US1845983A - Telephone system - Google Patents

Description

- Filed March 20. 1930 5 Sheets-Sheet l Inuen or Charles L. PETE F's" Feb. 16; j 1932. c. 1.. PETERS TELEPHONE SYSTEM Filed March 20, 1930 5 ShBQLS-Sheet Inusn 01'' Charles L. FEE-"5 Feb. 16, 1932. c PETERS 1,845,983

TELEPHONE SYSTEM Filed March 20. 1930 5 Sheets-Sheet 3 Irma? Charles L. PETEE C. L. PETERS SYSTEM Feb. 16, 1932.

TELEPHONE Filed March 20. 1930 5 Sheets-Sheet 4 Inuen or Charles L. PE are Feb. 16, 1932. c. L. PETERS 1,845,983

TELEPHONE SYS TEM Filed March 20. 1930 s Sheets-Sheet s Patented Feb. 16, 1932 c UNITED STATES PATENT OFFICE.

CHARLES LEONARD PETERS, 01 LONDON, ENGLAND, ASSI GNOR TO SItEMENS BROTHERS 86 COMPANY, LIMITED, OF LONDON, ENGLAND TELEPHONE SYSTEM Application filed March 20, 1930, Serial No. 437,544, and in Great Britain March 26, 1929.

The present invention relates to automatic and semiautomatic telephone systems and more particularlyto a system employing register controllers for recordingthe numbers dialled by subscribers and controlling selection oi the desired line and for other operations connected with the setting up of a call.

The invention though capable of wider applications is especially suitable for use in connection with small unattended exchanges and meets the demand for special services. The system shown herein may be considered as an improvement on the system shown in the patent to D. A. Christian, 1,738,564, granted December 10, 1929. y

it is provided in the present invention that a digit recording switch in the register controller or an equivalent of such switch e. g. a relay set hereinafter called a digit switch has more contact positions than those corresponding to the digits employed in the sub scriber numbering scheme, and the surplus contact positions are employed for special operations to be controlled by a distant operator. Such special operations include trunk oil'ering whereby the entry into an engaged line must be secured, getting access to a tone circuit which can signifya normal or abnormal condition at the exchange and controlling the starting or stopping of battery charging equipment.

The special operations are initiated by the operator dialling a digit or digits which sets the digit switch onto the appropriate contact where an appropriate relay may be operated.

A further feature of the invention is that to prevent any interference by ordinary subscribers, the relays concerned with the special operations are only connected to the switch contacts when the register controller is taken into use by an operator. To this end it may be arranged that whilst the incoming end of the junction from the operators position has line equipment such as is provided for a subscribers line, certain auxiliary equipment is provided whereby a relay is operated in the register controller and connects up therelays concerned with the special operations. If connections are made tothe surplus contacts whereby an ordinary subscriber may by dialling special digits bring aboutcertain operations such as the setting up of a connection to the manual operator or a throw-out of ex change apparatus on inter-party calls, these special digitsmay be used by an operator for other purposes by providing for a change of connections when the relay operated from the auxiliary equipment is energized.

Likewise if provision is made whereby a signalis given to a subscriber if he dials a digit not in the range of subscribers mom hers, the surplus contacts involved or any of them may be used for special operations controlled by the operator.

In connection with trunkofi'ering it may be provided that the operator dials a special first digittobring about circuit changes in the register controller of which allow of breaking into an existing connection.

In this case we may arrange that the first digit switchof the register controller after being operated by the special first digit causes a discriminating relay to operateandthen returns to normal to be operated subsequently by the first digit of the subscribers number.

.In a system in which the testing of a required subscribers line and the subsequent operations are effected from the register controller, the discriminating relay may control circuit for switching through the operator to the required subscribers line independently of whether the line is free orbusy.

WVhere the. register controller includes an additional switch or switches which are 0perated to select a ringing circuit for party line calls, one of the switches may also be used to select circuits for say battery charging control under the control of impulses sent by the operator, the first digit sent having operated a special operation relay which brings the ringing circuit selecting switch into the impulsing circuit.

Other features of the invention will become apparent upon a further perusal of the specification.

Reference will now be had to the accompanying drawings which show by way of (3X ample one anethodjof carryingout the invention. The drawings show circuits in a small unattended automatic telephone exthe register controller with it.

' exchange' apparatusin setting up a call change in which provision is made for local calls between individual line subscribers, calls to and from party line subscribers, and calls over junctions between the automatic exchange and an operators position at a main exchange. Besides the handling of ordinary subscriber calls, the operator at the main exchange is able to set up trunk calls to a subscriber who is already engaged in alocal call, and to control the chargingiof the battery at the automatic exchange and to ascertain if any faults exist at the automatic exchange and if so the class of fault.

For the purpose of the following description the drawings should be arranged with Figs. 1, 2 and'8 on the left, Fig. 4; to the right of Figs. 2 and 3', and Figs. 5 and 6 beneath one another below Fig. 4; Fig. 7 should be placed onthe right of Fig. 4.

' Fig. 1 shows equipment connected in between-the line circuit shown in Fig. 2 and the terminals on the main distributing frame connected to a'jun'ction to the main exchange which controls the special services provided for. The line circuit shown in Fig. 2 may be'usedin connection with subscribers" lines or with junction lines, the straps shown on the left of the figure being removed when the circuit is connected to equipment as'shown in Fig. 1. 'Fig. 3 shows'an assigner for allotting,-for use on'a call,'one of two register controllers which connects itself to-an idle connecting circuit and receives the dialled impulses, sets the connector of the connecting circuit on to contacts associated with the required line and 'performsany special servdetailed description of the circuits involved and of those concerned with the performance of the special services available toan oper- 'ator' at the'main exchange. i

On theinitiation of a call, the line relay- LA operatesand closes a circuit to the 'as-' signer AG which then assigns a' free register controller to deal with the *call. 'Ahunting switch CGF is set inmotio'n to connect'the' "ceeds' to search for the calling line whi'ch' register controller with a free connecting circuitjGC, the call finder CF o'f'which pro when foun'd is connected overthe' banks of theswitch CCF to the register controller. In the register controller arethree digit switches DT, DU and DA on which the digits of the subscribers number are recorded. The exchange in the present example is arranged for 50 lines, consequently individual subscribers numbers will comprise two digits only and these are recorded on' switches DT and DU. DA records the digit which designates a particular party on a party line and provides for the application of the appropri ate ringing code,[the control of the code ringing being effected I by switch DB.

