US2282564A - Telephone system - Google Patents

Description

May 1 2, 1942.

T. F. CROCKER TELEPHONE SYSTEM Original Filed March 29,` 1940y '7 Sheets-Sheet 1 i m .E

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INVENTOR THOMAS F. CROGKER ATTORNEYS May l2, 1942.

T. F. cRQcKgR TELEPHONE SYSTEM Original Filed March 29, 1940 INVENTOR THOMAS F. CROCKER ATTORNEYS May 12, 1942'. T. F. cRocKER TELEPHONE SYSTEM Original Filed March 29, 194C 7 Sheets-Sheet 3 www .l BEY MCM QS @sa ESE v N3 3, N2 .mol .tulo f m S l o I/ ooo a l S v www n um w mm oww R m uk 5.5% muzmmowm O m N .3mm 3G m o. w T mm u wom m May l2, 1942. 1'. F. cRocKER TELEPHONE SYSTEM y7 sheets-sheet. 4

original Filed March 29, 1940 vm. .man Emme E km om E - Mnsv INVENTOR THOMAS F. cRooKER ATTORNEYS May l2, 1942. .-r. F. cRoKER TELEPHONE SYSTEM Original Filed March 29, 1940 7 Sheets-SheetV 5 kokkm RUN n May l2, 1942. T. F. cRockER TELEPHONE SYSTEM original Filed March 2'9, 19'40 'Y'Sheets-Sheet 6 www Wim E ed lNVENTOR THOMAS F. cRocKl-:R

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xm mi GMI @N INVENTOR THOMAS F. oRocKER BY Y E i Z z u TToRNEYs Patented May 12, 1942 TELEPHONE. sYsTEivr i Thomas F. Crocker, Chicago, 'Ill., 'assig'nor to sociated Electric Laboratories, Inc., Ill., a corporation of Delaware i Chicago, ij

original application March 29, 1940, sentirmi,

326,619. Divided and thsapplication 4Qctolier 5, .1940, serial No..359,s71 1 I .i

The present invention relates to `telephone systems'and-more particularly to improved semiautomatic `telephone systems-of the character of that-disclosed and claimed in the clopending a-pv .plication of Thomas F. Crocker, Serial (No.

311,551, filed December l2.9, 1939. This application is adivisionof the copending application of Thomas F. Crocker, Serial -No. 326,619, iled March 29, 1940. v

In a conventional telephone system Aof the semi-automatic itype, 'the various manual `telephone lines terminate -in -jacks at the A 'and B operator positions; and an automatic switch train zprovided with a tdistributing system is interposed between the A operator positionsand the B operator positions. f In -a telephonesystem of :this type, :calls on the telephone lines are answered directly by thefoperators at the A operatorpositions and routed `loywayof the switch train `under ythe control of 'the distributing system Nto the Bioperator positions -to be completed.

Hence, in a telephone systemof this type, the traffic Vbetween the .A operator positions and the B :operator positions is governed by the distributing system. However, the tramo between thecalling telephone Vlines ofthe various A operator positions is not governed'but remains under the -manual control of the operators *at the A operator positions, rendering Ythe :number of Acalls on the telephone lines answered 'by an operator at a given A operator position 'and routed therefrom to the B-operator positions to be Acompleted entirely -within the discretion vof yth'egoperator at the .given Aoperator position.

Accordingly, it is an object Yof the present yinvention to provide in `a telephone vsystem of :the type described, improved apparatus `for 'fdistributing calls on telephone lines to a number of A operator positions to vbe answered, and improved apparatus at each A operator position for identifying a telephone line having a call thereon to be answered. i

Another object of the invention is to provide in a telephone system including anumber of A operator vpositions and a vnumber of B v,operator positions, an improved arrangement 'for distributing incoming calls on telephone lines toconnection having a `recall V-thereon to .be answered. i s A .n

A further object A,of theinvention is topprovide in al telephone system including l an Aoperator .position providedwithj.facilities :for answering incoming calls on telephone lines'fand yforanswer4 ing recallspn established connections including A' telephone lines, improved apparatus controllable from-the operator position for-identifying a .telei,

phone line havingan-incoming:call thereon-and for identifying a telephone IineinCluded .in an established connectionQhaving afrecall thereon. l

Affurther object-ortho invention is to provide` Y in .a telephone ,system including anumber `oi"y telephone `.lines eachi-being'identified bya -par l ticular multi-.symbol charactenan improyedarrangement for vindioatingthe symbols of `the particular character v-identifying Vav telephone line .having ia .predetermined condition thereon.

the A operator positions `to Aloe answered and for distributing .recalls on `established connections to the vA operator positions to be answered; and improved apparatus at each A operator position for identifying a telephone line having an incoming call thereon to -be answered Aand for identifying a telephone line included in an established i yThe `features of-the =present invention are-illus'- tratedlzasbeing incorporatedgina telephone system comprising :an exchange terminating a plu-i rality fof manualtelephoneflines and including a number-of A-operator.'positions,a -numberaof B operator positions nand-1a number of switching links AVTheswitching llinks have access to the telephone lines, Ito .the A operatorpositio'ns fand to .the V11? operator positions; v.while .B .operator positions have;accessv ;-to-the -telephonelines.

The telephone .-linesfcornpr-ise .two classes v:which 'are rendered corresponding classes Aot ,service 1 Consisting Of frrleSSagey register serv-ice and prepay service.

In accordance with onefeature of @the invention,the` telephonevsystem vcomprises ya Iplurality of telephone lines, vlajlfiluralityl of A operator positions and a foperatorfposition'. Also' the,y system comprises Lmeans for-routing 1 a-ca1l\on i any soneof vthe 'telephone lines-toan idle one of the A operatorpositions to be answered, means for routing acall from fthe onek Aoperator .posif tion to the B operator position, and :means vxfor establishing a connectionlbetween thelonetelef phone line and the'B operator position Yindepend-v ent-1of fthe-one A. Yoperator position, thereby-to route ifa-:call '-f'romfthe .one i telephone line` to the- B operatori position.' Eurther thesystem .corn-- prises -meansv for routing a recallvbvy -the operator at Vthe B-operator positionupon the established connection to .anidle oneof the Aoperatorposi-iy tions to be ans-wered. More particularly',--thev system oomprisesa Vswitching'link including'ian answer yswitch having .access Vtoi-the telephone lines, a finder-switch--having access-to theA opfer@v atorpositions anda-call switch `having access.:y to

operator positions. Also, each one of the A operv ator positions has an identity unit individually associated therewith which is controllable from the one A operator positioned to indicate the particular character identifying a calling telephone line seized by the iinder switchy of they link, each of the telephone lines being identified by a particular multi-symbol character.

