BE387903A - - Google Patents

Description

       

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    "Arrangement for automatic telephone installations"
The invention relates to automatic telephone systems comprising several exchanges, the subscriber numbers of which fall into a common series of numbers in which different digits for hundreds, miles, etc. are given to the various exchanges depending on the size of the number. 'installation. In installations of this kind, the different exchanges are generally linked to each other by communication lines so that each central can establish communications with each of the other exchanges via a corresponding number of groups of lines. communication therefore linking the various exchanges directly to each other.

   However, for economic reasons, this arrangement of the connection lines is not practical, in particular in rural telephone installations where the various exchanges are very distant from each other, so that the price of the connection lines is not practical. communication can become heavy. This is why we try to reduce as much as possible the number of lines of communication by ensuring

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 the service between exchanges determined in passapt by other exchanges and intermediaries. This arrangement also requires certain modifications to the automatic functioning of the coupling operations, because the selection of the various exchanges can no longer take place in the natural digital order.

   The object of the invention is to create a system for the service between different exchanges of an installation of the type described and it relates in particular to telephone systems in which conversational communications between different exchanges are established under the control of devices. that we will call recorders.



   The invention is essentially characterized by the fact that the recorder monitoring the coupling operations is aotionned, in the event of a call from another exchange passing through one or more intermediate exchanges, so as to repeat the control pulses used for select the different central offices, while the communication between one central and the other is successively transmitted by the intermediary of steering selector switches mounted to the intermediate exchanges and placed in position under the control of the - manager of the calling center.



   The direction selectors are mounted so as to be able to pass the communication selectively partly to one or more other exchanges and partly to the automatic telephone switch of their own exchange, the recorder being actuated in the first case so as to repeat the control pulses corresponding to the number of the desired exchange, and in the last case so as to monitor the positioning of the selector switches in the automatic telephone switch in accordance with the number of the desired subscriber.



   In the accompanying drawings:
Fig. 1 is a basic diagram showing the most essential parts of a telephone installation

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 in accordance with the invention and comprising the three automatic exchanges A, B, C and a manual central D,
Fig. 2 represents two pulse receivers TR1 and TR2 of the transit recorder TM forming part of the central A and ensuring the transit service,
Fig. 3 represents two pulse receivers RE1 and RE2 of the location recorders M forming part of the central A,
Figs. 4 and 5 represent analog pulse receivers TR1 and TR2, RE1 and RE2 of the transit recorder TM forming part of the central B or of the tracking recorder M 'forming part of the same central,
Figs.

   6 and 7 represent pulse receivers analogous to central C, this central C being also supposed to include a transit group, which however is not necessary in the installation shown in FIG. 1 (This group is omitted in Fig. 1, but if necessary it can also be mounted in central C as in the other central units),
Fig. 8 to 13 are individual circuit diagrams showing the establishment of telephone communications within an exchange as well as between one and another:

   
Fig. 8 shows the transit group of central A with its researchers TS, TV, the recorder TM and researchers IFV, IFS and UFS, UFV who provide the service coming from another central or leaving to another central,
Fig. 9 shows researchers AS, SV, SS and LV forming part of the automatic telephone switch looal of central A, as well as their set of MRS tracking relays,
Fig. 10 shows an M location recorder and its IM pulse repeater device,
Figs. 11, 12, 13 show corresponding arrangements at central B.



   Fig. 1 shows in principle the nature of the

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 automatic coupling of automatic connection exchanges, as well as the way in which these devices must cooperate with each other. A local communication is therefore established between two subscriber stations P1 and P2 via two pairs of selectors AS, SV and SS, LV with their ooidons SL1, SL2 and a communication line FL. In the example shown, it is assumed that all the selectors are non-digital selectors.

   The AS selector therefore serves as a call selector, while the SV selector searches for a free communication line FL, after which the establishment of communication is terminated by the fact that the SS selector is connected to the same communication line, while LV branches to the line of the desired subscriber. In the system described above, the communications are established under the control of location recorders M, the location recorder positioned in a known manner by pulses from the calling subscriber F. firstly taking up the position in a determined manner. line of the desired subscriber, after which the subscriber line thus identified is sought by the selector LV.



   For the establishment of communication between subscribers belonging to different exchanges, each automatic branching exchange comprises two groups of selectors UFS, UFV, and IFV, IFS formed by researchers and the first of which serves for the service starting from the exchange. and the other for the service arriving at the central. The selectors of these two groups are also linked two by two to each other by cords SL4 and SL3 and the selectors UFS and IFS are used to look for a communication line FL in the local telephone switch, and the selector UFV and IFV are used to establish a communication with a line BL communication link which links the corresponding exchanges.

   In the example shown, the communication lines are mounted in multiple on the UFV selectors as well as on the IFV selectors when they are used to provide service in both directions.

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   Fig. 1 shows, by way of example, the way in which communications are established between automatic telephone exchanges A, B, C and a manual central office D via communication lines AL, RL CL and DL.



  Trafio can take place in both directions on lines BL and CL, while lines AL and DL carry traffic only in one direction. In the example shown, the capacity of the installation is one thousand subscribers with the numbers 1000-1999, the central A being reserved for the numbers 1100-1299, the central B for the numbers 1300-1499, the eentral C for the numbers 1500-1599 and the central D at numbers 1000-1099. The different exchanges therefore differ from each other by the first two digits of the subscriber numbers. It is obvious that the capacity of the installation can be increased up to 10,000 subscribers without resulting in any changes in principle to the system; the invention is independent of the size of the installation.



   As far as the arrangement of the communication lines is concerned, the various exchanges are mounted in a series, the communications between the exchanges A and C for example having to be established by the intermediate central B, while a communication between C and D must be established by the intermediary of B and A. According to the invention, it is a question of allowing the establishment of these communications by one or more intermediate exchanges, without it being necessary to have return to devices mounted in these intermediate exchanges for local service.

   For this purpose all the exchanges used for the transit traffic have a special selector group which will be called hereafter the transit group, and by means of which the transit communications can be established directly so that the terminating communication line is directly connected by this group to an outgoing communication line going to another exchange. This transit group is similar in all exchanges and it contains at exchange A a certain number of se- -5-

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 readers serving as researchers, designated by TS. TV and interconnected two by two by cords SL5.

   These cords include direction selectors TM serving to receive pulses emitted by the repetition of the pulses from the registration recorder M at the central station of the calling subscriber. These selectors monitor the progress of the connections so that the communication is forwarded to another control or to the corresponding looal automatic telephone switch, depending on whether the desired subscriber belongs to another central office or to the exchange where the group is located. transit. In the first case the incoming communication line, for example BL, is connected by the selectors TS 'and TV' of the transit group to one of the communication lines leaving in the desired direction, for example CL, without we have returned for this to any part of the automatic telephone switch looal of central B.