7 Switch DA is also employed in connection with the control of the charging of the automatic exchangebattery; Switches DT, DU, DA are 25-point. switches, and as regards switches D1 and DU, the operative contacts in the first part of their banks are connected symmetrically to "contacts in the latter part of their banks. Only some of these contacts are requiredfor subscribers numbers, the remainder being used for special purposes. For instance in the arrangement shown contacts 2to 6 from the normal in the banks of switch DT areallotted to subscribers-numbers; contacts 1 and 8 are wired for dealing with dead number calls;'fcontact .7 is wired for the release o'f'the excha-ngeapparatus on interparty calls, in which case, before the call ing subscriber useshis hand generator to call the wanted party on the same line, he dials the digit 7 to effect the release of the seized exchange apparatus. Contact 9 of switch DT is wired for fault supervisory purposes and forfthe control of the battery charge while-contact 10 is used for outgoing junction calls from a subscriber and for the setting'up of preferred calls to a busy line by an operator at a distant exchange. This latter operation and those giving the special services provided for over Contact 9 can only take p'lace'whe'n the 'call is initiated ato'r at a distant exchange astherelevant circuits depend for their operation on the energization of relay J C' which canonly. occur when the register controller is connected over the junction equipment jumpered in between the main distributing frame and the line circuit. V

The switchCCF besides hunting for a free connecting circuit acts as a sequence switch with three positions. In the first position an idle' connecting circuit isseized an'dits call finder'ro'tated in search of the calling line.- When 'thishas been found theswitch CGF is stepped to its second position and the dialled digits are received in the register controller on the digit switches; Vhen all the digits have been-received the wanted" line is'marked in the bank' of the connector CS which is started in search of the marked line. 'The line when found is tested to ascertain whether it is free or busy andrif' free is marked engaged against. other call finders and connectors. The switch GCF'is then stepped to its third position I which ringby an opering current is connected to the line from the scribed. As regards Fig. 2 the straps between the terminals will remain as shown, the meter M being connected to wire (Z. VV1res a; and h are connected to the subscribers line on the main distributing framehen a subscriber lift-s his receiver to make a call his line is looped and line relay LA operates over the loop. At contact Zcl the test-in circuit of the connector GS (Fig. 4) is opened thereby marking the line engaged in the connector multiple. This can be seen by reference to Fig. 7. In its front position contact Zal connects battery over cut-otl relay CO and baclr contact p02 to the test bank contact of the call finder CF (Fig. l) to mark the line as calling in the call finder banks. At contact lei a circuit is closed for relay AS in the assigner. Relay PG is included in this circuit but does not operate owing to the resistance of the circuit.

If the assigncr circuits are in the position shown a circuit for relay AA is closed from battery over contact thi winding 1 of relay AA, hack contacts 661, col, contact cal to earth. Itelay AA operates and at contact cad closes a circuit from battery over winding I ot' relay CC, back contact 5M, front contact (Add, contact cal to earth. Relay CC operates and at the front position of its make-before breal: contact col, connects earth over contact cs1, winding II of relay CC and front contact (m3 to the starting wire oi a register controller, which wire is either connected to battery over starting relay EST it the register controller is free, or is disconnected it the register controller is engaged. If the register controller is free, relay CC holds in series with relay ST. Relay BB operates by means of its winding I in series with. winding I of relay AA and contact arr/2 when the short circuit across it is removed by the changing over of contact cal and opens contact 5122. Contact 5711 changes over leaving the two re lays dependent on relay AA. If the register controller assigned over the front of contact (m3 is busy, relay CC does not hold and on the restoration of contact 001, winding II of relay BB energizes over contacts M3, bbl, cal and asl. At the same time winding II of relay AA is energized in parallel with winding II of relay BB and as the windings of AA are arranged diflerentially, the latter relay releases and contact cal and M42 opening, leave relay BB dependent on relay CC for its continued energization. Contact ace falling back closes a circuit for winding I of relay CC over the front of contact Z1224 and winding II of relay CC is connected over back contact m3 to the other register controller, two register controllers being provided. When contact 001 changes over relay BB rcleases and opens the circuit of winding I of relay CC leaving that relay dependent onthe condition found on the wire connected to the back oi contact aa3. It the register con-' troller, the starting relay of which is connected to this wire is free, relay CG continues to hold otherwise it releases and relay AA re-operates to test the first-mentioned starting circuit again.

Assuming that one of the register control lers is free, relay ST operates in a circuit from battery over the relay winding, contact #1 2 of the ring tripping relay 'IR, contacts 91, 6Z7, wiper D313 of the tens digit switch in its normal position, contact (m3, winding II of relay CC, contacts 001 and cal to earth.

Switch CCF besides connecting the register controller to the connecting circuit acts as a sequence switch for the carrying out of various operations "through the connecting circuit under the control of apparatus situated in the register controller. For this purpose the switch has three positions associated with a connecting circuit. In the first, the test for a free connecting circuit is made, the call tinder set huntin for the calling line and the line extended to the register controller. In the second, the dialled impulses are received and the connector set on to the wanted line, and in the third, the called line is rung, and when the subscriber replies to the call, the calling subscribers meter is operated. The switch remains in the j ird position after use in which position t e test circuit over wiper 7 of switch CCF is either openor earthed. (in the closure of contact $252 a circuit is closed for magnet DF over an interrupter and the switch is stepped once to the first position associated with another connecting circuit. If this circuit is busy .the test relay T associated with switch GCF .will either be short circuited over Wiper 7 and contact Q11 in the other register controller or the circuit of relay T will be open at contact no? in the engaged connecting circuit. Switch CCF is stepped by the interrupter until a free circuit is found. Whilst in the second and third positions associated with an engaged connecting circuit, relay T will be prevented from operating in a similar manner to that in the first position.