In accordance with' another features of the f l invention, the telephone lines comprise first and second groups; and the identity unit associated with each operator position comprises first and second test devices, the first test device being operative to test ina predetermined order the lines in the firstgroup in order to detect a line therein Vseized by the finder switch ofthe link rand the' second test device being operative to test "in "a predetermined order the lines in the second group inV order to detect a line therein seized by the finder switch of the link. More particularly, the finder switch of the linkis operativegin a first-manner to seize a calling, line in the "first group and operative in a second manner to seize'a calling linein'the second group.l A controlarrangement is associated with theiden'tityunitwhich is` governed by the operation ofthe nder switch of the link in the firsftjmanner to preparethe rst test device to -beoperated `and governed by lthe operationbf the finder switch inthe second manner for preparing the second test device to be operated. Also the arrangement comprises means controllable--from an operator position for initiating operation" of a prepared 'one fofffthe test devices in-the'associated identity unit, 'a number of signals associated with Ithe operator position andcorresponding to the various symbols of the characters identifying the telephone lines, and means 'controlled by the operation of the one test Ydevice for' operating the signals to indicate the" symbols of the particular characterA identifying lthe line detected by the one test device.

- In accordance with f another featureof the invention, each of the groups of telephone lines is divided into a number of subgroups; andthe identity unit associated with each operator posivtioncomprises first and second test switches individually associated'withf'the first and second groups of lines, each test switch-being operative successively through a number Vof positions individually corresponding to the subgroups of lines 'the associated group. Also the arrangement comprises means controllable from :a given operator position for impressing an identifying -potentialiupon an identity conductor included in one' of the Vtelephone lines seized by the finder switch of the link routing a call on' the one telephone line to the the-'given operator position, and for initiating operation of the corresponding onef'of Ythe test switches, anda plurality of test relays. y Further the arrangement comprises means including the one test switch for successively connecting thevtestl relays to the identity conductors of the lines in the subgroups in the onegroup of lines, whereby the test relays are individually connected to; the identity conductors sponding given position, means controlled when any one of the test relays is connected to the identity conductor of a line having the identifying potential thereon for causing operation of the one test relay, and means controlled by the operation of any one of the test relays for arresting operation of the one test switch. Finally the arrangement comprises a number of signals associated with the given operator position and individually corresponding to the various symbols of the characters identifying the line, and means controlled jointly by the particular operated oneof the test relays and the particular arrested position of the one test switch for operating theories of the signals corresponding to the symbols of the particular character identifying the last-mentioned line.

Also, in the telephone system each switching link comprises control apparatus which is operative'in a first manner to create a call-back upon an established connection including a calling first line extending to a paystation or a calling second line extending to a substation and a called third line, and' operative in a second manner to release the link. Also the arrangement comprises means controllable over the third line ,for selectively governingl the manner of operation of the control apparatus, means for routing a call-back upon the established connection to an operator position -to` be answered, additional means operative under the control of an operator at the operator position for releasing the link, means operativeA under thecontrol of an operator at the operator position for governing coin collection and refund control means to cause coins deposited in a coin receiving means at the paystation'to be refunded in the event the first line is included intheestablished connection, and additional me'anscontrolled only in response to the release of the link by the control apparatus for governing the coin collection and refund control means to cause coins deposited in the coin re` ceiving means to be collected in the event the first line is'included in the established connection and for operating'a message register associated with 'the' second line in the event the second line is included in the established connection.

of the lines in a given subgroup in the one group 75 Further features 'of the invention pertain to the particular'v arrangement of the circuit elements thereof,Y whereby the above-outlined and additional operating features are attained.

'The novel features believed to be characteristic` of the invention, both as to its organization and method of operation, together with further objects vand advantages thereof, will best be understood by reference to the following speciflcation4 takenV inlconnection with the accompanying drawings in which Figure 1 illustrates the general arrangement of a telephone system including a local exchange and a distant exchange embodying the present invention; and Figs. 2 to '7, inclusive, when combined in the manner shown'in Fig. 8, illustrate the details of a system having incorporated therein the features of the invention, as briey outlined above.

Description ofthe apparatus incorporated in the telephone system 'Referring now more particularly to Fig. 1 of the drawings the telephone system there illustrated comprises a local exchange 20, a distant exchange 30 and a plurality of one-way trunk lines, including the trunk line 410, extending therebetween. The local exchange 20 and the distant exchange 30 are of the manual type, each serving a number of groups of telephone stations to which different classes of service are rendered. For example, the local exchange 20 serves a group of subscriber substations, including the subscriber substation Tl, which is rendered message rate register service; and a group of paystations, including the paystation T2, which `is rendered prepay service. A telephone line having a line circuit individually associated therewith extends to each telephone station in the local exchange; the telephone lines 205 and 245, respectively, extend to the subscriber substation TI and to the paystation T2. Also, it is noted that each telephone line in the local exchange 29 is identified by a particular multi-symbol character constituting a directory number in a manner more fully explained subsequently. The message rate line circuit 290 is individually associated with the telephone line 295; and the prepay line circuit 24D is individually associated with the telephone line 245. Each of the subscriber substations and paystations in the local exchange 29 is provided with station equipment including a telephone instrument and a ringer.

Further each of the paystations is provided with mechanism for receiving coins or the like and apparatus for controlling collection and refund of coins deposited in the coin receiving mechanism, which may be constructed and arranged in the manner shown and described in Oscar F. Forsberg Patent No. 1,043,219, issued November 5, 1912.

Also the local exchange 20 comprises va number of A operator positions, including the rst A operator position 590, and a number of B operator positions, including the rst B operator position A94. Also a group of toll lines, including the toll line 499, terminates at the local exchange 29 and extends to a remote exchange, not shown. Each A operator position has a trunk individually extending thereto, the trunk 520 individually extending to the rst A operator position 599; and each B operator position has a group of trunks individually extending thereto, the trunk 490 being included in the group of trunks individually extending to the first B operatcr position 494. Each trunk extending to each B operator position is provided with a trunk line circuit individual thereto, the trunk line circuit 1305 being individual to the trunk line 490 extending to the first B operator position 494. Each toll line terminated at the local exchange 20 is provided with a toll line circuit individual thereto, the toll line circuit 49 being individual to the toll line 499. Also each trunk line extending between the local exchange 2l) and the B operator position Q98 in the distant exchange 38 is provided with a trunk line circuit individual thereto, the trunk line circuit 412 being individual to the trunk line 419 extending between the local exchange 29 and the B operator position 498 in the distant exchange 39.

