which are set up for two independent conferences;
FIG. 5 illustrates the records which are utilized when two existing conferences are joined together into a single conference;
FIG. 6 illustrates the message flow when the originator of a second conference call is added to a first conference call;
FIG. 7 shows the messages which are transmitted by the originating station of the second conference call to update the various stations on the second conference call;
FIG. 8 reflects view of the conference manager of station set 101 of the multi-level conference as illustrated in FIG. 5;
FIG. 9 illustrates the view of the conference manager in station set 104 of the multi-level conference call illustrated in FIG. 5;
FIG. 10 illustrates the display provided by station set 101 for the multi-level conference call illustrated in FIG. 5;
FIG. I l illustrates the screen of station set 102 for the multi-layer conference call illustrated in FIG. 5;
FIG. 12 illustrates message flow to terminate a multi-level conference call;
FIG. 13 illustrates the display provided by station set 104 for a multi-level conference call;
FIG. 14 illustrates the records of the station sets after transmission of the messages of FIG. 12;
A

- 4 - h ~ a ~ ~ ~ 8 FIGS. 15 and 16 illustrate, in block diagrarn form, the operations performed by a terminal management application; and FIGS. 17 through 20 illustrate, in flow chart form, the operations perforrned by a conference manager application.

5 Detailed Description FIG. 1 illustrates a telecommunication switching system where station sets 101 through 106 are interconnected by switches 107 and 108. Both the station sets and the switches implement a conventional OSI model modified to implement the ISDN protocol. Certain modifications have been made to the standard OSI
10 model in order to include ISDN capabilities. Within the software model, there are eight software layers. (Note, that the OSI model is also designated as having seven layers where the highest layer combines layers seven and eight of the description in the present application.) The present application is presented in terms of the highest software layer and applications layer.
The present invention is described by the way of an example where station sets 101, 102, and 103 are placed in a first conference call, and station sets 104, 105, and 106 are placed in a second conference call. Station set 101 controls the first conference call, and station set 104 controls the second conference call. These two conference calls are then joined together to form a multi-level 20 conference call. The first conference call is set up by the message flow illustrated in FIG. 2. Within the message diagrams of FIGS. 2, 6, 7, and 12, the designations A, B, C, D, E, and F, refer to station sets 101, 102, 103, 104, 105, and 106, respectively.
Station set 101 first sends a set up message in line 201 to station set 102. The set up message contains the destination which is station set 102, the originator which is 25 station set 101, and includes the alphanumeric name of the user of station set 101.
Station set 102 responds in line 202 by tr~n~mitting a call proceeding message back - S - 2~ 3 ~&

~~ to station set 101. Station sct 102 t'hcn transmits t~hc alerting mcssagc back to station set 101 in linc 203. The alerting message contains the telephonc number (address) and the alphanumeric name of the user of station set 102. After thc user of station set 102 has gone off hook, station set 102 transmits back in line 204 a connect 5 message. Switch 107 is responsive to the connect message to set up a voice path between station set 101 and station set 102. Station set 101 is responsive to thc connect message from station set 102 to transmit back the connecdon acknowledgment message in line 205.
Station set 101 originates another call with station set 103 in lines 206 10 and 207 which perform the equivalent actions as lines 201 and 202 did for the first call. The user of station set 101 invokes the conference call by actuating the conferencing button on station set 101. By transrnission of the merge message ofline 208, station set 101 requests that switch 107 merge the first and the second call together in response to the user's actions. The merge function is different than a 15 conference function in that switch 107 only combines the B channels (voice portions) associated with the two calls for transmission to each of the three station sets and not the D channels (signaling portions). The signaling from stations sets 102 and 103 is only transrnitted to station set 101 which alIows station set 101 to retain control of the conference in accordance with the invention. If switch 10720 performed a conferencing funcdon, all three stations sets would receive both signaling and voice information which would result in no stadon set having control of the conference. In response to the merge message, switch 107 performs the merge function and transmits back the merge acknowledgment message in line 209.
Station set 101 then transmits to station set 102 in line 210 a notify message which informs stadon set 102 that the second party (P=2, with 2 being the ID number) on the conference is station set 103 and that stadon set 101 is the controlling station set (CP= A). Sirnilarly, station set 101 transrnits to station set 103 a notify message in line 211 that inforrns stadon set 103 that the first party on the conference is st~tion set 102 and provides the narne of the user of station set 102 to station set 103. In line 212, stadon set 103 transmits back an alerting message indicating that it is now alerting the user and provides its stadon set number as well as the name of the user of station set 103. Station set 101 is responsive to thealerting message in line 212 to transmit a notify message to inform station set 102 of the second party's name and the fact that the second party is being alerted.
When the user of station set 103 answers the telephone call, station set 103 transmits back the connect message in line 214. Stadon set 101 is responsive to the connect message to send a notificatdon message in line 216 to stadon set 102 - 6 - ~ 7~