The circuit of relay '1 being prepared at contact stl the relay operates when free contacts are encountered over wiper 7 inits first 5 nection is not completed within a prescribed test relay T to reduce the potential on the,

period. Contact st5 closes a holding circuit for relay ST against operation of relay Q.

When relay T operates. contact 61 short circuits the high resistance winding I of the testing contact to mark the connecting circuit engaged. Winding I of relay Q, is energized over contact 62 and the relay operates slowly. Contactt3 changes over to prepare the circuit of magnet DF for stepping the switch to its second position. Contact Z4 prepares the circuit of the callfinder test relay TC, contact 65 prepares a circuit. for

relay B and contact t6 operates magnet DC of.

the connector. Magnets DF, DA and DB are all of the reverse-drive type, i.; e., they step their switches on the release of their armatures. -Relay Q operating contact 94 opens the circuit of magnet DC and the connector takes one step.

Contact 91 opens in the operating circuit of relay ST but this relay is held over contact st5. A circuit is now closedzfrom earth over interrupter contacts g3, 55, 2, wiper 5 of switch CCF in its first position and contact 1603, magnet DD of the call finder to battery. The call finder CF is stepped in searth of the calling line unless it happens to be standing on contacts connected therewith at the time. When the calling line contacts are reached, relay TC operates in a circuit from earth over contact 254, wiper 2 of switch CCF, its winding I, wiper C of the call finder, contacts p92, Zal in the line circuit, relay CO to battery. Contact Z02 changes over to connect Winding II of relay TC in a holding circuit in series with winding II of relay T and in parallel with relay S. Contact tel connects earth to the. call finder test wiper to mark the line engaged and to operate relay CO which looks up over its contact 001. Contacts 002 and 003 disconnect line relay LA and on its release, relay PG. operates over contacts M2 and 004 but without effect. Contact Z03 opens the call finder magnet circuit and contacts 604, and tc5 connect the incoming speaking wires to the bank contacts of wipers 1 and 3 of CCF. Relay B having operated, the windings I and II of relay A are connected to wipers 1 and3, and that relay operates.

Contact [)6 opens a point in the interrupter circuit tor ma'gnet DF and contact 64 closing operates this magnet over front contact t3. Contact 57 operates the slow releasing dialling relay D via wiper DT2 and its normal bank contact. Relay A operates over the subscribers loop in the circuit traced and at contact a2 operates relay Va j Relay V operating-contact @1- short circuits relay T which thereupon releasesand at-contact t8 opens the circuit of magnet DF causing it to release and step. switch CCF to its second position. Relay-Q is released at contactt2 and contact 91' closes in the operating circuit of relay ST, which circuit however, is

7 now open at contact d7 which released relay ST when relay D operated. The register controller cannot now be assigned by an as signer as the circuit over contact m3 and winding II of relay CC is open. Other effects of the operation of relay V are the retention of the circuit of relayTP over contact e3, the preparation of a circuit for relay SA at contact '02, the preparation of a hold-' 'ing circuit during impulsing for relay D at contact 04: and of an impulsing circuit for the digit switch magnets DT and DU at contact '06. Contact 125 closes a holding circuit for relay B. Contacts (Z2 and (Z3 opens points inthe circuits of slowreleasing relays G and.

E, contact 614 prepares the impulsing circuit of the digit switch magnets, and contacts d5- opens the circuit over wiper DT6.

On the operation of relay B a dialling signal is applied to the line over wire DS, con-.

tact t05, normal bank contact and wiper DT L, condenser, contact 62, wiper 1 otCCF and contact to l and the subscriber commences todial the number of the wanted subscriber which, except in the case of a party line sub.- scriber, comprises two digits. The numbers 20 to 69 are allotted to subscribers in the pres-- repeated over contacts (12, 16, (Z4 and g-ito magnet DT. Switch DT is stepped in accordance with the number of impulses received and its wipers DT3 and DT6 are brought to one of the contacts 2-to 6, counting the normal contact as O. The operating circuit of relay D is-opened at the end of the first impulse at wiper DTZ and the relay is then dependent on back contact'al for its continued energization. The diallingsignal is cut cit at wiper DT4' and the starting circuit is further opened at wiper DT5. At the end of the impulse train relay A remains steadily operated and relay D releases. Relay G now operates from earth over contact 67, wiper and commoned contacts 1 to 10 in the bank of wiper DT2, contacts 81' and d2, and locks up over contact g1. Contact g substitutes magnet DU for magnet DT for the reception of the units digit, A circuit is also closed from circuit. Contact 73 closes a point-in the cir-.

cuit of the test rclayP for testing the called line, contact 95 opens a point in the busy signal circuit and contact 6 prepares a circuit for operatin inagnet DF. The units train of impulses is now dialled and is repeated to magnet DU which steps the switch in accordance with the number of impulses .received and wipers DIE- are brought to contacts connected to the marking bank as sociated with wiper D of the connector.

lit the end of the units train of impulses, relay D releases and a circuit is closed from earth over contacts at, al, g2, n1, jtl, Wiper DU? and common contacts, contacts (Z3, Z4, contact on the other register controller available over the assigner via wires 6, contact r45, relay Ill to battery. 9

It may here be noted that should the second register controller be in use at this time, confusion in the banks of the connectors might occur should the banks be marked over contact at and wiper DT3 and one of the banks of switch DU this time. It the calledline marked by the second register controller has not yet been found, its relay E shown in dotted lines at E at the bottom of Fig. 6 would be operated and its contact corresponding to e5 would be open thereby delaying operation of relay E.