Further the local exchange 20 comprises a number of finder-selector links,including the nderselector link illustrated, and a link distributor 39| for assigning idle ones of the links to the use of the telephone stations. For example, the link illustrated includes a nder switch 300 and a selector switch A00. Also a sequence switch is individually associated with each of the links, the sequence switch 389 being individually associated with the link illustrated. Further the local exchange 2E! comprises a main A operator position distributor 63D and an auxiliary A operator posiwith the control wiper 3H.

tion distributor 695, each of the A voperator position distributors being operative toV assign idle ones of the A operator positions td receive incoming calls or recalls to the local exchange 20 in a predetermined order. Finally the local exchange 20 comprises a call storage unit 600 and a number of identity units individually associated with the A operator positions, the rst identity unit 100 being individually associated with the rst A operator position 500.`

Each of the finder switches, such, for example, as the finder switch 300, constitutes an answer switch having access to each of the telephone lines in the-local exchange; each of the selector switches, such, for example, as the selector switch 499, constitutes a call switch having access to each of the trunks extending to the B operator positions and to the toll lines and to each of the trunk lines extending to the distant exchange 39; and each of the sequence switches, such, for example, as the sequence switch 389, constitutes a position and storage finder switch having access to each of the trunks individually extending to the A operator positions and to the call storage unit 699. Also it is noted that each B operator position in the .local exchange 20 has access to each telephone line therein.

The distant exchange 39 comprises a number of A operator positions, not shown, and a number of B operator positions including the B operator position `i398, previously mentioned. It is noted that the trunk line 4,10 extending between the local exchange 29 and the distant exchange 30 is terminated at the B operator position 498 in the distant exchange 39.

Preferably, each of the finder-selector links is identical to the link illustrated which comprises a finder switch 399 and a selector switch 400, as previously noted.' The finder switch 399, as best shown in Fig. 3, comprises a switching mechanism 3&9 of theZOG-point Strowger type including a carriage provided with a rst wiper set, including the wipers 3M, 355 andil', a second wiper set including the wipers 3| I, 3l2 and 3l3 and a control wiper 3H. It is noted that the wipers 3M, 355 and 345 of the first wiper set and the wipers 3l i, 3i2 and 313 of the second wiper set are capable of both vertical and rotary movements; while the control wiper 3H is capable of vertical movement. Further the mechanism 3H) comprises a circumferentially disposed main contact bank provided with twosections respectively associated with the first and second wiper sets and a vertical control contact bank associated Accordingly, in the mechanism 3H), the iirst and second wiper sets respectively have access to the rst and second groups of one hundred lines each, respectively terminated by the first and second sections of the main contact bank. Also the mechanism 319 is provided with a vertical magnet M395 for moving the first and second wiper sets thereof in the vertical direction, a rotary magnet M361 for moving the first and second wiper sets thereof in the rotary direction anda release magnet M369 for releasing the first and second wiper sets thereof and for causing these wiper sets to be returned to their normal positions.. Finally, the mechanism 3i@ has two sets ofl switch springs S352 and S359 operatively associated therewith, which are controlled in accordance with the movements of the rst and second wiper sets thereof, in a manner more fully described subsequently.

.Also the finder switch 399 comprises a number oi' relays including two switching relays R320 an videntity relay R360 and a cut-in relay R310 connected and arranged in a manner more fully described hereinafter.

The selector switch 400, as best shown in Fig. 4,'comprises a switching mechanism 410 of the 1D0-point Strowger type including a carriage provided with a wiper set including the wipers 411, 412 and 413. It is noted that the wipers 411, 412 and 413 of the wiper set are capable of both vertical and rotary movements. Further the mechanism 410 comprises a circumferentially disposed main contact bank associated with the wiper set. Accordingly, the wiper set has access to a group of one hundred lines terminated by the contact bank. Also the mechanism 410 is provided with a vertical magnet M414 for moving the wiper set thereof in the vertical direction, a rotary magnet M4161 for moving the wiper set thereof in the rotary direction, and a release magnet M418 for releasing the Wiper set thereof and for causing the wiper set to be returned to its normal position. Finally the mechanism 410 has a number of switch springs S419, S420, S421, S422, S423 and S424 operatively associated therewith, which are controlled in accordance with the movements of the wiper set thereof, in a manner more fully described subsequently.

Also the selector switch 400 comprises a number of relays including a control relay R425, a

coin and register relay R430, a call back relay R440, two hold relays R445 and R480, a line relay R450, a switch-through relay R460, a battery supply relay R410, a transfer relay R485 and a switching relay R490 connected and arranged in a manner more fully described subsequently.

Preferably, each of the sequence switches is identical to the sequence switch 380 individually associated with the link illustrated. The sequence switch 380 is of the rotary type and comprises, as best shown in Fig. 3, six rotary wipers 381, 383, 385, 381, 389 and 391 provided with individually associated rotary contact banks 382, 384, 386, 388, 390 and 392. Also the sequence switch 380 is provided with a rotary magnet M393 for moving the wipers noted in the rotary direction.

The link distributor 301 illustrated in Fig. 3 has access to each of the links in the local exchange 20 and is operative to assign an idle one of the links to the use of any one of the telephone stations in the local exchange 20. The details of the connection and arrangement of the link distributor 301 are not disclosed as they form no part of the present invention. However, for reference purpose, it is noted that the connection and arrangement of a link distributor of the type of the link distributor 301 is shown in the copending application of Edward S. Peterson, Serial No. 233,021, filed October 3, 1938. Also a marking network 280, shown in Fig. 2, is associated with the link distributor 301 in order to initiate operation thereof when a call is initiated on one of the telephone lines extending to a telephone station in the local exchange 20. Also the marking network 280 comprises a busy relay R285 associated with the link'distributor 301 and a tone transformer 290 commonly associated with the various line circuits, in a manner more fully described hereinafter.

Preferably, each of the message rate line circuits is identical to the message rate line circuit 200 individually associated with the telephone line 205 extending to the subscriber substation T1, shown in Fig. 2, which comprises a line relay and R330, a start relay R340, a stop relay R350,

R210, a cutoif relay R220 and a lockout relay R230 connected and arranged in a manner more fully described subsequently. Also, a signal lamp L218 and a message register provided with an operating magnet M211 is individually associated with the message rate line circuit 200.

Preferably, each of the prepay line circuits is identical to the prepay line circuit 240 individually associated with the telephone line 245 extending to the paystation T2, shown in Fig. 2. The prepay line circuit 240 comprises a line relay R250, a cutoif relay R260 and a lockout relay R210 connected and arranged in a. manner more fully described subsequently. Also a signal lamp L268 is individually associated with the prepay line circuit 240.

