FR2695786A1 - Switching device for automatic allocation of telephone line between several users - has selector connected to network line and to payment device associated with each user terminal to detect valid payment by phone card - Google Patents

Abstract

The selector (1) has a switching matrix (4) to make a connection between the network line (LT) and the user telephone lines (L1-Ln) which call or are called. An incoming call direct selector (5) controls the matrix for incoming calls to all lines, while an outgoing call direct selector (8) does so for outgoing calls on two-way lines and can detect the unhooking of a telephone. A phone card reader and associated managing microprocessor detects valid payment, and the line is connected if this condition is satisfied and the telephone is unhooked. A microcontroller prevents the action of the two direct selectors while a user is connected to the network. A voice synthesiser (7) may ask the incoming caller for additional digits to identify a particular terminal. USE/ADVANTAGE -E.g. in blocks of flats, public telephones. Increased line traffic without increasing number of lines. Allows separate charging of users.

Description

 The present invention relates to a device for sharing at least one telephone line between several user stations having different identification numbers.

 The invention is based on the following considerations: 1 "> The investment share in the telephone subscriber lines represents 70% of the total price of a telecommunication network.

 2) The profitability of these lines is given by the importance of the traffic more than by the collection of the amount of the subscription.

 3-) The international trend of telecommunication liberalization will lead to a decrease in the price of "long distance communications" and thus to increase the price of "local calls" and consequently the price of the subscription.

 It is clear that it would be of great interest to have a device that allows not only to automatically share at least one subscriber line between several user stations, for example 8 stations, and to charge a the user each of his telephone calls, but also to increase the traffic without increasing the number of subscriber lines.

 Current public or private branch exchanges do not fully meet this demand.

 The present invention therefore aims to provide a device for automatically sharing at least one telephone line between several user stations with different identification numbers and whose users can be taxed separately.

 For this purpose, the device of the present invention is characterized in that at least one of said user stations is associated with a respective payment device comprising means capable of detecting the presence of a valid payment means in the payment device, and in that it further comprises a selector connected on one side to the telephone line and, on the other side, to each payment device and which can be individually connected to one any of said user stations, said selector having a switching matrix adapted to establish the connection between the telephone line and a user station called or calling from among said user stations, a direct dialing device on arrival to receive a telephone call from the telephone line, determine to which user station this call is intended and accordingly control the switching matrix to establish the appropriate link, a dispo direct selection system at the beginning comprising a means able to detect the off-hook status of any one of the user stations <calling user station> and to establish, via the switching matrix, a connection between the telephone line and the calling user station under the dual condition that the off-hook detector means has detected the off-hook status of the calling user station and the valid payment means detector means of the payment device associated with the calling station. calling user has detected the presence of a valid means of payment, and management control means able to inhibit the operation of the direct selection device on arrival and the direct selection device initially as one of the positions user is connected to the telephone line.

With the device of the present invention, the user stations can, according to their authorization, that is to say according to whether or not a payment device is associated with them, or only automatically receive a call from the general telephone network. cycas of a user station not equipped with a payment device, either to automatically receive such a call that generate a call to the general telephone network if its access is free (case of a user station equipped with 'a payment device). The automatic reception of a call from the general telephone network is provided by the function
Direct Inward Selection (SDA). This SDA function can be performed both in the context of a closed type numbering and in the context of an open type numbering. As is well known to those skilled in the art, closed type dialing is a numbering where the number of digits dialing a subscriber's number is, for example eight digits in France. In this case, the final selection of a called user station can be done in a known manner either by analyzing the last digit (s) of the user's post identification number if the national operation has given several numbers. for the same line, or, in the negative, by multifrequency override (Q 23 codes) or decimal <option). Q 23 is a multi-frequency (frequency pair) one-digit coding standard. In the case of closed dialing, a known synthetic voice aid device may be provided to guide the calling subscriber.

 Similarly, as is well known to those skilled in the art, open dialing is a numbering where the number of digits dialing a subscriber's number is variable, as for example in Germany. In this case, the final selection of a called user station can automatically be obtained automatically by analyzing the last digit (s) of the identification number of the user's station or by over-numbering as in the case of closed numbering.

 The generation of a call to the general telephone network, if its access is free, is provided by the Direct Selection at Departure (SADD) function in combination with the payment device associated with the calling user station, provided that the double condition mentioned above is satisfied. apt. Thus, the payment device associated with the user station allows it to obtain access to the general telephone network. The user then uses his telephone, which may be a standardized telephone, to generate the number of his correspondent.