As soon as the other calling line is found and tested relay E releases and its contact 65 completes the circuits oi relay E which thereupon operates and locks up over contact (21 independei'itly of contact a1. Contact 65 opens to prevent operation of relay E in the other register controller at this time. Contact e2 closes a circuit from earth over the interrupter, contacts 83, e2, Z3, Z55, wiper r of CCF, magnet DC of the connector to battery and the connector wipers are stepped round the banlr.

Contact a l marks the called line in the bank of wiper D of the connector, the line marked depending on the position of the wipers of switches DT and DU, and contact 63 prepares a circuit for relay S, which circuit is closed when the connector wipers reach the marked line. The connector is stepped until its wiper D is brought to the marked contact whereupon the following circuit is closed 1 earth over contact a l, wiper DT3 and its bank contact, one of the wipers DIE-6 depending on the position of switch DT, wire 11, bank contact and wiper D of the connector, bank contact and wiper 8 0t CCF in position 2, contact 63, relay S, winding I, to battery. Relay S operates and at contact .93 opens the stepping circuit of the connector magnet. At contact cl relay S locks up over its winding II and contact 7)? to earth and opens the circuit oi relay G. Contact 82 closes the circuit for test relay 1? over wiper 6 of CCli and wiper C of the connector. A test of the called line is now made duringthe release period of relay G, the circuit being from earth over contacts g3, 82, windings I and II of relay P, wiper6 of CCF, wiper C of CS, contact Zal, (Fig. 7), relay CO to battery. It the line be free relay P operates and short circuits its high resistance winding I over contacts )1 and b1 and connects earth thereover for holding by means of its winding II and for reducing the potential of the test bank contact in the connector to mark the line engaged. Contact pet closes energizingniagnet DB of switch :CCF a Consequent on the release ofrelay G which now takes place, contact 96 opensthe circuit of magnet DF whichreleases and steps switch CCF to its third position. Relay E releases consequent on the opening of contact g2 and at contacts 02 and 63, a circuit is closed for ringing the called subscriber. This circuit is over the ringing generator RC, contacts Wt, 392, 63, wiper 8 of CCF in position 3,contact ce l in the connecting circuit, connector wiper B, the called loop, Wiper A of the connector, contact @423, wiperr of CCF, contacts as, Z3, 62, p5, r5, winding I of relay'TR to battery. Atthefsame time a ringing signal is transmitted to the calling subscriber over Wire RS, contacts T8, 193, (Z6, Z2, a3, 62 and wiper l of CCF.

When the called subscriber replies relay TR operates by means of its winding I in the above-traced circuit andflocks up over its winding II and contacts M1 in series with relay Q, winding II, contact '04 to earth. Contacts W3 and g6 connect battery over contacts jtQ and s6, wiper 4 0i? CF and D of CF, subscribers meter M (Fig. 2) to earth and the call is metered against the calling subscriber. Contacts 2W2 and 91 open in the circuit of relay ST and contacts W4 and g5 connect earth over wiper 2 of CCF to relay VV in the connecting circuit to operate it. At contacts col-wed the speaking circuit is switched through and current is fed to the calling lineover relay YA and to the called lineover relayYY and the register controller is disconnected from the called line side of the feeding bridge. Contacts @115 and 0126 connect earth to the test Wipers of the call finder and connector respectively of the con necting circuit, the latter contact short circuiting relay P, and contact oo7 opens the holding circuit of relay TC. Relays YA and YY operate and close a holding circuit for relay VV and contactyyQ connects earth to Wiper D of CF and conversation ensues.

onsequent on the release of relay TCby the opening of contact m7 relayA in the register controller releases followed shortly by relay V. IVhen relay V releases, earth over the front of contacted is disconnected and relays TR and Q, releases slowly. Relay B is released at contact '05, relay TP at contact o3 andrelay SA at contact o2. Relay S is released at contact Z27 and contacts 52 and 53 open further points in the circuit of relay A. Over the back of contact we a circuitv is-closed'for driving the digit switches to their normal positions. The units switch is first restored, its magnet DU selfstepping in a circuit including self-interrupting contact du, wiper DUl and contact '04 and when this switch reaches its normal position its stepping circuit is opened and a similar circuit for switch DT is closedover wiper DTl and normal contact in the bank of wiper DUl, the circuit being opened when the tens switch reaches, its normal position.-. When this occursthe circuit of relay ST is closed at wiper DT5 and all'the other, relays having 7 released, the register controller is free for use The line testsbusy so long as this condition persists by the disconnection of the connector.

test circuit at contact Zal whilst battery over relay CO and contacts Zal and p92 operates a high resistance relay foristarting a delayed alarm device. 7

It When the called line is tested, itis found busy relay P does not operate and on the release of relay G,ja busy signal is transmitted to the calling subscriber over. wire BS, contacts 84, g5, p3, (Z6, Z2, 123,62 and wiper 1 of CCF. V v

It will nowbe assumed that an individual line subscriber-wishesto make a call to another subscriber who is one of a number connected to a party line, The numbers, of party line subscribers contain 3 digits, the first two digits representing vthe linein the exchangenumbering scheme, the third digit being a digit forthe selection ofthe appropriate ringing code for calling the party desired. The first digit of party line subscribersis 4 and contact a in the bank of wiper DT6 is connected towiper DU8, contacts of which associated with party lines are commoned and connected to relay R which brings about circuit changes for preventing the connection of ringing current after the end of the second impulse train andfor the selection of-the' appropriate ringing code. a K