   In the second case the incoming communication line BL is connected to a communication line FL 'through the group of input selectors IFV', IFS of exchange B, after which the transit group is released and communication terminated by means of the devices / automatic telephone switch looal ends for a looal call.



   A local communication to central A is established as follows. When a subscriber P1 calls his line is linked to a cord SL1 through a call searcher AS and the communication is transmitted through the corresponding searcher SV to a communication line FL whose M mark recorder is free. The subscriber then transmits all the pulses corresponding to the number of the desired subscriber, pulses which are received by the tracking recorder M. This recorder then marks the desired subscriber line and simultaneously activates a connected LV selector. to a free cord SL2. This selector establishes communication with the requested subscriber line.

   The communication is completely established by the fact that the searcher SS connects the cable sl2 to l2 2

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 to the corresponding communication line FL. The location recorder M is now free and can be used for establishing another call.



   To establish a communication between a calling subscriber P1 of central A and a subscriber P2 of central B, the calling subscriber only needs to activate his pulse transmitter as previously, in accordance with the number of the requested subscriber; the pulses thus transmitted are received previously by the location recorder M. However, as the pulses indicate in this case that the call is intended for another exchange, the UFS selector of the outgoing selector group, then the corresponding selector UFV are first activated, so that the communication is transmitted to the central B by an SL4 cord and a BL communication line.

   This line BL is directly connected by a call seeker TS 'of the central transit group B to a cord SL5' and to the corresponding recording device TM '. The latter now sends back two impulses via communication line BL to the IM impulse repeater of central A, which is thus activated and which again emits the impulses corresponding to the first two digits of the telephone number. the subscriber, pulses which are received and recorded by TM '.

   As the call is in this case intended for a subscriber of the exchange B, the recording device TM 'causes a switching of the conversation communication which is transmitted through a pair of selectors IFV', IFS , from the group of arrival selectors to a free communication line FL 'of the exchange' B, after which the parts of the transit group used until then are released and ready to receive other calls.

   When communication is obtained with a location recorder M at central B, this recorder emits a single impulse received by the repeater IM of central A and which has the effect that this repeater now emits the corresponding impulses.

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 to the last three digits of the subscriber's number, pulses which are received as usual in the location recorder M 'of the central B. Then the location recorder M and the corresponding pulse repeater IM of the central A are released and the communication is established completely through a pair of selectors SS 'and LV' at exchange B as for a call from a subscriber of this exchange.



   If the calling subscriber P1 of exchange A wishes to obtain a communication with a subscriber P2 '' of exchange C, the communication is first transmitted to exchange B in the manner described, the communication line BL being connected as previously by the 'intermediary of a call finder TS' to an SL5 cord 'and to the corresponding direction selector TM'. The latter sends back two pulses as before to the pulse repeater IM, which repeats the pulses corresponding to the first two digits of the subscriber number.

   When TM 'has received these pulses at central B, the corresponding seeker TV' is iris in position so that the communication is transmitted to central C through this finder and a communication line CL . The communication line CL is connected directly by the intermediary of a pair of selectors IFV ", IFS" of the group of outgoing selectors of the exchange C to a free communication line FL "and, by the intermediary of this one. , to a location recorder M 'which now sends a pulse to the repeater IM of central A, which has the effect of causing a return transmission of the pulses corresponding to the last three digits of the subscriber's number, pulses which are thus received by the location recorder M "of the central C.

   The location recorder M and its repeater IM are then released to the central A and communication is completely established by means of a pair of selectors SS ". LV" of the central C as for a local call.



   In the example shown, the central C is not intended
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 to transmit a transi ± traffic and it does not have any con- Q.

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 sequent no "transit group".



   If a subscriber P1 "of the central C wishes a communication with a subscriber at the manual exchange D, the communication is set up as follows via the transit groups of the central B and A. The subscriber directly receives the communication with the central station. .communication line FL "and with a corresponding tracking recorder M" after which it transmits the pulses o corresponding to the subscriber number, pulses which are received by the recorder M "The communication is then transmitted to the exchange B by the 'intermediary of a pair of UFS ", UFV" selector switches and a CL communication line which is connected directly to a direction selector TM' of the transit group of the centralB by means of an oher- oheur call TS '.

   The direction selector TM 'sends two impulses to the repeater TM' 'of the central C which repeats the impulses corresponding to the first two digits of the subscriber number. As a result, communication is transmitted to central A through the TV finder 'of central B and a connection line BL which is / connected directly through a call finder TS to a direction selector. TM of the central transit group A.

   TM sends two impulses to the repeater IM "of central C which repeats once more the impulses corresponding to the first two digits of the station number, impulses which are now received by TM, the communication being transmitted to central D, via d A communication line AL and the researcher TV. The manual exchange D now sends a single impulse to the receiver TM "of the central C, after which the impulses corresponding to the last three digits of the subscriber's number are sent back to D where they are received by a number indicator. Communication is then established completely by hand using the jaok IJ.

   It may sometimes happen that the manual central may be

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 called only by means of the first two digits, that is to say the number 10, the impulse emitted by D causing it while the deactivation of the location recorder M "of the central C, after which the subscriber indicates to the operator of the central 'D the number of the subscriber he wants.



   The manual exchange can be connected to any subscriber or automatic exchanges via a DL communication line which terminates at central A on a finder IV through which communication can be obtained with a FL communication line. By means of an impulse transmitter connected to the jaok UJ the operator can then establish a communication whatever like a subscriber of Central A.



   From what has just been said, the transmission of communication in one direction or the other is supervised by the location recorder and the dialing selectors in accordance with the first two digits of the station number. subscribed. Figs. 2 to 7 show how the pulse receivers of track recorders and direction selectors are constructed and arranged for this purpose. The direction selector pulse receivers are constituted by two selectors TR1, TR2 (Fig. 2), powered by two electromagnets TRM1, TRM2 so that the contact arms move forward one step each time the The armature of the drive magnet drops out.

   The contact arms not shown connect in an oonnu manner in each contact position, contacts which face each other in the corresponding row of contacts. Each pulse receiver has several contact arms and a corresponding number of rows of switches each constituted by a continuous contact bar and several individual contacts corresponding to the different contact positions. The first row of contacts of each pulse receiver is used to determine the direction in which the communication is to be transmitted.