informing it that the second party is now connected and a connect acknowledge message in line 215 back to station set 103. Switches 107 and 108 are responsive to the connect message from station set 103 to set up voice paths to interconnect the three station sets.
FIG. 3 illustrates the records which have been set up in station sets 101 through 103 and in switches 107 and 108 in response to the messages of FIG. 2. The records and managers are located at the highest software layer, application layer, of the software structure of the station sets. As is described in greater detail later, the terrninal manager invokes the conference manager upon actuation of the conference 10 button on station set 101. Each terminal manager maintains a party record for each half of the call in which the terrninal manager is involved. Each party record contains a record of the names of users and addresses (telephone numbers) of theparties on the other half of the call. For exarnple, party records 302 and 303 contain the name and address of the users of station set 102 and station set 103, respectively.
15 The name and address for station set 102 stored in party record 308 is designated by "102". Station sets 102 and 103 reflect in their party records (306 and 308) thestation set that is the controlling station set and the sub-party station set. In party record 306, the narne and address, 101, for station set 101 has an asterisk after it denoting that this is the controlling party and the name and address, 103, for station 20 set 103 is enclosed in parenthesis indicating that it is a sub-party in the conference.
FIG. 3 only illustrates the logical message channels (such as logical channel 310) that are established between the station sets via switches. These logical channels allow the communication of messages between terminal managers. In addition, the switches are responsive to connect messages to establish voice channels 25 between station sets.
Within station set 101, conference manager 304 maintains conference record 301 which maintains the ID numbers utilized to identify the different users on the conference call as well as the station set associated with that user. Terminal manager 305 is responsive to messages related to a conference to relay those 30 messages to conference manager 304. These identification numbers were included in the notify messages of FIG. 2. In addition, conference manager 304 can directly access party records 302 and 303; and terminal manager 305 can directly access conference record 301. In party record 306 of station set 102, station set 101 (entry 101*) is designated as controlling the conference and station set 103 _ 7 _ 2~8~

(entry 103) is ~CStgrl~t~ a!~ bcing a su~party.
Station sct 102 builds party record 306 in responsc to thc sct-up mcssagc in line 201 of FIG. 2. Sincc station sct 102 reccives the set-up mcssage from stadon set 101, station sct 102 assumes that stadon sct 101 is the master station set if a S subsequent conference call is set up. The entry of "(103)" into party record 306 occurs when stadon set 102 receives the nodfication messages illustrated in lines 210 and 213 of FIG. 2. These two notification messages inform stadon set 102 that stadon set 103 is the second party on the conference call and gives the name andaddress for station set 103. Party record 308 in station set 103 is built in a similar 10 manner as party record 306.
FIG. 4 shows the configuration of party records and conference records after the second conference is established between station sets 1~)4 through 106.
Party records 402 through 410 are utilized in setting up this second conferencc.Conference record 401 which is maintained by conference manager 404 stores 15 infonnation ~ith respect to the second conference just as conference record 301 in station set 101 stores the information with respect to the first conference.
FIG. S illustrates the combining of the two conference calls into a multi-level conference call by station set 101 adding station set 104 into the first conference call and then by station set 104 setting up the multi-level conference call 20 by merging the first and second conference calls. FIG. 6 illustrates the messages for adding station set 104 into the first conference calL Lines 601 through 605 ilIustrate the setting up of a call path between station set 101 and station set 104. Lines 606 and 608 show that station set 104 is merged into the first conferencc. However, stadon sets lOS and 106 are not merged at this point in time since they are connected 25 to station set 104 via a different call path. In lines 606 and 608, station set 101 causes switch 107 to merge station set 104 into the first conference call. In line 609, station set 101 transmits a notify message to station set 102 informing it that station set 104 has been added to the first conference call, as party 3, that station set 101 is the controlling party, and that the name of the user of statdon set 104 is included.
30 Further, line 609 indicates that stadon set 104 is now connected.
In response to the notify message of line 609, statdon set 101 adds station set 104 as a sub-party to the multi-level conference call as illustrated in line S10 of party record 306 of FIG. S. At this point in time, lines Sl l and 512 for station sets lOS and 106 have not been placed in party record 306. Line 610 35 accomplishes similar operations in party record 308 of station set 103. Lines 611 and 612 of FIG. 6 are notify messages to station set 104 that define station sets 102 and 103 and allow station set 104 to build party record S0~ of FIG. S.

