May 2, 1933.

F. GOHOREL

1,907,062

SEMIAUTOMATIC TELEPHONE SYSTEM Filed Sept. ll, 1931

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Ferrard Golore

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May 2, 1933.

F. GOHORE SEMIAUTOMATIC TELEPHONE SYSTEM

907 062

led-lattentor tFernatid Gahorel

May 2, 1933.

F. GOHOREL

1,907,062

SEMIAUTOMATIC TELEPHONE SYSTEM Filed Sept. ll, 1931

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Patented May 2, 1933

UNITED STATES

1,907,062 PATENT OFFICE

FERNAND GOHOREL, OF PARIS, FRANCE, ASSIGNOR, BY WI2SNE ASSIGNVIENTS, TO ASSOCIATED ELECTRIC LABORATORIES, INC., OF CHICAGO, ILLINOS, A CORPORA. TION OF DELAWARE, -

SEMIAUTOMATIC AEEPRONE SYSEI Application filed September 11, 1931, Serial No. 562,241, and in France September 19, 1930.

The present invention relates to semi-au an office “tandem’’ and which is such that tomatic telephone systems in which commu for each junction at the preceding office nications between two subscribers are estab (with 'egard to the manual operator's posi lished at a distance, by manual operators. tion) three switches are provided to connect 5 The said invention is more particularly the said junction (which is called the prin 55 applicable to telephone networks called ru cipal junction) to subscribers or to the junc rail networks in which the subscribers are tions going towards the more distant office. grouped in small capacity offices connected The first of these switches (X) is used either either among themselves or to central man for finding a calling line and connecting it to ual offices of more importance. the corresponding main junction, or for 60 In general, the great number of these of to rotating it on to the called line through the fices and the Small number of circuits which action of impulses sent by the manual oper connect them render the necessary operations ator over the main junction, eventually to complicated for establishing communica connect subscriber or called sub 15 tions in these networks. This augments Scriber, ortheforcalling rotating it onto the main junc 65 chances of wrong connections and the time tion or to a second switch described here required for putting these connections after. through. second of these switches (Y) is used The present invention has for its object to forThe rotating onto a called line under the 20 remedy these inconveniences by suitable effect sent by the manual op 70 means, rendering always simple the opera erator ofoverimpulses the main and for con tions carried out by the operator for estab necting the Subscriberjunction thus called to the lishing these communications at a distance, subscriber already connected to the first and this no matter how many and how dis switch, eventually to permit establishment 25 posed are these offices in question. The of local communication circuit between the 75 choice of connecting circuits to connect up twoa subscribers. the first of the two whichever two subscribers attached to this Switches is used When for a connection between office of the same group or attached to the two of the same network the same office is effected solely by the sending thirdsubscribers switches (Z) is used for either 30 of impulsenumbers. trains corresponding to the sub findingofathese scribers' calling line or finding a called line 80 A rural network can be considered as through the action of impulses sent by the manual operator over the main junction, comprising a first office connected by a plu eventually to connect a calling or called sub rality of junctions to a more important office Scriber to the junction. 85 served by the manual operator. Also, other The inventionmain applicable to cases offices connected each one by a junction to where there are isa also plurality of groups of 85 the first office these said offices being able switches X and Y and a switch Z for each in their turn to serve more distant offices main junction. The groups of switches X to which they are connected by a juriction 40 and so on. . .. . and Y being used one after another in the case where there are several simultaneous 90 In the following, by “tandem' office is inward connections passing through the of meant an office which serves other offices more distant than itself from the central fice in question, switch Z being used for connections with the preceding office when manual office, and by “central terminus' of.- all the groups X and Y are engaged upon 45 fice is meant one which is not connected to inward connections. 95 any office more distant than itself from the central manual office. Another feature of the invention consists One of the features of the invention con in a second simple arrangement of switches in combination with offices having the first sists in the first arrangement of switches arrangement. This is more particularly ap 50 more particularly applicable to the case of plicable to terminus offices from whence it. 10

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1,907,062

Fig. 1 shows a schematic example of a will be noticed that in general a number of simple network. inward connections is very small which per Fig. 2 shows a detailed scheme of the

mits maintaining the junction occupied dur manual operator's position. Fig. 3 shows a detailed scheme of the

ing the said inward connections without re Sulting in an appreciable reduction in effi

ciency of the junction.

“tandem’ office.

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Fig. 4 shows a detailed scheme of a “ter To this end, the second arrangement is minus' office. constituted by the association of two 5 shows a dialing cord. switches with the junction going to the pre Fig. Fig. 6 shows a part of a regular cord 0 ceding offices, the first switch X’ analogous circuit. to the switch X described above, a second In the following the description is de switch Y analogous to switch Y described voted to the case where there is a “tandem’’’ office attached to a manual office, and a “ter above. Another feature of the invention resides minus’ office attached to a “tandem' office. 80 5 in an arrangement of electric circuits per The invention is not, however, limited to the mitting the starting off in the operation of case of a single “tandem’ office, but is ap switch Y described above only if the pre plicable also to the case of a plurality of liminary setting of switch X does not co connected tandem offices. respond to the digit which is to set switch Y. In Fig. 3 switch R1 represents switch X. 85 The object of this arrangement is to set in In Fig. 3 switch R2 represents switch Y. 20 operation the arrangement constituted by In Fig. 3 switch R3 represents switch Z. a group of switches X and Y which is des In Fig. 4 switch RC1 represents switch X'. tined to establish inward communications In Fig. 4 switch RC2 represents switch Y. 90 only in offices where they must be used. Each subscriber's line or junction from the Another feature of the invention consists office in question is equipped inside the office 25 in special means for keeping in abeyance With a cut-off C and a calling relay A and calls initiated by subscribers while permit is multipled on the banks of the connectors. ting the operator to put through other calls, In addition, the office connected directly to 95 the operator replying to the subscribers’ the manual position (perhaps equipped for 30 calls only at her own wish. one or more junctions with the said position) One of the most important devices in the has each of its circuits supplied at each end invention for attaining this object consists With an equipment as represented in Figs. 2 in the using of one of the two wires of the and 3. junction for the transmission of impulses In these main lines the operation is as 00 35 and signals and the other wire for the con follows: trol of different operations for effecting sig Manual office call by a rural subscriber naling, Supervision, release, etc.; this con trol being obtained by a polarized relay (a) The case of an office directly con 05 branched on the last-mentioned wire and op nected to the manual position. 40 erated at a distance in one direction or the The subscriber operates his magneto and other by the action of the manual operator. energizes its calling line relay A which A feature of the invention consists also causes the sending of a calling signal over in the arrangement of a circuit for operat One of the junctions (if they are free) to 10 ing the called subscriber's bell which con the manual position. The calling lamp asso 45 sists in the calling generator of the manual ciated with the junction in question lights. office, one wire of the junction, the bell of The operator replies by inserting the plug the called subscriber, and earth, at the at of a cord in the jack RP corresponding to said junction which causes by the send tached office considered, the other wire of the the junction being used for maintaining the ing of a suitable potential between one of 5 50 switches used in the connection in operative the wires and earth and also through the medium of a polarized relay the setting in condition. operation of a switch R1 (Z) (connector The invention is also characterized by the or R3 (Z) if the local connector 20 circuit for testing the impulse circuit, and finder), R1-R2 (XY) is occupied until it finds

which includes the sending wire and a relay the calling line upon which it stops. At at the manual office, whose energization pre this time the calling signal is removed, and vents the sending of impulses in such a man through this the call is automatically cut ner as to avoid this sending and signal the off at the manual position. operator of it as long as the switch which In addition, immediately upon plugging in 60 should be controlled by the impulse at the the Supervisory lamp flickers during the en rural office is not free, or is not in a position tire hunting period. It assumes a steady to permit it to reply to these impulses. during the calling period. It is ex The annexed drawings represent by way glow tinguished immediately upon the reply of of example one method of putting the in the calling subscriber. 65 vention into operation.

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In the case where no circuit is free at the

moment of the subscriber's call, his call re with the said dial is immediately caused to mains in abeyance on relay A. This call is flicker until the switches of the office con 5 transmitted as soon as a circuit becomes Cerned are in the dialling position, which available. During the entire period between callses by the sending from the rural office of a lamp. suitable signal the extinction of the 70 the reception of the call on relay A and Said the taking of the line by the finder an occu The operator can then. send her first pation tone is sent to the subscriber notify impulse train. ing him that his call is registered. To this end, she winds up the dial and (b) Case of connected terminus office. The general operation is identical with through this operation the energization cur 75 that described above and only differs in the rent of the polarized relay is reversed and following points: also the position of the said relay used for The subscriber operates his magneto and establishing different impulsing circuits. through the operation of his relay A (Fig. The impulses are sent and registered on a 4), for example, causes the sending of a call switch X1 of control RA, Fig. 3. This 80 ing signal over the junction from the office causes the movement of switch R1 (X) or in question to the office to which it is at R3 (Z) if R1--R2 (X1) are occupied fol 20 tached. In this latter office, this signal lowing upon the digit sent (characteristic causes the energization of a calling relay A of the office to be reached): of the junction concerned (Fig. 3). This (a) To select a subscriber if he is attached 85 call is then carried out in the same fashion to this office. In this case control switch as previously described. It is extended via RA moves automatically into the position he different connected offices until it ar for receiving the following digit. rives at the manual position. (b) To select a junction corresponding to The operations involved in the reply are the chosen office which causes if the said 90 of the same kind as previously described, and office is not engaged the connection of the the operations succeed one another in the terminus office with the manual position via 30 office concerned, until the taking of the call a tandem office. The switches of the tandem ing subscriber. At this time the call is of office are put out of circuit upon- the reply automatically cut off by the definitive sup the called subscriber. pression of the rural manual calling signal. The Operations then succeed one another 95 The communication over, the operator is at the terminus office (Fig. 4) in the same notified by the lighting of the supervisory manner as described above for the tandem lamp, the lighting being caused by the hang office. In both cases at the manual position ing up of the calling subscriber. The opera as Soon as the dial returns to its normal OO tor withdraws her plug. All the Switches position the dialling lamp is again made to return to normal. flicker until the switches of the “tandem

40

of thethe“terminus' are intrain. position Rural subscriber called by the manual office tooffice receive followingoffice impulse