Preferably, each of the trunk line circuits is identical to the trunk line circuit 405 individually associated Vwith the trunk line 490 extending to the first B operator position 494, shown in Fig. 4, which comprises a line relay R401 and a busy relay R403 connected and arranged in a manner more fully described subsequently.

Preferably, each of the B operator positions in the local exchange 20 is identical to the rst B operator'position 494, shown in Figs. 4 and 2. The lirst B operator position 494 comprises conventional answering equipment, not shown; conventional calling equipment including a number of call jacks J 201 and J 202 respectively terminating the telephone lines 205 and 245; and a number of conventional cord circuits, not shown.

Preferably, each of the A operator positions is substantially identical to the first A operator position 500, shown in Fig. 5, which comprises a trunk circuit provided with a set of position keys including a refund key X505, an error release key K510, an identity key K515, a trunk disconnect key K530 and an A operator position distributor key K590. Also the trunk circuit at the first A operator position 500 comprises telephone apparatus 511 including the usual telephone instrument and repeater, not shown, a retarder coil 530, a key sender K520, and a number of relays including three tone relays R510, R520 and R525, a refund relay R530, a send relay R540, an error relay R535, a disconnect relay R550, an answer relay R545 and a busy relay R560. Also -associated with the first A operator position 500 are a peg count meter provided with a register magnet M548 and an identity lamp 1.1583. The key sender K520 is of a well-known type; accordingly, the details of the connection and arrangement thereof are not disclosed as they form no part of the present invention.

As previously noted, the other A operator positions are substantially identical to the first A operator position 500, and the other A operator positions being different from the first A operator position 500 in that they do not include an A operator position distributor key and a busy relay, as only the first A operator position 500 includes this apparatus.

'I'he callV storage unit 600, shown in Fig. 6, comshown in Fig. 6, a hold relay R610 and a number of position relays R530, R540, R550, etc., respectively corresponding to the various A operator positions, connected and arranged in a manner more fully described subsequently.

Preferably, each of the identity units is identical to the first identity unit 100 individually associated with the first A operator position 500 which comprises, as shown in Fig. '1, a iirst test switch 1I0 individually associated with the first group of one hundredlines accessible to the finder-selector links associated with the first A operator position 500; and a second test switch, not shown, individually associated with the second group of one hundred lines accessible to the finder-selector links associated with the first A operator position 500. The test switch 1I0 is of the rotary type and comprises six rotary wipers 1II, 1I3, 1I5, 1I1, 1I9 and 12I provided with individually associated rotary contact banks 1I2, 1I4, 1I6, 1I8, 120 and 122. Also the test switch 1I0 is provided with a rotary magnet M123 for moving the wipers noted in the rotary direction.

Further, the iirst identity unit 100 comprises a rst start relay R130 andy a first stop relay R140 individually associated with the first test switch 1I0, and a second start relay anda second stop relay, not shown, individually associated with the second test switch. Also the first identity unit 100 includes a test transformer 155, a lockout relay R150, a switching relay R150, five testing relays I2U, 3412i, EBU, 18U and QBU and ten marking relays ID to IBD, inclusive. Finally, the iirst identity unit 100 comprises a group of identity lamps including a thousand-digit lamp MLI, two hundred-digit lamps CLI and CL2, ten ten-digit lamps DLI to DLIO, inclusive, and ten unit-digit lamps ULI to ULIE), inclusive. The rst identity unit 100 is so connected and arranged that, when the identity key X515 at the rst A `operator position 500 is operated, the first identity unit 100 operates ina manner more fully described hereinafter, thereby to cause the four of the identity lamps to be illuminated which correspond to the directory number of the line seized by the nder switch of the finder-selector link associated with the first A operator position 500.

A better understanding of the connection and arrangement of the apparatus incorporated in the telephone system will be facilitated from a consideration of the detailed operation of the various pieces of apparatus incorporated therein incident to the completion and handling of the various calls at the first A operator position 500, as will appear hereinafter.

General operation of the system Considering now the general operation of the system with reference to Fig. 1 of the drawings, it is noted that, when al call is initiated at any one of the subscriber substations or at any one of the paystations in the local exchange 20, the line circuit individually associated with the telephone line extending thereto is controlled, thereby to initiate operation of the link distributor 30|. The link distributor 30I is of the preselective type and operates to select an idle one of the links when a previously selected link is assigned to the use of a calling telephone station. Accordingly, the link distributor 30I operates at this time in order to assign a previously selected one of the links, such, for example, as the link illustrated, to the use of the calling telephone station; whereupon the finder switch 300 thereof operates to seize the telephone line extending to the calling telephone station, and operation of the sequence switch 380 individually associated with the link illustrated is initiated. When the finder switch 300 seizes the telephone line extending to the calling telephonel station, such, for example, as the telephone line 205 extending to the subscriber's'ubstation TI, the link distributor 30| is released and operates toA preselect another idle link, as previously noted.

The A operator position distributor 330 preselects one of the idle A operator positions for use; and when a preselected one of the A operator positions is taken for use the A operator position distributor 530 operates to preselect another idle one of the A operator positions for use. Upon operating, the sequence switch 380 seizes the trunk extending to the previously selected A operator position, such, for example, las the trunk 520 extending to the first A operator position 500, thereby to extend the call from the calling subscriber substation TI to the selected first A operator position 500. The operator at the first A operator position 500 answers the call and then operates the key sender at her position., thereby to control the operation of the selector switch 400 in order to. extend the call to its destination. In this connection it is noted that the selector switch 400 may be selectively controlled toA extend the call to any idle B operator position in the local exchange 20, to the B operator position 498 in the distant exchange 30 or over a toll line,l

such, for example, as the toll line 499.

In the event the call is to be routed to a telephone station in the local exchange 20, the selector switch 400 is controlled in order to route the call to an idle B operator position in the local exchange 20. The operator at the idle B operator position in the local exchange 20 answers the call and then extends the call to the called telephone station in the local exchange 20, in

the usual manner. In the event the call is to be routed to a telephone station in the distant exchange 30, the selector switch 400 is controlled in order to route the call to the B operator position 498 in the distant exchange 30. The opera-I tor at the B operator position 498 in the distant exchange 30 answers the call and then extends the call lto the called telephone station in the distant exchange 30, in the usual manner. In the event the call is to be routed toll, the selector switch 400 is controlled in order to route the call to an idle one of the toll lines, such, for example, as the toll line 499. Thereafter the call is further extended over the toll line to its destination in the usual manner.