,The call proceeds in the manner above described until the end of the second train of impulses. The tens digit switchhas been set tothe fourth contact in its banks and the tact,.wiper DT8,.commoned contacts to. relay contact rcZl by which it holds during the subsequent impulse train. Contact 12 prepares a circuit for magnet DA of the code select- 7 ing switch. Contact 14 disconnects theringing generator which provides the interrupted ringing current for ordinary subscribers lines and prepares a circuit for the application to thefcalled line of code ringing current; contact r3 disconnects the. ordinary ringing signal circuit over wire RS. Contact r5 disconnects relay TR from the ringing circuit and closes an alternativeureturn circuitfor the ringing current. Contact r6 opens the circuit of relay E untillthe third trainof impulses is dialled thereby preventing the. stepping of the connector should the calling subscriber delay or omit to dial the third digit. The receipt of the third digit by relay A is repeated to magnet DA in the following circuit :.earth over contacts a2, '06, 034, MM, 7 2, magnet DA to battery. Contact a3. holds relay RD during the receipt of the impulse train. Switch DA is provided with 6 wipers and corresponding banks of which wipers DAQ and DA3 are directly concerned with the ringing of the particular party required. The. bank contacts of wiper DA3 are connected to" wipers DB2DB6 of a' switchDB to which reference will shortly be .made whilst the even contacts'of wiper DA2 are commoned and connected to certain contacts in banks DB26.and to relay RR, the wiper DAQ itself being connected to certain other contacts in the banks of switch DB prior to-those which determine the end of a ringing code period. t I

7 When switch DAis steppedfrom its normal position relay E is re-operated, and closes the circuit for the connector driving magnet which steps the connector to the contacts of the required line marked over wiper DT'3 and oneof the wipers DU2-6 and the usualtest is made... On the-release of relay RD at the end of the third digit and assuming. for the'moment the line to be free, an interrupter isc-onnected over contacts n5 and rcZ2,.wiper cZa-5, front contact p6 of the test relay P, magnet DB to battery. Magnet DB is energized intermittently to step the wipers DB16 and after a few steps a circuit is closed. from earth over contact 1'd3, wiper DA3, one of the wipers DB26, relay RR to battery. This is thecommencementof thecode ringing period. Relay RR operates and at contact W1 connects the continuous ringinggenerator over front contact R4 and wiper 8 of CCF in position 3 to the called line while contact W2 connects a tone over wire DS.'COIlt-1CtS 723, (Z6, Z2, n3, wiper 1 of CCF to the calling line to provide a ringing signal similar to the code to be transmitted.

As switch DB is stepped, relay RR is intermittently operated depending on its connections to the bank oi switch DB and the particular bank of that switch in use. It will is noticed that each wiper of the set DB2-6 is connected to consecutive pairs of contacts in the bank of wiper DA3 so that as far as this wiper is concerned the same code would be sent out for two positions of the code selecting switch DA. However, in order to distinguish between the digits represented by a pair of contacts in the bank of wiper DA3, a wiper DAQ and bank are employed, the even contacts only in this bank being utilized. ll iper DA?) is connected to contacts in the banks of switch DB immediately before these which determine the end of the code and the comnioned even contacts are connected to relay RR so that for even third digits, an extra ring is included in the code. When the whole code has been transmitted, switch B is: stepped on to the cominoned contacts in the latter part of its bank con nected to relay RT which thereupon operates and remains operated until the switch reaches its normal position. A circuit is now prepared tor relay TR as follows :earth, winding 1 of relay T 1, contacts M2, r5, 5, 62, Z3, wiper of CUF in position 3, contact on3, the called line wires, contact 10%}, wiper 8 of GOP, contacts 63,122, rel, rrl, will, to battery. This circuit is prepared at the end of each code ringing period and when the subscriber replies to the call relay TR operates and locks up and in conjunction with relay Q; brings about the switching through of the connection. Contact cs6 short circuits relay P which releases and at contact p6 opens the stepping circuits of switch DB and closes a circuit for its rapid return to normal should not have reached tiis position. In the normal position of switch DB1 a homing circuit for switch DA is prepared.

Following on the switching through of the connection, the register controller is released and on the release of relay V the Funits and tens digit switches are restored in turn.

The disconnection of earth over front contact he releases relay 1t and thehoming circuit for switch DAis closed over contact r2, selfinterrupting contact do, wipers Bill and D131, and switch DA is stepped to its normal position. The register controller circuits are now all in their normal conditions and the apparatus may again be taken into use.

H the called line is busy when tested relay P does not operate and switch DB is not stepped so that ringing current is not applied to the line. The calling subscriber receives busy signal as in the case of a call to a busy individual line.

l'Vhen a call is orignated by a party line subscriber the procedure is similar to that de scribed for a call by an individual subscriber.

It a party line subscriber desires to call another party on the same line, he proceeds as tollows:- t

On removing the'receiver from its hook and on receipt. of the dialling signal, the subscriberdials the digit 7, after which, and with the receiver still oil, he uses the hand magneto generator provided with the instrument for calling the party required, manipulating it seas to apply ringing current on to the line in accordance with the code of the required subscriber.

When the receiver. is first lifted, a free register controller at the automatic exchange is taken into use and the dialling signal is connected to the calling line when it has been found by the call finder CF. Thedigit 7 is received by relay A and switch DT is stepped to its seventh bankcontact. At the end of the impulse train, relay D releasesand earth over contacts 414 and (Z5 and wiper DT6 is connected to relay RL, which thereupon operates and locks up over contact 1% independently of switch DT. Contact rZl connects battery over a high resistance and wiper 4 of GOP to wire 05 in the line circuit which in the case of a party line has an auxiliary equipment as before mentioned connectedbetween it and the main distributing frame. A relay in this equipment connects earth to wire 0 to hold relays CO and PG operated and to disconnect the line circuit from the assigner andto mark the line engaged in the connector multiple, this earth connection being extended over contact 001 to the test bank contacts in the call finders. Contact rZ2 opens the holding circuitot relay B which in turn releases relays A and V and the register controller circuits are restored to their normal condition. The engaged marking is maintained for the duration of the call and is controlled by the auxiliary equipment referred to. When both parties replace their receivers, this earth is removed, relays CO and PG release and the line circuit reverts to its normal condition. It may be noted that although relay PG is operated, there isno circuit over contact 1092 to the alarm relay circuit due to relay LA being unoperated.