The operator inserts the plug of a cord This Operation is repeated in an identical 05 in the calling jack which causes the sending manner for the two following impulse trains between one of the wires and earth of a corresponding to the tens and units digits. 45 potential such that the polarized relay of This arrangement allows of maximum the rural office is energized in a sense oppo 'eliability of operation. site to that used for the reply to the call, as In addition, and in spite of this signal, 10 if thesystem operator winds upimpulses her dial istooimme soon, described above. By this means the switches the for Sending of the office in question are set in condition for “reception of the dialling' the same as it diately rendered inoperative. At the end the last impulse train counted by switch the said office is in calling condition, in of RC associated with the equipment of the 5 which case the rural manual calling signal circuit position, Fig.2) the calling is immediately suppressed and postponed Current (manual is automatically cut off. If the sub pending the release of the circuit in question. 55 Scriber is busy a signal sent immediately by Through the medium of associated relays the putting in this position of the polarized the taken rural position prevents the cutting 20 relay permits also the using of the other off of this call and the supervisory lamp of the cord in question is set flashing, thus position (initial Y used for the “finding of riotifying the operator. The subscriber 60 a call” as has been seen above) for the real free, the Supervisory lamp is lit with ization of another operating condition as abeing glow during the entire period of 25 described in the following and thus until thesteady call. The unhooking by a called sub the release of the circuit by the Operator. Scriber causes the suppression of the call The latter inserts in an associated dialling and the extinction of the supervisory lamp. jack of the circuit in question the plug of in addition, upon the sending of the first her calling dial. A dialling lamp associated digit corresponding to an engaged connected 30

1,907,062

4.

office, the dialling lamp remains flashing, so notifying the hanging operator.up, the subscriber's Upon the supervisory lamp lights and the operator Withdraws her plug. By this operation and through the medium of polarized relays re turning to their middle positions, the switches of the office in question return to

further operations to dial the number of the second subscriber, the operations at this time being identical to those described above. .Special operations (1) Supervision and release of local con

nections the operator. She can,byafter unplugging and when any

of the inlets to the local connector are free, 75 enter into the conversation. In order to 0 do this she plugs in on the calling side, Local connections winds up her dial, and does the following: These connections can be established be (a) In the case where the local connector tween subscribers of the same network. X, Y is that of a terminus office, she dials 80 (a) Upon a call of a calling subscriber: the special number for this office. The con operations having been carried out nector X or Z at the tandem office thus 15 asThese indicated in the corresponding para chooses the circuit going to the found group graph, the operator without removing her X, Y and the connection is established answering plug introduces her dialling plug between the operator and the two conversing 85 into the corresponding jack. By this op subscribers. 20 eration the switches of the office concerned (b) In the case where the local connector are set in the dialling position, as in the X-Y is that of a tandem office, she dials same proceeding described above (call by a number which is special for this opera a manual exchange). It suffices then to tion. Switch Z of this office is then switched 90 send the number of the called subscriber. a position which connects the circuit Sending of the first digit received solely into to the group XY and the conversation be on the control switch RA, Fig. 3, of the tween the operator and the two subscribers tandem office directly connected causes the takes place.these circumstances the operator rotation of switch R2 (Y), Fig. 3, either to Under select a junction or to select a subscriber of can free the local connection by pressing a 95 30 the said office. In the case where the digit special key, individual to the position and received on the control switch RA (Fig. 3) the forced listening and releasing corresponds to a circuit occupied by the con called cey. This operation reverses the energiza nector R1 (X) which is associated with it, tion current of the polarized relay of the 00 the connector R2 (Y) is not set in use and office concerned. The latter by a group of 35 the connection (impulse Supervision) with relays which are associated with it at this the said circuit is established as at the be moment causes the release of a relay which ginning by switch R1 (X). The following itself brings about the release of the con impulses received at the terminus position nection. causes the rotation of connector RC2 (Y) (2) Verification of the nature of the busy 105 from the said position, (Fig. 4), the super connections met with vision being the same as that described above for the dialling of a first subscriber. These are signalled by means of super At the end of the third impulse train the visory lamps. In general, listening to estab call to the called subscriber is cut off (if he lished communications is done directly 110 is free) until his unhooking which causes through the medium of the ordinary listen the extinction of the supervisory lamp. The ing key only when these connections are operator can enter upon the conversation established by the local connector at a ter and can withdraw her plug immediately minus office. In all other cases the operator upon the establishment of the connection be has to use her forced listening key. This 50 tween the two Subscribers. The connectors operation reverses the energization current R1, R2 or Ro1, Re2 are maintained in busy of the polarized relay of the tandem office condition in the office where they are used which by a group of relays which are as and maintained if there are any and through with it at this moment completes 20 their medium the connectors R1 or Ro1 sociated the connection of the circuit with the oc 55 from beyond. The switches not mentioned cupied portion reached by the switches X above to normal. Z of this office. Uponarethereturned hanging up of either of the orThe following is a detailed circuit de subscribers the Switches held in the connec normal.

tion are freed.

Scription.

I. Call by a rural subscriber (b) Local connections can be established by successive dialling of two subscribers. In the following description T denotes The first subscriber is called as described an operated contact and R, a normal con in paragraph “Rural subscriber called by the manual exchange'. This first subscriber tact.First case: The subscriber is attached to a 65 having replied, it is sufficient without any

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1907,082

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tandem office, Fig. 3, the said subscriber Upper winding of said relay is put out operates his magneto and energizes relay A of (b) circuit by the opening of contacts 105. over the circuit: magneto, lower line, upper (c) At T106 H1 is short circuited. winding of relay A, RC1, upper line, normal (d) T102 thecontact rotation circuit of the count contacts of switch hook to the other pole of ing switch is completed over the circuit: bat 70 the magneto. A holds up from battery tery, winding of motor magnet through the lower winding of A, TA1, RC2, home contact of the bank C, wiperRC,W,T102, nor relay P, to earth. anal contact of the motor magnet RC1 and The latter relay energizes and at TP1. earth. The latter operates by self-interrup 0. sends an earth to relay 9 of one or the tion, and leaves its initial position and comes 75 other of the idle circuits, the circuit being to position 1, where we get the following cir from R21, lower winding of relay 9, to bat cuit: battery, winding of the motor magnet tery. A busy relay opens this circuit at RC, T102, wiper W, contacts 1, 2, 3 of bank contact, 21. 15 C in parallel, RC1 and earth. The In addition, at TP2 relay O is operated Switch continuesT82, its hunting and stops in 80 in a vibrating circuit through the medium position 4. of its contact O1, the interruptions of the (e) At T103 a circuit is closed for the current in the lower winding of said relay lighting of the busy lamps LO correspond 20 produce in the upper winding an alternating ing to other positions. current of musical frequency, which is super (f) Finally at T104, battery (with posi imposed upon the holding circuit of relay A tive earth return) is sent on the lower wire through the upper winding of relay O, of junction from positive through a safe coupling condenser C9, RC2, TA1, lower ty the resistance, T61, T104, winding of the re 25 winding of relay A. By induction between tard S, lower left-hand winding of the trans the two windings of relay A, this current former and lower line of the junction. is sent on to the calling subscriber. If the The calling lamp LA is extinguished by 9. latter takes off his receiver he hears the sig of H (normal position of RC). nal of occupation notifying him that his theinopening addition upon the arrival at position 4 30 call is registered but is in abeyance. of the control switch we get the circuit: In If a circuit is free and by the energiza terrupted earth, position 4 on the bank B, 95 tion of relay 9 as seen above, the calling sig wiper W1, T51, upper winding of relay 2, nal is sent to the manual position over the and battery through the safety resistance. circuit: battery, upper winding of retard The operation of relay 2 causes the period 35 S1, T91, R132', R41, upper wire of the junc ic opening of contact. 23 which periodically tion circuit connected to the manual position. removes the short circuit from the lower At the manual position, Fig. 2, the circuit winding of relay 10, during which time this continues by upper wire of the junction R11, relay maintains itself by its two windings R41, upper left-hand winding of the trans in series, but the Supervisory lamp LS 40 former, winding of relay 5, and earth which flashes, advising the operator that hunting energizes relay 5 and lights the calling lamp is set in operation at the rural position. . associated with the junction over the circuit: In Fig. 3, we have the circuit from battery 05 earth, T52, H (normal position of the count on the lower wire of the junction, winding ing switch RC) and battery through the of polarized relay 15, to earth. This relay 45 calling lamp L.A. Relay 3 is energized over operates and closes its contacts 152 and 154, the circuit T52 and battery through the Relay 12 operates from battery, winding of O winding of said relay. The operator replies relay 12, R61, T154, and earth. Relay 2 by inserting a plug of a cord in the answer operates through T152. This slow-to-re ing jack. lease relay will remain held up during the Relay 8 operates by battery through the movement of relay 15 from One operated po 50 supervisory lamp. LS, sleeve of the plug sition to the other. and the answering jack, R105, upper wind The operation of relay 2 causes: (1) At T23 the connecting of earth to ing of relay 8, to earth. . s main hold wire and the operation of re Relay 6 operates over the circuit: battery, the 55 through its upper winding, T81, and earth. lay 27 by battery, winding of said relay 20 T23, and earth. ; Relay 10 operates from earth, R23, upper R321, (2) At 21 the opening of the circuit of winding of 10, H1 (normal position of RC) relay 9 which holds itself energized from T62 and battery, through supervisory lamp earth T122, R103, and lower winding of said LS. This lamp lights in series with the up relay. 60 per winding of relay 10. Through the operation of relay 12 we get 25 The energization of relay 10 causes: battery through the safety resistance T124. (a) At T101 a holding up of relay 8 from R322, winding of relay 31, H2, H, and earth, T101, T83, lower winding of relay earth. 8, R43, R71, and battery, through the safety Relay 31 operates and holds up at T313. resistance,

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Switch R1 starts to hunt from a circuit:

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the circuit: battery, winding of relay earth, RP1, R101, T121, T311, R262, motor over C, T1, lower winding of relay 26, T261, magnet R1, through its interrupter. It op and earth. of relay C causes the re erates by self-interruption to advance its T271, The energization wipers over the bank contacts where are ar lease relay A. by the opening O ranged different subscribers' lines. The of C2ofandassociated the opening of C1 removes the wipers arrive on the line of the calling sub connection between the upper line and re scriber. A. We then get the circuit: earth, TA2, bank layThe calling circuit being thus completed, 75 contact A, and wiper A1, switch R1, T313, the circuit is closed from the upper wire of T123, lower winding of relay 10, battery. 0. the junction, R41, T81, R141, R323, R291, The latter operates and opens at 101 the T263, wiper and contact - of the hunting circuit indicated above, causing finder R1, upper bank wire of the subscriber's thus the stopping of the finder switch R1 line, hook, bell, condenser, lower wire 80 on the contacts corresponding to the calling of theswitch subscriber's line, bank contact and subscriber. Relay 10 holds up from battery, upper wiper of the finder R1, T265, R292, R324, T82, and earth. winding of said relay T102, T23, and earth. R141', The calling subscriber's bell is thus rung, The circuit of relay 9 is opened at contact notifying of the reply of the operator. 85 103 which removes by the opening of con During him the time the calling current is 20 tact 91 battery from the upper wire of the removed the release of relay 7 causes relay junction. 8 to return to normal which places a battery This causes at the manual position, Fig. via retard S1, R142, R82, etc. 2, the release of relay 5 which opens at 51 the Thistheis circuit, extended to the lower wire of the 90 intermittent circuit of relay 2. At R23 the subscriber's line. The upper wire is con circuiting of the lower winding of 25 short to earth through the winding of re relay 10 lights the supervisory lamp LS nected lay 9 over the circuit, R141, R81 upper with a steady glow which notifies the opera winding of relay 9, H1 (normal position of tor of the finding of the calling subscriber, and earth. ld of the cut-off of the call as indicated be RA) The above circuit is opened at the sub 95 30 OW. station by the interposition of a The release of contact of relay 3 by the scriber's condenser in series with the subscriber's opening of 52 causes interrupted earth to bell, and will be closed in series with extend from position 4 of bank A of the the receiver andonly the secondary of the induc 00 counting switch RC, wiper W2, R31, and tion coil if the subscriber takes off his re battery through the winding of relay 1, The operation reproduces itself pe which operates and releases intermittently. ceiver. During the period of energization of the riodically until the subscriber unhooks his said relay, at T11 we get alternating current receiver. We then get by the operation of relay 9 as 105 with an earth return sent over the upper indicated above the following circuit: bat wire of the junction. During its normal 40 upper winding of the retard S1, T91, period we get at R11 the upper wire of the tery, R1327, R41, upper wire of the junction to junction connected to relay 5, Fig. 2. A condenser C1 allows the operator to as the manual position (Fig. 2). R11, R41, and relay 5 to earth. sure herself by the operation of a listening transformer 10 By the operation of relay 5 we get: key of the cut-off of the call. The operation of relay 3 via T52, In addition, a circuit is closed from earth (a) by the opening of 32 deemergizes the R32, position 4 of bank C, T102, wiper W, which battery through the motor magnet RC, the motor magnet RC (operated during the en latter energizes and remains operated until tire preceding period). The wiperS move 15 to position 5. The circuit of relay 1 is 50 the opening of the said circuit. At the rural position, Fig. 3: opened at 31, and also at contact 4 bank A. During the period of sending of alter (b) Operation of relay 2 from earth, bank nating current on the upper wire of the contact 5, of bank B, wiper W1, T51, upper junction a circuit is closed from the upper winding of relay 2, and battery through 20 55 wire of junction R41, R132, R91, condenser safety resistance. C10, winding of alternating current relay theThe lower winding of relay 10 is again 7, and earth. unshort the associated supervisory Relay 8 operates from T71. The follow lamp. LScircuited, of the cord going out. ing circuit then closes: earth, T83, R131, The operator, notified of the answering 25 60 T312', the windings of relay 26 in series, the subscriber, can listen in on the con wiper T1 and bank contact T of the finder of versation by the operation of her listening R1, and battery through the winding of re kew. lay C of the subscriber in question. The conversation currents are transmitted The two relays C and 26 operate in series. over the two-line wires in series through 6. The latter holds up in series with relay C

1,907,062

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(at the rural office, Fig. 3) condensers C1 fromrelay earth, R21, R132, lower winding of 9 toTP1, battery. The conversation finished, the subscriber By the operation of relay 9 a circuit is replaces his receiver which causes the open closed the retard S1, R42, T91, ing of the holding circuit of relay 9 (Fig. 3) R63, andthrough upper wire of the junction con 70 and the removal of battery placed on the nection to the tandem office (Fig. 3) RO1, upper wire of the junction. This at the of calling relay A. to earth. manual position through the release of re winding The operation of the said relay causes at lays 5 and 2 causes the lighting of super TA1 the operation of relay 9. visory lamp LS. and C2.

10

calling signal is then re-transmitted 75 The operator is notified of the hanging to The the manual position, and is treated in the up of the calling subscriber. Same fashion as in the previous There is provided an arrangement for re paragraph. The described operation identical up calling the subscriber if necessary by the to the time of setting R1 inisoperation. 5 simple operation of a calling key. The finder arriving on the position cor 80 The sending of alternating current from responding to the calling junction is stopped the cord in use causes the operation of re by the opening contacts 101, due to the lay 9 through the condenser C2, closes the energization of ofrelay 1() in the following circuit: earth, T91, bank contact 5 of bank 20 A, wiper W2, R31 and battery through relay circuit.: earth, TA2, bank contact A, wiper A1, of the finder R1, T313, T123, lower 85 1. The latter energized sends via T11, alter winding relay 10, and battery. The ener nating current from earth to line as before. gization of circuit relay $) is opened at 103, The operator repeats the operation of throw which causes theof removal of battery from ing the calling key until the subscriber by the upper wire of the junction. unhooking extinguishes the lamp L.S. The following circuit is also closed: earth, 90 in every case the operator, having re TA'2, contact C, wiper C1 of the finder, ceived the finishing signal, releases the cir T312, T104, winding of relay 14, to cuit by withdrawing the plug from the jack battery. Thislower relay energizes and holds up in question. 30. This operation causes the release of relays from battery resistance R1, upper winding 95 said relay T143, T23, and earth. 10, 8, and 6. The counting switch RC re ofThe circuit is closed from earth, T143, turns to its initial position over the circuit: R131, T312', both windings in series of relay earth, interrupter RC1, bank D, wiper W3, 26, T. bank contact, T1, winding of R102, motor magnet of the said switch to l'elaywier C, to battery. These two relays en 35 battery. At 103, the busy lamps corresponding to ergize in series and hold up by lower wind 00

ing of relay 26, T261, T271 and earth. The operation of relay C opens at C1 the circuit of the calling relay A. Battery comes from the terminus position 40 via the upper wire of the junction, and is sent to the manual position over the circuit: wire of the junction, bank contact and leases relay 12 which at 124 deenergizes re upper wiper +1, of the finder R1, T263, R291, lay 31. R323, T141, R41, and upper wire of the 45 Opening of contact 152. This releases junction going to the manual position. relay 2 which at 23 opens the circuit of re The removal the battery during the lay 27 which by opening its contact 271 period between of the operation of relay 10 deenergizes relays 26 and C. and the deemergization of relay 9 and the The following circuit is then closed: bat 50 tery through the motor magnet of R1 via holding up of relays 14 and 26 does not produce the cut-off of the call, the momen its interrupter, R262, R311, and earth tary release of relay 5 not having produced through bank X1. The switch hunts until the deenergization of the slow-to-release re itis then reaches its home position. Everything lay 3, (Fig. 2). normal. The energization of relay 5 is now con 55 Second case: The subscriber is attached trolled from the terminus position. to a terminal office (Fig. 4). In addition at the tandem office (Fig. 3) As indicated previously, the sending of through the energization 14 a posi calling current by the subscriber is received tive battery extends over oftherelay lower wire of on relay A (upper winding) which holds 60 up in series with relay P through winding the junction and is sent to the terminus office. of P. TA1, lower winding of A, RC3, and The circuit extends from positive battery earth. An occupation tone is sent over the on the lower wire to T141, R324, R292, calling subscriber's line as in the previous T265, wiper and bank contact - 1 of the system. By the operation of P a circuit is closed finder Ri, lower wire of the junction to the circuits are extinguished. At 104 positive battery is removed from the lower wire of the junction. By the return to its middle position of relay 15 (Fig. 3), we get: (a) Opening of contact, 154. This re

the terminus office (Fig. 4), winding of the

05

0.

20

8

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conversation currents pass through polarized relay 16, to earth. This relay theThe two wires connected directly to the tan closes its contacts 162 and 164.

office and through the condensers C1 (a) Relay 3 is operated by 162 and closes den and C3 at the terminus office. its contact 31.

Upon the subscribers hanging up, relay 9 70 releases and removes the supervisory battery. Lamp LA lights at the manual position. The removal of the plug causes by the re moval of positive battery from the lower 75 wire of the junction the return to its middle position of the polarized relays. (a) Polarized relay 15 at the tandem of.tery. fice (Fig. 3) causes the release as described The arrival of the finder on the bank con already. tact associated with the calling subscriber (b) Polarized relay 16 at the terminus 80 15 closes a circuit from earth, the two windings office, Fig. 4, releases, which causes at 164 in parallel of relay C, TA2, bank contact the release of relay 10, and at 162 the re and wipers of bank T1, T102, and battery lease of relay 3, which by opening contact through the winding of relay 13. 31 releases relay 12. Switch RC1 returns 85 The operation of relay 13 opens the cir to over the circuit: earth, R31, bank 20 cuit at 131, of the motor magnet, at 132 it andnormal wiper R101, interrupter of the ro opens a circuit of relay 9, which releases tary magneta1,RC1, winding of the magnet. and removes at T91 the battery from the to battery, and during rotation also over upper wire of the junction. another circuit from earth, R71, R124, bank 90 In addition, relay C energizes and holds a1, etc. All the pieces of apparatus return 25 up in series with relay 13 from earth, wind thus to their initial positions. ings of relay C in series, TC1, bank contact II. Subscriber called by the operator and wiper, etc. At C3 and C4 the energization and hold The operator puts a plug of the cord intu ing circuits of the calling relay A are opened. calling jack and so closes a circuit from 95 30 The removal of battery from the upper the battery, lamp LS, sleeve of the wire of the junction causes as described plug andsupervisory the jack considered, H1, (if the above the cut-off of the calling current. Al counting switch is at zero), upper winding ternating calling current is impressed on the (b) A circuit is closed from earth, T164, R22, and battery through the winding of relay 10. The finder is set in operation over the cir cuit: earth, T31, T92, R131, T101, inter rupter spring and through the winding of the motor magnet of the finder RC1, to bat

relay 10, R23, to earth. This causes: upper wire of the circuit from the manual of (a) At T106 the short circuiting of H1. 35 position as previously described, extends via (b) At T103 the lighting of the busy R63, R91, alternating current relay 5, and lamps L.O on the other positions. earth through condenser C5 which causes (a) At T102 a circuit is closed from the energization of relay 8 at T51. earth, interrupter spring of RC1, home con By the operation of the latter a circuit tact of bank C, wiper W, T102, motor mag 40 is closed from earth, T31, T81, lower wind net, to battery. The latter operates by self ing of relay 12, to battery. interruption to move the wipers to posi Relay 12 holds up from battery, upper tion winding of said relay T121, T31, to earth. (d)1. At T104 a circuit is closed from The calling current is then sent to the negative battery and extended to the lower 45 Subscriber's bell over the circuit: upper wire wire of the junction through the safety re of the junction, T82, H2 (normal position sistance, R61, T104, retard S. lower left of switch RC2), T125, bank and wiper +1

winding of the transformer, etc. and contact associated with the subscriber hand The operator next inserts her dialling

in question, upper wire, bell, condenser, low er wire, bank contact, wiper and bank -1, T126, T83,the andother earth.period of the ringing, During and if the subscriber unhooks, a circuit is closed from battery, left-hand winding of 55 retard S2, RS3, T126, the previously de scribed circuit via the receiver and second ary of the induction coil of the unhooked subscriber's station, T125, H2, RS2, upper winding of relay 9, earth. 60 Supervisory battery is sent from the up per line wire of the junction from battery, retard S1, R.42, T91, upper wire of the junc