After the call has been routed from the first A operator position 500 in the local exchange 20 to an idle one of the B operator positions in the local exchange 20, to the B operator position498 in the distant exchange 30 or over one of the toll lines, and the information concerning the extension of the call has been conveyed to the called operator, the operator at the iirst A operator position 500 releases the'connection between her position yand the finder-selector link, whereupon a direct connection is completed between the finder switch and the selector switch of the link excluding the rst A operator position 500. It is noted that the called operator ata B operator position in the local exchange 20 or at the B operator position 498 in the distant exchange 30, to which the call is routed by the selector switch 400, may recall the operator at an idle one of the A operator positions in the local exchange 20 by causing the sequence switch 380 individually associated with the link illustrated to seize the trunk extending to the idle A operator position under the control of the A operator position distributor 630, in the manner previously explained.

It is noted that the selector switch 400 comprises apparatus which is so connected and arranged that, when the connection is released, the charge for the call is made automatically. More particularly, in the event the connection includes a telephone line in the local exchange 20 rendered message register service, the'message register in the line circuit associated with the telephone line is operated in order to register a call; on the other hand, in the event the connection includes a telephone line in the local exchange 20 rendered prepay service, the coin collect and refund mechanism at the paystation associated with the telephone line is automatically controlled to collect the coin deposited therein. Also the coin collect and refund mechanism at a paystation associated with a line included in a connection may be controlled from the first A operator position 500, thereby to cause it to refund the coin deposited therein.

Also it is noted that, when a connection is routed to the first A operator position 500, the operator thereat may initiate operation of the first identity unit 100, thereby to cause the first identity unit 100 to .operate yand identify the directory number of the calling telephone line in the local exchange 20 included in the connection, as determined by the operation of the finder switch 300 of the link illustrated to seize the calling telephone line in the local exchange 20.

In the event all of the A operator positions in the local exchange 20 are busy .when operation of the sequence kswitch 380 is initiated, the sequence switch 380 seizes the call storage unit 600, More particularly, the sequence switches individually associated with the links in thelocal exchange 20 seize the respective positions of the call storage unit 600 in a predetermined order, thereby to cause the calls and recalls to be stored in the call storage unit 600 in a predetermined order when all of the A operator positions in the local exchange 20 are busy. At this time, when a number of calls and recalls on a number of the links are stored in the call storage unit 600 and one of the A operator positions in the local exchange 20 becomes idle, the A operator position distributor 630 operates to assign the idle A operator position for use and causes the call storage unit 600 to initiate operation of the sequence switch corresponding t0. the first stored call or recall in the call storage unit B00. The sequence switch corresponding to the first stored call or recall in the call storage unit 600 then operates to nd the assigned A operatol` position. The call storage unit 600 then operates to cause each of the remainder of the sequence switches to be advanced one position, thereby to advance, by one position, the calls and recalls stored in the call storage unit 600. Accordingly, the call storage unit 600 operates to cause incoming calls and recalls to be stored in a predetermined order when all of the A operator positions in the local exchange 20 are busy; and causes the stored calls and recalls to be released to be answered at the A operator positions in the same predetermined order as the A operator positions in the local exchange 20 become idle. l

After a call from a calling telephone'station has been extended from onelof the A operator positions to one of the B operator positions in either the local exchange 20 or the distant exchange 30, the release of the established connection is primarily under the controlof the operator at the called operator position. On the other hand, after a call from a calling telephone station has been4 extended from one of the A operator positions to a toll line, the release of the established connection is under the joint control of the calling `telephone station and a toll operator position associated with the toll line.

M essaye rate subscriber substation call A call from a message rate subscriber substation, such, for example, as the subscriber substation Tl, is initiated by removing the receiver of the telephone instrument thereat from its associated switchhook. When the receiver of the telephone instrument at the subscriber substation TI" is removed from its associated switchhook, a bridge path is completed between the line conductors C206 and C201 of the telephone line 205 extending to the subscriber substation TI. When this bridge path is completed between the line conductors of the telephone line 205, a circuit is completed for energizing in series the upper and lower windings of the line relay R2|0. This circuit extends from ground by way of the contacts 281, C294, the lower winding of R2|0, the contacts 222, C201, the bridge path between the line conductors C201 and C206 at the subscriber substation Tl, C206, the contacts 22| and the upper winding of R2|0 to battery. When energized over the above-traced circuit the line relay R2|0 operates to complete, at the contacts 2|3, an obvious path for applying ground potential tothe control conductor C209 of the telephone line 205 terminating in the jack J 20| at the iirst B operator position 494, thereby to mark the telephone line 205 as busy to the first B operator position 494. Also this application of ground potential to the control conductor C209 of the telephone line 205 marks the telephone line 205 as busy to the other B operator positions in the local exchange 20. Also the line relay R2|0 completes, at the contacts 2|2,

y obvious multiple paths for applying battery potential by way of the resistor 2|6 and the winding of the cutoff relay R220 to the control conductor C208 of the telephone line 205, thereby to mark the telephone line 205 as a calling line to the finder switches having access thereto. Further the line relay R2|0 completes, at the contacts 2| a path for applying resistance ground potential to the start conductor C308 extending to the link distributor 30|, this path extending from ground by way of the contacts 2|I and 23|, C283, the resistor 282 and the contacts 288 to the start conductor C308. Also the line relay R2|`0 completes, at the contacts 2||, an obvious path for applying direct ground potential by way of the marking conductor C283 to the first contacts in the Vertical control contact banks of the finder switches. The application of resistance ground potential to the start conductor C308 initiates operation of the link distributor 30|; and the application of direct ground potential to the rst contacts in the Vertical control contact banks of the finder switches marks the telephone line 205 as terminating in the first level of the main contact banks of the nder switches.

The link distributor 30| is of the preselective type and operates to select another idle link as soon as the finder switch of a previously selected link operates to nd a calling telephone line after it has been taken for use. Assuming that the link distributor 30| has previously selected the link illustrated to be taken for use at this time, the link distributor 30| operates to cause ground potential to be applied to the start conductor C302, thereby to complete an obvious circuit or energizing the winding of the start relay R340 in the iinder switch 300 of the link illustrated. The start relay R340 then operates to interrupt, at the contacts 346, a point in a multiple path for applying ground potential to the all-link-busy conductor C309 and to complete, at the contacts 34|, an obvious path for applying ground potential to the control conductor C364 of the trunk 360. The previously mentioned path for applying ground potential to the all-linkbusy conductor C303 in the finder switch 300 extends, when completed, from ground by way of the contacts 346 and the contacts 358 of the set of switch springs S356 to the all-link-busy conductor C300. Also the start relair R340 prepares, at the contacts 34|, obvious multiple circuits ior energizing the lower windings of the switching relays R320 and R330, prepares, at the contacts 345, a circuit traced hereinafter for energizing the vertical magnet M365, and prepares, at the contacts 344, a circuit traced hereinaiter for energizing the rotary magnet M361.