Thesystem provides forthe connection of small private branchexchanges and those are called in the same manner as an individual line by dialling the number of the first of the group oflines connected to the P. B. X. If this line be busy, the connector proceeds to hunt over the P. B. X. group in search oi a tree line. In order that allthe lines of a P. B. Qshall be marked when a call to one ismade, the appropriate bank contacts of switch DU are conimoned and the corresponding marking wires 11 are connected to the bank contacts of wiper D of the connector over a break contact jig 3 shown in Fig, 7, the dotted line connection being removed except in the case of the last line oi the group when the strap is retained, as whatever the condithe markin tion of the last line of the group, the con nector must be stopped thereon. As the operation of the connector is that of a hunting switch searching for a marked line, it will be realized that switch CS willflbe. stepped until a marked line is reached. If any of the lines of the group other thanthe last are busy, the marking in the bank of wiper D of the connector will not be present owing to circuit being open at contact 3993, relay G being operated consequent on the operation of the cuteofi' relay CO, and the connector will be stepped on until a marked contact isreached. Should all the .linesof a P. B. X. group be busy, the connector is stopped on the last contact of the group as this contact is always marked, the contact 1293 of the line circuit being short circuited.

by the strap. 7

If any group often lines is. not connected, such asthe groups having first digits 1 and 8 in the-present example, the corresponding contact in the bank of wiper DTG is connected to a relay L." If any. individual line 2' in a group is not connected, the corresponding contacts in the bank of wiper C of the connectors, are connected towire 13 which is also connected to relay L in the register controller when relay E is operated. If, now,

either the digit 1 or 8 be dialled as the tens digit, relayL operates by means of its winding I on the release of relay D and locks up over contacts Z1 and 124. Contact Z4 opens preventing operation of relay E, and contact Z2 connects a distinctive tone signal over wire NU, contact as, wiper 1 of CCF to the calling line to notify the calling subscriber that he has called a dead number. Should the tens digit be correct, but the whole number represent a dead line, relay L is not connected over-wiper DTG. 'At the end of the second train of impulses, relay E opcrates and at contact 66 battery over winding II of relay L is conn'ectedvia wire 13 to the multipled contacts in the bank of wiper C of the connector, the usual marking circuit being completed over wire 11. When the marked line is reached, relay S operates and connects relay P in the test circuit, but owing to the high resistance of windings II of relay L, relay P does not operate but relay L does. Contact Z1 closes a locking circuit over winding I of relayLv and contact Z8 opens inthe stepping circuit of the connector while switchCCF is in'its second position.

The distinctive toneis connected to the calling line at contact Z2.

Consideration will now be given to calls,

made over a junction between the automatic exchange and a manual operator at a main exchange. The auxiliary equipment shown in Fig. 1 is connected'between the junctionterminals on the main distributing frame and'the line circuit, Fig. 2, and Fig. 1 must be assumed to be now connected-to the. left of thefline circuit shown in Fig. 2. The strap connecting wire 01 from. the connector multiple and wire. 0 from relay CO is disco-n.- nected and meter .M is disconnected from wire (Z in Fig. 2. ires 0 and 01 are now joined through the low resistance winding I of relay JS and wire 61 is connected to winding II of relay JS. in the auxiliary equipment.

There may be junctions to only one main I In thefirst exchange or to more than one. case, a subscriber Wishing to make a call over a junction, dialsthesingle digit 0. In the second case he dials the digit 0 followed by anotherdigit signifying the particular group of junctions required. As re- 'gards the connector circuit, arrangements the marking bank of the connector in a manner similar to the described for P. B. X. lines. lVhen there is more than one junction group, the tenthcontact in the bank of wiper DT3 is disconnected fromwire' 12 and connected to one of the wipers DU26 depending on the tens group in which it is desired to connect the junctions.

When there is only one group of'junctions, a subscriber wishing to make a call over a junction dials thesingle digit 0 and at the end of the impulse train relay J T operates over its winding I and wiper DTG. Relay G operates and earth over contacts 414:, a1, 92, n1, front contact jtl, contacts .cZ3,'Z4,. wires 6,

contact T6, is extended to relay E- which thereupon operates instead. of awaiting the end of a second train of impulses. The strap across back contact y'tl shown in dotted lines is removed sothat relay vD does not re-operateon the closure of contact 92.

. 1. Consequent on the operation of relayE the connector is stepped in search of a free junction and when one 1s found, relay S operates via the connector marking bank, Wire 12, and.

wiper DT3. Relay P operates over Wiper C ofthe connector, winding I of relay J S (Fig. 1) and relay CO in the line-circuit and switch CCF is stepped to itsthird position where ringing current is appliedto the junction;

Relays J Sand CO operate, the latter extending earth first over the low resistance wind-' ing of relay P and later over contact @126, the connector wiper C and bank contact, contacts Zal and 001 in the-line circuit to the .testbank contacts of the call finders to mark the line engaged in the fall finder banks. Relay JR operates but neither it nor relay JS serve any useful function at this stage. On the operation of relay JT contact jtz? opens the metering circuit to prevent metering on junction calls and prepares a locking circuit for winding 11 of relay J T when the operator replies to the call. At the end of the conversation when the calling subscriber replaces his receiver, relays YA and VV in the connecting circuit G release and contact @126 opens the circuit of relay J S releasingit and relay GG. Relay LA is re-connected to the junction in the line circuit and during the release period of relay JR, the current in the junction is reversed thereby giving a clearing signal to the operator.

If there is more than one junction group, the back contact jtl is short circuited by the strap shown in dotted lines and the connec tion of the tenth contact in the bank of wiper DT3 is made as above described. The subscriber dials the requisite digits to reach the exchange desired and at the end of the first train, relay D releases and operates relay J T. At the same time relay Gr operates and on the closure of contact 5/2 relay D re-operates over normal contact and wiper BUT, the strap across the back of contact y'tl, contacts n1, g2, a1, and o l, and opens the circuit of relay E before this relay has time to operate in a circuit including the front of contact 61. The second digit is now dialled and at the end of the impulse train, relay ltl ope ates and search for a junction in the marked group by the connector takes place.