50

65

plug in the corresponding jack and a circuit (a) Earth, through the contact C1 of the dial, ring of the plug, dialling jack and

00

G

5

is closed from:

battery through the winding of relay 7,

which operates. (b) Interrupted earth via R22, sleeve of

the dialling plug, dialling lamp LN, to bat tery, and the lamp flashes. The operator can only dial during this

signal. The sending on the lower wire of the junction of a negative potential causes at tandem office, Fig. 3, the operation of tion, etc. . . . The call is terminated and the polarized relay 15 to its negative position. the Supervisory lamp extinguished, as de which, therefore, closes contacts 151 and 30 scribed above.

i,907,062

li53, operating at T151, relay 2. It is to be T61, T154, to earth. At R132 battery is from the upper wire and the latter calling at this office the signal will be re isremoved connected at T132 to the impulsing 5 moved from the upper wire of the junction relay 1. by the release of relay 9, releasing from the At the manual position, Fig. 2, upon the 70 opening of contact 21. Relay 6 is operated release the dial, contact C1 of the said over the circuit: battery, through the wind dial is ofopened a number of times corre ing of said relay, hi, (normal position of spending to the digit set up. This causes RA) T153 to earth. alRelay 27 operates the release of relay C. 7 a similar number of through contact T23. Relay 6 holds up over times causing the Sending over the upper the circuit: battery, upper winding, T63, wire of a corresponding number of battery R84, T23, to earth. impulses over the circuit: battery, The operation of relay 6 sends a circuit resistance, R71, T41, R11, upper wire safety from battery through the safety resistance, junction, to the rural position (Fig.of the 3), T65, R322, winding of relay 31, to earth. T41, T132, winding of relay 1, to earth. via contacts H1 and H2 in series. The said The latter energizes a number of times 80 circuit is only closed if the two switches R1 corresponding to the digit set up on the and R2 are in normal position. The operation of relay 31 short circuits dial, causing at T11 the advance of control 20 at 313 the contacts H1 and H2. A circuit switch R.A. addition, as soon as the latter leaves 85 is closed from battery through the motor innormal position, contact h' is opened. magnet R1, R262, T311, Ri21, upper wind its Relay 4 remains held up via T45 and its ing of relay 4 and earth, through h' (nor lower winding, which is itself short cir mal position of switch R.A.). it may be cuited at R11 between each which 1. seen that relay 4 only energizes if the dif causes the maintaining in impulse, the operative ferent pieces of apparatus in this circuit are position of the relay during impluse train. a 90 in suitable positions. soon as the ten-point switch RA leaves The operation of the said relay causes the Asnormal position, the following circuit sending of the dialling signal over the cin'- its is closed: earth, bank 1', T62, R31, R142, cuit: battery, upper winding of retard S1, T311, R262, interrupter of the motor 95 R132, T41, upper wire of the junction to the magnet of switch R1, tospring battery. manual position, (iig. 2), R11, R41, relay The said Switch is set in automatic ro 5, and earth. tation until it arrives on the contacts corre Relay 2 operates over the circuit: earth, sponding 3S to the position of control switch 5 wiper Wii, position 1 of bank B, T51, upper R.A. At this the stepping circuit 00 winding of relay 2, and battery through is as follows: moment, earth, R323, J2 (in its nor the safety resistance. mal position) J1, bank contact and control The opening of contact 22 extinguishes wire corresponding to the position of RA, lamp L.N. 1, lower winding of relay 3, battery. The operator can now send the first digit. bank The operation of relay 3 causes at R31. 105 To this end, the dial is wound up so closing the opening of the rotation circuit of R1, the circuit: earth, TC2, (contact of the dial operated until its return to Zero) tip of the which is thus stopped on a position corre plug, T21, lower windings of relays 2, 4, 6, sponding to the digit sent, that is, a junction to battery (through T71 for relay 4). This connected to another office or the line of a 110 C8SeS: subscriber of the present office. (a) The holding up of relay 2. connected to the (b) The operation of relay 4 which (1) Call to a subscriber first office holds up via T42, upper winding, to bai:50 tery. At T44 a circuit is closed from earth, The digit sent is in this case ten corre T44, R82, wiper W, position 1 of bank C. sponding to ten impulses. Switch RA is 15 T102, motor magnet RC, and battery. The moved into the last position of banks 1, 1’, latter energizes and remains in the operated 1/7. position. Switch R1 being in a corresponding posi 55 (c) Relay 6 operates and negative bat tion, relay 3 is energized. The train of im tery is removed from the lower wire of the pulses finished, relay 4 releases, owing to a 20 junction being replaced by positive battery. prolonged short circuit of its lower wind At the rural position, (Fig. 3) relay 15 ing at R11. The following circuit is closed: changes to the positive position, con earth, bank 1'. T62, T31, R43, last position 60. tacts 151,over 153, opening. Contacts 152, 154 of the bank 1 interrupter spring of the 125 close. Relay 2 remains held up via T152 motor RA, to battery. The latter (during the movement to the middie posi is set inmagnet automatic rotation and comes to the tion 152, and 151 open the said relay not position of banks 2, 2', 2''. releasing, being slow to release). At T154 normal During time relay 3 remains held up relay 13 energizes over the upper Winding, in parallelthis with the motor magnet, RA over 130 noted that if a subscriber at this time is

1O

1,907,062.

of dialling battery on the upper wire of the circuit R44, upper winding of relay 3, the junction. to battery. In the case where the equipment is only In addition, at the manual position provided for fifty subscribers (example (Fig. 2) the dial returns to its normal posi chosen in Fig. 3) five tens only are used, and 70 tion, the relays 2, 4, and 6 releasing. if by error switch RA is positioned on a po At the release of relay 2, the dialling sition corresponding unused ten the lamp LN is again caused to flicker at R22. system is locked up. toTheanlocking is At the release of relay 4 and by the open closed on the unused positions 5-9. circuit On these ing of 44 the counting switch irC1 (by the the stopping of the rotation of 75 10 deemergization of its motor magnet previ positions switch R1 is caused by operation of relay 3 ously energized) moves into position 2. (opening of R31), which finds an earth on At the release of relay 6 positive is re bank switch R.A. moved from the lower wire of the junction The2 ofconcluding of the impulse train and replaced at R61 by negative. causes the release of relay 4. A circuit is 80 5. At the tandem office (Fig. 3) polarized from earth, bank 2', T62, T31, relay 15 returns to the negative position closed R43, bank 2' on positions 5, 6, 7, 8, or 9, and relay 2 is held up via T151. Upon the T131', and lower winding of relay 13. The opening of 154, relay 13 releases. remains held up and by the opening The ten-point switch having come to the latter 20 initial positions of banks 2, 2', 2' as seen of contact, R132, dialling battery is pre 85 vented from being reset over the upper above, relay 4 energizes immediately upon wire of the junction. The dialling lamp as the closing of h’’ in the circuit already de sociated the dial flickering warning the scribed. Dialling battery is again sent over operator with the upper wire over the circuit: battery, circuit. of the locked up condition of the 90 25 upper winding of retard, S1, R132, T41, In case the switch comes to rest on posi etc. . . . The operations are repeated at tions 2, 3, or 4, relays 4 and 13, being the manual position as described above. released1, and stopping relay 3 energized, The dial is wound up. Positive is pro the setting intheautomatic rotation of switch 95 jected on the lower wire. The Brig.e RA is assured by the following circuits: 30 'elay passes to the positive position. (a) Positions 1, 2, 3, 4 . . . . . T31, R43, lay 13 operates. Impulses are transmitted to bank contacts in question of balk 2', relay 1 over the lower wire of the junction. motorand magnet Relay 4 remains operated via T45. Switch interruption. RA, which operates by Seif RA leaves its normal position, and stops on (b) Positions 5, 6, 7, S, 9 . . . . . T31, the position corresponding to the tens digit. R43, bank contact in question, bank 2', 100 In addition, the following circuit is R131', and motor magnet RA set in self-in closed: earth, bank 2' of the switch RA, terrupted operation. If the switch is T62, R31, R142, T311, R262, switch R1. stopped at the tenth position corresponding The latter rotates automatically and stops 40 by the opening of contact R31 (by the opera to digit 0 the rotation is resumed directly. 105 Supposing the chosen digit suitable, as tion of relay 3) when it has arrived in po weInhave seen above, the projecting of dial sition corresponding to the position of R.A. ling potential on the upper wire permits by At the manual position (Fig. 2), the dial the extinction of the dialling lamp the send 110 returns to normal, which causes: ing of the third digit corresponding to units. 45 (a) The movement of counting switch RC The operations are identical to those already from position 2 to position 3. described, the following being (b) The disconnection of the upper wire The dial is operated, positivea summary: is of the junction from the impulsing circuit projected over the lower wire, relaybattery 13 oper and its connection to relay 5. s 50 (c) Flickering of the dialling lamp LN. ates at the rural position (Fig. 3) through (d) Finally, the replacing of positive bat the movement of the polarized relay to its tery on the lower wire by negative battery. positive position. are sent over the upper wire. At the rural position (Fig. 3), polarized Impulses Switch RA rotates in accordance with 20 relay 15 moves to its negative position. Re 55 digit chosen, and switch R1 consequently lay 13 releases. Relay 4 has remained nor the rotates on to the line in question. mal from the time of the last impulse. If switch R1 is in the position corresponding Relay 3 operates, relay 4 releases. A cir to that of RA (representing the position of cuit is closed from earth, bank 3' of Switch RA, T62, T31, R43, bank 3, winding of re 60 the tens digit chosen), the following circuit 11, R121, T311, R262, and battery is closed: earth, bank 2' of switch R.A., T62, lay T31, R43, bank 2, interrupter of rotary through the motor magnet R1. The latter does not energize in series with relay 11, magnet RA. The latter comes to the normal but relay 11 energizes and closes at T112 a 30 position of banks 3,3,3', closing h’, which circuit and holds up for relay 9 over earth, 65 causes the release of relay 4, and the sending