This call and the resulting call will be debited to the calling subscriber by the payment device which receives and manages the charging pulses transmitted by the general telephone network in a manner similar to telephone devices called "public phones" installed in public telephone booths. . In a manner known per se, the payment device may comprise a help device displaying messages on the screen of a display, of the liquid crystal or light-emitting diode type, to guide the user and to indicate to him in particular a ) the state of access to the telephone network (free or busy), b) the number of taxes paid; (c) the validity of the means of payment used.

 The device according to the invention is more particularly, but not exclusively, useful in developing countries or for buildings with timeshare properties. For example, a user telephone without a payment device, only able to receive telephone calls, can be installed in each apartment or fractional ownership of a building, while one or more telephone sets with payment device may be installed in the common areas of the building.All telephone sets, with or without payment device, are then connected to a selector according to the invention, itself connected to one or more telephone subscriber lines, the number of said lines being however less than the total number of telephones connected to the selector.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: - Figure 1 is a general diagram of the device of the present invention; FIG. 2 is a functional diagram of the selector of FIG. 1; FIG. 3 is a block diagram illustrating an embodiment of the selector of FIGS. 1 and 2; FIG. 4 is a block diagram of one of the payment devices of FIG. 1; FIG. 5 represents a mode of connection of a telephone set and a payment device according to the invention; FIG. 6 is a flowchart illustrating the operation of the device of the present invention
In this specification, the following terms or expressions have the meaning indicated below - subscriber: a person subscribing to a general telephone network; user: user of the device of the present invention; - user station: standard telephone set used by a user; - Taking line: action of a looping interface (known type interface) which establishes the connection with a telephone line of a general telephone network; - release: action of the looping interface which removes the connection with the telephone line; - stall: action of landing a user's post; - hang-up: action to hang up a user station; - off-hook: state of a user station after stall; - hung up: state of a user station after hang up.

- over-dialing: one or more digits to add to the subscriber identification number given by a national operator to completely identify a user's station.

 The device of the present invention shown generally in FIG. 1 comprises several user stations P1 ... Pn connected respectively by user lines L1 * .. Ln to a selector 1 itself connected to several telephone lines. LT1 ... LTm of a general telephone network (with mAn).

Among the user stations P1 ... Pn, the positions P1. . . Pi are for example stations that only have the possibility of receiving telephone calls, while the stations Pi + 1 ... Pn are stations having both the possibility of receiving the possibility of generating telephone calls. At each of the user stations Pi, l ... Pn is associated with a payment device
DPi + 1 ... DPn, which will be described later. At each user station Pl ... Pi can be associated a plug B1 ... Bi adapted to allow the receipt of a call by any one of the positions P1. . . Pi from the selector 1, the absence of such a cap prohibiting any possibility of reception.Although all user stations P1-Pn consist of standard or standard telephone sets, the positions P1 .. Pi which n do not have the possibility of making calls could be constituted by telephone sets devoid of dial or dial pad.

 In the following description of the device of the present invention, the particular case where m is equal to 1 and where n is for example equal to 8 will be described.

 Figure 2 illustrates the main functions of the selector of the device of the present invention.

 In Figure 2, the telephone subscriber line LT, connected to the telephone network of a national operator, leads to a loopback type line interface 2, which simulates the presence of a normalized telephone. This interface is galvanically isolated from the rest of the circuits of the selector 1 in a manner to be described later. The looping interface 2 is coupled to a single power interface 3, which can be connected, via a switching matrix 4, to any one of the user lines L1 ... Ln and which allows the management of the one any of the standard telephones Pl. .Pn as will be seen later. At the looping interface 2 are also coupled an Direct Dialing Device (SDD) which analyzes the significant digit (s) of the address. the called user, a telephony counter 6, which receives, formats and counts the charging pulses from the telephone line LT during a telephone call generated by one of the user stations Pi, ... Pn, and a voice aid device 7, able to send on the telephone line LT voice help messages for a calling subscriber in the case of an over-dialing, to invite him to dial said supernumber identifying the called user station. reader 1 further comprises a device 8 of Direct Selection at Departure <SDD> which is linked to the switching matrix 4 and which analyzes and determines the access to the telephone line LT by any one of the user stations Pi, 1 ... Pn, as will be seen below, and a multipoint modem 9, which is connected by lines 1 F respectively to the payment devices DP1 + ... DPn of FIG.