The link distributor 30| then operates to cause ground potential to be applied to the vertical conductor C335, thereby to complete the previously mentioned circuit for energizing the vertical magnetl M365, this circuit extending from the grounded vertical conductor C305 by way of the contacts 345 and the vertical magnet M365 to battery. When energized over the above-traced circuit the vertical magnet M365 operates to drive the rst and second wiper sets of the mechanism 3|0 one step in the vertical direction and to complete, at the contacts 366, an obvious path for applying ground potential to the interrupter conductor C306. The application of ground potential to the interrupter conductor C306 causes the link distributor 30| to interrupt the application of ground potential to the vertical conductor C305; whereupon the vertical magnet M365 restores t interrupt, at the contacts 366, the previously mentioned path for applying ground potential to the interrupter conductor C306. Accordingly, the vertical magnet M365 operates intermittently, thereby to drive the first and second wiper sets of the mechanism 3|0 step by step in the vertical direction until the control wiper 3|1 engages a contact in the associated vertical control Contact bank having direct ground potential thereon; whereupon an obvious path is completed for applying ground potential to the test conductor C301 extending to the link distributor 36|. In the present instance, the first and second wiper sets of the mechanism 3|0 are driven only one step in the vertical direction; whereupon the vertical control wiper 3 |1 engages the first contact in the associated vertical control Contact bank having ground potential thereon. The application of ground potential to the test conductor C301 causes the link distributor to operate, thereby to interrupt the application of ground potential to the vertical conductor C305 and to apply ground potential to the rotary conductor C304. f

The application of ground potential tothe rotaryv conductor C304- completes the previously mentioned. circuit for energizing the rotary lmag'- net M361, this circuit extending4 from the grounded rotary conductor C304I by way of the contacts 344, 338 and 328 andthe rotary magnet M361 to battery. When energized. over the above-traced circuit the rotary magnet M361 operates to drive the iirst and second wiper sets of the mechanism 3|0 one step in the rotary direction and to complete, at the contacts 368, an obvious path for applying ground potential to the interrupter conductor C306. This application of ground potential to the interrupter conductor C306 causes the link distributor 30| to operate and remove the application of ground potential to ther rotary conductor C304; whereuponv the rotary magnet M361 restores to interruptat the contacts 368,'the previously mentioned path for applying groundpotential to the interrupter conductor C306. Accordingly, the rotary magnet M361 operates intermittently, thereby to drive the first and second wiper sets of the mechanism 3|0 step by step in the rotary direction until either the control wiper 3|6 or the control wiper 3|3 of the respective first and second wiper sets engages a ycontact terminating the control conductor of a calling telephone line having battery potential thereon.

In the present example, the telephone line 205 is included in the rst section-oi the main contact bank of the mechanism3l0. Accordingly, when the control wiper 3|6 of the'iirst wiper set of the mechanism 3|0 engages the contact of the contact set in the first section of the main contact bank of the mechanism 3|0 terminating the control conductor C208 of the telephone line 236, a circuit is completed for energizing the upper winding of the switching relay R330. This circuit extends from the grounded marking conductor C233 by Way of the vertical control wiper 3|1 of the mechanism 3|0, the upper winding of R330, the contacts 324 and the control wiper 3&6 of the rst wiper set of the mechanism 3|0 to the control conductor C208 of the telephone line 205, the control conductor C208k of the telephone line 205 having battery potential thereon. When the upper winding of the switching relay R330 is energized this relay operates exceedingly fast to interrupt, at the contacts 338, the previously traced circuit for energizing the rotary magnet M361 and to complete, at the contacts 331, a holding circuit for energizing in series the rotary magnet M361 and the lower winding of the switching relay R330. This holding-circuit extends from ground by way of the contacts 34|, the lower winding of R330, the contacts 331' and 328 and the rotary magnet M361 to battery. When this holding circuit is completed the rotary magnet M361 remains in its restored position due to the high series resistance of this holding circuit. Accordingly, further operation of the mechanism 3|0 is arrested. Also the switching relay R330 interrupts, at the contacts 334, a

point in an obvious circuit for energizing the upper Winding of the switching relay R320, thereby positively to prevent operation of the latter relay at this time. Further the switching relay R330- interrupts, at the contacts 330, a point in f a circuit traced hereinafter for energizing the release manget M369 and completes, at the contacts 336, a connection between the rotary conductor C304 and the guard conductor esta, this connection extending from the rotary conductor C304 by way of the contacts 344, 336 and 342. to thegua-rd conductor C303. When the rotary conductor C304 is connected to theguard conductor C303, operation of the link distributor 36| to control the nder switch 300 is arrested,whereupon the link distributor 30| operates automatically to select for use another idle one of the links,

Also it is noted that, ,when the carriage of .the mechanism 3|0 isdriven one step in the vertical direction, the sets of switch springs S352 and S356 are actuated. More particularly, the contacts 351 and 358 of the set of switch springs S356 are actuated respectively into engagement and disengagement, thereby to prepare a further point in the previously mentioned circuit for energizing the release magnet M369 and to interrupt a further point in the previously traced path for applying ground potential in the nder switch 300 to the all-link-busy conductor C309. Finally, the contacts 354 and 353 of the set of switch springs S352 are` actuated respectively into disengagement and engagement,A thereby to interrupt the connection between the control conductor C364 of the trunk 360 and the guard conductor C303 and to prepare a path traced hereinafter for applying ground potential to the guard conductor C303. Finally, upon operating, the switching relay R330 completes, at the contacts 33|, 332 and 333, connections between the conductors of the trunk 360 extending between the nder switch 300 andthe selector switch 400 and the rst wiper set of the mechanism 3I0. More particularly, a circuit is completed, at the contacts 333, for energizing the winding of the cutoi relay R220, this circuit extending from the grounded control conductor C364 of the trunk 360 by way of the contacts 313', 362, 333 and 324, the wiper 3| 6, the control conductor C208 of the telephone line, 205, the contacts 2|2 and 236 and the winding of R220 to battery. When the winding of the cutoi relay R220 is thus energized this relay operates to interrupt, at the contacts 225, the previously mentioned path for applying battery potential by way of the resistor 2| 6 to the control conductor C208 of the telephone line 205 and to complete, at the contacts 224, a holding circuit for energizing the winding of the cutoi relay R220, this holding circuit eX- tending from the grounded control conductor C208 of the telephone linev 265 by way of the contacts 224 and the winding of R220 to battery. Also the cutoiT relay R220 interrupts, at the contacts 226, a point in an obvious circuit for illuminating the signal lamp L2|8 and completes, at the contacts 223, an obvious circuit for energizing the winding of the lockout relay R230, thereby to cause the latter relay to operate. Finally, the cutoff relay R220 interrupts, at the contacts 22| and 222, the previously traced circuit for energizing the winding of the line relay R2 Il), thereby to clear the telephone line 205 of impedance elements and to cause the latter relay to restore.