1,907,062 11. T112, lower winding of relay 9, to battery. lel on the two conversation wires, the two Relay 9 energizes. light-hand lines in parallel of the trans The dial returns to normal position, caus former, upper winding of relay 6, to ing the release of relay 13. By the move battery. R81, The operation of relay 6 causes ment of the polarized relay from the posi the changing over on the lower 70 tive to the negative position, a circuit is wire of the junctionoftobattery positive from nega closed via S1, T91, R1327, R41, upper wir tive as long as the forced listening key is of the manual position, where the operations depressed. Succeed . one another in the following man At the rural position (Fig. 3), the move O e : ment of the polarized relay 15 to the posi 5 Upon the return to normal of the dial the tive operates relay 13. Relay 5 op counting switch RC leaves position 3 and eratesposition over the earth, T111, T131, moves to position 4. By the removal of winding of relaycircuit: 5, to battery. wiper W2 from position 3 of bank A, the The conversation circuit is established 5 circuit of the slow-to-release relay 3 is from upper wire of the junction, condeiaser 80 opened, battery being placed at this moment C1, condenser T51, T314, wiper and on the upper wire of the junction. The said bank contact -- C5, 1 of switch R1, upper wire relay remains held up at T52 by the opera of the subscriber's line, and lower wire of tion of relay 5. the junction, condenser, C2, R32, R141', con 20 (a) Case where subscriber is free. denser C6, T52, T314, wiper, bank con 85 At the tandem office (Fig. 3) a circuit is tact - 1 of switch R1, lowerandwire of the closed from earth, T111, R131, T312', lower subscriber's line. and upper windings of relay 26 in series, operator can warn him of the urgen wiper and bank contact T1 of switch R1, cy The of the communication. He releases the winding of relay C of subscriber in question, prior communication by hanging up, to be 90 to battery. These two relays energize in automatically recalled by the circuit, in series and hold up over the circuit: T271, question. T261, lower winding of relay 26, winding of In all cases, the subscriber being or becom C. to battery. free, battery is removed from the upper The operation of relay 26 causes at 262 ing wire as described above. The call is cut 95 the opening of the energizing circuit of off automatically at the manual position, relay 11. Relay 11 releases and opens the Fig. 2. We get as already the re circuit of relay 9, which also releases, and lease of relay 5 which at 51 described, opens the battery is removed from the upper wire. of the interrupted earth, so releasingcircuit. relay 35 (b) Case where the subscriber is engaged. 2 (Supervisory lamp LS gives a fixed glow). (He is engaged through the medium of Relay 3 releases by the opening of con 00 another connector). tact 52. In this case relay 26 (two windings in Relay 1. operates intermittently via R31 series) does not energize, being shunted by in accordance with the interruptions for con the lower winding of an identical relay of trolling calling current. 05 the finder connector held up by the sub RC energizes via R32. scriber. By this means relay 11 is main alternating current is projected tained held up, 9 is also held up, and battery on Periodic the upper wire of the junction. At the is maintained on the lower wire. rural position 3), alternating current At the manual office (Fig. 2), the switches relay 7 operates(Fig. and 8 operates via O are in the position indicated above. A contact T.I.. The call isrelay extended the sub circuit is closed from interrupted earth, posi scriber by the upper wire of thetojunction, tion 4 of bank B, wiper W1, T51, upper R41, T81, R141, R323, R291, T263, wiper winding of relay 2, and battery through the and positive bank contact, upper conductor 50 safety resistance. of the subscriber's line, bell, condenser, 5 Relay 2 operating intermittently, at its lower conductor of the subscriber's line, contact. 23 causes the unshort-circuiting of contact and negative wiper T265, R292, the lower winding of relay 10. The super bank R141, T82, to earth. visory lamp LS is thus caused to flash. R.324, 55 in addition, at R84 the holding circuit The operator advised of the busy condi of the upper winding of relay 6 is opened, 20 tion of the subscriber, withdraws the plug. the lower winding of this having been The switches always return to the normal opened at 262, it releases. relay We get: position as we shall see. (a) Automatic rotation of RA over the if the communication is urgent, the opera circuit: earth, bank 3', R62, interrupter 60 tor can enter into conversation with the spring, magnet R.A. and battery, via 25 busy subscriber in the following manner: the homerotary contact. In position 4 we get: The listening key of the cord used is de earth, R64, home contact of bank 4, motor pressed, then by the operation of the “busy magnet of RA, to battery. switch subscriber's listening key” (individual to the moves to position 1, bank 4, andSaid a circuit operator's position) an earth is sent in paral closed from earth, bank 4'', R62, motor magis 30

1,907,062 12 mal position of Switch RC2) H1 (normal net RA, to battery. The latter moves to the position of RC1), lower winding of relay home position of bank 1, closing hl, h/1. 9, to battery. latter operates and closes h'1. Relay 6 energizes from earth, T153, the following The circuit: battery, retard S1, h/1, upper winding of said relay, to bat R42, T91, R63, upper wire of the junction

5 tery.

(b) By the momentary opening of con tact T65 relay 31 deemergizes, and by the opening of 313 its locking circuit to T65 is opened permanently (H1 of R1 being 10 opened). When the called subscriber re plies, relay 9 operates (h1 being closed) and following the same operation as previously described in chapter “Reply to a Call', bat tery is sent via the upper wire of the junc 15 tion. At the manual position (Fig. 2), we get energization of 5, energization of 2, extinc tion of supervisory lamp LS, and at contact 32 the opening of the circuit of RC and its 20 passing from position 4 to position 5. The operator, being notified, can enter into the conversation with the subscriber as already described.

to the tandem position, Fig. 3, bank contact

70

and positive wiper of switch R1, T263, R291, R323, T141, R41, and upper wire of the junc tion to the manual position. This causes the 75 extinction of the dialling lamp LN. The operator is now able to send the sec ond digit. In the case where the junction is not free, relay 26 not being able to oper ate in parallel with the lower winding of 80 a similar test relay, the circuits indicated above remain open at contacts 263 and 265. The operator notified of this condition by the flickering of the dialling lamp LN can enter by force into the conversation as de scribed above (busy condition of a subscrib 85 er to the tandem office) earth being extended to the circuit of relay 5 at T143. In reconsidering the case of a free junc tion, the operator sends the tens digit, the 90 office being in the example chosen (2) Call to a subscriber attached to the ter terminus equipped for twenty subscribers, the said minus office 0 or 1 (ten impulses or one im Let us return to the stage of the opera digit being A special arrangement at the ter tion corresponding to the finish of the send pulse). permits without the interposi ing of the first digit supposing the latter ininusofoffice auxiliary rotary switches finds sub 95 30 corresponds to a junction (in the example tion in accordance with normal numeri chosen position 6, 7, 8, and 9 of bank 1, Scribers cal order. Fig. 3), the switch R1 remains in this case Upon the winding up of the dial, positive locked up in this position until the time instead of negative is projected on the lower 100 of a call or until the calling plug is with wire of the junction, and at the tandem office 35 drawn. ". (Fig. 3), this causes relay 15 to move to The following circuits are closed: earth, its positive position. Relay 13 energizes and bank 1', T62, T31, R-43, position 6, 7, 8, opens at contact 132 the circuit of the upper or 9 of bank 1 as chosen, lower winding of Winding to earth of relay 7 via the upper 05 relay 14, to battery. wire before the transmission of the impulses. Relay 14 energizes and holds up from bat It 40 may be noted at this point that the upper tery in series with resistance R1 via its up dialling is directly connected to the per winding T143, T23, to earth. A circuit terminus wire office without any shunt. is also closed from earth, T143, R131, T312, the terminus office (Fig. 4), the polar IO the two windings in series of relay 26, wip izedt relay passes from its negative to 45 er and bank contact T1 of switch R1, wind its positive 16 position, at contact 161 ing of cut-off relay C of the junction being the circuit of relay 3,opening immediately reclosed considered, to battery. at contact T162. This relay being slow to Relay 26 energizes in series with relay release remains operated during this change C, and holds up from earth, T271, T261, of position. 50 lower winding of relay 26, wiper and bank over At T164 a circuit is closed from earth, contact, T1, C' to battery. T64, T22, winding of relay 6, to battery. At this time negative battery existing on The latter energizes and opens at R63 the the lower wire of the junction is extended circuit of the supervisory battery and con 120 to the terminus office over the circuit: T141, i.ects the upper wire of the junction to re 55 R324, R292, T265, wiper and negative bank lay 1 at contact which is above to re contact of switch R1, R1, lower wire of the ceive the impulse T63 of the junction and polarized relay 16 to the ter the manual position. tens digit sent from minus office (Fig. 4). Relay 16 energizes (a) The digit sent is 1. to its negative position, closing its contacts Relay energizes in response to the im 60 161 and 163. A circuit is closed at T161, pulse and1 closes at contact 11 the following to energize relay 3 which closes its contact circuit: earth, T11, R151, left-hand wind T81. ing of relay 15, to battery. The latter en At T163, relay 2 energizes and holds up ergizes on its left-hand winding alone and 30 over the circuit T24, T31, to earth. It closes closes contact T151.

65 the following circuit: earth, T23, H2, (nor

1,90?,062

13

At the opening of contact, 11, a circuit, exists on the upper wire. The call is closed from battery, left-hand winding of isbattery cut of manual position. relay 15 in series with right-hand winding (a) At atthethetandem (Fig. 3), the of safne relay, T151, R81, T31, to earth. The energization of relays 7office and the clergization of the right-hand winding of 'elease of relay 6, as for a call 8tocauses a tandem the said relay causes the closing of coin office subscriber. This insures (1) the auto 70 tacts 151, 152, and 1537. matic rotation of switch RA, through the The impulse train being terminated, the medium of banks 1’, 2’, 3, 4', and R62 polarized relay 16 returns to its negative O position, causing the deemergization of re and the normal positions 2’, 3, 4, R64. The latter then returns to the home position of 75 lay 6. A circuit is closed from earth, T31, banks 1, 1, 1’, closing the contacts 1, h’1, T92, (RC1 being in its initial position) h'1. Relay energizes via contact hl. (2) R111, R62, T152. lower winding of relay During the 6opening of contact, T65, relay 5 7, to battery. The latter holds up over 31 has remained released as we have previ the circuit T152', T72, T31, to earth. seen. 80 Dialling battery is projected on the upper ously in addition, relay 14 being always ener wire at R63. the closure of contacts 81 and 82 is (b) The digit sent is 0 (ten impulses). gized, without their circuits being opened As before, the first impulse causes the at R141 effect, and R1417. 20 energization of relay 15 via its two windings. The calling current goes direct to the ter 85 The following nine impulses are sent to ininus position by the upper wire. A cir the switch RC1 over the circuit: earth, T11, cuit is closed (Fig. 4), from R63, R91, al T 151, R122, motor magnet RC1, to battery. When the Switch arrives at position 9, a cir ternating current relay 5, to earth, via con

25

cuit is closed from earth, R71, R124, contacts 9 and 10 of bank a 1, R101, motor magnet RC1 which is in self-interrupted operation, to battery. The latter moves over the two marked positions by automatic rotation and comes to rest in a position corresponding to

dense' C5. Relay 8 operates via T51. At R81 the energizing circuit of relay 15 is

