WO2005117408A1

WO2005117408A1 - Method and device for setting up a telephone conference call

Info

Publication number: WO2005117408A1
Application number: PCT/EP2004/005725
Authority: WO
Inventors: Philippe Lottin; Jean-Louis Cheviet
Original assignee: France Telecom
Priority date: 2004-05-26
Filing date: 2004-05-26
Publication date: 2005-12-08

Abstract

The invention relates to a method and device for setting up a telephone conference call between a first subscriber of a telecommunication network and at least two other subscribers of the telecommunication network, whereby each subscriber is identified by an identifier and the first subscriber communicates with a server by means of a telecommunication terminal. The invention is characterised in that the telecommunication terminal of the first subscriber: detects a pre-determined datum in a data frame transmitted by the server (E506); and, subsequently, detects the identifiers (E509) of the other subscribers in at least one data frame, stores the identifiers (E508), interrupts (E510) the communication with the server, transfers (E513, E518) said identifiers to the telecommunication network and generates pre-determined commands in the direction of the network, in order to establish a conference call between the first subscriber and the other subscribers.

Description

Method and device for establishing a conference call.

The present invention relates to a method and a device for establishing a conference call between at least three correspondents from at least two telephone numbers, obtained via a telecommunications network. Are known the services offered by telecommunications operators in which it is possible to establish a conference call between several subscribers. The "three-way conversation" service as proposed by the applicant is one of these services offered to date. In the three-way conversation service, a first subscriber in telephone communication with a second subscriber can control the establishment of simultaneous telephone communication with a third subscriber. To do this, the first subscriber presses a predetermined key on their telephone handset and dials the telephone number of the third subscriber. When the telephone communication is established between the first and the third subscriber, the first subscriber by pressing the predetermined key again and then on the three key of his telephone handset controls the establishment of a conference call. simultaneous with the other two subscribers. The PABX to which the telephone subscriber of the first subscriber is connected is responsible for connecting the three subscribers simultaneously. This type of service requires that the subscriber who wishes to benefit from this service carry out the various operations of the procedure previously described correctly if he wants the conference to be established. The operations to be carried out are often difficult to memorize by a user, especially when they are not used regularly. This penalizes the use of this service by a good number of subscribers. The invention aims to solve the drawbacks of the prior art by proposing a method and a telecommunication device which allow simple and automatic establishment of conference calls. To this end, according to a first aspect, the invention provides a method of establishing a conference between a first subscriber of a telecommunications network with at least two other subscribers of the telecommunications network, each subscriber being identified by an identifier. in the telecommunications network, the first subscriber being in communication with a server of the telecommunications network via a telecommunications terminal, characterized in that the method comprises the steps carried out by the telecommunications terminal of the first subscriber of: - detection of predetermined information in an information frame transmitted by the server, - detection of identifiers of other subscribers in at least one information frame transmitted by the server, storage of the identifiers detected, - interruption of communication with the server, transfer to the telecommunications network of stored identifiers and generating predetermined commands to the telecommunications network for the establishment of a conference, via their respective telecommunications terminals, between the first subscriber and the other subscribers whose identifiers have been transferred. Correlatively, the invention relates to a telecommunications terminal for establishing a conference between a first subscriber of a telecommunications network with at least two other subscribers of the telecommunications network, each subscriber being identified by an identifier in the communications network. telecommunication, the first subscriber being in communication with a server of the telecommunication network via the telecommunication terminal, characterized in that the telecommunication terminal of the first subscriber comprises: - means for detecting predetermined information in a frame of information transmitted by the server, - means for detecting identifiers of other subscribers in at least one frame of information transmitted by the server, means for storing detected identifiers, means for interrupting communication with the server, - means of transfer to the telecommunications network of the stored identifiers and generation of predetermined commands to the telecommunications network for the establishment of a conference, via their respective telecommunications terminals, between the first subscriber and other subscribers whose identifiers have been transferred. Thus, it is possible to establish a conference between several subscribers without it being necessary for the first subscriber to carry out the various operations necessary for establishing conference according to the state of the art. By receiving predetermined information from the server as well as the identifiers of other subscribers, the telecommunication terminal of the first subscriber enters an automatic conference establishment procedure without the user having to carry out the various operations of the state of the technical. All errors related to the handling by the user of the telecommunications terminal are thus avoided. According to another aspect of the invention, the telecommunication network is a switched telephone network, the conference is a conference call between the first subscriber with two other subscribers, the identifiers are telephone numbers and a telephone number included in the information frame is associated with predetermined information different from the predetermined information associated with the other telephone number included in the information frame. Indeed, certain telecommunication devices, when they receive two telephone numbers in the same information frame and in the same format, ignore the second telephone number. By associating each telephone number with a different identifier, the two telephone numbers are taken into account and the telecommunication terminal enters a conference call establishment procedure. According to another aspect of the invention, the information frame comprising the predetermined information is an information frame conforming to the V23 protocol and the identifiers of the other subscribers are included in the information frame comprising the predetermined information. Thus, all the information necessary for establishing the conference call is included in a single information frame. This thus simplifies the information transfer protocol between the server and the telecommunications terminal. According to another aspect of the invention, the predetermined information is a command call. According to another aspect of the invention, the establishment of a communication with each other subscriber is detected and the predetermined commands are generated on each detection of the establishment of the communication with each other subscriber. User intervention is therefore no longer necessary when setting up the conference call. According to another aspect of the invention, the telecommunications terminal of the first subscriber is connected to a telephone handset and the telephone handset is connected and disconnected from the telecommunications network. Thus, it is possible to use conventional telephone handsets which do not have the functionalities of the present invention. By inserting the telecommunication terminal between the telecommunication network and one or more handsets, ^users' or of these handsets can still benefit from the conference service of the present invention. According to another aspect of the invention, a loop current is generated when the telephone handset is disconnected from the telecommunications network by the telecommunications terminal of the first subscriber. Thus, setting up a conference call is possible even if the telephone handset is suitable for detecting line power outages and disconnecting from the telephone network upon detection of a line power outage. The invention also relates to a method of transferring information for the establishment of a conference between a first subscriber of a telecommunications network with at least two other subscribers of the telecommunications network, each subscriber being identified by an identifier in the network of telecommunication, the first subscriber being in communication with a server of the telecommunication network by means of a telecommunication terminal, characterized in that the method comprises the steps carried out by the server of the telecommunication network of: - obtaining a selection, by the first subscriber, of identifiers of other subscribers for the establishment of a conference between the subscribers, - transfer of at least one frame of information to the telecommunications terminal of the first subscriber, the information comprising at least the selected identifiers and predetermined information, the identifiers and the predetermined information being representative of a command from the telecommunication terminal of the first subscriber for establishing a conference with the subscribers whose identifiers have been selected. Correlatively, the invention relates to an information server for establishing a conference between a first subscriber of a telecommunications network with at least two other subscribers of the telecommunications network, each subscriber being identified by an identifier in the network. telecommunications, the first subscriber being in communication with the server via a telecommunications terminal, characterized in that the server comprises: - means for obtaining a selection, by the first subscriber, of identifiers other subscribers for establishing a conference between the subscribers, means for transferring at least one information frame to the telecommunication terminal of the first subscriber, the information comprising at least the selected identifiers and a predetermined information, the identifiers and the predetermined information being representative of a command from the telecommunication terminal Communication of the first subscriber for establishing a conference with the subscribers whose identifiers have been selected. The invention also relates to a signal transmitted over a telecommunications network by a server of a telecommunications network in a communication with a subscriber via a telecommunications terminal and the telecommunications network, each subscriber of the telecommunications network. being identified by an identifier in the telecommunications network, characterized in that the signal comprises information comprising at least identifiers of other subscribers of the communication network telecommunication and predetermined information, the identifiers and the predetermined information being representative of a command from the telecommunication terminal of the first subscriber for setting up a conference with the other subscribers whose identifiers are included in the information signal. According to another aspect of the invention, the signal includes predetermined information associated with each telephone number included in the signal, the predetermined information associated with a telephone number is different from the predetermined information associated with the other number. telephone included in the signal. The invention also relates to computer programs stored on an information medium, said program or programs comprising instructions making it possible to implement the method or methods previously described, when they are loaded and executed by a computer system. The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the accompanying drawings, among which: FIG. . 1 shows a telecommunication network in which the telecommunication terminal according to the invention establishes a conference call with at least two other telecommunication devices; Fig. 2 shows a schematic view of the architecture of the telecommunications terminal according to a first embodiment of the invention; Fig. 3 shows a schematic view of the architecture of the telecommunications terminal according to a second embodiment of the invention; Fig. 4 shows a schematic view of the architecture of the server according to the invention; Fig. 5 shows the algorithm performed by the telecommunications terminal according to the first embodiment of the invention; Fig. 6 shows the algorithm performed by the telecommunications terminal according to the second embodiment of the invention; Fig. 7 shows the algorithm performed by the server which communicates at least two telephone numbers to the telecommunications terminal according to the invention; Fig. 8 represents a table comprising the various elements of a V23 data frame sent by the server according to the invention; Fig. 9 represents a table summarizing the different types of connections included in the fourth byte of the V23 data frame of FIG. 8; Fig. 10a represents a table describing the content of a data frame