   AT

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 For this purpose, these rows monitor on the one hand the circuit of a relay B1 which comes into action when the call concerns a central subscriber of which the corresponding transit group belongs and on the other hand two tracking circuits H, V for the TV seeker of the transit group, one or the other of these circuits coming into action when the call concerns a subscriber of another exchange. Continuous communication can be transmitted in two different directions, in the example shown, by the TV finder, either to the right or to the left in FIG. 1, for example from central B to central C when the call comes from A, or from central A when the call comes from C.

   A transit call can also be transmitted to A and D when the call comes from B, or even to B when the call comes from another exchange not shown in FIG. 1. In order to monitor the movement of the TV seeker, so that the latter searches for a free communication line only in the group of lines going in the desired direction, corresponding test paths HV pass through two corresponding groups of DG and BG contacts in the TV finder. In accordance with the distribution, indicated above and in Fig.



  1, of the numbers on the subscriber lines forming part of the various exchanges, the group of contacts BG, (Fig. 2) which corresponds to the communication lines BL going to the stations B is connected to the third, fourth and fifth contacts of the receiver of pulses TR, contacts which correspond to the digits of the hundreds 3, 4, 5 of the row of numbers, while the group of contacts DG, which corresponds to the communication lines going to the central D is connected to the tenth contact of the pulse receiver TR2. contact that corresponds to the hundreds digit zero of the row of numbers.

   Relay B1, which must only be actuated for a call from a subscriber of exchange A, is connected in accordance with the above to the first and second contact of the

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 pulse receiver TR2, oontaots which correspond to the hundreds digits 1 and 2 of the row of contacts.



   In conjunction with the above the contact group CG of the TV finder '(Fig. 4) corresponding to the number 5 of the hundreds is connected to the fifth contact of TR @. while the group of oontaots AG corresponding to the hundreds digits 1, 2 and 0 is connected to the first, second and tenth contact of TR2 '. The relay BI ', which must be actuated to call a subscriber within the central B, is connected, in accordance with the above, to the third and fourth contact of TR2.



   When the exchange C has a transit group, the corresponding pulse receivers TR1 "and TR211 can be arranged according to the system indicated above, as shown in Fig. 6.



     Figs. 3, 5 and 7 represent the pulse receivers corresponding to the location recorders of the various exchanges and recording the first and second digits of the subscriber numbers. The purpose of these pulse receivers is to determine the direction in which the communication of a communication line, FL, FL 'or FL "is to be transmitted; in this connection there are also three different possibilities at the exchanges A and B, communication with a subscriber of the same central through the intermediary of selectors SS, LV or SS 'LV' or with a subscriber of one or the other of two other exchanges through the intermediary of UFS, UFV selectors or UFS ', UFV'.

   In the first case, a relay Rl comes into action and its circuit passes, so as to correspond to the distribution chosen for the numbers in FIG. 3, by a contact from the first contact position of the pulse receiver RE2. In the other two cases, the UFV or UFV searcher must be able to search for a free communication line in two groups of communication lines starting in directions

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 different. It is therefore necessary that the UFV searcher of central A can selectively establish a communication with a communication line BL or a communication line AL, and that the UFV searcher of central B can establish a communication with a communication line. CL or a BL communication line.

   For this purpose, the test circuits of these researchers are monitored by means of corresponding relays UFR1 UFR2 or UFR1, UFR2, the circuits of which are monitored on their side by the pulse receivers RE2. RE2 '. As can be seen from FIG. 3, the UFR1 relay is connected, in accordance with the distribution chosen for the numbers to the third, fourth and fifth oontaots of the pulse receiver, which corresponds to the digits of HUNDREDS 3, 4 and 5 of the numbers of subscribers, while the UFR2 relay is linked to the tenth contact, which corresponds to the hundred digit 0.

   Correspondingly, the relay RI '(Fig. 5) is connected to contacts of the third and the fourth position of the pulse receiver RE2 while the relay UFR1 is connected to a contact of the fifth row of. contaots and the UFR2 relay to oontaats of the first, second and tenth rows of oontaots.



   From the central 'C, communications can only be established in one direction, through the CL communication lines to the central B, A and D. Consequently this central does not include, in addition to the RI relay ", which is activated for a call from a subscriber of central C, than a UFR2" relay which is activated for a call from another exchange. It follows directly from Fig. 2 where the circuits of these relays are to be monitored by the pulse receivers for the distribution or selected for the numbers in this case.



   It will be assumed that the selectors AS, SV, SS, LV, IV, IFV, IFS, UFS, UFV, TS, TV and the corresponding selectors of the other central units are rotary selectors whose control arms.

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 contact always turn in the same direction and that they do not lead to a determined normal position, but instead they remain in the position that they do when the communication is cut off and they are resumed. walk from this last position each time they come into action again. The selectors may be of the same type as the pulse receivers described above and forming part of the track recorders and transit groups.



   Each location recorder contains four pulse repeaters which, at the central A, are designated by RE1, RE2 RE, RE4, and a follower switch SO1 by which the different series of pulses are distributed over the various pulse re- ceptors . The pulse receiver TR1, TR2 of the transit group is monitored in a similar fashion by a follower switch SO3 To each tracking recorder M is added a repeater of IM pulses consisting of a repeater RE5, a follower switch SO2 and the oor relays - respondents (Fig. 9). All the follower switches SO1, SO2, S03 as well as the pulse repeater RE5 are in general of the same type as the pulse receivers described above.

   The circuits by which the desired subscriber lines are logged are monitored from the location registers in a known fashion by means of a set of MRS tracking relays (Fig. 9) which contains a number of relays. of hundreds LH and a certain number of relays of tens LT
To explain the operation with the help of Fig. 9 to 13 it will first be assumed that a subscriber connected to the exchange A wishes to obtain a call with another subscriber (FIG. 9) connected to the same exchange. When the calling subscriber picks up his apparatus, he closes a circuit 1 passing through his line 11, by the coil LL1, of the corresponding line relay LR1 and nn starting relay LG common to a group of subscribers.

   Line relay LRis a combined call and cut-off relay and in this -14-

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 which oonates its construction o is what is called a stepped or two-step relay, the armature of which can be placed in position by currents of different intensities in two different positions in which they act on two different groups of contacts. By the current of. cir- cuit 1 the line relay draws its armature to the first position, which has the effect of preparing a test circuit for the AS call seekers. Simultaneously, the LG relay draws its armature and the IA relay closes a starting circuit 2 on all free call seekers AS of the corresponding subscriber group.