90

opened. It releases and opens contact, T152, so opening the energizing circuit of the lower winding of relay 7 which falls back, except ing when the switch RC1 is in positions 19 and 10. In this case relay 7 remains held 95. the digit 10, closing H1. up its uppei' winding as described above. The impulse train being terminated, relay AtbyT81, 12 is energized over the cir 6 releases through the movement of polarized cuit: T81, relay T81, lower winding of relay 12, relay 16 to its negative position. to battery. Relay 12 holds up over the cir 35. A circuit is closed from earth, T23, H2, cuit: battery via its upper winding, T121, 00 H1, T153, lower winding of relay 9, to T31, earth (the latter opens in the present battery. Relay 9 operates. At T91 dialling case to at R124, the holding circuit of relay battery is extended to the upper wire of the 7). At this moment, the call is extended to junction. the subscriber the circuit, upper wire 40 It may be seen from the preceding that of the junctions,over R.63, T82, H2, (normal po 05 the said battery can only be sent if the sition RC2), T125, bank +1 and positive switch in question is in the home position, bank contact of the chosen subscriber, upper corresponding to the tens digit chosen (clos wire of the subscriber's line, bell, condense, ing of H1 or H1). 45 The operator then sends the units digit. lower wire of the subscriber's line, negative contact, bank -1, T126, T83, to earth. O This causes the movement of switch RCI bank The subscriber's calling relay A to the corresponding position over the cir energizeschosen through its upper winding, it be cuit: earth, T11, T151, R122, motor magnet, ing inserted in the line. By the closing of RC1, to battery. contact TA2, relay Cenergizes in series with 50 If the switch is rotated to one of the two relay and opens at C4 the circuit of the 15 subscribers corresponding to the numbers 19 calling13relay A. relay C then remaining en and 10 in moving over the contacts corre ergized via TC1. sponding to a 1, the automatic rotation cir The following operations are then identi cuit previously described is opened at R71, cal with those described above in Chapter I 55 relay 7 being energized. In addition, the by a rural subscriber'. - 120 switch having arrived in this position, the “Call III. Local communications-the description, following circuit is closed: battery, winding from the time of the reply ofof RC1, interrupter spring, R101, bank con continating the Snthsayiber The operations being the same as de 60 tact, 9 or 0 of bank a 1, R124. T71, upper winding of relay 7, to earth via T31. Relay scribed in positions: Section I, Fig. the apparatus is in the 125 7 is thus maintained operated and will re following 2, plug of a cord is main held up if the circuit of its lower in an answering jack. winding is opened. The third impulse train inserted Supervisory lamp LS is extinguished (the 65 having terminated, a negative battery exists calling subscriber having answered the recall on the lower wire of the junction and no signal). Relays 3, 5, 2, 8, 10 are energized, 30

1,907,062 ter being connected to a tandem office or a switch RC is in position 5, positive battery terminus office. 14

is on the upper wire of the junction. The operator having taken the requirements of the subscriber inserts the dialling plug in the corresponding jack and this causes the energization of relay 7. The holding circuit of relay 8 is opened at R71. The latter opens at TS1 the energizing circuit of relay 6 which falls back and so extends negative O battery to the lower wire of the junction. At the tandem office (Fig. 3), polarized relay 15 moves to its negative position. Re lay 2 remains energized via T151. The cir cuit of relay 12 is opened at T154 and it 15 opens at T124 the circuit of relay 31, which falls back. At T153 relay 6, which is slow to operate, is energized by its upper winding, via hl. It holds up over the circuit: T63, R84, 20 T23, to earth.

(2) Case where the calling subscriber is The beginning of the operations is the same as those described above. Reiay 6 (Fig. 4) energizes and holds up. In the case considered, relay 14 being en ergized remains held up via T143 and T23, to earth. The inversion of battery on the upper wire has been received at the terminus of fice, Fig. 4, on relay 16, and this causes the energization of relay 2 which holds up at T24. Relay 10 deemergizes.

connected to a terminus office.

70

75

80

The conditions at this office are then as follows:

At the manual position (Fig. 2), dialling lamp LN being extinguished the operator

Winds up her dial and a circuit is closed by the closing of the dial contact C2 to en 25 ergize relay 4 in series with TT1. The said relay holds up at T42. Relay 6 also holds up and at T61 sends positive battery to the lower wire of the junction. This causes at the tandeh office, Fig. 3, 30 the energization of relay 13 at T154 (the polarized Irelay moving to its positive posi tion).

Switch RC1 is held by the calling sub

relayrelays C of the line isscriber, energized, 12, 9,said2, 3,subscriber's are energized,

relay 16 is in the negative position. All the other relays are normal. Upon the winding up of the dial preced ing the first digit train, relay 15 (Fig. 3) moves to its positive position. Relays 13, 4, and 22 energizes as already described. Upon the energization of relay 4, the cir C it of the upper wire of the junction is

85

90

(i) eled at R.41 and is connected to relay at E4.1. it will be noticed that the first im buise train will orily be received on rela 1 at the tandon offibe. Three distinct cases then present them The following circuit is closed: battery, selves:

OO

1 (Fig. 3) causes the rotation of switch subscriber. RA into the position determined by the digit In the two first cases a, and b the local chosen. At the closing of bank 1', a circuit is connection may be established through the

O

via the safety resistance, T65, R322, T264, (a) The called subscriber is connected to R311, winding of relay 22, T133 to earth. the tandem office. Relay 22 energizes and holds up via cor (b) The called subscriber is connected to tact T221. Relay 4 energizes via T133. a terminus office different from that of the (1) Case where the calling subscriber is cailing subscriber. in the tandem office. The called subscriber is connected to 40 The first impulse train received by relay the(c)same terminus office as the calling

35

medium of Switches R1 and R2 of the closed from earth, bank 1', T62, R31, R142, tandem T222, R242, battery via motor magnet R2, In theoffice. third case (a) only switches RC1 which operates by self interruption. and RC2 of the terminus office in question d Switch R2, leaving its normal position, will be used. closes the following circuit: earth, a2, bat (i) The subscriber is connected to the 50 tery via the winding of relay 29, which en office. ergizes. The latter opens circuits of super tandem A number received on Switch RA has yision of S1, and also of relay 9 of the call caused the innovealent of this switch on to ing Subscriber at R291 and R292. The sub the stopping wire corresponding to the ar'scriber's line being reconnected at T291 and 55 T292, on to a similar arrangement consti rangement of the subscribers in the office, contrary to the operation previously tuted by battery through the upper winding but, described, switch R2 has not been set in of retard S2, T292, lower wire of the sub rotation through the closing of bank 1', Scriber's substation, upper wire T291, relay the circuit previously described being ob 25, to earth. The latter energizes. The cali 60 ing subscriber remaining in the main cir tained at R142 (14 being energized). At the end of the impulses, relay 4 de cuit via condensers C3 and C4. energizes and a circuit is closed from: earth, next by The dialling operations follow alk 1, T62, R31, T142, R42, resistance using this time Switch R2, by a medium of R1, battery, which causes relay 14 to be relay 22 in the same manner as described in shorttocircuited. 65 This relay releases. The

45

Section II (dialling a subscriber), the lat

5

20

1,907,062

15

rotation circuit of R2 is closed at R142. The minus office as previously described in Sec latter starts off in rotation and is stopped tion the only difference being at the at the desired position by the energization manualII, position, Fig. 2, where the posi of relay 3 in the following circuit: earth. tions of the cousting RC1 are suc R323, J2, via the bank of switch R2, control cessively 5, 6, 7, 8, switch and 9, respectively, 70 wire considered etc. . . . to the positions 1, 2, 3, 4, and 5. Switch R2 leaving its normal position idelitical In the of the two examples already uts of the control earth of wiper J1 at 52 mentioned,case and at the end of the operations, and at a:2 energizes relay 29. 0. the call being cut off, alternating current The apparatus at the terminus office is relay 7 operates at the tandem office, Fig. 3, then held up from the tandem office in oper and also relay 8. At contact the hold ated position over the circuit: battery, ing circuit of relay 6 is opened, 84, which upper winding of retard S2, i292, T262, the return to zero of switch RA, the causes latter etc. . . . 5 closing its contacts hi, h^1, h’1. Relay Polarized relay 16 of the terminus posi reenergizes at h’1. By the opening of T65,6 80 tion (Fig. 4) is at its negative position. relay 22 releases and does not reenergize In addition, the supervisory battery (as upon the reclosing of contact, T65, its cir long as the calling subscribe' remains on the cuit being opened at T221 and T133. If 20 line) is extended by the upper wire of the the called subscriber replies the operator is junction to relay 25 of the tandem office notified (as previously described) by the (Fig. 3) over the circuit.: T263, T291, wind extinction of supervisory lamp ILS. The two ing of relay 25, to earth (the subscriber Subscribers calling and called converse remains in circuit via the condensei's C3 through the medium of condensers C3 and C4. 25 and C4). The operations follow at the tandem office The operator can release the operation of 90 as already described in Chapter III. not utilized by the local connec (b) The called subscriber is connected to the circuit, To this end, she withdraws the plugs a terminus office, different from that of the tion. (dialling plug), the potential of occupation 30 calling subscriber. (negative) from the lower wire 95 The number received on switch RA, Fig. of the mainis removed circuit, and causes the 3, has caused the movement of this switch release of polarized relay 15this at the tandem until the stopping wire corresponding to the office (Fig. 3). junction to be used is reached. A circuit is then closed from earth, R221, 35 As previously, the switch R2 is not set in T224, lower winding of relay 32, R322, wind rotation until the conclusion of the impulse ing of relay 2, to battery (this circuit 00 train. prepared at the time of the call of the second Relay 4 releases and short circuits the subscriber only causes the energization of upper winding of relay 14, which releases. relay 32 upon the opening of the short cir 40 Switch R2 is set in operation, and the cir cruit at T151). The latter energizes and cuit of the calling subscriber is moved to up at T321 to battery via resistance the local connection device at T291, and holds R2. At T324 battery is sent on the lower T292 by the operation of relay 29. wire either of the subscribers if he is con The stopping on the junction considered nected to a tandem office or of a junction if 45 is brought about by the operation of relay 3. he is connected to a terminus office. In this A circuit is then closed from earth, bank, case this battery replaces that which is about :0 1', T62, T31, R43, bank 1', bank contact to be removed from the manual position and corresponding to a junction, winding of maintains through the medium of polarized relay 14, to battery. The latter energizes relay 16, Fig. 4, the terminus office appa 50 and when the dial returns to normal (15, ratus in the operated position, the momen in the negative position, 13 released) causes removal of the said battery not having 5 the energization of relay 24 (if the junction tary caused3. the release owing to slow release considered is free) over the circuit: earth, relay T143, R131, T223, the two windings in series in both cases, there will be a battery on 55 of relay 24, wiper T2, bank contact T, relay the upper wire as long as the called sub 20 C of the chosen junction to battery. These scriber on the line. This battery at two relays energize in series and hold up at T323 isremains sent via relay 23 to earth. Relay 241 to the earth at T271. The main circuit is from that time di 23 energizes. The holding circuit is then closed from earth, T231, T251, relay 27, bat rectly connected to the junction of the call tery, 60 the said relay (slow to release) having ing subscriber's terminus office, over the cir just had cuit: upper wire R41, T141, R323, T242, R.32. its energizing circuit opened at wiper and bank contact. --2, etc., lower In addition, at T322 the switch-taking wires T141, R324, T245, wiper and bank circuit is transferred to relay 28. 63 contact, -2, etc. . . . At 323 control earth is removed from 30 The operations follow next at the ter J2 and is the transferred to J3.