V23 in which the server according to the invention communicates a first telephone number to the telecommunications terminal 10; Fig. 10b represents a table describing the content of a V23 data frame in which the server according to the invention communicates to the telecommunications terminal 10 the name of the user of the telecommunications terminal 30 associated with the telephone number communicated according to FIG. 10a or FIG. lOd; Fig. 10c represents a table describing the content of a data frame

V23 in which the server according to the invention communicates to the telecommunications terminal 10 the date and time of the call made by the telecommunications terminal 30 associated with the telephone number communicated according to FIG. 10a or FIG. lOd; Fig. lOd represents a table describing the content of a V23 data frame in which the server according to the invention communicates a second telephone number to the telecommunications terminal 10.

Fig. 1 shows a telecommunication network in which the telecommunication terminal according to the invention establishes a conference call with at least two other telecommunication devices. The telecommunication network 30 includes a server 20. The telecommunication network is for example a switched PSTN telephone network. The network 30 can also be a network of ISDN type (Digital Network with Service Integration) or a cellular telephone telecommunications network such as a network of GSM (Global System for Mobile communications), UMTS (Universal Mobile Telecommunications System) type, GPRS (General Packet Radio Services), etc. The server 20 is for example a voice server 20 which broadcasts voice messages through the network 30. The voice messages are associated with information frames. By voice messages is meant sound sequences comprising recordings of human voice obtained by recording the voice of a person or by text-to-speech. By information frames is meant data adapted to be processed by telecommunication terminals and represented in accordance with FIGS. 8 to 10 which will be described later. The voice server 20, such as for example an Audiotel server of the company France Telecom, is accessible via a network of the public telephone network of the company France Telecom in which it is identified in a conventional manner by a telephone number. The voice server 20 communicates with the caller using voice messages. Voice messages are sent in block form in response to commands transmitted by the caller. Each voice message block is prerecorded and stored with appropriate addressing in a storage means of the voice server 20 described later with reference to FIG. 4. In general, a welcome voice message is sent when a telecommunication terminal 10 is connected to the voice server 20, then one or more specific messages are sent each time a key on the telecommunication terminal 10 is actuated thus forming a command to the voice server 20. The voice server 20 is for example a server able to memorize inter alia the directory of telephone numbers associated with the communication device 10. The voice server 20 generates a data frame whose content is representative of a conference call establishment command to the telecommunication device 10. This data frame comprises inter alia predetermined information and several telephone numbers so that the telecommunication device 10 establishes the conference call with these telephone numbers . The telecommunications terminal 10 is connected to the telecommunications network 30. It will be described in more detail with reference to FIGS. 2 and 3. The telecommunication network 30 includes means for establishing a conference call 31 between several correspondents. Upon detection of a predetermined command generated by a telecommunication terminal 10, the conference call establishment means 31 establish a conference call between the telecommunication terminal that generated the predefined command and the telecommunication terminals corresponding to the transmitted telephone numbers by the telecommunications terminal 10. These means for establishing a conference call 31 between several correspondents are included in the PABX to which the telecommunication device 10 is connected. Only two other telecommunication terminals 33 and 34 are also shown in FIG. 1. Of course, a much larger number of terminals are connected to the telecommunications network 30. These are the telecommunications terminals 33 and 34 with which the telecommunications terminal 10 establishes a conference call according to the invention. Fig. 2 shows a schematic view of the architecture of the telecommunications terminal according to a first embodiment of the invention. The telecommunications terminal 10a is for example a telephone handset comprising a processor l ia connected to a memory 12a, a screen 15a, a keyboard 16a, a means for detecting frames V23 and for generating DTMF signals 14a (Dual

Tone Modulation Frequency) or voice frequencies, a line interface 13a as well as a speaker 17a and a microphone 18a. The memory 12a stores the program implementing the method according to the invention which will be described in detail with reference to FIG. 5. The memory 12a temporarily stores the telephone numbers received via the network 30. The processor 11a executes the instructions of the program corresponding to the algorithm which will be described with reference to FIG. 5 and controls the line interface 13a, the screen 15a, the keyboard 16a, the frame detection means V23 and generation of DTMF signals 14a and the activation / deactivation of the speaker 17a and the microphone