   For its part, relay IA closes a pulse circuit 3 for the corresponding drive magnet ASM. The call seeker who first meets the line of the calling subscriber is stopped by the fact that a test circuit 4 is closed on a test relay IT. which attracts its armature and cuts the drive circuit 3. At the same time, this relay short-circuits part of its winding, which indicates that the line of the corresponding subscriber is cut off and can no longer be cut by the other researchers. call. The relay IT1 also closes a pulse circuit 5 through the drive magnet SVM for the finder SV of the lead lead, which finder is thus started to search for a free communication line FL.

   The call finder test circuit also contains an LL2 winding of the LR1 line relay which, when test circuit 4 is closed draws its armature to the second position, the circuit passing through; the LL1 winding and the relay LG boot being cut. The line relay, however, keeps its armature attracted. The line circuit is now closed by circuit 6 which contains the relay IA. When the searcher SV encounters an FL communication line comprising a free location recorder M, ur. test circuit 7 is closed via the pulse receiver RE1 of the recorder in the first

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 first position.

   The IT2 test relay attracts its armature and the FL communication line is occupied by the fact that the IT2 test relay oorouites part of its winding.



  The circuit)? contains an ST relay which now attracts its
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 frame and connects the recorder to the oanmunioation line.



  Relay I'I'2 switches relay IA off, the line oirouitide being now closed by an ir.upulsion relay:?,. this the recorder and through contacts 8 and 9 of the ST relay. The RA relay now attracts its armature and puts in it a delay RHl rel3.iSr which on its own closes an oirouit0 for a relay RH2 and a buzzer 11 starting from a current source SU1 and passing through the oom- SO1 follower mutator in its first position. The buzzer current passes through a SUL winding of the remake RA and
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 resulting in an alternating current in the line eireuit, which has the effect of warning the subscriber that the line is now connected to a recorder and that the transmission of
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 pulses can oonmenoer.

   There is simultaneous switching of the test circuit 7 which is now connected to the relay RH1 by a contact 12.



   The first interruption of the line circuit produced. by the emission of the pulses cuts off the excitation of the pulse relay RA, a circuit 13 being closed by a delay relay RV. In addition, a circuit 14 is closed for
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 maneuver mantle REMi of the impulSion4REl receiver and oet magnet attracts its armature without however moving the contact arms forward. A circuit 15 is also closed for the operating magnet SOM1 of the follower switch SO1, a magnet which also attracts its armature without moving the contact arms forward. As soon as the pulse relay RA attracts its armature again after the first interruption in the line circuit, the circuit 14 of the operating magnet REM1 is switched off, while the relay RV maintains its armature attracted.

   The

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 contact arm of the RE1 pulse sensor then advance by one step. Subsequent interruptions of the current in the line circuit cause the contact arms of the pulse receiver RE to advance by one step, in a similar fashion, which comes to occupy a position corresponding to the number of pulses emitted. When the first series of pulses is completed, the relay RV oess to be energized, the circuit 15 is cut and the follower switch So1 is brought to the second position. In this position, the operating magnet REM2 of the pulse receiver RE2 is inserted into the circuit 14. The following series of pulses is therefore received and recorded by RE2.

   Pulse receivers RE3 and RE4 similarly register the third and fourth Series of pulses. It will be assumed that the recorder's pulse receivers have been set to correspond to a called subscriber number 1101. The pulse receivers RE1 RE3. and RE4 are then in their first numerical adjustment positions from the normal position (completely to the left in the drawing), while RE2 is in its position.



   Immediately after the transmission of the first two series of pulses, a circuit 16 is closed by means of the pulse repeaters RE1 and RE2 by a relay RI which determines that the call concerns a subscriber of the same exchange. The relay RI attracts its armature and prepares a circuit 17 which is closed by means of a contact of the follower switch SO1 in its fifth position, which the follower switch SO1 reaches when all four series of pulses have been emitted. . Circuit 17 contains a relay RG1 which now attracts its armature and remains energized on its contact 18.



  In addition, the RG1 relay closes a circuit 19 by the Oentaines LH1 relay which for its part closes a circuit 20 by the LTO tens relay, the latter now closing a circuit.

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 fired marking and test 21 on a resistance W2. This circuit, which is used to test the line of the subscriber requested and requested to locate this line, is only closed if the requested subscriber is free. Circuit 21 contains an RL relay which now attracts its armature. In the meantime, the idle magnet SOM1 of the follower switch SO1 has been inserted into a pulse circuit 22, which causes the follower switch SO1 to advance step by step. If the subscriber is free, this movement is interrupted as soon as the relay RL is energized, SO stopping in an intermediate position.

   The relay SL also closes a circuit 23 on a delay relay US forming part of a pair of free selectors SS, LV, this relay now drawing its armature and for its part closing a pulse circuit 24 for the magnet LVM. LV line selector drive. If LV meets the subscriber line identified by circuit 21, a test channel 25 is closed and RL receives current through this circuit parallel to the current of circuit 21 through resistor W2. The test relay ut1 contained in the circuit attracts its armature, which has the effect of stopping the line selector. Simultaneously a pulse circuit 26 is closed for the drive magnet SSM of the seeker SS connected to the same lead, which causes this seeker to start up.



  When it encounters the FL communication line identified in the recorder by the relay RG1, a test circuit 27 is closed by the relays SDR and UT2. The TT2 relay attracts its armature and stops the finder: The starting cirouit 23 ect cut at the same time.



   When the US relay drops its armature after a while, the start circuit is switched so that a next call acts on the next pair of SS, IV switches and its cord. In fact, following the energization of the test relay UT2, the switching on relay US is switched off and on the other hand the cirouitde

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 start-up 23 is extended until the start relay of the next bead and its pair of selectors U2, U3.



  To prevent the researcher connected to this lead from being set in motion by the same call, the US relay operates slowly, so that circuit 23 remains interroided; then on this relay until the switch-on 23 has been definitively interrupted in the recorder (e.g.
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 the separatiorjantre the recorder and the ooirgmnioation line). If all the oordons are occupied, the circuit 23 is on the contrary closed by a relay RU and 11 abcmn1 ', "()' oi a buzzer signal produced by the current source SU2.



  In addition a circuit 28 is closed by the inteùn41.iair = of the third conductor and of the line relay LR2 of the called subscriber, relay which draws its armature directly to the second position. Finally the communication is final-
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 ment established through contacts 29., 30 on relay UT2.