- 8 - 2~7~g ~~ Information about station set 101 ~s add~l to confcrcncc record 401 of FIG. S in responsc to thc receipt of thc mcssages in lincs 601 through 60S as illustrated on FIG. 6. Station sets 102 and 103 arc addcd to conference rccord 401 in response to the notify messages transrnitted from station set 101 to station sct 104 in S lines 611 and 612 of FIG. 6. Station set 104 considers stadon set 101 as party 3, station set 102 as party 4, and station set 103 as party 5. The terminal manager in station set 104 correlates these ID numbers with the ID numbers used by stadon set 101 in conference record 301 by utilizing thc inform~tion in party record 502 which shows that station sets 102 and 103 are sub-parties to station set 101. From 10 party record 502, the conference manager in station set 104 can determine that station set 102 has an ID of 1 in the conference controlled by station set 101.
FIG. 7 gives the message flow which allows station sets 105 and 106 to be placed into the multi-level conference call with stadon sets 101 through 104.First, station set 104 transmits a merge message to switch 108 as illustrated in15 line 701 of FIG. 7. This causes switch 108 to join the conference call that is established between station sets 104 through 106 into the multi-level conference call which is established between station sets 101 through 104. Switch 108 responds back to station set 104 with the acknowledge message in line 702.
Party record 410 in station set 105 is expanded by entlies 505 20 through 507 to reflect the multi-level conference call by transmission of notify messages from station set 104 to station set lOS as given in lines 703 through 705 of FIG. 7. These messages add the entri~s 505 through station sets 101, 102, and 103, respectively, to party record 410. In party record 410, station set 105 reflects the fact that station sets 102 and 103 are sub-parties to station set 101. The notify messages 25 of lines 707 through 708 are utilized by station set 106 to enter the information with respect to station sets 101 through 103 into party record 409.
Station set 104 utilizes notify messages 709 and 710 to transmit to station set 101 information that station sets 105 and 106 are su~parties to station set 104 (since CP = D) in a conference call. Station set 101 utilizes this information 30 to complete party record 501 and conference record 301. Note, that all of the notify messages transmitted in FIG. 7 also contain the name of the user of each station set.
Station set 101 is responsive to the notify messages of lines 709 and 710 to complete the entries into party record 501 and conference record 301 and also to transmit this information to station sets 102 and 103 using notify messages given in lines 71135 through 714 of ~IG. 7. Station sets 102 and 103 utilize the information from thc messages of lines 711 through 714 to complete par~ records 306 and 308 of FIG. 5.
For example, station set 102 is responsive to the notify messages of lines 711 _ 9 _ ~a a8~8 and 712 to makc en~ics Sl 1 and 512 into party recor~ 306.
FIG. 8 reflects thc vicw of station set 101 to thc multi-lcvel confercncc call that has bccn established in FIG. S on thc basis of party record 501 and conferencc record 301. Sim~larly, FIG. 9 reflects view of station sct 104 to thcS multi-level conference call on thc basis of party record 502 and conference record 401. As can be seen &om FIGS. 8 and 9, both station sets 101 and 104 consider themselvcs in control of the multi-level conference call. However, station set 101 cannot individually disconnect station sets 105 or 106 from the conferencc;
but station set 101 can disconnect station set 104 from the conference which results 10 in station sets 105 and 106 also being disconnectedL Sirnilarly, station set 104 can only disconnect station set 101.
A terminal manager in a station set is responsive to the inforrnation in a party record to display that information to the parties on a display screen of the terminal manager's station set. FIG. 10 illustrates the display screen of station 15 set 101 which reflects the information stored in the party records for station set 101 as defined in FIG. 5. Sirnilarly, FIG. 11 shows the screen of station set 102 for FIG. 5. The displays shown on FIGS. 10 and 11 are but one of many ways that the information contained in the party records of these two station sets could be displayed' In addition, as stadon set information changes the party record, thc 20 terminal manager displays that informadon on the screen of the stadon set. Illis allows the user of a station set to have constant informatdon of how the conference is developing. In addition, the user can control a conference call with the display and associated keys.
In accordance with the invention, in a muld-level conference, the stadon 25 controlling an individual conference can terminate any station set on that conference and can terminate the connecdon to the multi-level conference. A station set which is a sub-party to a conference can only terminate itself from the conference and is incapable of terminating another stadon set. Similarly, in a multi-level conference, a stadon set that is controlling one conference cannot terminate station sets which are 30 su~par~es on another conference. To ilIustrate this, consider the folIowing examples. In the first example, station set 101 terrninates station set 103 from the multi-level conference call; and in the second example, station set 104 terminates the multi-level conference call. In the first example, the user of station set 101 actuates the disconnect of st~don set 103 by posidoning cursor 1003 on the display of stadon 35 set 101 as illustrated in FIG. 10 next to entry 1001 for station set 103 and actuating disconnect 1005 button. To terminate/disconnect st~tion set 103, station set 101transrnits a disconnect n~ssage to switch 1~7 as illustrated in line 1201 of FlG. 12.