18a. The keyboard 15a and the screen 16a provide the man-machine interface with the user of the telecommunication terminal 10. Via the screen 15a, the processor 1 displays the telephone number or numbers received through of the telecommunications network 30. The keyboard 16a allows the user using the telecommunications terminal 10a to dial the telephone number of the voice server 20, to indicate to the voice server that he wishes to establish a conference and to select the numbers of telephone of conference call participants. The telecommunication terminal 10a comprises a line interface 13a adapted to the telecommunications network 30. The line interface 13a comprises inter alia at least one relay controlled by the processor l ia allowing the connection or disconnection of the telecommunications terminal 10a to the network 30, at least one transformer making it possible to isolate the telecommunications terminal 10a from the telecommunications network 30 and at least one 2-wire 4-wire converter circuit allowing the separation of the incoming and outgoing signals. The line interface 13a also includes means capable of temporarily interrupting the current loop between the line interface and the automatic switch 31 when the terminal 10a is connected to the telecommunications network 30. Such an interruption is carried out on command from the processor l ia when a press on a predetermined key on the keyboard 16a, for example the R key, is detected. This interruption is in accordance with the ETSI TBR 21 document entitled "Terminal Equipment (TE); Attachment requirements for pan-European approval for connection to the analogue Public Switched Téléphone Networks of TE in which network addressing, if provided, is by means of Dual Tone Multi Frequency signaling ". ETSI is the acronym for "European Telecommunication Standards Institute". The telecommunications terminal 10a also includes a microphone 18a and a conventional speaker 17a. It should be noted that the loudspeaker 17a and the microphone 18a can be deactivated by the processor l ia during the reception and / or the generation of DTMF signals according to the invention. The telecommunications terminal 10a also includes a means for detecting frames V23 and for generating DTMF signals 14a. This means of detecting V23 frames and generating DTMF signals 14a is for example a modem or a DSP (Digital Signal Processor). The means for detecting V23 frames and for generating DTMF signals 14a is able to detect, decode V23 type signals and generate DTMF signals according to the protocol standardized at ETSI and described in the document ETSI EN 300 659-2. entitled Public Switched Telephone Network (PSTN): Subscriber line protocol over the local loop for display and related services- Part 2: Off-hook data transmission and the document ETSI EN 300 659-3 entitled Access and Terminais (AT); Analogue access to the Public Switched Telephone Network (PSTN): Subscriber line protocol over the local loop for display and related services- Part 3: Data linlc message and parameter. Fig. 3 shows a schematic view of the architecture of the telecommunications terminal according to a second embodiment of the invention. In this embodiment of the invention, the telecommunications terminal 10b is placed between a telecommunications terminal, more particularly a conventional telephone handset 35 and the telecommunications network 30. The telecommunications terminal 10b is for example included in a box located nearby of the telephone handset 35 or placed at a predetermined location in the home of the subscriber owning the telephone handset 35. The telecommunications terminal 10b comprises a processor 11b connected to a memory 12b, a frame detection means V23 and generation of DTMF signals 14b (Dual Tone Modulation Frequency), a line interface 13b, a voltage generation module 19b and two relays Ra and Rb. It should be noted that the voltage generation module 19b can also be a loop current generator so as to comply with the specific specifications of certain countries. The processor 11b executes the instructions of the program corresponding to the algorithm which will be described with reference to FIG. 6 and controls the line interface 13b, the frame detection means V23 and generation of DTMF signals 14b and the relays Ra and Rb. The memory 12b stores the program implementing the method according to the invention and which will be described in detail below with reference to FIG. 6. The memory 12b temporarily stores the telephone number received via the network 30. The telecommunications terminal 10b has a line interface 13b adapted to the telecommunications network 30. The line interface comprises inter alia at least one relay controlled by the processor 11b allowing the connection or disconnection of the telecommunications terminal 10b to the network 30, at least one transformer making it possible to isolate the telecommunications terminal 10b from the telecommunications network 30 and at least one 2-wire 4-wire converter circuit allowing the separation of the incoming and outgoing signals. The line interface 13b also includes means capable of temporarily interrupting the current loop between the line interface 13b and the automatic switch 31 when the terminal 10b is connected to the telecommunications network 30. Such an interruption is carried out on command of the processor 1 lb as will be described later with reference to FIG. 6. This interruption is in accordance with the ETSI TBR 21 document. The telecommunications terminal 10b also includes a means for detecting frames V23 and for generating DTMF signals 14b. This means of detecting V23 frames and generating DTMF signals 14b is for example a modem or a DSP (Digital Signal Processor). The means for detecting frames V23 and generating DTMF signals 14b is identical to the means for detecting frames V23 and generating DTMF signals 14a. It will not be described further. The means for detecting V23 frames and generating DTMF signals 14b is connected to the line interface 13b so as to receive V23 frames and / or transmit the DTMF signals according to the invention when the telecommunications terminal 10b is connected to the network telecommunications 30. The means for detecting V23 frames and generating DTMF signals 14b is also connected to the connections denoted 31 connecting the relays Ra and Rb so as to be able to receive and / or transmit the DTMF signals according to the invention when the handset telephone 35 is connected to the telecommunications network 30. The telecommunications terminal 10b also includes two relays Ra and Rb controlled by the processor 11b allowing the telecommunications terminal 10b to connect to the telecommunications network 30 in place of the telephone handset 35 and recreate a current loop to the telephone handset 35 so as to simulate a connection to the telephone handset onic 35 to the telecommunications network 30. FIG. 4 shows a schematic view of the architecture of the server according to the invention. The voice server 20 comprises a processor 21 connected to a ROM read-only memory 22, a random access memory 23, a voice memory 24, a data memory 25, a means 27 for detecting DTMF signals and for generating V23 (Dual Tone Modulation) frames Frequency) and a line interface 26. When the voice server 30 is put into service, the program instructions corresponding to the algorithm of FIG. 7 are loaded from the read-only memory 22 into the random access memory 23 and are executed by the processor 21. The processor 21 controls, via a link denoted 28, the line interface 30, the detection means 27 of DTMF signals and V23 frame generation and ensures the transfer of information contained in memories 24 and 25 to the telecommunications terminal 10a or the terminal telecommunications 10b and the telephone handset 35 via the telecommunications network 30. The voice server 20 comprises a line interface 26 adapted to the telecommunications network 30. The line interface comprises inter alia at least one relay controlled by the processor 21 allowing the connection or disconnection of the server to a calling telecommunications terminal 10, at least one transformer making it possible to isolate the voice server from the telecommunications network 30 and at least one 2-wire 4-wire converter circuit allowing the separation of the incoming and outgoing signals. The voice server 20 also includes a signal detection means 27

DTMF and V23 frame generation. This means 27 for detecting DTMF signals and for generating V23 frames is for example a modem or a DSP (Digital Signal