   When the test circuit 27 closes, the SBR relay has also drawn its armature and closed a circuit 31 via a delay relay SHA which on its side closes a holding circuit for the BRR relay by
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 1internal contact 32. It occurs simultaneously tà. an OOmnl.l..i, j "f1 of line circuit 7, which must now pass through a resistor W3. The current is interrupted by the connection relay ST, which causes the recorder to is switched off. The microphone circuit of the calling subscriber is now closed by
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 the intermediary of the contacts 33, 34 and of the windings of a relay SA. The SHA relay now remains crossed by the current via a contact 35 of the SA relay.
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  When the connection relay ST has let its armature drop, the relays RA, E, Hl and RI have successively ceased to be energized. The RH relay fires booster circuits 36, 37, 38, 39 and 40 for the pulse receivers.

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 sions RE1, RE, RE3 and RE4, which are returned to their normal position.

   The recall pulses actuate a delay relay RE which cuts a contact 41 in the test circuit 7, which causes that a new connection through the intermediary of a communication line FL connected to the recorder. cannot take place until the recorder has been returned to its normal position. It will be understood that the other relays of the recorder, as well as the relays of the MRS cue relay group, now cease to be energized.



  Circuit 23 is cut at RG1 in the recorder before the delay relay US has had time to drop its armature, which prevents the LV and SS selectors of another transmission cord from being actuated.



   The called subscriber ap is called as follows. The BBR relay closes a circuit 42 passing through a calling device PW by which a periodic alternating current is sent to the circuit 43 and to the line L2 of the called subscriber. Circuit 43 contains a winding AL of a delay relay STR which, however, is not actuated by the inrush current. If the called subscriber answers, the line circuit is closed by the subscriber's apparatus so that the relay STR attracts its armature, the calling apparatus PW being switched off and the relay STR switching on first. its winding RL in a holding cirouit 44. At the same time a relay SB is put in the line circuit of the connector called STR relay xel receiving holding current through contact 45.

   The conversation communication is thus established.



   When the calling subscriber first hangs up his device at the end of the conversation, the SA relay stops being energized, it cuts the SHA relay circuit at 35 and, on the other hand, switches the SHB relay on via the intermediate of oon- taot 46. Circuits 7 and 4 are oouped and line relay LR1 ceases to be energized. Subscriber line l1 is

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 thus separated from the call and the subscriber can call again. The called subscriber remains connected to the FL communication line until he has hung up his device. The SB relay lets its armature drop and thus cuts off the excitation of the SHB, STR, SBR, UT2, UT1 and LR2 relays.

   If, on the contrary, it is the called subscriber who first hangs up his device, SB stops energizing, but STR and SBR continue to receive on-hold current through SHA contact 32. In this case, the communication therefore remains maintained until the calling subscriber has also hung up his device.



   If the called subscriber is cut, the circuit 21 cannot / be closed, as seen above, and the relay RL therefore remains idle. The follower switch SO1 therefore continues its movement until its last position in which the relay RU receives current via a circuit 47. This relay then attracts its armature, remains energized by 48 and 49 and closes a buzzer circuit 50 supplied by a current source SU2 via the winding SUL of the relay RA. Relay RU cuts circuit 17 of relay RG! which thus ceases to be excited and which in turn cuts the circuits of the marking relays of the MRS group of marking relays.

   The buzzer announces to the calling subscriber that the called subscriber is busy. When he hangs up his device, the RA relay ceases to be energized, communication is cut off and the recorder is returned to its normal position.



   It will now be assumed that a subscriber of central A wishes to obtain a communication with a subscriber connected to central B, for example with the number 1351. The calling subscriber sends current pulses corresponding to this number. The connection with the recorder still takes place in the manner described above, as well as the positioning of the recorder by the first two series of pulses, ie the pulse receivers RE1. and RE2 are brought together

 <Desc / Clms Page number 22>

 the first and the other in the third position: In this case the RI relay is not activated. This has the consequence that the call is transmitted to exchange B, as will be seen later.



     After the emission of the second series of pulses, the follower switch SO1 goes to the third position in which a circuit 51 monitored by the relay RI is closed by the relay RG which attracts its armature and goes into a maintenance circuit. by its contact 52. At the same time the communication line FL is identified as being the calling line in the UFS call seekers (Fig. 8), of the group of outgoing selectors, RG2 connecting by its contact 53 the pole negative from the battery to the test contact of the communication line in the UFS call finder.

   In addition, the RE2 relay marks the direction of the outgoing call by closing a circuit 54 per UFR1 relay run (Fig. 8), which has the effect that the UFV searcher only seeks a communication with the communication lines BL going to the central B. The third and fourth series of pulses which follow bring the pulse receivers RE3 and RE4 one to the fifth and the other to the first position as de- written above.



   When the UFR1 relay (Fig. 8) attracts its cancellation, an arming circuit 55 is FURMED for all the free UFS seekers. This circuit contains a UFA relay which attracts its armature and closes a circuit 56 for a UFH time delay relay which in turn closes a pulse circuit 57 for the call seeker drive magnet USM. The first call finder that encounters the communication line marked FL closes a test circuit 58 and a UFTI test relay mounted in that circuit draws its armature and turns off the selector. The test circuit still contains an SFR relay, (Fig. 9) which also attracts its armature, which.

 <Desc / Clms Page number 23>

 however, currently has no effect.

   Relay
UFT also closes the drive circuit 59 of the UVM researcher drive magnet UFV and simultaneously prepares for this magnet a test circuit 60 which is closed as soon as UFV encounters a free communication line EL leaving. in the direction determined by UFR1. When the corresponding test relay UFT2 consequently attracts its armature, the start circuit 55 is cut and on the other hand the circuit 61 passing through the UFA relay and an MT relay (Fig. 10) is cut in the repeater 1M. , The xxxxxx MP relay attracts its armature and locks using cir- cuit 62.

   It simultaneously cuts off circuit 51 of the relay
RG2, which ceases to be excited and cuts the circuit 54 of the UFR1 relay (FIG. 8), the circuit 60 also being cut. The UFT2 relay (Fig. 8) nevertheless continues to receive current through its contact 63. When RG2 (Fig. 9) lets its armature drop, circuit 58 is cut by contact 53, but the test circuit nevertheless remains closed by via a contact 64 of the SFR relay. The test circuit 60 (Fig. 8) contains an FBR cut-off relay which has drawn its armature and thus switched off the line relay FLR of the communication line BL. Communication is thus established completely up to central B.



   When the UFT test relay attracted its armature, a line circuit 65 was closed by the communication line BL. Line 65 also contains a line relay FLR ', (Fig. 11) forming part of the transit group of exchange B, this relay now drawing its armature and thus masking the communication line BL as being the calling line. . The FLR relay 'therefore closes a starting circuit 66 for all free call seekers TS' and at the same time prepares a test circuit by closing its contact 67.