 The management of the selector 1 is provided by a microcontroller (not shown in Figure 2) whose software programming allows in combination with other circuits the functional realization of the blocks 5 to 9 as will be seen later.

 A power supply unit 11 connected to a current source, for example the 220 V AC network, ensures at least the distribution of the electrical energy necessary for the operation of the selector 1 and, preferably, also the power supply of the power supply stations. Pl ... Pn and that of payment devices DPi.w ... DP <.

 One possible embodiment of the selector 1 of FIG. 2 is shown in FIG. 3 in the form of a block diagram. In FIG. 3, it is still possible to see the looping interface 2, which comprises, in known manner, a protection device 12 against overloads, for example a surge arrester, a ring detection circuit 13, a clipping device 14 for clipping the speech signals. exceeding a predetermined level, a diode bridge 15 for connecting the selector 1 to the telephone line LT without taking into account the polarity of this line, and a unit 16 acting both as a 2-wire / 4-wire converter, for separating the broadcast speech signals and the reception speech signals, and the role of a controllable line current control circuit (15mA). This unit 16 is a well-known unit and it is therefore not considered useful to describe it in detail.

The unit 16 is coupled by two translators T1 and T2 for the speech signals, respectively in reception and in transmission, on the one hand to a feed line interface 17 and, on the other hand, to a coding-filtering-decoding circuit 18 (COFIDEC) of the selector 1. The functions of the circuits 17 and 18 will be described later. The ring detection circuit 13 and the unit 16 of the looping interface 2 are respectively coupled by photocouplers 19 and 21 to the microcontroller 22 of the selector 1. Thus, the two translators T1 and T2 and the two photocouplers 19 and 21 provide a galvanic isolation between the looping interface 2 and the rest of the selector 1.

The power supply unit 11 of the selector 1 comprises a DC power supply 23 capable of supplying the DC supply voltages necessary for the operation of all the circuits of the selector 1 (except the telephone line LT>, a remote power supply circuit of the user station 24, capable of supplying the current <for example 30mA> necessary for the operation of any one of the user stations Pl ... Pn, and a payment device remote supply circuit 25, capable of supplying the DC voltage (for example). example 5 V) necessary for the operation of the remote payment devices DPi.
The COFIDEC circuit 18 is connected to a signal processor 26, which is itself connected by a local bus 27 on the one hand to a programmable fixed memory 28 (PROM>, which stores the software modules executed by the signal processor 26 , and on the other hand to a RAM 29 <RA>, which stores the variable data processed by the processor 26.

 The microcontroller 22, of the type MC68HC1 1, for example, communicates with the processor 26 via an internal bus 31 to which a programmable fixed memory 32 (PROM), which stores the software modules executed by the microphone, are also connected. controller 22, and a random access memory 33 CRAK which stores the variable data processed by the microcontroller 22.

 The switching matrix 4 of the selector 1 may be constituted by a switch 34 with electronic relay relays or electromechanical relays, for example relay bars called relays "REED") associated with a connection memory 35.

 The microcontroller 22 is connected to the connection memory 35 by a line 36, to a display 37 via a line 38, to the interface supplying 17 via a line 39, to a ringing generator 41 via a line 42, the generator 41 being itself connected to the supply interface 17 via a line 43. The microcontroller 22 is also connected to lines li + .ln via an interface 44.

 The selector 1 described above operates in the following manner. The looping interface 2, which is coupled by the photocouplers 19 and 21 to the inputs / outputs of the microcontroller 22 which manages them, makes it possible to take a line tap on the general telephone network side in a manner well known to men of art.

 The supply interface 17 performs the following functions: a) the supply of current, for example 30 mA continuous, of a selected user station, via the switching matrix 4; (b) overvoltage protection, for example by means of integrated circuits "TRAKSILS"; c) the ringing of the called user station by connecting the ring generator 41 to the selected user station via the switch 34; d) the monitoring of the user's station (detection of off-hook and on-hook status, transmission of the numbering issued by the station); e) four-wire / two-wire conversion (each user station is usually powered by two wires).

 The management of the supply interface 17 is provided via line 39 by the microcontroller 22.

 The switch 34 associated with the connection memory 35 provides, under the control of the microcontroller 22, an exclusive referral of the interface supplying 17 to the selected user station (one of eight for example).