Processor). The means 27 for detecting DTMF signals and for generating frames

V23 also complies with the standards explained for the V23 frame detection and DTMF 14a signal generation means described with reference to FIG. 2. It will not be described further. The means 27 for detecting DTMF signals and for generating V23 frames is connected to the line interface 26 so as to receive and / or transmit V23 data frames according to the invention when a telecommunications terminal 10 is connected to the server vocal 20. FIG. 5 shows the algorithm performed by the telecommunications terminal 10a according to the first embodiment of the invention. In step E500, the processor l ia, when the telephone handset 10 is lifted, controls the line interface 13a so that the latter carries out a connection to the telecommunications network 30. The processor l ia transfers the telephone number dialed by l 'Intermediate of the keyboard 16a by means of generation of DTMF signals 14a so that it is generated. This number here corresponds to the telephone number associated with the server 20 according to the invention. Once this step has been completed, the processor goes to step E501 and waits for the reception of a SAT signal (modem receiver activation signal). This SAT signal is a dual-frequency signal (2130Hz and 2750 Hz) which is transmitted over a TSAT time between 80 and 85 milliseconds (ms). This signal is transmitted by the server 20 via the telecommunications network 30 to the telecommunications terminal 10a and detected by the frame detection means V23 and generation of DTMF signals 14a. When this SAT signal is detected, the processor 1 passes it to the next step E502 and controls the frame detection means V23 and generation of DTMF signals 14a so that it generates a DTMF signal informing the voice server 20 of taking the SAT signal into account by the telecommunications terminal 10a. This DTMF signal is preferably representative of the letter D. The processor 11a then goes to step E503 and waits for the reception of a data frame V23. This data frame consists of a set of four bytes. The data frame is a frame making it possible to inform the telecommunications terminal 10 that the server 20 has specific functionalities. This data frame will be described with reference to Figs. 8 and 9. This data frame is transmitted by the server 20 via the telecommunications network 30 and detected and decoded by the frame detection means V23 and generation of DTMF signals 14a. Upon detection of this frame, the processor 11a goes to the next step E504 and checks whether the fourth byte of the frame received in step E503 is equal to the value 08 coded in hexadecimal. If not, the server 20, with which the telecommunications terminal

10a is connected, does not offer the service as realized by the invention. The program according to the invention ends. It is a classic interrogation of a classic voice server such as existing in the state of the art. If so, the server 20, by transferring this predetermined value and equal to 08 in hexadecimal, means that it has the service according to the invention. The processor 10a then goes to step E505. In step E505, the processor 11a controls the means for detecting frames V23 and for generating DTMF signals 14a so that the latter generates a DTMF signal thus informing the voice server 20 of the taking into account of the frame V23 detected at step E503 by the telecommunications terminal 10a. Once this operation has been completed, the processor 11a then goes to step E506 and waits for the reception of a data frame V23. This data frame consists of a header byte equal to the value 80 coded in hexadecimal. This message is transmitted by the server 20 via the telecommunications network 30 and detected and decoded by the frame detection means V23 and generation of DTMF signals 14a. Upon detection of the header byte 80 in hexadecimal, the processor l ia goes to the next step E507 and decodes the data contained in the frame and in accordance with those which will be described with reference to FIGS. 10a to lOd. This data includes at least two telephone numbers. These telephone numbers are for example the telephone numbers of telecommunication terminals 33 and 34. According to the invention, the frame comprises a telephone number presented according to the table in FIG. lOd and another telephone number presented according to the table in FIG. 10a. According to a preferred embodiment, each of the telephone numbers is also associated with data such as that which will be described with reference to FIGS. 10b and 10c. These data are decoded by the frame detection means V23 and generation of DTMF signals 14a, transferred to the processor 11a which transfers the content of these to the screen 15a. These received data are stored in step E508 in the memory 12a of the telephone handset 10. These stored data, the processor l ia goes to the next step E509 which consists in checking whether, in the stored data, two telephone numbers are present. These telephone numbers are each preceded by a predetermined header byte. If the data stored in step E508 does not include two telephone numbers presented in formats such as those which will be described with reference to Figs. 10a and 10d, the information frame does not concern a conference call establishment, the processor 1a stops the present algorithm and returns to step E500. If the data stored in step E508 includes at least two telephone numbers, the processor 1 passes it to the next step E510. In a preferred embodiment, the verification of the presence of at least two telephone numbers is carried out by checking whether the stored data does not include information on the identity of a first called line. This called first line identity is represented by a first byte set to the hexadecimal value 12 followed inter alia by the telephone number. The representative byte of the identity of a first line called will be described in more detail with reference to FIG. lOd. The data frame consists of a succession of information in a form identical to that which will be described with reference to Figs. 10a to lOd. Indeed, certain telecommunication devices, when they receive two telephone numbers in the same information frame and in the same format, ignore the second telephone number. According to the preferred embodiment of the invention, the first telephone number included in the information frame is transmitted in accordance with the format of FIG. 10a and the second telephone number included in the information frame is transmitted in accordance with the format of FIG. lOd. Thus, the processor 11a, by detecting the presence of a byte representative of the identity of a called first line, determines that two telephone numbers are present in the information frame. If the data stored in step E508 does not include information representative of the identity of a first called line, that is to say the byte of value 12 in hexadecimal, only a single telephone number is included in the frame. The information frame does not concern a conference call establishment, the processor 1 stops the present algorithm and returns to step E500. If information is representative of the identity of a first line called, the processor 11a goes to step E510. At this stage, the processor 11a generates a command intended for the line interface 13a so that the latter disconnects from the telecommunications network 13a. As a variant, the processor 1 ia commands deactivation of the loudspeaker 17a so that the user of the telecommunications terminal is not hampered by the signals which will then be transmitted. The processor l ia goes to step E511 and generates a command intended for the line interface 13a so that the latter connects to the telecommunications network 13a. It should be noted that the processor 1 waits for a predetermined time of the order of a few hundred milliseconds between steps E510 and E511. Once this step has been completed, the processor 11 goes to step E512 and reads from the memory 12a the telephone number representative of the identity of a first line called and associated with the hexadecimal code 12. This telephone number is for example the telephone number of the subscriber with the telephone handset 33. The The read telephone number is then transferred to the V23 frame detection and DTMF 14a signal generation means. The frame detection means V23 and generation of DTMF signals 14a then generates in step E513 the DTMF signals corresponding to the telephone number of the telecommunication terminal 33. This operation carried out, the processor ia checks in step E514 whether communication is established with the subscriber whose telephone number was dialed. More precisely, the processor l ia checks in step E514 whether the subscriber whose telephone number has been dialed has picked up his telecommunication terminal 33 or not. The detection of the disconnection of the telecommunication terminal 33 is conventionally carried out by the means V23 frame detection and DTMF 14a signal generation which is capable of detecting ring return tones, line busy tones. If, for a predetermined period, for example 30 seconds, the off-hook is not detected, the processor 1a goes to step E515 and commands the generation of a message informing the user of the telecommunications terminal 10 of the failure of the conference call. This message is for example transferred via the screen 15a. The processor l ia then interrupts the communication and stops the present algorithm. If the correspondent whose telephone number was dialed has picked up his telecommunication terminal 33, the processor 1 passes it to step E516. At this stage, the processor 11a commands the generation of an interruption of the current loop between the line interface 13a and the automatic switch 31 in accordance with the ETSI document TBR 21. This interruption is representative of a function call . As a variant, the processor l ia commands the generation on the screen 15a of an invitation message to press the function call key of the telecommunications terminal 10. Upon detection of a press on the function call, or R key, of the terminal, the processor 11 has the generation of an interruption of the current loop between the line interface 13a and the automatic switch 31 in accordance with the ETSI document TBR 21. This operation performed, the processor l ia goes to step E517 and reads from memory 12a the second telephone number stored in step E508. This telephone number was received in a format corresponding to the table in FIG. 10a and the hexadecimal code 03 is associated with it. The telephone number read is then transferred to step E518 by means of detection of frames V23 and generation of DTMF signals 14a. The frame detection means V23 and generation of DTMF signals 14a then generates the DTMF signals corresponding for example to the telephone number of the telecommunications terminal 34. This operation carried out, the processor ia checks in step E519 if the communication is established with the subscriber whose telephone number was dialed. More specifically, the processor l ia checks whether the subscriber whose telephone number has been dialed has picked up his telephone handset 34 or not. If, for a predetermined period, for example 30 seconds, the off-hook is not detected, the processor l ia goes to step E520 and controls the generation of a message informing the user of the telecommunication terminal 10 of the unsuccessful conference call. This message is identical to that described in step E515. The processor l ia then interrupts the communication and stops the present algorithm. If the correspondent whose telephone number has been dialed has picked up his telecommunication terminal 33, the processor 1 passes it to step E521. At this stage, the processor 1 commands it to generate an interruption of the current loop in accordance with the ETSI document TBR 21 followed by the generation of a voice frequency DTMF corresponding to the number three. As a variant, the processor 1 ia controls the generation on the screen 15a of an invitation message to press the function call key R and the dialing key 3 of the telecommunications terminal 10a. This operation carried out, the automatic switch 31 of the telecommunications network 30, on reception of these signals, puts the user of the telecommunications terminal 10 in contact with the users of the telecommunications terminals 33 and 34. The algorithm as described in Fig. 5 shows the establishment of a conference call between three subscribers. A conference call between a larger number of subscribers can also be established in accordance with the invention. Fig. 6 shows the algorithm performed by the telecommunications terminal 10b according to the second embodiment of the invention. In step E600, the processor 11b of the telecommunications terminal waits for the detection of a SAT signal. This signal is transmitted by the voice server 20 via the telecommunications network 30 and detected by the frame detection means V23 and generation of DTMF signals 14b via its connection with the link 31. Upon detection of this signal SAT, the processor 1 lb goes to the next step E601 and controls the means for detecting frames V23 and for generating DTMF signals