   Circuit 66 contains a start relay TA 'which now attracts its armature and switches on

 <Desc / Clms Page number 24>

 for its part, by its contact 68, a delay relay TH which closes a pulse circuit 69 for the magnet TSM 'for driving the call seeker. The call finder TS 'which first meets the communication line BL closes a touch circuit 70 containing a test relay TT! which attracts its frame and stops the call seeker. This test circuit contains a relay FBR 'which draws its ammature and switches off the line relay FLR'. On the other hand, the relay TA 'is introduced into the line circuit by a circuit 71.

   When the test relay TT1a attracted its armature, a pulse circuit 72 was closed by the follower switch drive magnet SOM3 SO3. The follower switch was thus brought to the second position in which the drive magnet again receives current through a pulse circuit 73 so that the follower switch is moved to the fifth position in which it remains temporarily stopped.

   On passing through the second and fourth position, two pulses have 0té xxxx emitted successively and in series by a circuit 74 and by a return pulse relay BSR 'which reverses the direction of the current in the line circuit 65, 71, which has the effect of exciting at the central A (Fig. 8), a polarized relay UFP mounted in this circuit, so that the relay attracts its armature twice. As a result, two pulses are erected in a circuit 75 which goes up to repetition of pulses IM, (Fig. 10); this circuit, which passes through the follower switch SO2 (Fig. 10) in the first position, comprises a connection passing through a delay relay MK and through the operating magnet SOM2 of the switch around.



  These pulses advance the follower switch S02 two steps to the third position. When the relay MK lets its armature drop after the emission of the second pulse, a circuit 76 is closed on a relay MS which attracts its armature and closes a circuit 77 passing through the REM5 file.

 <Desc / Clms Page number 25>

 drive of the pulse repeater RE5. However, the REMS drive magnet remains inactive in this circuit, while a relay MR1 mounted in the same circuit fires its armature and switches on a relay via its contact 58
 EMI25.1
 kIR2 which oourt-cirouite the 1-wire relay by attracting its frame.

   Consequently the maneuvering magnet 2'11L to draw #, z <, 1 = t eiànt its armature, without however advancing the contact arms of the pulse repeater. It was only when the relay
 EMI25.2
 iliR2 ceases to be axoited, because the PdRl relay drops its armature, the REMS drive magnet ceases to be energized and switches the pulse repeater RE5 through
 EMI25.3
 at its first numeric position of r, laJe. At the same time, the circuit 61 monitored by the relay Mu 2 is cut once.



  This interruption of the short circuit is stopped by the UFA relay (Fig. 8) and transmitted to the TA "relay (Fig. II), of the central transit group. Consequently, 10 if the relay at TA 'lets its armature drop. , a pulse is sent in
 EMI25.4
 the circuit 79 and the switch .suiveur S05 'in the fifth position by the magnet TR' 1 of entrainei: rent t - receiver of pulses TR1 'which advances by one step.



   Due to the interplay between MR1 relays and
 EMI25.5
 kIR2 of the pulse repeater (Fig. 10) the ir-pulse repeater RE5 will advance in steps, as can be seen directly) at each step a pulse is sent to the transit group as described. , which makes the TR pulse receiver! of the transit group is msi in position to the oadenoe of the pulse repeater RE6, until the repeater RES reaches the contact position corresponding to the setting position of the pulse receiver RE5. In the assumed case, RE1 has been brought to the first position; consequently, the pulse repeater RE5 was also only brought to its first position.

   The pulse receiver TR1 of the transit group is therefore now also dars

 <Desc / Clms Page number 26>

 its first digital position. In those RE positions! and RE5 a circuit 80 passing through an MT relay is closed; this relay attracts its armature and cuts the circuit 77, which has the effect of stopping RE5 and stopping the emission of the pulses. At the same time, a circuit 81 passing through the magnet SOM2 driving the follower switch SO2 is closed; the magnet attracts its armature without however advancing the follower switch. In addition, a MV Delay relay is switched on through contact 82 and cuts off circuit 80 and therefore also circuit 81.

   As a result the follower switch now advances to the fourth position in which the MS relay is traversed by current as before. Relay MV, which is kept energized by a contact of RE5 now puts the REMS drive magnet in a pulse circuit 83, which has the effect of returning RE5 to its nominal position.



  In the normal position of the pulse repeater, the MV relay holding circuit is cut off; cerelais lets its armature fall and closes circuit 77 with REM5 and MR1.



   At this moment, the described coupling operations are repeated, ie the pulse repeater RE5 again advances step by step under the reciprocal action of the relays MR1 and MR2. pulses being sent simultaneously to the transit group (Fig. 11).

   After the emission of the first series of pulses during which the delay relay TR '(Fig. II) has attracted its armature and consequently kept a circuit 85 closed by the operating magnet of the follower switch S03 'relay TK has dropped its armature, which causes follower switch SO3' to occupy the sixth position in which pulse receiver TR2 is on and ready to receive the pulses of the second xxxxx series. The second set of pulses will therefore now put the pulse receiver

 <Desc / Clms Page number 27>

 TR2 'in position.

   In this case the number of pulses sent to TR2'ast determined by the position that the pulse receiver RE2 occupies in the registration recorder M (Fig. 10); the MT relay now receives current via a circuit 84 corresponding to circuit 80 and now closes via contacts of RE @ and in their third position. After the emission of these pulses the follower switch SO2 goes to its fifth position, while the pulse repeater is returned to its normal position in the manner previously described. When TK '(Fig. 11) lets its armature drop, the tracking switch SO3 of the transit group also goes to its seventh position.



   The coupling operations can take place in two ways, depending on whether the call concerns a subscriber of exchange B or a subscriber of exchange C. In the assumed case the subscriber of exchange A has called the subscriber with number 1351 and connected central B. Accordingly, the pulse receptors TR1 and TR2 'of the central transit group B were brought to the first and the other to the third contact position. These two pulse receivers will therefore now monitor the pairing operations so that the communication is established completely inside exchange B in much the same way as if the call originated from a subscriber of exchange B.

   The communication line BL will therefore be linked, via the group of selectors IFV 'and IFS' (Fig. 11), to a communication line FL '(Fig. 12) inside the central B and to a tracking recorder M '(Fig. 13) which is then put into position by a transmission of pulses from the location recorder M of exchange A according to the number of the requested subscriber, after which the communication is completely established. via a pair of SS 'and LV' selectors. The ocuplage operations are as follows.