1 o -- 2 1 ~ 8 7 3 8 Swi~ch 107 is respons~ve to thc di~c4nnect mcssagc to tem inatc thc lin~ bct~
station set 101 and switch 107 which was suppordng thc call connection to station set 103. In addition, switch 107 transmits a disconnect message to station sct 103 and te~n~nates the link that was uscd to support the call with station set 103.
S Terminal managcr 309 in station set 103 is responsivc to thc disconncct mcssage to remove party record 308.
Next, station set 101 transmits a notify message as illustrated in linc 1202 of FIG. 12 to station set 102 to notify station set 102 that station sct 103 is no longer part of the first conference call. Station set 102 is responsive to thc notify 10 message of line 1202 to remove entry 513 from party record 306 as illustrated in FIG. S.
In addition, station set 101 transmits the notify message of line 1203 to station set 104. Terminal manager 405 of station set 104 is responsive to the notify message to remove entry 503 from party record S02. Conference manager 404 is 15 responsive to this notify message relayed from terminal manager 405 to removeentry 504 from conference record 401. Further, terrninal manager 405 of station set 104 transmits the notify messages illustrated in lines 1204 and 1205 to station sets 105 and 106, respectively. Terminal manager 407 of station set 105 is responsive to the notify message of line 1204 to rernove entry 507 from party 20 record 410 as illustrated FIG. 5. Sirnilarly, terminal rnanager 408 of station set 106 removes the reference to stadon set 103 from party record 409 by removing entry 514.
Consider now the second example where station set 104 terminates the multi-level conference call. The user of station set 104 actuates the termination of 25 the multd-level conference by positioning the cursor on the screen of station set 104 as illustrated in FIG. 13 next to the entry for station set 101 and actuating the discoMect button. Terminal manager 405 of station set 104 is responsive to that action to transmit the disconnect message illustrated in line 1206 of FIG. 12.
Terrninal manager 405 informs conference manager 404 of the termination of station set 101. In response, conference manager 404 removes all references to s~ation sets 101 and 102. In response to the disconnect message, switch 107 terminates the connection between station set 104 and station swi~ch 107. Further, switch 107 transmits a disconnect message to station set 101 and removes the coMection between station set 101 and switch 107. In response to the disconnect message from switch 107, station set 104 updates the party records of station sets 105 and 106 by transmitting the notify messages illustrated in lines 1207 and 1208. Terminal manager 407 of station set 105 is responsive to the noti~y message of linc 1207 to elim;n~tc cntr~cs SOS and S06 wb{ch ref~cncc station scts 101 and 102. Ia eliminating those cntries, termlnal managcr 407 uscs thc fact that stadon set 101 has been disconnected to also elim;~tc ~ntry 506 sincc station set 102 is a sub-party on a confcrence call controllcd by stadon set 101. Tcrrninal managcr 408 of station5 set 106 performs similar operations in response to the notify message of linc 1208.
Terminal manager 305 of station set 101 is responsive ~o thc reccipt of the disconnect mcssage from switch 107 to transmit the notify message of linc 1209 of FIG. 12 to station set 102 and to inform conference manager 304 of the fact that station set 104 has terminat~d the call. Terrninal manager 307 of station set 102 is 10 responsive to the notify message of 1209 to remove entries 510, 511, and 512 of party record 306. Conference manager 3~4 is responsive to the termination of station set 104 to remove entries relating to station sets 104, 105, and 106 from conference record 301.
After the two previous examples have been implemented by the 15 transrnission of messages illustrated in FIG. 11, the records of station sets 101, 102, 104, 105, and 106 are illustrated in FIG. 14.
In flow chart form, FIG. 15 illustrates the operations perforrned by a terminat manager in response to stlmuti received as a result of user actions perforrned on the terminaL FIG. 16 illustrates the operations performect by a 20 terminal manager application in response to ISDN messages being received fromother terminats or switches. FIGS. 15 and 16 illustrate the operations to be performed either by a terminal manager of a terminal that is the controtling terminal of a conference or simpty a terrninat that is a party to a conference. Two flags are utilized by the terminal management application: control flag indicating whether the 25 terminal is controlling a conference and hold flag indicating whether a calt had been placed on hold. Decision bloctc 1501 of FIG. 15 determines whether or not a message has been received cither as a result of a user action on the terminat or from an external source. Blocks 1502 through 1509 illustrate the operations performedwhen the user of the terrninal actuates the conference button. Blocks 1515 through 30 1519 and 1524 through 1527 illustrate the operations perforrned when the user of a terrninal actuates the hold button. Blocks 1521 and 1522 illustrate the operations performed when the user of the terminal selects a party to be disconnected by positioning the curser next to that party name on the station set display and actuating the disconnect button. Blocks 1529 through 1533 illustrate the operations to be 35 performed when the user of the terminal hangs up by going on hook. Blocks 1534 through 1536 illustrate the operations performed when the caller performs the initial call origination. Block 1538 detennines whether the user of the terminal has - 12- 2~.38~33 -- pc. ro~ cd any othe~ operations.