Consideration will now be' given to calls made by a manual operator over the junc tion to a subscriber on the automatic eX- change, after which the various special services available only to an operator will be dealt with.

An operator at the main exchange desiring to make a call to the automatic exchange inserts a calling plug into the junction jack thereby operating relay LA overa loop closed in the cord circuit. The assigner allots a free register controller to deal with the call and the register controller hunts for and seizes a free connecting circuit and the associated call finder is rotated in search of the calling unction. When this is found the register controller and switch GOP is stepped from its first to its second position. Relay B operates when the junction is found and a circuit is now closed from earth over contact Z71, windingl of relay J G, contacts t02, r11, 86, wiper l of GGF, wiper D of the call tinder, wire of winding II of relay J S to battery. Relay J G which is of high resistance operates but relay J S does not. At contact jol a locking circuit is prepared for winding 11 of relay J G, this circuit being closed on receipt of the first impulse of the tens digit train. It will be noted that relay JG can only operate on calls made by an operator over a junction as in the case of subscriber initiated calls, Wire dis earthed over the meter M. The operator receiver dialling signal and the connection is set up in the manner described for calls made by a subscribe When the called subscriber replies relay YY operates and at contact g g/Q connects a comparatively low resistance earth to Wiper D 01' the call finder and rela J S operates. Contact jsl operates relay R to prepare for the giving of the ring-oil signal. When the called subscriber clears relay YY releases and aticontact yg/Q releases relay J Contact jsl opens the circuit of relay JR, but this relay being slow to release a period occurs when with relay J S released and relay JR operated, a reversal of current in the junction Wires takes place which-operates the clearing indicator at the main exchange. Current is cut oil the junction on the subsequent release of relay VV. 7

If the operator wishes to Offer a trunk call to an engaged subscriber, the junction is eX- tended through a free connecting circuit to a register controller and relay JG is operated. Contact 7'03 disconnects relay JT and pre pares a circuit for relay TO. a

The operator on receiving dialling signal dials the directory number of the wanted subscriber prefixed by the digit 0. At the end of the last impulse of the first train of impulses representing the digit 0, relay TO operates over wiper DTG and locks up over its contacttol and contact at, and relay JG locks up over. its winding II and wiper DT2, the circuit over its winding I being opened at contact $02. Gontact 2605 opens the dialling signal circuit. A circuit is now closed from earth over contacts jc2,.t03,wiper DUl and normal contact, wiper DTl and commoned contacts, self-interrupting contact (it, magnet DT to battery. Switch DT self-steps to normal whereupon thelocking circuit of relay JG is opened at wiper DT2. Relay TO remains held. The remaining digits representing the subscribers directory number are now dialled and the connectorsearches for the line marked in itsmarking bank. l/Vhen this is reached relay S operates and the test circuit is closed at contact 82 in the usual Way. At the same time, relay VV in the connecting circuit is operated from earthover contacts 85 and 2504, and wiper 2 ofGGF in position 2. Contact @126 short circuitsrelay Pancl relay TG is released atcontact/vo7 thereby initiating release of the register controller. The connection is switched through and as the called subscriber is already engaged in a connection, relay YY will operate round the loop which is already closed. The operator can speak to the wanted party and request him to clear the connection and await the offered trunk call. Contact y 2 operates relay J S and when the Wanted party clears, a clearing signal is received by the operator. .She then clears the connection in order to release If-the operator desires tofascertain whether a fault exists in the automatic exchange or, if a fault has been previously signalled, whether it still persists, she dials the single digit 9; The register controller being taken into useby an operator, relay JG is operated and at contact 3'04 relay N is connected to the ninth contact in'the bank of wiper DT6 in place of relay L. At the endof the impulse train "relay N operates and at contact n3 connects the fault tone lead FT over wiper DA6 and normal contacts at each end of its bank, and wiper 1 of CGF to the line so that the operator receives a tone denoting the type of. fault existing, assuming there to be one.

It may be noted that should a'subscriber ,dial. 9 as a first digit, relay L will operate over wiper DTG, bank contact 9 andlback contact ja l and he will receive the dead number tone.

By dialling certain numbers, the operator can control the charging of the battery at the automatic exchange and ascertain by means of a tone signal the state of charge of the battery. This being another service available to operators only, its operation is made deany possible-stepping of switch DB. The

second train comprising 3, 5 or 7 impulses is dialled and is repeated in a circuit from earth over contacts a2, o6, (MEWZA Q to magnet DA and switch DA isstepped accordingly. 'At-the end of the impulse train, relay RD which is held duringimpulsing overcontacts a3 and Tell, releases andwinding-III of relay D is connected over contacts r0l5 and net and wiper DA6 to the appropriate lead. Ifthe second digit is 3 a tone is transmitted over the leadconnected to contact 3 in the bank of wiper DAG towinding III of relay A and the tone is induced in the windings I and II of thisrelay and thence over the junction to the operators position. If the second digit be 5? or 7 earth over winding III of relay A operates the relay to effect the re quired operation. Relay A is not held by this winding owing tothe resistance of the circuit in whichit is included. The register controller is released by the withdrawal ofthe plug from the junction jack by the operator.