   When SO2 (Fig. 11) reaches the seventh position,

 <Desc / Clms Page number 28>

 a circuit 86 is closed on a delay relay BI 'which attracts its armature and cuts the test circuit 70, which causes the relay FBR' to cease to be energized. At the same time the TT1 relay. also ceases to be excited, which means that the link between the communication line BL and the transit group is cut and this group is released. When FBR- 'lets its armature drop, the FLR relay' is put back into the line circuit instead of TA ', BI' receiving holding current through circuit 87 which contains the IFA starting relays', of all free call seekers IFV 'of the group of seekers that forwards the incoming traffic.

   The call seekers IFV 'are set in motion, in the manner previously described, by the closing of a circuit 88. The first call seeker which meets the communication line BL closes a test circuit 89, which makes that the cut-off relay FBR 'comes into action again and switches the line relay FRL off. At the same time the call seeker is stopped by the fact that the test relay IFT1 'attracts its armature. When the test relay IFT1 'attracts its armature, the line circuit is closed via contacts 91,92 by the relay IFA' and a resistor W4 '. At the same time, the ISM 'driving the IFS finder' magnet receives a pulse current through circuit 93, which causes the IFS finder to turn on.

   When the seeker encounters a free communication line FL '(Fig. 12), a test circuit 94 is closed; the IFT test relay attracts its armature and stops the seeker. The test circuit 94 also contains the connection relay ST 'of the location recorder MX M [(Fig. 12) and this relay now attracts its armature. At the same time, the test relay IFT2 (Fig. II) transposes the line cooked air so that it is now closed by the pulse relay RA 'from the location recorder (Fig, 13).

 <Desc / Clms Page number 29>

 



  The delay relay RH1 'is switched on by means of a contact 95 and for its part closes the circuit 96 of the relay RH2, which cuts off the return circuits of the pulse receivers of the switch. 'recorder. Relay RH1 also causes a transposition of test circuit 94, which means that the latter now remains closed by the intermediary of a contact 97.



   When the recorder has been connected to the communication line FL ', a circuit 98 containing the relays RSR' (Fig. 13) and BSR '(Fig. 11) is closed. The relay BSR 'now reverses the direction of the current in the line circuit 65 on the contacts 99, 100. This has the effect that the polarized relay UFP (Fig, 8) attracts its armature, so that the circuit 75 is closed by via the follower switch SO2 in its fifth position, e-circuit passing through the relay MK (Fig 10), as well as through the follower switch drive magnet SOM2.



  The magnet SOM2 attracts its armature without advancing xxxxxxxxxxxx however the follower switch. The MK relay also attracts its armature. When the relay RSR '(Fig. 13) attracted its armature, it went into a holding circuit 101.



  At the same time a pulse loop 102 was closed for the maneuvering magnet SOM1 of the follower switch SO1 which had the effect of making the follower switch go to the second position. Circuit 98 has been cut and relay BSR '(Fig. 11) has ceased to be energized. Consequently the direction of the current is now reversed again in the line circuit, the polarized relay UFP (Fig. 8) letting its armature drop and cutting the circuit 75, which causes the follower switch SO2 (Fig. 10), advance to sixth position. At the same time, the excitation of the MK relay is cut off.



   In the sixth position of the follower switch SO2 a circuit 103 is established, this circuit containing the relay -on-

 <Desc / Clms Page number 30>

 which attracts its armature and remains energized by 104. In addition, the MB relay tarnishes a return circuit 105 For) the follower switch drive magnet SOM2 which is returned to its first position in which the circuit 105 is cut. At the same time a circuit 106 is closed for the MA relay, which remains energized as a function of the RH1 relay,
The pulse emitted in the line circuit by the relay BSR '(Fig.

   It) at the time of connection of the registration recorder M '(Fig. 13) caused in the manner indicated a transposition by which the pulse repeater IM (Fig. 10) is now actuated so as to transmit, under the control of the location recorder M, a number of pulses corresponding to the subscriber number, pulses which are receded by the location recorder M ', (Fig. 13).



  The emission of the pulses is deolanohée by the MA relay (Fig, 10) which receives current through 107, when SO2 reaches its first position. Circuit 77 is then closed and pulse repeater RE5 is set in motion in the manner described above. While the pulse repeater is moving forward, pulses are emitted as before by relay MR2, transmitted to central B, where they actuate the pulse relay RA 'of the tracking register, M'.

   However, as the follower switch SO2 (Fig. 10) is now in its first position and the MB laughter is excited, the pulse repeater is in this case monitored by the pulse receiver RE !, because the circuit of the stop relay MT is now closed on part of circuit 84 and on part of circuit 107 by a contact of SO2 MV is put into action, cuts 77 and stops RE5. At the same time SOM2 receives an impulse by 81 , SO2 passing to the second position. RE5 is also brought back to the normal position as described above. In the meantime MV continues to receive current through a circuit monitored by RE5 and cuts off when RE5 reaches its normal position.

 <Desc / Clms Page number 31>

 



  As soon as MV therefore drops its armature, the circuit 77 is retained and the pulse repeater RE5 is put into action once again. This time its positioning is monitored by RE3. When RE5 has been stopped on the switch marked with RE3, SO2 goes to the third position, after which RES is returned to position, this time under the control of RE4.



   When the pulses corresponding to the last three digits of the subscriber number have been sent in this way to the central location selector B, the follower switch S02 (Fig. 10) goes to its fourth position, in which a circuit 108 is closed by relay SHA, (Fig. 9) which attracts its armature and cuts the circuit of the branohement relay ST, which has the effect of separating the recorder M from the communication line FL. The circuit passing through the third oonduotor then remains closed by a contact.
109 of the SHA relay and a resistor W3. The SHA relay simultaneously causes the circuit of the calling subscriber to be transposed to the contacts 110, 111, so that the aforementioned blackout is now known by the UFA relay (Fig. 8).



   The pulses emitted by the pulse repeater IM, (Fig. 10) through the relay MR2 actuated the pulse relay RA 'of the location recorder M' XX of the central B (Fig. 13) of the way mentioned above, which had the effect of putting the recorder / in position in a manner analogous to that which was described above with respect to the location recorder M.

   However, says the follower switch SOF 'is now in its uxth position, the pulse receiver REF' is not activated, but the first series of pulses which corresponds to the second digit of the number of the The subscriber will cause the RE2 pulse receiver to be placed in position. This is done, the RE2 pulse receivers. and RE4 'are set exposure by the following series of pulses in the manner described above.