To illustratc the operations of a tcrminal managcr and a confcrencc managcr application, consider an cxample which assumes an initial statc as illustrated in FIG. 4 and progresses through thc prc~ious cxamplcs to the statc S illustrated in FIG. 14. In FIG. 4, station sct 101 is controlling a conferencccomprising station set 102 and station set 103; whereas, stadon sct 104 is controlling a oonferencc comprising station sets 105 and 106. Consider now thc operations pclro~ cd by thc terminal and conference managers to progress to thc state of a multi~onferencc call as illustrated in F~G. 5. First, the user of stadon set 10110 actuates the hold button. Decision block 1501 of FIG. 15 detects this actuation and transfers control to decision block 1515 (via decision block 1502) which determines that the hold button has been actuated. In response, control is transferred to decision block 1516 which checks if the hold flag is set. In the present situation, it is not set and control is transferred to decision block 1517 which sets up party record 501 for a 15 second call and sets the hold flag. Block 1518 ~hen places the present conference on hold which is the conference comprising station sets 101, 102, and 103. Block 1519 transmits notify messages to station sets 102 and 103. In response to the user dialing the telephone number of station set 104, terminal manager 305 transmits the setup message of line 601 of FIG. 6 to station set 104. When stadon set 104 responds with 20 the call proceeding message of line 602 of FTG. 6, the operations performed by FIGS. 15 and 16is the execution of block 1614 since the call proceeding message match none of the messages tested for in FIGS. 15 and 16. (Note, that if the messages tested for in FIG. 15 are not found, control is transferred to decisionblock 1601 of FIG. 16.) When station set 104 transmits back the alerdng message of 25 line 603, this is detected by decision block 1602 of FIG. 16, and block 1620 is executed which adds station set 104's information to party record 501 and conference record 301 of FIG. S by execution of block 1620. Wben station set 104transmits back the connect message of line 6()4 of FIG. 6, this message is detected by decision block 1611 and control is transfened to block 1619. The latter block 30 transmits back to station set 104 the connection acknowledge message of line 605.
Finally, block 1618 updates party record 501 of FIG. S to show that station set 104 is connected.
In response to station set 104 being shown on the disp]ay of station set 101 as being connected, the user of station set 101 can talk with the user of 35 station set 104. When the user of station set 101 wants to join station set 104 into the conference, the user of station set 101 activates the conference button. lllis activation of the conference button is detected by docision Uock 1502 of FIG. IS and -- 13 ~ 21~ 38 - eontrol ~s transferrod to deeidon bloclc 1509. Sinee tbe hold flag lud been previously set, eontrol is transferrcd to block lS03. Thc lattcr bloclc rcscts thc hold flsg and transfers eontrol to deeision block 1504. Since station set 101 is controlling a conference, the eontrol flag is set; and deeision block 1504 transfers control to S bloek 1507. Bloek 1507 then transfers the information concerning the fact that the eonference button has been actuated to the conference manager which perforrns the operations illustrated in ~IG. 17. l~is eauses the execution of bloek 1705 whichtransrnits the merge message to switch 107 as illustrated in line 606 of FIO. 6.When the merge aeknowledgment is receiYed back from switch 107 by 10 station set 101 as illustrated in line 608 of FIG. 6, this is detected by decision bloek 1613 which causes block 1616 to be executed. Block 1616 transfers control to the eonference manager and causes the execution of block 1706 of F~G. 17.
Blo~k 1706 transmits the notify messages of lines 609 through 612.
At the present time only station set 104 is part of the conference call lS between station sets 101, 102, and 104. To add station sets 105 and 106 and create a multi-level conference, the user of stadon set 104 actuates the eonference button which as was previously described results in blocks lS09, 1504, and 1507 being executed and station sets lOS and 106 to be merged into the conference. The execution of block 1507 causes the conference manager to execute block 1705 which 20 transmits a merge request to switch 108. When switch 108 responds with a merge acknowledgment, the terminal manager of station set 104 detects this by the exeeution of decision block 1613 and transfers eontrol to block 1617. The exeeution of block 1616 causes the eonferenee manger of station set 104 to exeeute bloek 1706 of FIG. 17. I~e exeeudon of bloek 1706 results in the tr~nsmi~ion of the notify 25 messages of lines 703 through 710 of FIG. 7 from stadon set 104.
When the nodfy messages are received by terminal manager 305 of stadon set 101, they are detected by decision bloek 1610 whieh adds this informadon to party reeord S01 of FIG. S and transfers control to deeision block 1606. Since the control flag is set in station set 101, control is passed to bloek 1607. The execution 30 of block 1607 causes eonferenee manager 304 of stadon set 101 to perform the operations illustrated in FIG. 18. l~e message type is identified by decision block 1~07 as notify rnessages and these rnessages are repeated to station sets 102 and 103 as illustrated in the messages of lines 711 through 714 of FIG. 7. As stadon sets 102 and 103 receive these messages they update their party records as indicated 35 by block 1603 of FIG. 16 which defines the response of a terminal manager to a notify message. HoweYer, since the eontrol flag has not been set in sl~tion sets 102 and 103, deeision block 1606 transfers eontrol to bloek 1624 of FIG. 16.