14b so that the latter generates a DTMF signal D, via the link 31, to inform the voice server 20 that the SAT signal has been taken into account by the telecommunications terminal 10b. The processor 11b then goes to step E602 and waits for the reception of a data frame V23. This data frame consists of a set of four bytes. The data frame is a frame making it possible to inform the telecommunications terminal 10 that the server 20 has specific functionalities. This data frame will be described with reference to Figs. 8 and 9. This domiee frame is transmitted by the server 20 via the telecommunications network 30 and detected and decoded by the frame detection means V23 and generation of DTMF signals 14a. Upon detection of this frame, the processor 1 lb goes to the next step E603 and checks whether the fourth byte of the frame received in step E602 is equal to the value 08 coded in hexadecimal. If not, the server 20, with which the telecommunications terminal 10b is connected, does not offer the service as provided by the invention. The program according to the invention ends. It is a classic interrogation of a classic voice server such as existing in the state of the art. If so, the server 20, by transferring this predetermined value and equal to 08 in hexadecimal, means that it has the service according to the invention. The processor 10b then goes to step E604. In step E604, the processor 1 lb controls the frame detection means V23 and generation of DTMF signals 14b so that the latter generates a DTMF signal thus informing the voice server 20 of the taking into account of the frame V23 detected in step E602 by the telecommunications terminal 10b. Once this has been done, the processor 11b then goes to step E605 and waits for the reception of a data frame V23. This data frame consists of a header byte equal to the value 80 coded in hexadecimal. This message is transmitted by the server 20 via the telecommunications network 30 and detected and decoded by the frame detection means V23 and generation of DTMF signals 14b. Upon detection of the header byte 80 in hexadecimal, the processor 1 lb goes to the next step E606 and decodes the data contained in the frame and in accordance with those which will be described with reference to FIGS. 10a to lOd. This data includes at least two telephone numbers. These telephone numbers are for example the telephone numbers of telecommunication terminals 33 and 34. According to the invention, the frame comprises a telephone number presented according to the table in FIG. 1 Od and at least one other telephone number presented according to the table in FIG. 10a. According to a preferred embodiment, each of the telephone numbers is also associated with data such as that which will be described with reference to FIGS. 10b and 10c. These data are decoded by the frame detection means V23 and the generation of DTMF signals 14b, transferred to the processor 1b which transfers these to the screen 15b. These received data are stored in step E607 in memory 12b. Once this data has been stored, the processor 11b goes to the next step E608 which consists in checking whether, in the stored data, two telephone numbers are present. These telephone numbers are each preceded by a predetermined header byte. If the data stored in step E607 does not include two telephone numbers presented in formats such as those which will be described with reference to Figs. 10a and 10d, the information frame does not concern a conference call establishment, the processor 11b stops the present algorithm and returns to step E600. If the data stored in step E607 includes at least two telephone numbers, the processor 1 lb goes to the next step E609. In a preferred embodiment, the verification of the presence of two telephone numbers is carried out by checking whether the stored data does not include information on the identity of a first called line. This Called first line identity is represented by a first byte set to the hexadecimal value 12 followed, among other things, by the telephone number. The byte representing the identity of a first line called will be described in more detail next to the