16

1,907,062

i'angement as explained at the beginning of the cases () or (b). The first digit in this case received on switch RA of the tandem office. Fig. 3, has 70 :aused the rotation of switch R1 on to the conti'ol wire corresponding to the position (ccupied by switch RA. A circuit is closed from earth, R323, J2 on its normal position, J1, control wire considered, bank 1 of switch R.A. aid battery through the lower 5 winding of relay 3 which energizes. The latter opens at R31 the short circuit to relay 14, which in this case remains held up. 32 remains energized. Owing to this fact, switch R2 will not be 80 When the conversation between the two 5 local subscribers is finished, they hang up put in operation, its rotation circuit remain at R142. and this causes the release of the apparatus ingAtopen end of the first impulse train, re used for the establishment of the said con lay 4 the releases and will not be reenergized nection. during the two trains, its circuit being 85 Upon the hanging up of either one of the opened at h’1.other At R41 the main circuit 20 two subscribers, supervisory battery is re is again directly connected to the calling moved from the upper wire of the junction office which is about to receive the either directly or through the medium of terminus following impulse trains, during the relay 9, Fig. 4. if the subscriber in ques two course of which in the talden office, relay 90 tion is connected to a terminus office, this 13 (through the medium of relay 15) will 25 causes at the “tandem’ office the release of open at T132 the circuit of relay 7 to corresponding relays 23 or 25, or both. earth. These at 231 or 251 open the energizing cir At the terminus position, Fig. 4, we have cuit of 27 which releases some time after the following: relay 9 being held operated 95 wards (the latter being made slow to release 30 in order to avoid a momentary opening of through the answering of the cailing sub and also the sending of dialling bat the circuit indicated above which would scriber tery to the manual position immediately cause the completion of the previously de By the the release). opening of T271, the circuit of upon scribed circuit to the tandem office. relays 24 and 26 is opened, these release and The operator winds up the dial, polarizes 00 35 open the lines respectively at 263,265, and 16 moves to its positive position. Re 242, 245, which causes the removal of bat relay lay 6 and connects at T63 relay tery (through retard S2) from the lower 1 to theenergizes upper wire junction. wires. This causes in the present case the The impulses sent ofarethereceived on the said 05 release of the terminus office used through 40 the deenergization of polarized relay 16 relay which as previously described corre spond to the digits 1 or 0 (one or ten im (Fig. 4). This causes the energization of At tandem office the release of relay 26 pulses). relay 15 and the maintaining in its initial causes also the resetting to normal of switch position of Switch RC2, or its return to the O R1 over the circuit: earth, at1, R311, R262, beginning of the Second ten over the circuit: 45 motor magnet R1, to battery. battery T11, T151', (after first impulse) The release of relay 24 causes the resetting T122, R142, motor magnettheRC2 to battery, to zero of switch R2 over the circuit: earth, T11, T151', (after the first impulse) ac2, R222, R242, motor magnet R2, to bat R142, motor magnet RC to battery. T122, The 5 tery. Upon the opening of a;2 relay 29 latter thus moves automatically to the nor 50 releases. mal position of the second ten over the cir Finality, at 244, the energizing circuit of cuit: earth, T1, R145, positions 9 and 0 of the lower winding of relay 32 is opened. the first ten, bank a2, and battery via the If the main circuit is occupied at this time motor magnet which is in self-interrupted 20 (using the switch R3) relay 32 remains ener operation. 55 gized over the circuit: battery, upper wind impulse train having finished, relay ing. T321, T23, to earth, maintaining thus 16The returns to its negative position, relay 6 the switched condition of the connection on releases, dialing battery is sent, over the R3. The circuit having become released, the upper wire, relay 9 being held up, in the 25 said relay releases and reprepares the 60 switching on to switch R1 at R323, R322', first case (beginning of first ten) by the hanging up of the calling subscriber as R321', R323, R324. previously, in the second case (beginning (c) The called subscriber is connected to of ten) over the circuit: earth, the same terminus office as the calling Sub T23,theH2,Second H2, T2, T153, lower winding of 30 scriber. relay 9 to battery; the upper winding of the 65 Let us consider the functioning of the ar

Polarized relay 15 releases (returns to its middle position) and the restoration to nor mal of the apparatus associated with the principal circuit, is brought about and this includes relays 1-15 of switch R.A. The principal or tandem office circuit can then deal with either rural-manual or man al-rural calls through the medium of switch R3 in the same fashion as previously de 10 scribed in Chapters I and II with the use of switch R1. Relay 31 being replaced in the description by relay 28 as long as relay

1,907,032 17 said relay being disconnected from the up tion is established as above, the junction per wire of the calling subscriber at 12 as

is taken for the establishing of a manual communication through the medium of Switches ii.1, R2, or R3 of the tandem of fice, the following takes place: 70 The operator after sending the first digit receives the busy signal through the flick ering of the dialling lamp (battery being removed from the upper wire of the junc tion at the terminus office at R42). The operator by the operation of her listening key enters into the conversation directly With the subscribers in the local connection and asks them to release. It is possible, in cases of extreme urgency, to force the re 80 lease of a local connector by the operation chosen ten of switch RC2 on to the called of her forced listening key which causes as subscriber. previously the movement from the The call is seat in the usual nainner, which negative to described the positive position of polarized 20 causes the energization of 'elays 5 and 6 relay 16. (the cail is not sent to the calling subscrib Relay 6 energizes, and at 61 opens the 85 er-his circuit being opened at H2 holding circuit of relay 14. Relay 9 deen R82). The energization of relay 8 causes ergizes. Upon the withdrawal of the plug, 25 also at T81 the energization of relay 14 the Switches return to normal as described through its lower winding unshort-circuited above. by the opening of H'2. It holds up via The various preceding descriptions relat 90 T141, R61, T3i, to earth. to the putting into communication of The call is at this time extended towards ing two local subscribers following upon the call he called subscriber as already described of a calling can equally well be 30 by the closing of T144 and T146. Upon applied to thesubscriber case where both subscribers taking of the receiver by the latter, relay 9 are dialed. energizes over the circuit.: earth, upper The first stage is described in Section II winding of 9, R82, T144, substation T146, (call of a subscriber) then without further 35 R84, to battery through left-hand winding operations being included, the dialing of of retard S2. Supervisory battery is sent the second subscriber takes place as de 00 on the upper wire of the junction. The scribed above in Section i. calling finished, the operator is notified of in addition, at the tandem office, Fig. 3, the withdrawing reply of the the subscriber an arrangement for listening and for re by plug. and can release leasing the local connection is provided. 40 The two subscribers are in cominunica The operator dials on the principal cir 105 tion via the condensers C2 and C4. cuit corresponding the local engaged con Upon energization of relay 14, relay 11 nector a digit whichto causes al is put in circuit at T143 on to the calling ready the movement of switchas described R3 on to the subscriber instead of relay 9 which is trans listening circuit. Relay 21 energizes in the ferred to the called subscriber. The two same manner as cut-off relays C and C. 0. subscriber's being unhooked, these two relays Listening in, and the conversation is then are energized. dependent upon condensers C7 and C8. When the operator releases, relay 16 comes The operator can advise the subscribers to to its middle position, and a circuit is closed hang up and can, in cases of extreme ur 50 from T31. T92, T111, lower winding of re gency, from the office by the operation 15 lay 4, to battery through the winding of of her release forced listening key the subscribe's relay 3. . the connection. Relay 4 energizes and holds up through in To end, the following takes place: its upper winding at T41. At T43 the low Relay this 15 moves positive position. Re i er winding is next short circuited, finally lay 13 energizes.to itsRelay is short cir 20 by the opening of 42 battery is removed cited over the circuit, T211,23T133, to earth. from the upper wire of the junction. The latter releases, causing the deemergiza Upon either subscriber hanging up, the ion of relay 27, which causes the switches 60 switches are returned to norinal, T92 or 111 used in the local connection to return to nor opens. Relay 3 releases slowly, the holding nai. The operator can after plugging use 25 circuits of relays 2, 4, 12 and 14 are opened switches at T31, switch RC1 returns to its home po nections. R1 and R2 to establish other con sition via F.31 and R71 as already described, What is claimed is: and switch RC2 via R23 and 71. In a telephone system, two offices, call If during the time when a local connec ing1. lines and called lines in one office, a 30 soon as switch RC2 leaves its. normal posi 5 in addition and in both cases, eelgizes over a circuit.: earth, T3:... T92, R11), R62, R152, lower winding of relay 7 to battery. Relay 7 hoids up over the saine winding 0 T152', T72, and earth at T31. This from that time by the opening of R71 permits switch RC2 to rotate to positions 9 and 0 of the first ten, withot being aitomatically taken back to the hone position of the foll lowing ten. 5 The units digit is then sent in the usual manner, which cases the iotation in the tion in the first ten.

sy

c...ii.V.