2~ 7~8 Consider now, how the state of thc systcm of FI~ s transferred from that illustrated in FIG. S to that illustrated in FIG. 14. Flrst, the user of station set 101 positions the cursor by the name of the user of stadon set 103 and actuates the diseonnect button. This actuadon is detected by decision block 1521 of FIG. IS.
5 Decision block 1521 transfers control to block lS22 which causes the conference manager of station set 101 to execute the operations illustrated in FIG, 19. Decision block 1901 of FlG. 19 determines that the party being diseonnected is not a eontrolling party by examination of conference record 301. Based on this determination, decision block 1901 transfers control to block 1905 which causes the 10 transmission of the disconnect message to station set 103 as shown in line 1201 of FIG. 12. Next, block 1906 is executed which results in the transmission of the notify messages illustrated in lines 1202 and 1203 of FIG 12. Finally, block 1908 removes reference to station set 103 from party record 303 and conferenGe record 304. Note, that station set 104 is responsive to the notify message of 1203 to transmit the notify lS messages of lines 1204 and 1205. This results because when the notify message of line 1203 is received by terminal manager 405 of station set 1()4, it is detected by decision block 1610 of FIG. 16 which causes the execution of blocks 1603, 1606, and 1607. As previously described, execution of block 1607 results in the execution of the operations of FIG, 18 by conference manager 405 of station set 104. During 20 the execution of the operations of FIG, 18, blocks 1807 and 1808 are executedresulting in the tr~nsmission of the notify messages of Unes 1204 and 1205 of FIG. 12.
Next, the user of station set 104 positions the cursor on the display of station set 104 by the name of the user of station set 101 and aauates the disconnect 25 button. Terminal manager 405 of station set 104 detects the e~eeution of the disconnect button by deeision block 1521. The latter decision block transfers control to block 1522 which results in conference manager 404 of station set 104 performing the operations illustrated in FIG. 19. Decision block 190! determines that station set 101 is a controlling party by examining party record S01 and control is 30 transferred to block 1902. The latter block causes the tr~nsmission of the disconnect message illustrated in line 1206 of FIG. 12. Next, block 1903 is executed which caus~s the tr~n~mi~sion of the notify messages of lines 1207 and 1208 of FIG. 12.
Finally, block 1904 removes all entries for station set 101 and parties controlled by station set 101 from party record 502 and conference record 401 of FIG. S. Fmally, 35 station set 101 is responsive to the not;fy message of Une 1206 to transmit the notify message of line 1209 to station set 102. ~e final result is that ~}e system of FIG. 1 is now at the state illustrated ~n FIG. 14.