Fig. lOd. If the data stored in step E607 does not include information representative of the identity of a first called line, ie byte 12 in hexadecimal, only a single telephone number is included in the frame. The information frame does not relate to a conference call establishment, the processor l ia stops the present algorithm and returns to step E500. If information is representative of the identity of a first line called, the processor 11a proceeds to step E609. In step E609, the processor 11b controls the loop control circuit 19b so that it is activated. This operation carried out, the processor 11b controls, in step E610, the relay Ra so as to disconnect the telephone handset 35 from the communication network 30 and connect the telephone handset 35 to the loop circuit 19. A connection is thus simulated. It should be noted that certain types of telecommunications terminals, when the current in the current loop between the telecommunications network 30 and the telephone handset 35 is canceled, automatically cut the communication. This is particularly troublesome for the invention. In fact, the telecommunication terminal 10b will establish a conference call with the telecommunication terminals whose telephone numbers have been received in step E606. If the telephone handset 35 has released the call, the telecommunications terminal 10b will not be able to establish a conference call between the parties. Once this step has been completed, the processor 11b goes to step E611 and controls the relay Rb so as to connect the line interface 13b to the telecommunications network 30. The processor 11b generates, in step E612, a command intended for the line interface 13b so that it connects to the telecommunications network 13a. This step carried out, the processor 11a goes to step E613 and reads from memory 12b the telephone number representative of the identity of a first line called and associated with the hexadecimal code 12. The telephone number read is then transferred to the V23 frame detection and DTMF 14b signal generation means. The frame detection means V23 and generation of DTMF signals 14b then generates in step E614 the DTMF signals corresponding for example to the telephone number of the telecommunications terminal 33. This operation carried out, the processor 11b checks in step E615 if communication is established with the subscriber whose telephone number was dialed. More specifically, the processor 11b checks whether the subscriber whose telephone number has been dialed has picked up his telecommunication terminal or not. The detection of the off-hook of the telecommunication terminal is conventionally carried out by the frame detection means V23 and of generation of DTMF signals 14b which is capable of detecting ring return tones, line busy tones. If, for a predetermined period, for example 30 seconds, the off-hook is not detected, the processor 1 lb goes to step E616 and controls the relays Ra and Rb so that the telephone handset 35 is connected to the network Telecommunication 30. The user of the telecommunication terminal 10b is thus informed of the unsuccessful conference call. The processor 11b then stops the present algorithm. If the subscriber whose telephone number has been dialed has picked up his telecommunication terminal 33, the processor 11b proceeds to step E617. At this stage, the processor 11b controls the generation of an interruption of the current loop between the line interface 13b and the automatic switch 31 in accordance with the ETSI document TBR 21. This operation carried out, the processor 11b switches to l step E618 and reads from memory 12b the second telephone number stored in step E607. This telephone number was received in a format corresponding to the table in FIG. 10a and the hexadecimal code 03 is associated with it. The telephone number read is then transferred to step E619 by means of detection of frames V23 and generation of DTMF signals 14b. The frame detection means V23 and generation of DTMF signals 14b then generates in step E619 the DTMF signals corresponding for example to the telephone number of the telecommunications terminal 34. This operation carried out, the processor 11b checks in step E620 if communication is established with the subscriber whose telephone number was dialed. More precisely, the processor 11b checks whether the correspondent whose telephone number has been dialed has picked up his telecommunication terminal 34 or not. If, for a predetermined period, for example 30 seconds, the pickup is not detected, the processor 1 lb goes to step E621 and controls the relays Ra and Rb so that the telephone handset 35 is connected to the telecommunications network 30. The user user of the telecommunications terminal 10b is thus informed of the unsuccessful conference telephone. The processor 11b then stops the present algorithm. If the correspondent whose telephone number has been dialed has picked up his telecommunication terminal 33, the processor 1 passes it to step E622. At this stage, the processor 11b controls the generation of an interruption of the current loop in accordance with the ETSI document TBR 21 followed by the generation of a voice frequency DTMF corresponding to the number three. Once this operation has been carried out, the processor 11b controls in step E623 the relays Ra and Rb so that the telephone handset 35 is connected to the telecommunications network 30. This operation carried out, the automatic switch 31 of the telecommunications network 30, on reception of the signals generated in step E622, connects the user user of the telecommunication terminal 10 with the user users of the telecommunication terminals 33 and 34. The algorithm as described in FIG. 6 shows the establishment of a conference call between three subscribers. A conference call between a larger number of subscribers can also be established in accordance with the invention. Fig. 7 shows the algorithm performed by the server which communicates at least two telephone numbers to the telecommunications terminal according to the invention. The server is for example a voice server 20. In step E700, a call from a telecommunication terminal 10 is detected by the line interface 26 connected to the telecommunication network 30. The voice server 20 then establishes communication with the calling telecommunications terminal. Once this step has been completed, the processor 21, in step E701, controls the means 27 for detecting DTMF signals and for generating frames V23 so that the latter generates, via the line interface 26, a signal SAT to the calling telecommunications terminal, for example telecommunications terminal 10. The SAT signal is a dual-frequency signal (2130Hz and 2750 Hz) which is transmitted over a TSAT time comprised between 80 and 85 milliseconds (ms). This signal is transmitted by the voice server 20 via the telecommunications network 30. Following the sending of the SAT message, the processor 21 goes to step E702 which consists in checking whether, within a predetermined period, a DTMF response signal representative for example of the letter D has been received by the means 27 for detecting DTMF signals and for generating frames V23. If not, the telecommunication terminal 10 does not have a means of generating frame detection V23, the processor 21 stops the present algorithm. If a DTMF response signal D has been received by the means 27 for detecting DTMF signals and generating frames V23 in step E702, the processor 21 goes to step E703. In step E703, the processor 21 controls the means 27 for detecting DTMF signals and for generating frames V23 so that the latter generates a sequence of signals constituting a data frame V23 intended for the telecommunications terminal 10 by the via the network interface 26 and the telecommunications network 30. This data frame consists of a set of four bytes. The data frame is a frame allowing to select a terminal with a specific function. This data frame will be described with reference to Figs. 8 and 9. This step carried out, the processor 21 then goes to step E704 which consists in verifying whether a DTMF response signal has been received by the means 27 for detecting DTMF signals and for generating frames V23. This response signal is a DTMF signal indicating that the message transmitted in step E705 is taken into account by the telecommunication device 10. If not, the processor 21 stops the present algorithm. If so, the processor 21 goes to step E705 and transfers the telephone directory associated with the telecommunications terminal 10. The transfer is for example carried out in the form of voice messages. The processor 21 reads from voice memory 24 different voice messages in the form of blocks and transfers them to the line interface 26. A voice message is sent in the form of blocks in response to commands issued by the caller. Each voice message block is prerecorded and stored with an appropriate address in the voice memory 24. In general, a welcome message is sent upon connection between the voice server 20 and the telecommunications terminal 10, then a specific message is issued each time the user of the telecommunications terminal 10a presses a key on the keyboard 16a forming a command to the voice server 20 or each time that the user of the telecommunications terminal 10b presses a key on the telephone handset 35 forming a command to the voice server 20. Thus, a voice message is transmitted for each name of correspondent included in the directory or according to the commands generated by the user of the telecommunications terminal 10 by pressing a key of the telecommunications terminal 10. This generation of voicemail is classic. It will not be described. In the next step E706, the processor 21 obtains the selection of the telephone numbers with which the user of the telecommunication terminal 10 wishes a conference call to be established. The processor 21 obtains these numbers by memorizing the selection commands made by the user of the telecommunication terminal 10a or of the telephone handset 35 in response to the previously transmitted voice messages. This operation carried out, the processor 21 forms in step E707 a data frame comprising a header byte at the value 80 in hexadecimal and at least two telephone numbers. More particularly, one of the telephone numbers selected is in a format such as that described in FIG. lOd, the other telephone number is presented in a format such as that described in FIG. 10a. In a preferred embodiment, the processor inserts after each telephone number, the name of the correspondent in a format such as that described in FIG. 10b, or even the date and time in a format such as that described in FIG. 10c. It should be noted here that, according to the format of FIG. lOd, the telephone number is preceded by a byte at the value 12 in hexadecimal. This corresponds to the insertion by the server 20 into the message of a command for the establishment of a conference call by the telecommunications terminal 10. This operation carried out, the processor 21 generates in step E708 a command intended for the means 27 for DTMF signal detection and frame generation V23 so that it generates and transfers a V23 data frame comprising the previously formed frame to the telecommunications terminal 10 via the line interface 26 and the telecommunications network 30. It should be noted that variant, the processor 21 modifies the stored telephone numbers so as to make them directly usable by the telecommunication terminal 10. In fact, if the telephone number is a foreign subscriber number, the server 20 inserts into the number telephone call sign for a call abroad, ie "00". Also, when the telecommunications terminal 10 is placed behind a PABX, the server 20 inserts at the beginning of the telephone number the digit "0". This operation carried out, the processor 21 waits at step E709 for the disconnection of the telecommunication terminal 10 to return to step E700 to wait for a new call to be processed. Thus, by inserting predetermined information and two telephone numbers in the same information frame, the server 20 has generated information representative of a command to establish a conference call. Thus, the server 20 according to the invention has inserted, in a signal transmitted to the telecommunications terminal 10, a command to establish a conference call, in this case by inserting the bytes 08H and 12H in hexadecimal in a frame of V23 data. Fig. 8 represents a table comprising the various elements of a V23 data frame sent by the server according to the invention. The data frame V23 transmitted by the voice server in step E703 of FIG. 7 and received by the telecommunications terminal 10a in step E503 or by the telecommunications terminal 10b in step E602 consists of four bytes of data. The table in FIG. 8 consists of four columns denoted 81 to 84 and four rows denoted 85 to 88. Column 81 contains the number of the byte in the V23 frame considered, column 82 contains the binary value of the byte considered, column 83 contains the hexadecimal value of the byte considered and column 84 the meaning of the byte considered. The first byte in line 85 has a binary value of 0100 0000 or 40H in hexadecimal. This byte represents a code identifying that the content of the frame is relating to a request from the voice server 20 in order to interrogate the telecommunications terminal 10 if it includes a predetermined function. The second byte in line 86 counts the bytes composing the message which follow this byte. In our example, this byte 86 has a binary value of 0000 0010 or 02H in hexadecimal. The third byte in line 87 determines the type of information in this frame.