Briefre-ference-will now-be made to the arrangements provided for releasing the register controller if it is not otherwise released within a prescribed time. 1 I

Vhen the register controller is taken into use relay ST'operates and at contact st3closes a circuit forrrelay TP, the circuit being maintained after the calling line has been found by the call finderby contact '03. Relay TBoperates and star-ts up a timing device and earth isconnected to wire 14, thence over contacts ml and 122 to relay SA. Relay SA operates and locks up over contact sal and at contact -sa2'conn'ects relay ZA to wire-15. After the elapseof a prescribed'time interval and if relay V has not yet been released earth is If a-fault develops on a subscribers line or a subscriber fails to clear after aconversation, or his line is otherwise looped, relay CO is released either by relay: VV in the connecting circuit or by the forced release of the register controller and relayLA re-operating, relay 'PG- remains held. A circuit is then closed from battery over relay CO, contactslal and 1292 for relay PL which is of high enough resistance to prevent operation of'relay CO and after the elapse of a prescribed interval, an alarm'relay is operated. The operated condition of this relay may be ascertained by means of a tone signal connected to a junction in consequence of an operator dialling the digit 9 to ascertain ifa' fault exists. I

WVhat is claimed is: I

.1. t In a register controller arranged to control the setting of automaticswitching apparat-us by the application of a marking potential to one of a plurality of marking conductors, marking conductors divided into groups, a register operable in accordance with a digit of a telephone number to select a marking conductor ineacli of said groups, and a register operated in accordance with a dilf'erent digit in the telephone number to select a particul ar one of the markingcondu ctors selected in accordance withthe firstnamed 2. In a telephone system wherein automatic switchesare guided into connection ductors, and means for preventing the marking of a conductor by one register controller at a time when a conductor is marked by the other register controller.

In a telephone system, two register controllers, a plurality of connector switches having access to called lines, means for extending a connection from a calling line to one of said connector switches and for rendering one of said register controllers temporarily individual to such connector switch, means controlled over any one of a plurality "of marking conductors for operating said connector switch as a finder to find a called line, means including registering apparatus in the register controller set over the calling line to mark one of said conductors, and means for preventing the marking of one of said conductors by one of said register controllers at a time when a conductor is marked by the other register controller.

a. In a telephone system, a trunk line, a plurality of register controllers, means for completing a connection between a calling line and said trunk line and for rendering one of said register controllers temporarily individual to said trunk line, means including registering apparatus in the register controller for recording the number of the de' sired line and for recording the designation of the desired party on the line in case a party line is called, automatic switching mechanism controlled in accordance with the setting of said registering apparatus to ex tend a connection from said trunk line to the desired line, and means including a ringing-code generator individual to said regis ter controller to generate and transmit to the called line the particular code of the called party as indicated by the setting of the said registering apparatus.

In a party-line telephone system, a code generator comprising a plurality of codegenerating devices for generating separate codes corresponding to different parties on a party line, a digit register having access to said code generating devices and arranged to select the same device upon the registration oi either of two digits, and means associated with said registering device for mak ing an addition to the selected code automatically when it is set in one of the two said positions.

6. In a party-line telephone system, a code generator comprising a plurality of codegenerating devices for generating separate codes corresponding to different parties on a party line, a digit register having access to said code-generating devices and arranged to select the same device upon the registration of either of two digits, and means associated with said registering device for automatically modifying the selected code when it is set in one of said two positions.

7. In an automatic telephone system, an

automatic hunting switch having access to lines, means for extending a connection r'rom a calling line to said switch, means including registering apparatus set over the calling line in accordance with the destination of the call for marking a group oflines accessible to said switch, means for automatically causing said switch to advance to the marked group of lines, and meanscontrolled by the busy or idle condition of the lines within thegroup for continuing the hunting movement of said switch until an idle line is encountered.

8. In a telephone systeim'an automatic switchhaving access to lines, atest contact for each line, a marking contact for each line, means including registering apparatus for marking one of said markingcontacts, means for operating said switch into engagement with the marked contact, and means controlled over the associated test contact for continuing the movement of the switch in case the line associated with the marked contact is busy; 1 a

9. Ina telephone system, a manual switchboard, another switchboard, aline extending between said switchboards, means for setting up a connection over said line through said switchboardsand for setting up a current flow over said line, means for breaking down said connection at the said other switchboard, and means thereupon effective for momentarily reversing the current flow over said line. Y I p 10. In a telephone system, means including automatic switching apparatus for setting upconnections to subscribers lines responsive to impulses representing the digits in the telephone numbers of said lines, means included in said automatic switching appa ratus for denying the connection in case the called line is busy, and means for causing the connection to be completed to a busy line in case a preassigned digit is prefixed to the subscribers number.

11. In an automatic telephone system, automatic switching apparatus for the common use of operators and calling subscribers to set up connections to called lines, means for denying the connection in case a called line is busy, and means responsive only in case the call is being set up from an operators switchboard for completing a connection to a busy line responsive to prefixing a preassigned digit to the digits of the telephone number.

12. In a telephone system, a switch controlling device comprising registering apparatus for registering the tens and units digits in called numbers, said registering apparatus having one movement for the tens digit and another movement for the units digit, and means for causing said apparatus to operate twice in its tens digit movement in case the first digit received by such apparatus is a predetermined digit, the last named means inl siing ang me t tom ti lly r leasing said apparatus at the end of the said predetermined digit. 7

a 13. In a'telephone system, a telephone ex.-

change including automatic switches and reg ster controllers arranged to be set n accordance with desired numbers to'control said switches, a line incoming to said exchange,.means 1n said exchange for giving signals indicative roflconditions Withinthfe exchange, and means including said register controllers for extend ng the incoming l ne into assoclation with the=last named means,

whereby the conditions existing in the ex- [which said registers are operated, means change maybe determined over said line.

14. In a register controller for use in con.- trolling the operation of automatic switches in an automatic telephone exchange, a tens register, a units register, and a party register arranged to be operated to register the tens, units, and party selecting digits in a telephone number, an impulsing circuit over automatically etfective for shifting said impnlsing circuit from the tens register to the units register and for later switching it from the uni-ts register to the party register, and a means responsive to said tens register being set in a predetermined position for there-- upon switching the impulse circuit directly from the tens register to the party selector.

15. In telephone system, three registering. devices arranged to respond successively to three digits, and means responsive to the setting of the firstregister in accordance With a predetermined digit for causing the third register to respond to the second digit. lnwitness whereof, I hereunto subscribe name t i 2 t ay f ebr ry, A- D.-

CHARLES LEONARD PETERS. Y

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