 <Desc / Clms Page number 32>

 
 EMI32.1
 deJ1.1f.1 in t.
 EMI32.2
 



  After reception of all the pulses the follower ooinnutatmt SO1 'moved to its fifth position in which a circuit 112 is fe0; This circuit passes through relay 1 which attracts its armature and causes the MRS 'locating relay to enter into action in the manner described above, after which the
 EMI32.3
 aouznunioatioii is established in the same way as for a call from a subscriber to the same exchange. When the connection has been fully established, the SHA 'relay kicks in as described above, which has the effect of turning off recorder XX M'. At the same time the oirouit of li-
 EMI32.4
 gne 65 is switched so that it now goes to r9 '"' lais SA '. Communication is then maintained by the' lais SA 'and SB' and is terminated in the manner previously described.



   When a conversation communication is established between a subscriber of exchange A and a subscriber of exchange C, this communication is transmitted to exchange B and the setting of the pulse receivers TR1 and TR2 'of the transit group ( Fig. 11) takes place exactly as described
 EMI32.5
 upper. However, TR2 'is brought to the fifth position, while TR1' is brought as before, the first projection. When the follower switch SO'3 goes to the seventh position after the two pulse receivers have been placed in position, a pulse circuit 113 is closed on the TVM 'drive magnet TV'; The researcher sets off to find a CL communication line going to central C.

   The CL communication lines are marked in the TV finder by the fact that the corresponding group of GG test contacts is connected to the positive pole of the battery
 EMI32.6
 via TR'2 Toril and SO'3. When the TV seeker encounters a free CL communication line, a circuit
 EMI32.7
 114 is closed on the BRR cut-off relay 'of the. leads the line, this relay attracting its armature and putting

 <Desc / Clms Page number 33>

 hear the corresponding line relay FLR '. The TT2 test relay which is in the circuit also attracts its armature and goes into a holding circuit via 115.

   At the same time, circuit 113 is cut and the searcher is stopped. Further, the test relay TT2 closes a line circuit 116 which contains a polarized relay TP '(Fig, 11) at the central B and the relay / line FLR "of the communication line CL at the central C.



   When the central C does not have a switch group, the FLR line relay "activates the incoming selector group IFV", ITS ", (Fig. 1), so that the communication line is connected to a free communication line FL "and to a location recorder M". In addition, the current direction is reversed in the line circuit 116 in a manner analogous to that which has been described for the Figs. 11 12,13 ce which causes the polarized relay TP '(Fig.

   It) attracts its armature and closes a circuit 117 which contains the relay BSR ', this relay coming into action and sending a pulse to the central A, so that the pulse repeater of this central sends to the location recorder M 'of central C, in the manner already described, a number of pulses corresponding to the last three digits of the subscriber's number. The communication is then definitively established in the way described above ?.



   If the exchange C comprises on the other hand a transit group, this group causes the transmission of two pulses to the central A in the manner described above. This has the effect that the follower switch S02 which is in the fifth position after the position selector switch has been put in the central B position, now advances to its seventh position in which the MS relay is switched on again. , this relaissermant its oôté the circuit 77 and starting the pulse repeater RES.

   This last is now placed in position as before, first under the

 <Desc / Clms Page number 34>

 control of RE1, then under the control of RE. When the pulses corresponding to the first two digits of the subscriber's number have been transmitted once again in this way via the relay MR1, the follower switch SO2 goes to its ninth position in which it remains until further notice.



   The pulses thus repeated put the pulse receivers TR "i and TR" 2 (FIG. 6) of the central C in a position analogous to that which was previously described for FIG. 11. When the emission of the pulses is finished the relAS B1 "is activated in this case, which makes that the communication line CL is connected to a communication line EL" and to a registration recorder M "by the Intermediate group of arrival selectors IFV "IFS" Communication is then fully established at exchange A as described, under the control of the location register.



   It follows from this description that the location recorders M, M '. M "can function partly as digital selectors for establishing local communications and partly as recorders for establishing communications with subscribers in other exchanges.



  In the second case, they operate as described by cooperating with the pulse repeaters 1M, IM 'IM' to send a number of pulses corresponding to the registered number to digital selectors or to pulse receivers such as TM or M 'from the other exchanges. It is obvious that the monitoring function of the registers can also be brought about by means of pulses emitted by another exchange xxxx and received by the register of the calling exchange as in known mechanically driven systems.



   The invention is not limited to systems of the type described in which the digital selectors (M, TM) only serve to select lines and groups of lines, but not to. maintain conversation communications; she can -34-

 <Desc / Clms Page number 35>

 also be applied to the usual systems in which the selectors also serve as branching devices by which the lines entering the conversation communication are interconnected.



   CLAIMS.



   1. Arrangement for automatic telephone installations in which two-way calls are established under the control of recorders between subscribers connected to different exchanges, arrangement characterized by the fact that a recorder (such as M, IM) is set up. aotion by passing through one or more intermediate exchanges (such as B) when another exchange (such as C) is called so as to repeat the command pulses used to select the various exchanges by gradually transmitting the communication d 'one exchange to the other by means of direction selectors (such as TM ") mounted to the intermediate exchanges and put in position all the control of the recorder (M, IM) of the calling exchange (A).


    

Claims (1)

2: 'Arrangement according to claim 1, characterized by the fact that the dial-up selector (TM') is constructed so as to be able to transmit the communication selectively to one or more other exchanges or to the automatic branching switches. of its own exchange, the recorder '(M, M) of the calling central (A) being iris in action in the first case so as to xx repeat the number of control pulses corresponding to the number of the central desired, to monitor in the second case the positioning of the selectors (M ') in accordance with the number of the requested subscriber. 3. Arrangement according to claim 2, characterized in that the recorder (M, IM) can be activated by means of two different signals and activated by another central, so as to fulfill two monitoring functions. <Desc / Clms Page number 36> different, that is to say to put a direction selector (such as E TM ') in position according to the number of the desired exchange, or to put the digital selectors (such as M') of the central,! desired (B) in position following the number of the requested subscriber. 4. Arrangement according to claim 1, characterized in that the communication lines (BL) arriving at a central (such as B) and coming from another central (such as A) can be connected on the one hand to d 'other communication lines (such as CL) and on the other hand to communication lines (FL') in the local automatic branch switch, through searchers (TS ', TV' or 1FV ', 1FVS ') operating under the control of common direction selectors (TM'). 5. Arrangement according to claim 1, characterized in that the communication lines (BL) arriving at a central (such as B) and coming from another central (such as A) can be connected to oarmuni- lines oation (such as (CL) starting in other say ctions, this link taking place through a group of selectors independent of the local automatic branch switch, and made up of a certain number of researchers (TS ', TV ') connected in pairs by means of oordons (SL'5) and one of which (TS') is used in each pair of selector switches to connect a direction selector (TM ') to the calling communication line ( BL).