Upon operating, the lockout relay R230 prepares, at the contacts 232, a point in a holding circuit traced hereinafter for energizing the winding thereof, completes, at the contacts 233, an obvious alternative path for applying ground potential to the control conductor C209 of the telephone line 205, thereby to mark the telephone line 205 as busy to the B operator positions in the local exchange 20 having access thereto, and prepares, at the contacts 235, a further point in the previously mentioned circuit for illuminating the signal lamp L2I8.` Upon restoring, the line relay R2|0 interrupts, at the contacts 2| I, the previously traced paths for applying direct ground potential to the marking conductor C283 and resistance ground potential to the start conductor C308 extending to the link distributor 30|. f

Further itis noted that the link distributor 30| operates in order to select another idle link for use only in the event ground potential appears upon the all-link-busy conductor C309 in the nder switch of at least one of the links, ground potential being removed from the alllink-busy conductor C309 in the finder switch 300 of the link illustrated at this time, due to the operated condition of the set of switch springs S356, as previously noted. Also, at this time, ground potential is applied to the guard conductor C303 in the finder switch 300, thereby to prevent the link distributor 30| from preselecting the link illustrated due to the busy condition of this link. The path for applying ground potential in the finder switch 300 to the guard conductor C303 extends from ground by way of the contacts 353 of the set of switch springs S352 and the contacts 343 to the guard conductor C303, the startrelay R340 being restored at this time. Further it is noted that the start relay R340 is of the slow-to-release type and restores shortly after the link distributor 30| is released. Upon restoring, the start relay R340 interrupts, at the contacts 34|, the previously traced path for applying ground potential to the control conductor C364 of the trunk 360, ground potential being applied to the control conductor C364 of the trunk 360 in the selector switch 400 at this time. Further the start relay R340 interrupts, at the contacts 344 and 345, additional points in the previously traced circuits for respectively energizing the rotary magnet M361 and the vertical magnet M365. However, the previously traced holding circuit for energizing the rotary magnet M361 and the lower winding of the switching relay R330 in series is retained completed, due to the presence of ground potential upon the control conductor C364 of the trunk 360 in the selector switch 400 at this time.

When the trunk 360 is connected to the telephone line 205 due to the operation of the switching relay R330 in the nder switch 300, a loop circuit is completed for energizing in series the upper and lower windings of the line relay R450 in the selector switch 400. This circuit extends from ground by way of the lower winding of R450, the contacts 466, 433 and 428, C362, the contacts 316 and 332, and the wiper 3|5 to the line conductor C201 of the telephone line 205, and from battery by way of the upper winding of R450, the contacts 463, 43| and 426, C36I, the contacts 313 and 33| and the wiper 3|4 to the line conductor .C206 of the telephone line 205, the line conductors C206 and C201 of the telephone line 205 being connected together by way of the bridge path at the subscriber sub-station Tl. When the upper and lower windings of the line relay R450 are thus energized this relay operates to complete, at the contacts 453 and 45|, an obvious circuit for energizing the winding of the hold relay R480, thereby to cause the latter relay to operate. Upon operating, the hold relay R480 completes, at the contacts 483, the previously mentioned path for applying ground potential to the control conductor C364 of the trunk 360, as previously noted. Also the hold relay R480 completes, at the contacts 48|, an obvious circuit for energizing the upper winding of the switching relay R490, thereby to render the latter relay exceedingly fast to operate when the lower winding thereof is subsequently energized. Further the hold relay R480 prepares, at the contacts 482, a point in a circuit traced hereinafter for energizing the lower winding of the switching relay R490 and prepares, at the contacts 484, a circuit traced hereinafter for energizing in multiple the lower winding of the transfer relay R485 and the Vertical magnet M4|4. Y

When ground potential is applied to the control conductor C364 of the trunk 360 an obvious circuit is completed for energizing the upper winding of the transfer relay R485, thereby to cause the latter relay to operate. Upon operating, the transfer relay R485 prepares, at the contacts 488, a further point in the previously mentioned circuit for energizing in multiple the lower winding of the transfer relay R435 and the vertical magnet M4|4 and completes, at; the contacts 486, an obvious path for applying ground potential to the control conductor C383 of the trunk 360. This application of ground potential to the control conductor C363 of the trunk 360 prepares a circuit traced hereinafter for energizing the winding of the stop relay R350 in the finder switch 300 and completes a circuit for energizing the winding of the rotary magnet M393 of the sequence switch 380. The circuit for energizing the rotary magnet M393 of the sequence switch 360 extends from the grounded control conductor C363 of the trunk 360 by way of the contacts 35| and 319, the conductor C321 in the cable 320, the contacts 394 and the rotary magnet M393 to battery. When thus energized Vthe rotary magnet M393 operates to condition the wipers noted of the sequence switch 380 to be driven one step in the clockwise direction and to interrupt, at the contacts 394, the previously traced circuit for energizing the rotary magnet M393; whereupon the rotary magnet M393 restores to drive the wipers noted of the sequence switch 390 one step in the clockwise direction and to recomplete, at the contacts 394, the previously traced circuit for energizing the rotary magnet M393. Accordingly, the rotary magnet M333 operates intermittently, thereby to drive the wipers noted of thesequence switch 300 step by step in the clockwise direction until the stop relay R350 is operated in a manner more fully described hereinafter to interrupt, at the contacts 35|, the previously traced circuit for energizing the rotary magnet M393.

At this point it is noted that, immediately `the link distributor 30| assigns the link illustrated to Vthe use of the calling subscriber substation TI,

operations of the finder switch 300 and the selector switch 400, previously described, are initiated, and that the operation of the selector switch 400 initiates operation of the sequence switch 380 individually associated' with the link illustrated. Accordingly, operation of the sequence switch 380 to kfind an assigned one of the A operator positions 'or to find a storage position in the call storage unit 600is initiated prior to the seizure of the telephone line-205 extending to the calling subscriber substation T| by the finder switch 300.