Claims

1. An apparatus for establishing and controlling a multi-level telecommunication conference between a plurality of telecommunication terminals interconnected by a telecommunication switching system, comprising:
means, in a first telecommunication terminal, for establishing a first telecommunication conference among a first subset of the telecommunicationterminals including the first telecommunication terminal, via the telecommunication switching system and for controlling removal of any one of the telecommunication terminals from the first telecommunication conference;
means, in a second telecommunication terminal, for establishing a second telecommunication conference among a second subset of the telecommunication terminals including the second telecommunication terminal, via the telecommunication switching system, and for controlling removal of any one of the telecommunication terminals from the second telecommunication conference;
means, in the first telecommunication terminal, by communicating with the second telecommunication terminal, for forming a multi-level telecommunication conference to combine the second telecommunication conference and the first telecommunication conference via the telecommunication switching system;
means, in the first telecommunication terminal, for notifying each of the first subset of the telecommunication terminals of identities of users of the other ones of the first subset of the telecommunication terminals;
means, in the second telecommunication terminal, for notifying each of the second subset of the telecommunication terminals of identities of users of the other ones of the second subset of the telecommunication terminals;the notifying means, in the second telecommunication terminal, further notifying the first telecommunication terminal of the identities of users of the second telecommunication conference; and the notifying means, in first telecommunication terminal, further notifying the other ones of the first subset of the telecommunication terminals of the identities of users of the second telecommunication conference.

2. The apparatus of claim 1, wherein the notifying means, in the first telecommunication terminal, further notifying the second telecommunicationterminal of the identities of users of the first telecommunication conference; and the notifying means, in the second telecommunication terminal, further notifying the other ones of the second subset of the telecommunication terminals of the identities of users of the first telecommunication conference.

3. The apparatus of claim 2, wherein the notifying means, in the first telecommunication terminal, uses notify messages to directly transmit the identities of users to the other ones of the telecommunication terminals of the first telecommunication conference.