1,907,062 18 said second switch to connect with the trunk line connecting said offices and termi ing line. nating at said one office in switching mecha calling 6. In a telephone system, two offices, lines nism having access to said lines, and means terminating in one office, a two-way trunk 70 responsive to one operation at the other of line connecting said offices and terminating 5 fice for operating said switching mechanism at said one office in a switch having access to find a calling line and means responsive to said lines, a signal at the other office, to a different operation at the other office means responsive to the establishment of a for operating said switching mechanism to calling connection over said trunk line by find a called line. of said lines for operating said signal, 2. In a telephone system, two offices, a one O means connecting with said trunk line trunk line connecting said offices and ter at said for other for extending a connec minating at one office in an automatic tion to one ofoffice said and means for switch, lines at said one office accessible to disabling said signal lines, to the es said switch, a signal at the other office, tablishment of said lastresponsive connection with the 80 5 means responsive to the initiation of a call trunk line. on one of said lines for operating said sig 7. In a telephone system, two offices, a nal over the trunk line, and means con trunk line connecting said offices and termi trolled over the trunk line from said other nating in an automatic switch at one office, a 85 office for operating said switch to connect dialling circuit at the other office and means 20 with the calling line. for connecting it to the trunk line to direc 3. In a telephone system, a main office tively control said a supervisory sig and a branch office, a trunk line connecting nal associated withswitch, said circuit, for said offices and terminating in a manual operating said signal responsive tomeans the con switchboard at the main office and in an au nection of said circuit with the trunk line, 90 25 tomatic switch at the branch office, lines ac means for extinguishing said signal in case cessible to said switch, a signal at said said switch is in normal position, and means switchboard, means responsive to the initia for maintaining said signal operated in case tion of a call on one of said lines for oper said switch is in an off-normal position. ating said signal over the trunk line, and 8. In a telephone system, two offices, a 30 means responsive to the establishment of a trunk line connecting said offices and termi connection with said trunk at the switch nating at one office in a switching device board for operating said switch to connect comprising two selective switches, a third with the calling line. -associated with said selective 4. In a telephone system, two offices, a switch Switches, calling and called lines at said one 00 trunk line connecting said offices and ter office, means controlled over the trunk line minating at one office in a plurality of from said other for operating the first switches, lines at said one office accessible to selective switch office to connect a calling said switches, a signal at the other office, line, means controlled over with the trunk line 05 means responsive to the initiation of a call from said other office for directively operat 40 one one of said lines for operating said sig ing said third switch to designate a called nal over the trunk line, means at the other and means responsive to the operation office for connecting with said trunk line, line, of said third Switch for operating the second means responsive to the establishment of a switch to establish a connection connection with the trunk line for operating selective with the called line designated by said third one of said switches to connect with the call switch. ing line, and means controllied from the 9. In a telephone system,- two offices, a other office over said trunk line for operat two-conductor trunk line connecting said ing another of said Switches to connect with offices and terminating at One office in a another of said lines as a called line. device comprising a selective 5. In a telephone system, three offices, a switching switch and a register switch, means at the trunk line connecting the first and second other exchange for transmitting impulses office and terminating at the second oilice over one conductor of the trunk line to di in an automatic switch, a second trunk line rectively operate said means for connecting the second and third offices and operating said switch toregister, a particular posi terminating at the third office in a second 55 in accordance with the setting of said automatic switch, lines in the third office tion register, operated over the other accessible to said Switch, a signal at the first conductorandof means said trunk line for maintain office, means responsive to the initiating of a ing said switch in said particular operated call on one of said lines for operating said position. 60 signal over said two trunk lines, means re In a telephone system, a two-conduc sponsive to an operation at the first office to10.trunk two offices, a line for operating said first switch to collect terminatinglinein connecting one office, means responsive with the second trunk line, and means re to the condition of said line transmit sponsive to the establishment of the connec ting a plurality of separate andfordistinct sig 130 65 tion with the second trunk line for operat

i,907,062

nails over one conductor of the trunk line, switches to connect with a called line, means and means at the other office for transmit for establishing a talking connection be ting a plurality of separate and distinct tween the lines connected with by said two signals over the other conductor of the switches, means controlled over said lines trunk line. for maintaining said talking connection in O 11. In a telephone system, a trunk line deeendent of control the trunk line, terminating in a switching device compris means for operating over the third of said ing three automatic switches, calling and Switches to connect with said talking con called lines accessible to said switches, nection, and means rendered effective re means controlled over the trunk line for op sponsive to said last connection and coin 75 erating the first and second of said switches trolled over the trunk line for forcibly re to establish a talking connection between leasing said talking connection. a calling and called line, and means con 16. in a telephone system, a trunk line 15 trolled over the trunk line for operating the extending from an operator's position to a third of said switches to establish a connec Switching device comprising three auto 80 tion with a calling line while said first con matic switches, lines accessible to said nection is maintained. a signal at the position, means re 12. In a telephone system, a trunk line Switches, sponsive to initiation of a call. On one terminating in a switching device compris of said linesthe for operating said signal ovel' 2 ing three alltomatic switches, calling and the trunk line, an operator's link circuit 85 callied lines accessible to said switches, at the position and means for connecting means for operating the first of said it to the trunk line, means responsive to the Switches to connect with a calling line, connection of the link to the trunk line for means for operating the second of said operating the first of said switches to con switches to connect with a called line, means nect with the calling line, means for restor 90 for establishing a talking connection be ing the signal to normal responsive to the tween the lines connected with by said two establishment of the connection with the switches, and means for operating the third calling line, means at the position for olp of said switches to connect with another erating the second of said switches to con 30 'alling line while maintaining said first con nect with another of Said lines, means for 95 lection. establishing a talking connection between 13. In a telephone system, a trunk line the lines connected with by said two terminating in a Switching device compris switches, means for freeing the trunk line 35 ing three automatic switches, a calling line from said connection without releasing the and a called line, means controlled over the connection responsive to the disconnection of 00 trunk line for operating the first of said said link circuit from the trunk line, means Switches to connect with the calling line, responsive to the initiation of a call on an means controlled over the trunk line for di other of said lines for reoperating said sig rectively operating the second of said nal over the trunk line, and means respon 40 Switches for locating said called line, means sive to the reconnection of said link cir 05 for operating the third switch to connect, cuit to the trunk line for operating the third with said called line, and means for estab of said switches to connect with said other lishing a talking connection between said calling line. lines via said first and third switches and 17. In a telephone system, a trunk line 45 for releasing said second switch. extending from an operator's position to an 14. In a telephone system, a trunk line automatic Switch, a calling line accessible to O terminating in a switching device compris said switch, a link circuit at the position ing three automatic Switches, calling and adapted to be connected to the trunk line, .50 called lines, means controlled over the trunk a signal associated with said link, means line for operating the first of said switches responsive to the connection of the link cir 5 to connect with a calling line, means con cuit to the trunk line for operating said trolled over the trunk line for operating the switch to hunt for the calling line, means for Second of said switches to connect with a operating said signal in one manner during called line, means for establishing a talking 55 connection between the lines connected with the hunting operation of said switch, and means for operating said signal in a differ 20 by said two switches, and means controlled ent manner responsive to said switch finding over the trunk line for operating the third the calling line. of said switches to connect with said talking 18. In a telephone system, a two-conduc connection. tor trunk line, two link circuits adapted to 60 15. In a telephone system, a trunk line tei'- the trunk line, means responsive to the con minating in a switching device comprising nection of the first link to the trunk line three automatic switches, calling and called for connecting a source of current of one lines, means for operating the first of Said polarity to one of said trunk conductors, to connect with a calling line, means including the other link for transmit 65 switches means for operating the second of said ting impulses over the other of said trunk 30 s

1,907,062

conductors, and means controlled from said other link for disconnecting said current source of one polarity and for connecting a current source of the opposite polarity to

the first office, means responsive to the initia tion of a call on one of said lines for oper

ating said signal over said two trunk lines, means responsive to an operation at the first office for operating said first switch to con said one trunk conductor during the trans nect with the second trunk line, means re mission of impulses.

-

70

to the establishment of the connec 19. In a telephone system, two offices, a sponsive with the second trunk line for oper trunk line connecting said offices and termi tion nating at one office in an automatic switch, atting said second switch to connect with O lines at said one office accessible to said the calling line, a source of signalling cur rent at the first office, and means responsive switch, a signal at the other office, means to establishment of the connection with responsive to the initiation of a call on One thethe calling line for connecting said current of said lines for operating said signal over Source to the calling line via said trunk 80 the trunk line, means controlled over the 5 trunk line from said other office for oper lines. telephone system as claimed in claim ating said switch to connect with the calling 2324.in Awhich disconnection of the source line, and means responsive to the establish of signallingthecurrent the calling line ment of the connection with the calling line is controlled over thatfrom line. for signalling the line. 25. In a telephone system, three offices, a 85 20 20. In a telephone system, two offices, a line connecting the first and second trunk line connecting said offices and ter trunk and terminating at the second office in minating at one office in an automatic switch, offices lines at said one office accessible to said a Switching device comprising two auto matic switches, a second trunk line con 90 switch, a signal and a source of signalling necting the second and third offices and ter. 25 current at the other office, means responsive to the initiation of a call on One of said minating at the third office in a second lines for operating said signal over the trunk switching device comprising two automatic lines at the second and third offices line, means controlled over the trunk line switches, accessible to the respective switches, a sig 95 from said other office for operating said nal at the first office, means responsive to 30 switch to connect with the calling line, and initiation of a call on one of the lines means responsive to the establishment of the the connection with the calling line for in at the third office for operating said signal termittently transmitting signalling current Over the two trunk lines, means responsive from said source over the trunk line and the to an operation at the first office for oper 00 ating one of the switches at the second office 35 calling line. 2). In a telephone system, two offices, a to connect with the second trunk line, means trunk line connecting said offices and ter responsive to the establishment of the con minating at one office in an automatic switch, nection with the second trunk line for oper lines at said one office accessible to said ating one of the switches at the third office connect with the calling line, means at 40 switch, a signal and a source of signalling to current at the other office, means responsive the first office for transmitting series of im to the initiation of a call on one of said lines pulses over the first trunk line indicative for operating said signal over the trunk of called lines in either the second or third and means whereby the other switch O line, means controlled over the trunk line offices, . 45 from said other office for operating said at the second office is set responsive to series switch to connect with the calling line, means of impulses indicating a called line at that responsive to the establishment of the con office and whereby the other switch at the nection with the calling line for connecting third office is set responsive to series of im said current source to the line via said trunk pulses indicating a called line at that office. line, and means controlled over the calling 26. In a telephone system, two offices, a line for disconnecting said current source trunk line connecting the offices and termi therefrom. nating at the second office in a switching 22. A telephone system as claimed in device two automatic switches, claim 21 in which a Supervisory signal is lines atcomprising the second office accessible to said 20 operated while signalling current is applied a signal at the first office, means to the line and disabled when the signalling switches, responsive to the initiation of a call on one current is disconnected from the line. of Said lines for operating said signal over 23. In a telephone system, three offices, the trunk line, means responsive to an oper a trunk line connecting the first and second 60 offices and terminating at the second office ation at the first office for operating one of switches to connect with and signal the in an automatic switch, a second trunk line said calling and means responsive to an connecting the second and third offices and operationline, by the party on the calling line terminating at the third office in a second for disabling said signalling means and for 130 automatic switch, lines in the third office 65 accessible to said second Switch, a signal at rendering the other of said switches di

1,907,062

Fectively controllable over the trunk line 27. In a telephone system, a trunk line terminating in an automatic switch, a relay having a normal position and two operated positions in the Switch, means for operating the relay to one position responsive to the trunk line being taken into use, means con trolled by the relay in said one position for O placing the switch in holding condition, eans controlled over the trunk line for operating the relay to the other position, and means controlled by the relay in said other position for placing the switch in 5 operating condition. 28. In a telephone system, a trunk line terminating on an automatic Switch, a re lay having a normal position and two oper ated positions in the Switch, an impulse re lay and a holding relay in the switch, means for operating said first relay to One posi tion responsive to the trunk line being taken into use, means controlled by said first relay in said one position for operating said hold 25 ing relay, means for Operating said first re lay to the other position over the trunk line, and means controlled by said first relay in said other position for maintaining said holding relay operated and for connecting 30 said impulse relay to the trunk line. in witness whereof, hereunto subscribe my name this 29th day of July, A. D. 1931. from the first office.

FERNAND GOHOREL. 35

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