Telephony device comprising a base station and at least a subscriber unit, subscriber unit for such a telephony device and method used in such a telephony device

A telephony device is formed by a base station and subscriber units. The telephony device includes a responder circuit formed predominantly by a flash memory located in the base station. The responder circuit has various states: on line, in service, in possession or not of a message . . . etc. These states may be displayed on the screens of all the subscriber units by a broadcast of messages transmitted from the base station.

FIELD OF THE INVENTION
 The invention relates to a telephony device comprising a base station
 connected to the switched network, at least a subscriber unit and at least
 a communication element of the responder type, notably linked with the
 base station which has a management element formed, inter alia, by a
 processor assembly, by a memory containing an execution program and by a
 random-access memory.
 The invention likewise relates to a method used in such a telephony device
 and also relates to a subscriber unit suitable for such a telephony
 device.
 The invention finds interesting applications in telecommunication systems
 implying protocols which is notably the case with telephony devices
 satisfying the DECT standard, for example.
 BACKGROUND OF THE INVENTION
 The telephony devices of this type very often comprising numerous
 subscriber units offer more and more functions to the user. One of these
 functions is that of the responder which makes it possible to receive and
 transmit messages for those who call and which authorize the return of
 messages to the user at his request.
 A problem posed with this type of device is for the user who may be located
 far from the base station to know whether he has messages. The user may
 also have the need to make an announcement and thus desires to know
 whether his responder is available. This problem is all the more serious
 when one faces devices that satisfy the DECT standards which may thus
 comprise a large number of subscriber units.
 SUMMARY OF THE INVENTION
 The present invention proposes a device of the type defined in the opening
 paragraph which permits a user to manage in an easy fashion the accesses
 to the responder inserted into the base station.
 Therefore, such a device is characterized in that data about the state of
 the communication element is broadcast to all the subscriber units.
 The idea of the invention consists of utilizing the possibility of
 broadcasting data to all the subscriber units so as to make known to them
 the state of their responder and, possibly, communicating with them.

DESCRIPTION OF PREFERRED EMBODIMENTS
 In FIG. 1, the device which is represented is a device satisfying the DECT
 standards. Reference 1 shows the base station BS to which may be
 connected, by radio channel, a plurality of subscriber units (handsets)
 HS1, HS2, . . . This base station 1 comprises, inter alia, a line circuit
 10 which makes it possible for connecting the base station to the switched
 network by a telephone line 12 and a radio circuit 14 which authorizes the
 dialogue with the various subscriber units HS1, HS2, . . . , by emitting
 and receiving waves via an antenna 16. For processing all the analog
 information which transits the basic circuit, a signal processing element
 15 is provided formed around a digital signal processor DSP which
 processes notably the speech signals. A flash memory 17 is used for
 performing the function of responder. That is to say that it contains the
 speech data coming from remote subscribers through line 12 and also
 announcement data which are more often than not intended for these remote
 subscribers. The data of this memory 17 are processed by the circuit 15
 which carries out the various analog/digital conversions and vice versa.
 All the elements of this basic circuit 1 are managed by a microprocessor
 assembly 20. This assembly is formed, notably, in usual manner by a
 random-access memory 24, a read-only memory 26 containing the instructions
 and operation of the device and a management processor 29. With this
 assembly it is possible to know when the flash memory 17 which is the main
 constituent part of the responder function is available or not and if a
 message has been registered there or not.
 The subscriber unit HS1, only shown in detail (the unit HS2 may have an
 identical structure) comprises a communication assembly 40 with an antenna
 41 which permits the unit to communicate with the base station BS and from
 there with the other subscriber units HS2, . . . This assembly processes
 the information coming from the microphone 42 and also produces signals
 for an earphone 44. Also provided is a management element 50 formed, just
 like the management element 20, by a random-access memory 54, a read-only
 memory 56 containing the operating instructions of the device, and by a
 management processor 59. The subscriber unit HS1 also has a screen 60 on
 which the various data are displayed and a keyboard 61. These handsets are
 mobiles and because of this they are fed by an accumulator not shown on
 the FIG. 1.
 According to the invention, the state of the responder circuit is shown on
 the screen 60 without the intervention of the user. This is achieved due
 to an interesting characteristic feature of the invention by realizing a
 message broadcast. For this purpose, the prescriptions of the paragraph
 7.2.4.3 of the ETS standard 300 175-3 are used.
 The Table I below shows how this standard is used.
 TABLE I
 Data binary word
 Responder in service M1 = 0111 0011 0000 0001
 Responder not in service M1' = 0111 0011 0000 0000
 Registered messages M2 = 0111 0011 0000 0010
 No messages M2' = 0111 0011 0000 0011
 Aligned responder M3 = 0111 0011 0000 0100
 Non-aligned responder M3' = 0111 0011 0000 0101
 Thus, word pairs are found which are mutually exclusive. M1 and M1' are
 mutually exclusive as are the pairs M2, M2' and M3 and M3'. These words
 are explained at the places referenced a32 to a47 of said standard.
 In FIG. 2 are explained the operation steps of the responder circuit.
 The state ST1 is considered which indicates that the responder is not in
 service, thus the word M1' is transmitted in the direction of all the
 subscriber units. If the responder is put into operation, for example, by
 validating this start which appears on a menu visible on a screen of the
 base station, then state ST2 is proceeded to, the word M1 is thus
 transmitted. After that, the responder may be aligned, state ST3
 corresponding to the transmission of the word M3 for carrying out a task
 such as: registering a message which comes from the telephone line 12,
 broadcasting an announcement over this telephone line 12 or also returning
 a message to a user on one of the subscriber units. Having performed its
 task, the responder changes to the state ST4 corresponding to the
 transmission of the word M3' by passing either through the state ST5 which
 indicates that no message has been registered during the alignment, or by
 passing through state ST6 which indicates that a message has been
 registered. The states ST5 and ST6 imply the transmission of the words M2'
 and M2, respectively. It is evident that from each of these states one may
 come back to the state ST1 by deactivating the responder function.
 Starting from a subscriber unit, one may consult the state of this
 responder circuit by validating certain items of a menu. This is shown in
 a diagram in FIG. 3.
 If the word M1' has been transmitted, which is detected in box K1, thus
 signaling that the responder is not in service, only this data M1' is
 visible to the user. He is thus shown that the responder is not in service
 (box K2). If the word M1 has been transmitted, then the data concerning
 the words M1, M2 or M2', M3 or M3' are visible (box K3).
 These various words are transmitted periodically, so that, if a subscriber
 unit is no longer in the coverage area of the base station, the state data
 concerning the responder will be updated the moment the subscriber unit
 will come back to said coverage area.
 However, it should be observed that the words M1' and M2 are not exclusive.
 Indeed, it may happen that the user has:
 put his responder into operation, transmission of the word M1,
 received messages, transmission of the word M2,
 put his responder out of operation, without reading the messages,
 transmission of the word M1'.
 In this case, the words M2 and M1' will be transmitted at the moment of the
 change of state and after that periodically. And the data corresponding to
 the words M2 and M1' will have to be visible.