This byte can be representative of a type of connection as in the invention as described and is then equal to the binary value of 0000 0001, ie 01H in hexadecimal. This third byte allows in other applications to define for example the number of multiple subscribers or Multiple Subscriber Number MSN. The last byte in line 88 contains the code associated with the type of connection. This code takes the different values described with reference to FIG. 9. Fig. 9 represents a table summarizing the different types of connections included in the fourth byte of the V23 data frame of FIG. 8. The table in FIG. 9 consists of three columns denoted 901 to 903 and nine lines 904 to 912. Column 901 contains the possible binary value of the byte considered, column 902 contains the hexadecimal value of the byte considered and column 903 the meaning of the byte considered. Lines 904 to 911 are classic and described in the ETSI EN 300 standard.

659-3 Access and Terminal; Public Switch Telephone Network; Subscriber line protocol over the local loop for Display (and related) services; Data link message and parameter codings. They will not be described in detail. Line 912 includes a binary value byte 0000 1000, in hexadecimal 08H which is a new code allowing the voice server 20 or a telecommunications terminal 33 according to the invention to transmit a command call type message. This “command call” message indicates to the telecommunications terminals 10 that the server 20 wishes the telecommunications terminal 10 to execute, following the transfer of at least one telephone number, a disconnection and an establishment of communication with the number or numbers phone transferred thereafter. Fig. 10a represents a table describing the content of a V23 data frame in which the server according to the invention communicates a first telephone number to the telecommunications terminal 10. The data frame V23 is transmitted by the server 20 in step E708 of FIG. 7 and is received by the telecommunications terminal 10a in step E506 or by the telecommunications terminal 10b in step E606. The table in FIG. 10a consists of four columns denoted 101 to 104 and a number of five rows denoted 105 to 109. Column 101 contains the number of the byte in the frame considered, column 102 contains the binary value of the byte considered , column 103 contains the hexadecimal value of the byte considered and column 104 contains the meaning of the byte considered. Lines 105 to 109 are classic and described in the ETSI EN 300 standard.

659-3 Access and Terminal; Public Switch Telephone Network; Subscriber line protocol over the local loop for Display (and related) services; Data link message and parameter codings. They will not be described in detail. Fig. 10b represents a table describing the content of a V23 data frame in which the server according to the invention communicates to the telecommunications terminal 10 the name of the user of the telecommunications terminal 30 associated with the telephone number communicated according to FIG. 10a or FIG. lOd. The data frame V23 is transmitted by the server 20 in step E708 of FIG. 7 and is received by the telecommunications terminal 10a in step E507 or by the telecommunications terminal 10b in step E606. The table in FIG. 10b consists of four columns denoted 111 to 114 and a number of five rows denoted 115 to 119. Column 111 contains the number of the byte in the frame considered, column 112 contains the binary value of the byte considered , column 113 contains the hexadecimal value of the byte considered and column 114 contains the meaning of the byte considered. Lines 115 to 119 are classic and described in the ETSI ES 200 standard

659-3 in publication or the ETSI EN 300 standard 659-3 Access and

Terminal; Public Switch Telephone Network; Subscriber line protocol over the local loop for Display (and related) services; Data linlc message and parameter codings. They will not be described in detail. Fig. 10c represents a table describing the content of a V23 data frame in which the server according to the invention communicates to the telecommunications terminal 10 the date and time of the call made by the terminal of telecommunication 30 associated with the telephone number communicated according to FIG. 10a or FIG. lOd. The data frame V23 is transmitted by the server 20 in step E708 of FIG. 7 and is received by the telecommunications terminal 10a in step E507 or by the telecommunications terminal 10b in step E606. The table in FIG. 10c consists of four columns denoted 1201 to 1204 and a number of ten lines denoted 1205 to 1214. Column 1201 contains the number of the byte in the frame considered, column 1202 contains the binary value of the byte considered , column 1203 contains the hexadecimal value of the byte considered and column 1204 contains the meaning of the byte considered. Lines 1205 to 1214 are classic and described in standard ETSI EN 300 659-3 Access and Terminal; Public Switch Telephone Network; Subscriber line protocol over the local loop for Display (and related) services; Data link message and parameter codings. They will not be described in detail. Fig. lOd represents a table describing the content of a V23 data frame in which the server according to the invention communicates a second telephone number to the telecommunications terminal 10. The V23 data frame is transmitted by the server 20 in step E708 of Fig. 7 and is received by the telecommunications terminal 10a in step E507 or by the telecommunications terminal 10b in step E606. The table in FIG. lOd consists of four columns denoted 1301 to 1304 and a number of five lines denoted 1305 to 1309. Column 1301 contains the number of the byte in the frame considered, column 1302 contains the binary value of the byte considered , column 1303 contains the hexadecimal value of the byte considered and column 1304 contains the meaning of the byte considered. Line 1305 has the first byte of binary value 0001 0020 or 12 in hexadecimal. The value of this first byte is representative of the identity of the first line called according to the standard ETSI EN 300 659-3 Access and Terminal;