 The display 37, constituted for example by a liquid crystal screen or by light-emitting diodes of colors, makes it possible to visualize the state of the selector 1.

 The interface 44, for example of the RS 422 type, is an embodiment, adapted to wired support, of the multipoint modem 9 of FIG. 2. This interface makes it possible to exchange data of computer type (protocol) between the selector 1 (FIG. micro-controller 22) and the remote payment devices DPI ... DP, of Figure 1 (the distance can reach a few kilometers). In addition, the interface 44 can provide remote power remote payment devices.

The interface 44 may for example be made from standard integrated circuits such as circuits
MC 3486 and MC 3487.

 The SDD function of block 8 of FIG. 2 is performed by the running of a software module stored in the PROM 32 and executed by the microcontroller 22.

 It associates and controls the data coming from one of the payment devices, each in turn, and the stall of the corresponding user station, by acting on the switch 34 and the feed interface 17.

When the data received by the microcontroller 22 are coherent, that is to say when it detects a valid payment means in the payment device DP associated with one of the user stations P and when it simultaneously detects the off-hook of the corresponding user station, the microcontroller 22 causes the telephone line LT to be taken by command of the looping line interface 2. The physical link between the user station and the telephone line LT is thus established, authorizing the user to dial the number of the desired subscriber. Once communication is established and during the conversation, the teletax meter transmits the tax signals to the microcontroller 22 which routes them through the interface 44. to the payment device DP of the user station P concerned, which physically decrements the credit of the means of payment of the user (for example a payment unit account contained in the memory of a card>.

 In the embodiment of FIG. 3, the teletaxes counting function (block 6 of FIG. 2) is carried out by the signal processor 26 which executes a software module stored in the programmable fixed memory 28. This module provides digital filtering. and reformatting <frequency> teletaxes from the LT line. For this purpose, the COFIDEC circuit 18 performs an analog / digital transformation of the signals. This circuit, which is a conventional digital telecommunication circuit, may for example consist of an integrated circuit of the TMS 2913 type.

 The SDA function (block 5 of FIG. 2) can be performed by the running of a software module stored in the programmable fixed memory 32 and executed by the microcontroller 22. This function is initiated by the detection of an incoming call. on the line LT (detection of a ringing signal by the circuit 13>.

In response to this call, the microcontroller 22 controls the taking of the line LT by the looping interface 2. In the case of a closed-dial telephone system, the microcontroller 22 requests the signal processor 26 to generate a voice assistance message, by the execution of a voice synthesizer software module contained in the programmable fixed memory 28 and performing the function of the block 7 of FIG. 2.This voice assistance message is sent by the COFIDEC circuit 18 to the calling subscriber via the loopback interface 2. The microcontroller 22 then sets the signal processor 26 in a <multifrequency Q23 or decimal residue numbering receiving mode by activating another software module which is stored in the programmable fixed memory 28 and which receives the dialing signals from the telephone line LT and identifying the called user station P (one of eight in the example described here). In the case of a telephone system without over-numbering, a standard processing of the function
SDA can be realized in a conventional manner by the microcontroller 22 which executes a software module stored in the programmable fixed memory 32. The number or numbers received by the signal processor 26 are transmitted to the microcontroller 22 which ensures the ringing of the substation. called user P, by connecting the ringer generator 43 (70 V AC, 50 Hz) to said user station via the power interface 17 and the switch 34.

The final establishment of the communication between the calling subscriber and the called user station is performed upon detecting the stall of the user station. As indicated above, this detection is conventionally provided by the feeding interface 17.

 During the entire duration of a telephone call established following a call from the telephone line LT, the payment devices DP have no action.