4. The apparatus of claim 3, wherein each one of the first subset of the telecommunication terminals in response to being added to the first telecommunication conference transmits the identity of the user of each of the first subset of the telecommunication terminals to the first telecommunication terminal; and the establishing means, in the first telecommunication terminal, stores the identities of the users of the first subset of the telecommunication terminals in an internal table of the first telecommunication terminal.

5. The apparatus of claim 4, wherein the notifying means, in the first telecommunication terminal, in response to the identities of the second subset of the telecommunication terminals received from the second telecommunication terminal, stores the identities of the users of the second telecommunication conference in the internal table; and the notifying means, in the first telecommunication terminal, uses the contents of the internal table to form the notify messages for transmission to the other ones of first subset of the telecommunication terminals.

6. The apparatus of claim 5, wherein each of the other ones of the first subset of the telecommunication terminals in response to the notify messages from the first telecommunication terminal stores the identities of users in an internal table in each of the other ones of the first subset of the telecommunication terminals.

7. The apparatus of claim 6, further comprises means, in each of the other ones of the first subset of the telecommunication terminals, for displaying the contents of the internal table of each.

8. A method for establishing and controlling a multi-level telecommunication conference between a plurality of telecommunication terminals interconnected by a telecommunication switching system, the method comprising the steps of:
establishing, by a first telecommunication terminal, a first telecommunication conference among a first subset of the telecommunication terminals including the first telecommunication terminal, via the telecommunication switching system, and controlling removal of any one of the telecommunication terminals of the first subset of the telecommunication terminals;
establishing, by a second telecommunication terminal, a second telecommunication conference among a second subset of the telecommunication terminals including the second telecommunication terminal, via the telecommunication switching system, and controlling removal of any one of the telecommunication terminals of the second subset of the telecommunication terminals;
forming, by the first telecommunication terminal, by communicating with the second telecommunication terminal, a multi-level telecommunication conference to combine the second telecommunication conference and the first telecommunication conference via the telecommunication switching system;
notifying, by the first telecommunication terminal, each of the first subset of the telecommunication terminals of identities of users of the other ones of the first subset of the telecommunication terminals;
notifying, by the second telecommunication terminal, each of the second subset of the telecommunication terminals of identities of users of the other ones of the second subset of the telecommunication terminals;

the notifying step, by the second telecommunication terminal, further notifies the first telecommunication terminal of the identities of users of the second telecommunication conference; and the notifying step, by the first telecommunication terminal, further notifies the other ones of the first subset of the telecommunication terminals of the identities of users of the second telecommunication conference.

9. The method of claim 8, wherein the notifying step, by the first telecommunication terminal, further notifies the second telecommunication terminal of the identities of users of the first telecommunication conference; and the notifying step, by the second telecommunication terminal, further notifies the other ones of the second subset of the telecommunication terminals of the identities of users of the first telecommunication conference.

10. The method of claim 9, wherein the notifying step, by the first telecommunication terminal, uses notify messages to directly transmit the identities of users to the other ones telecommunication terminals of the first telecommunication conference.

11 . The method of claim 10, further comprises the step of transmitting by a telecommunication terminal added to the first subset of the telecommunication terminals of the first telecommunication conference the identity of the user of the added telecommunication terminal to the first telecommunication terminal; and the establishing step, by the first telecommunication terminal, stores the identities of the users of the first subset of the telecommunication terminals in an internal table of the first telecommunication terminal.

12. The method of claim 11, wherein the notifying step, by the first telecommunication terminal, in response to the identifies of the second subset of the telecommunication terminals received from the second telecommunication terminal stores the identities of the users of the second telecommunication conference in the internal table; and the notifying step, by the first telecommunication terminal, uses the contents of the internal table to form the notify messages for transmission to the other ones of first subset of the telecommunication terminals.

13. The method of claim 12, further comprises the step wherein each of the other ones of the first subset of the telecommunication terminals, in response to the notify messages from the first telecommunication terminal, stores the identities of users in an internal table in each of the other ones of the first subset of the telecommunication terminals.

14. The method of claim 13, further comprises the step of displaying, by each of the other ones of the first subset of the telecommunication terminals, the contents of the internal table of each.