Public Switch Telephone Network; Subscriber line protocol over the local loop for

Display (and related) services; Data link message and parameter codings. According to the invention, using the identity of the first line called coded 12 in hexadecimal in combination with the identity of the called line coded 03 in hexadecimal, it it is possible to transfer two telephone numbers so that the communication terminal 10 dials these numbers and enters into a conference call establishment procedure. The lines 1306 to 1309 being identical to those described in the standard ETSI EN 300 659-3, these will not be further explained. Note that the conference was described in detail for a conference call between three subscribers. Of course, the conference call can also be set up for a larger number of subscribers. Likewise, videophone conferences can also be established according to the present invention. Of course, the present invention is not limited to the embodiments described here, but encompasses, quite the contrary, any variant within the reach of ordinary skill in the art.

Claims

1) Method for establishing a conference between a first subscriber of a telecommunications network (30) with at least two other subscribers of the telecommunications network, each subscriber being identified by an identifier in the telecommunications network, the first subscriber being in communication with a server (20) of the telecommunication network via a telecommunication terminal (10), characterized in that the method comprises the steps carried out by the telecommunication terminal (10) of the first subscriber of: - detection of predetermined information in an information frame transmitted by the server (E506), - detection (E509) of identifiers of other subscribers in at least one information frame transmitted by the server, - storage (E508 ) of the identifiers detected, interruption (E510) of the communication with the server, - transfer (E513, E518) to the telecommunications network (30) of the identifiers m emitted and generation of predetermined commands (E516, E521) to the telecommunication network for the establishment of a conference, via their respective telecommunication terminals, between the first subscriber and the other subscribers whose identifiers have been transferred . 2) Method according to claim 1, characterized in that the telecommunications network is a switched telephone network, the conference is a conference call between the first subscriber with two other subscribers, the identifiers are telephone numbers and in that at a telephone number included in the information frame is associated with predetermined information different from the predetermined information associated with the other telephone number included in the information frame.

3) Method according to claim 1 or 2, characterized in that the information frame comprising the predetermined information is an information frame conforming to the V23 protocol and the identifiers of the other subscribers are included in the information frame comprising the predetermined information. 4) Method according to any one of claims 1 to 3, characterized in that the predetermined information is a command call.

5) Method according to any one of claims 1 to 4, characterized in that the method further comprises the steps (E514, E519) of detecting the establishment of a communication with each other subscriber and in that the commands predetermined values are generated each time a call is established with each other subscriber. 6) Method according to any one of claims 1 to 5, characterized in that the telecommunication terminal (10b) of the first subscriber is connected to a telephone handset (35) and in that the method further comprises the connection steps and disconnecting the telephone handset (35) from the telecommunications network (30). 7) Method according to claim 6, characterized in that the method further comprises in the step of generating a loop current when the telephone handset is disconnected from the telecommunications network by the telecommunications terminal of the first subscriber. 8) Method for transferring information for establishing a conference between a first subscriber of a telecommunication network (30) with at least two other subscribers of the telecommunication network, each subscriber being identified by an identifier in the network telecommunications, the first subscriber being in communication with a server (20) of the telecommunications network via a telecommunications terminal (lθ), characterized in that the method comprises the steps performed by the server of the telecommunications network of: - obtaining (E706) a selection, by the first subscriber, of identifiers of other subscribers for establishing a conference between the subscribers, - transfer (E708) of at least one frame of information intended for the telecommunication terminal of the first subscriber, the information comprising at least the selected identifiers and a predetermined information, the identifiers and the predetermined information being representative of a command from the terminal of telecommunication of the first subscriber for establishing a conference with the subscribers whose identifiers have been selected.

9) Method according to claim 8, characterized in that the network is a switched telephone network, the conference is a conference call between the first subscriber with two other subscribers, the identifiers are telephone numbers and that at one number of telephone included in the information frame is associated with predetermined information different from the predetermined information associated with the other telephone number included in the information frame.

10) Method according to claim 8 or 9, characterized in that the information frame comprising the predetermined information is an information frame conforming to the V23 protocol and the identifiers of the other subscribers are included in the information frame comprising the predetermined information.

11) Method according to any one of claims 8 to 10, characterized in that the predetermined information is a command call.

12) Telecommunication terminal for establishing a conference between a first subscriber of a telecommunication network with at least two other subscribers of the telecommunication network, each subscriber being identified by an identifier in the telecommunication network, the first subscriber being in communication with a server of the telecommunications network through the telecommunications terminal, characterized in that the telecommunications terminal of the first subscriber comprises: - means for detecting predetermined information in an information frame transmitted by the server, - means for detecting identifiers of other subscribers in at least one information frame transmitted by the server, - means for storing the detected identifiers, means for interrupting communication with the server, means for transferring stored identifiers to the telecommunications network and generation of predetermined commands to the telecommunications network for the establishment of a conference, via their respective telecommunication terminals, between the first subscriber and the other subscribers whose identifiers have been transferred.

13) Information server for establishing a conference between a first subscriber of a telecommunications network with at least two other subscribers of the telecommunications network, each subscriber being identified by an identifier in the telecommunications network, the first subscriber being in communication with the server via a telecommunications terminal, characterized in that the server comprises: - means for obtaining a selection, by the first subscriber, of identifiers of other subscribers for setting up a conference between the subscribers, - means for transferring at least one information frame to the telecommunications terminal of the first subscriber, the information comprising at least the selected identifiers and a predetermined information, the identifiers and the predetermined information being representative of a command from the telecommunication terminal of the first subscriber for u n establishment of a conference with subscribers whose identifiers have been selected.

14) Computer program stored on an information medium, said program comprising instructions making it possible to implement the method according to any one of claims 1 to 7, when it is loaded and executed by a computer system.

15) Computer program stored on an information medium, said program comprising instructions making it possible to implement the method according to any one of claims 8 to 11, when it is loaded and executed by a computer system.

16) Signal transmitted over a telecommunication network by a server of a telecommunication network in a communication with a subscriber via a telecommunication terminal and the telecommunication network, each subscriber of the telecommunication network being identified by a identifier in the telecommunications network, characterized in that the signal includes information comprising at least identifiers of other subscribers of the telecommunication network and predetermined information, the identifiers and the predetermined information being representative of a command from the telecommunication terminal of the first subscriber for establishing a conference with the other subscribers whose identifiers are included in the information signal .

17) Signal according to claim 16, characterized in that the network is a switched telephone network, the conference is a conference call between the first subscriber with two other subscribers, the identifiers are telephone numbers and in that the signal comprises a predetermined information associated with each telephone number included in the signal, the predetermined information associated with a telephone number being different from the predetermined information associated with the other telephone number included in the signal.