 The payment devices DPi.l ... DPn of FIG. 1 may be identical and only one of them, generally designated by DP, will be described with reference to FIG. 4, the line 1 coming from the interface 44 of FIG. 3 ends on the one hand with a supply circuit 45 capable of supplying the voltage or the voltages necessary for the operation of the circuits of the payment device DP from the voltage produced by the remote power supply circuit 25 of FIG. 3 and delivered to the line 1 by the interface 44. The line 1 ends up on the other hand with a microcontroller 46, via an interface 47 of the RS 422 type such as the interface 44 of the selector 1 of Figure 3.In the case where the means of payment used with the payment device DP is a credit card or calling card 48 of the type used in public telephone booths, which is equipped with a chip 49 whose memory stores a number of units account, representing the credit available to the user, the payment device DP includes a card reader 51 which provides the physical link between the card 48 and the microcontroller 46.The card reader 51 may for example comprise a connector type C70210M0082054 of SOCAPEX. The microcontroller 46 may for example consist of an integrated circuit of the EfC68HCll type. During a telephone call initialized by the user of the station P associated with the payment device DP, the microcontroller 46 receives the information and the commands from the selector 1 via the interface 47 and executes a software module stored in its internal programmable fixed memory This software module conventionally provides management, control and writing in the card 48 of the charging information received from the selector 1. The microcontroller 46 also provides the display on the screen of a display 52, for example of the liquid crystal type, help with the progress of the operation and the monitoring of the operation (display of the number of the called subscriber, duration of the telephone call, number of units or credit still available on the calling card, ...).

 The payment device DP furthermore includes a sound alarm 53, for example an acoustic buzzer, whose operation is also managed in a known manner by the microcontroller 46. For example, the latter activates the alarm 53 when the user forgets to withdraw from the reader 51 the call card 48 at the end of a telephone call or when the credit available on the calling card 48 is exhausted, to warn the user that he must replace the calling card whose credit is exhausted by a other valid calling card.

 The software module managing the functions described above of the payment device is quite conventional and can be identical to that used to manage the same functions in a public telephone booth. The microcontroller 46 of the payment device DP and the associated software may be further designed to control the display on the display of the display 52 of a message indicating the state (free or busy) of the telephone line LT when the user station P associated with the payment device DP is not in communication, to warn the user of the station whether or not he can make a phone call.

When a user whose post P is equipped with a payment device DP wishes to generate a phone call, but at this point the telephone line
LT is "busy" (this state being displayed on the screen of the display 52>, the audible alarm 53 of the payment device DP can also be activated to warn this user as soon as the telephone line has become free and a priority call can be given to him for a pre-established time interval to allow him to take the line.

For this purpose, when the user enters his calling card 48 in the reader 51 or when acting on a control (not shown> such as a push button or touch sensitive switch, for example, which can be provided on the box of the device A signal representative of a call request is generated which is connected to the microcontroller 46. This signal is sent to the microcontroller 46 which transmits it to the microcontroller 22 of the selector 1 via the interface 47. line 1 and the interface 44. If the line LT is busy, the processor 22 confirms the line information occupied by the processor 46 which causes the display of a message to take account of the call request on the 52. With the aid of another software module stored in the memory 32 of the selector 1, the microcontroller 22 assigns the call request a priority order number and likewise manages any other requests. of appeal by giving each a number of As soon as the line LT is released, the microcontroller 22 sends the corresponding information to the payment device DP which has issued the highest priority call request Cla priority can be established on a time basis - the first request is the first served - or on a local base linked to the user lines themselves> and the microcontroller 46 of this payment device DP activates its alarm 53 to warn the user that the line LT is free. In a pre-set time interval the microcontroller 22 then waits for the valid payment means information from the microcontroller 46 of the relevant payment device DP and the off-hook status information of the user station P corresponding. If the microcontroller 22 receives these two pieces of information within the pre-established time interval, the jack of the telephone line LT is effected as indicated above. In the opposite case, the microcontroller 22 sends the free line information to the next payment device, that is to say the one that issued the call request having the priority immediately below the highest priority. process described above is repeated with said next payment device, and so on until the microcontroller 22 receives both information (valid payment means and off-hook) relating to a pair of payment device DP- user post P which had been assigned a priority.If, within a pre-established deadline, none of the users corresponding to payment devices or devices to which a priority had been allocated generated a call after the LT line was restored free, the microcontroller 22 is put in a waiting state for receiving a call from the line LT or waiting for a call from any of the payment devices DP <san s priority
Although in the embodiment just described it is planned to remote-power the payment devices DP from the selector 1, it goes without saying that each payment device DP can have its own autonomous source of energy (battery or battery for example) or have its own power supply connected to the mains.

 Each of the user stations P1 ... Pn of FIG. 1 may consist of a telephone handset P of a conventional standard form Cmultifréquence or decimal> connected by a cord 54 to a standard contactor 55, as shown in FIG. The circuits and other components of the payment device DP associated with the user station P can for example be housed in a housing 56 <FIG. 5), one side of which is provided with a slot 57 for the introduction of a calling card 48. in the telephone reader 51. The screen 58 of the display 52 is preferably on the same side of the housing 56 as the slot 57. However, the slot 57 and the screen 58 could be on different faces if The housing 56 of the DP payment device is connected by a cable 59 to a jack socket 61 into which the contactor 55 plugs in as shown in FIG. 5. The male part of the jack socket 61 can itself be plugged into a wall socket A female 62 of standard form, connected by a four-wire cable 63 to the selector 1. The cable 63 contains a section of one of the lines L1. .Lv. and, in the case where a payment device DP is associated with the user station P, also a section of one of the lines lj ... Figures 2 and 3. The cord 54 represents the remaining portion of one of the lines L ... Ln and the cable 59 represents the remaining portion of one of the lines li. 1-.

 Thus, the jack socket 61 provides the connection for the voice signals between the user station P and the selector 1 via the cord 54 and the cable 63 and the connection for the data signals between the payment device DP (box 56). ) and selector switch 1 via cables 59 and 63.

In order to prevent fraud attempts, means may be provided to prevent a direct connection between a standard telephone set, such as the telephone set.
P, and the selector 1. For this purpose, although the female wall socket 62 has a standard shape, for the implementation of the present invention it is preferably wired in a manner different from the standard two-point wiring usually used for to power a standard telephone. In this respect, it will be recalled that standardized wall outlets and contactors usually have six connection points, of which only two predetermined points are used.

 In the case of the present invention, the contactor 55 may be a standardized contactor, while the four son of the cable 63 will be connected to four of the six connection points of the wall outlet 62 in a manner such that at least one of the two predetermined points usually used in a standardized socket, are not used in the present case for the supply of the station P. Under these conditions, the internal wiring of the socket socket 61, between the male and female parts thereof is realized in order to restore the standardized wiring for the contactor 55. In the case where no payment device DP is associated with the user station P, no cable is connected to the jack socket 61 and this one plays the role of any of the plugs B1 .. Bi of Figure 1.

 The diagram of FIG. 6 describes the logical sequence of operations of the device according to the invention.

A general polling loop processes incoming calls, i.e. calls from the telephone line LT is the right branch of the diagram of Figure 6), and outgoing calls, ie say calls from one of the user stations Pl ... Pn (this is the left branch of the diagram of Figure 6). These two branches are exclusive and the priority is for example given to incoming calls as indicated by the test 64.

 On an incoming call (right hand branch), the selector 1 automatically takes the telephone line LT (operation 65) by controlling the looping interface 2. If necessary (in the case of a closed-dial telephone system), a synthetic voice aid is then generated and sent to the calling subscriber <operation 66). The selector 1 then performs the reception and processing of the significant digits of the called user's station address and automatically triggers the ringing (calling) of this station by appropriately controlling the power interface 17 and the switch 34. <operations 67, 68 and 69). When the selector 1 detects the off-hook state of the called user station (result of the test 71), it sets the communication (operation 72>. The selector 1 then goes into a state of waiting for the hang-up of the user station involved (state 73). Meanwhile, the other user stations are informed that the telephone line LT is unavailable by displaying a "busy" message on the screen 58 of the display 52 of all the payment devices DP which are associated with non-communicating user stations When the selector 1 detects the hang-up of the user station which was in communication, it releases the telephone line LT cooperator 74 in the diagram of Figure 6).

An outgoing call is triggered by scanning the DP payment devices when the phone line
LT is free, that is, when the result of test 64 is "no". Each payment device DP is scanned sequentially in a preset order (operation 75 at the top of the left branch of the diagram of Figure 6). The detection of an outgoing call request from a user results from the conjunction, on the one hand, of the presence of a valid means of payment (for example a card> in the card reader 51 of the payment device DP scanned at the moment considered and on the other hand, the off-hook status of the corresponding user station (test 76) When the result of this test is affirmative, the selector 1 automatically takes a telephone line LT (operation 77) The user station is then connected to the general telephone network and the user can dial a number on his telephone to call a subscriber.

The selector receives, processes and transmits the dialing on the telephone line LT (operation 78>. After the telephone communication has been established with the remote subscriber, and during the entire conversation between the user and the remote subscriber, the processor signal 26 of the selector 1 receives the teletaxes information from the telephone line LT and, after appropriate formatting, transmits them, via the microcontroller 22 of the selector 1, to the microcontroller 46 of the payment device DP associated with the The processor 46 manages the charging by decrementing the credit available on the card 48 as and when the receipt of the pulses of teletaxes (operation 79) .Trait the credit is valid and as long as the user station remains off hook <the result of test 81 is "yes"), communication can continue. In the opposite case, a new test is performed (test 82> to determine whether the credit is exhausted If the result of the test 82 is affirmative, the microcontroller 46 of the payment device DP activates the alarm 53 (operation 83> to warn the user that his credit is exhausted, and the selector 1 goes into the waiting state 73 already described If the result of the test 82 is negative, it means that the user station has been hung up and, in Under these conditions, the system goes directly to operation 74 (release of the telephone line LT> .The device is then ready to send or receive a new call.

it goes without saying that the embodiment of the invention which has been described above has been given as a purely indicative and non-limiting example, and that many modifications can be easily made by the man of the art without departing from the scope of the invention. In particular, although the described payment device DP uses a calling card or other credit card as a means of payment, it goes without saying that the payment device could be a device able to receive other payment methods such as coins coins, tokens, etc., as is well known in the case of a public payphone. In addition, although the links described above between the selector 1, on the one hand, and the user stations Pi .. .P and the payment devices DPi + 1 ... DPn, on the other hand, are wired type links carrying electrical signals, it goes without saying that the links in question could be replaced by links of the wireless type or by optical links with or without optical fibers. Furthermore, although the invention has been described in its application to a telephone network, it is obvious that it applies equally well to a network of the ISDN type (network
Digital Integration Service, for example network "umeris").

Claims (7)

 1. Device for automatically sharing at least one telephone line (LT) between several user stations <Pl ... P) having different identification numbers and whose users can be taxed separately, characterized in that at least one of said user stations (Pi + 1 ... Pn) is associated with a respective payment device (DPi + 1 ... DPn) comprising means (46, 51) capable of detecting the presence of a valid payment means (48) in the payment device, and in that it further comprises a selector C1) connected on one side to the telephone line (LT) and on the other side to each payment device (DP1 + 1 ... DPn) and can be connected individually to any one of said user stations (Pl ... P), said selector C1) having a switching matrix (4) adapted to establishing the connection between the telephone line and a user station called or calling from among said user stations (P1 ... Pn), a selector device direct reception (5) to receive a telephone call from the telephone line (LT), determine to which user station this call is intended and accordingly control the switching matrix (4) to establish the link appropriate, a direct selection device at departure (8) comprising means (17) for detecting the off-hook status of any of the user stations (calling user station> and to establish, via the matrix of switching (4), a link between the telephone line (LT) and the calling user station under the dual condition that the off-hook detector means (17) has detected the off-hook status of the calling user station and that the valid means of payment means (46, 51) of the payment device (DP) associated with the calling user station (P) has detected the presence of a valid payment means (48>, and control means and management (22) apt to inhibit the functioning of the direct dialing device (5) and direct dialing device C8) as long as one of the user stations CP ... P) is connected to the telephone line (LT).  2. Device according to claim 1, characterized in that, in the case where there is provided an over-dialing, the selector <1) further comprises a voice aid device C7) adapted to send on the telephone line (LT) a a message requesting a remote subscriber to dial an over-dialing identifying the called user station.  3. Device according to claim 1 or 2, characterized in that the selector (1) comprises a teletaxes counter (6) adapted to receive charging pulses from the telephone line (LT) and transmit them via the control and management means (22), the payment device <DP) associated with a calling user station (P) for the duration of a link established between the calling user station and the telephone line.  4. Device according to claim 3, characterized in that each payment device (DP) comprises control and management means (46) able to verify the credit amount of the payment means (48) introduced by a user in the payment device (XP) and issuing a valid credit signal to the selector (1) when the credit is greater than a predetermined amount, receiving the charging pulses from the selector (1), decrementing said credit amount as soon as the charging pulses are received and, in the event of the credit being exhausted, to issue an exhausted credit signal to the selector.  5. Device according to claim 4, characterized in that each payment device (DP) comprises an alarm (53), which is activated by the control and management means (46) when the credit is exhausted.  6. Device according to claim 4 or 5 wherein the means of payment (48) is a telephone credit card or calling card, and each payment device (DP) comprises a card reader (51>.  7. Device according to any one of claims 1 to 6, characterized in that an anti-fraud plug (Bl ... Bi) is inserted in each line (Ll ... Li) connecting the selector (1) to user stations (Pl ... Pi) to which no payment device is associated.