Prior to continuing with the operation of the sequence switch 380, it is noted that the A operator position distributor in use, the main A operator position distributor 630 in the present example, is operative to preselect an idle one of the A operator positions to be seized by the sequence switch 380. VAssuming that the first A operator position 500 has been preselected by the main A operator position distributor 630 to be seized by the sequence switch 380 at Vthis time, a holding circuit is completed Vfor energizing in series the winding of the hold relay R610 and the righthand winding of the position relay R630, the position relay R630 corresponding to the first A operator `position 500. This holding circuit extends from ground byV way of the contacts 56|, C50|, the contacts 594 4of the A operator position distributor key K590, C683, the windingoi R610, the contacts 646 and 634 and the righthand winding of R639 to battery. The operated position. relay R630 retains interrupted, at the contacts 636, a holding circuit traced hereinafter for energizing the winding of the hold relay R610 in series with the right-hand winding of the position relay R650. Also the position relay R630 prepares, at the contacts 633, an operating circuit traced hereinafter for energizing the lefthand winding of the position relay R640, completes, at the contacts 632, a path for applying battery potential by way of the resistor 6|2, C682, the winding of the answer relay R545 and the contacts 559 to the control conductor C525 of the trunk 520 extending tothe rst A operator position 500 and completes, at the' contacts 63|, a path for applying ground potential tothe control conductor C680, for a purpose more fully described hereinafter. `The path Vfor applying ground potential to the control conductor C680 extends fromground by way of the contacts 546, C686, thescontacts 63|, C685 and the contacts 592 of the A operator position distributor key K590 to the control conductor C680. Further it is noted that no potential whatever appears upon the marking conductor C530 to C535, inclus ive; while battery potential appears upon the marking conductor C536. `The path for Yapplying battery potential to the marking conductor v C536 extends from battery by way of the winding of the first marking relay IM` and the contacts 62| to the marking conductor C536.

Continuing now with the operation of the sequence switch 380, the rotary magnet M393 Voo n- `tinues to operate intermittently in order to drive the wipers noted of the sequence switch 360 step by step in the clockwise direction until the wiper 39| engages the seventh contact in the associated contact bank 392 terminating the marking con- Yductor C536; whereupon a circuit is completed for energizing in series the windingof the stop relay R350 and the winding of the marking Arelay IM. This circuit extends from the ground- Y ed control conductor C363 of the trunk 3.60 by way of the winding of R350, the contacts'311', the

control conductor C325 in the cable H3-2i), the

wiper 39| and engaged seventh contact in the associated contact bank 392 of the sequence switch 380, the marking conductor C536, lthe contacts 62| and the winding of IM to battery. When the winding of the stop relay R359 is thus energized this relay operates to interrupt, at the contacts 35|, the previously traced circuit for energizing the rotary kmagnet M393,l thereby positively to arrest further operation'of the sequence switch 380, l

. When the winding of themarking relay IM is thus energized this relay operates shortly thereafter, this relay being of the slow-to-operatetype, to complete, at the contacts |M2, a circuit for energizing the winding of the release relay K by way of the grounded control conductor C680. Also the release relay R620 completes, at the contactsV 623, an obvious circuit for energizing the winding of the control relay R6 I0, thereby to cause the latter relay to operate shortly thereafter, Ythe latter relay being of the slow-to-operate type. Further the release relay R620'interrupts, at the contacts 62|, the previously traced circuit for energizing in series the winding ofthe stop relay R350 and the winding of the marking relay IM. Upon operating, the control relay R6|0 completes, at the contacts 6II, an obvious path for applying battery potential by way of the winding of the marking relay IM to the markingY conductor C536.

Accordingly, the marking relay IM and the stop relay R350 restorel when the previously traced circuit for energizing in series the windings thereof is interrupted incident to the operation of the release relay R620. Upon restoring, the stop`relay R350 completes, at the contacts 35|, the previously traced circuit for energizing the rotary magnet M393 of the sequence switch 380, thereby to cause the rotary magnet M393 again to operate intermittently. In the present instance, the rotary magnet M393 operates and restores only once; whereupon the wiper 39| thereof engages the eighth contact in the associated contact bank 392 of the sequence switch ,Y

380 terminating the control Yconductor C525 of the trunk 520, thereby'to complete a series circuit for energizing the winding of the answer relay R545 and the winding of the stop relay R350. This circuit extends from the grounded R545 are energized, thereby to cause these relays to operate. Upon operating, the stop relay R350 again interrupts, at the contacts the previously traced circuit for energizing the rotary magnet M393 of the sequence switch 380, thereby again to arrest operation of the sequence switch 380. Upon operating, the answer relay R545 interrupts, at the contacts 546, the previously traced holding circuit for energizing the winding of the release relay R620, thereby to cause the latter relay to restore and interrupt, at the contacts 623, the previously mentioned circuit for energizing the winding of the control relay R6I0, thereby to cause the latter relay to restore. Also the answer relay R545 completes, at the contacts 541, an obvious circuit for energizing the winding of the disconnect relay R550, thereby to cause the latter relay to operate.

Upon operating, the disconnect -relay R550 completes, at the contacts 552', a holding circuit for energizing the winding thereof, this circuit extending from ground by way of the contacts 58| of the trunk Ydisconnect key K580, the contacts 552 and the winding of R550 to battery. Also the disconnect relay R550 interrupts, at the contacts 559, the previously traced circuit for energizing in series the winding of the stop relay R350 and the winding of the answer relay R545 and completes, at the contacts 551, a circuit for energizing the winding of the cut-inl relay R310, this circuit extending from ground by way of aasascli e the contacts 551, the control conductor C526 of the trunk 520, the Wiper 38| Yand engaged contact in the associated contact bank 382 of the sequence switch 380, the control conductor C326 in the cable 320 and the winding of R310 to battery. When thus energized the cut-in relay R310 operates to interrupt, at the contacts 311, a further point in the previously traced series circuit for energizing the winding of the stop relay R350 and the winding of the answer relay R545, to prepare, at the contacts 318, a

circuit traced hereinafter for energizing the winding of the identity relay R360 and to interrupt, at the contacts 319, a further point in thepreviously traced circuit for energizing the rotary magnet M393 of the sequence switch 380. The stop relay R350 and the answer relay R545 then restore. Accordingly, at this time, the wipers noted of the sequence switch 380 engage the contacts in the associated contact banks thereof terminating the conductors of the trunk 520 extending to the first A operator position 500.

Further, the disconnect relay R550 interrupts, at the contacts 553, an obvious connection between the line conductors C52| and C523 of the trunk 520, interrupts, at the contacts 556, an obvious connection between the line conductors C522 and C524 of the trunk 520, completes, at the contacts 55| and 552, a connection between the conductors C52| and C523 of the trunk 520 and the retarder coil 530 and the telephone apparatus 5I1 at the first A operator position 500, and completes, at the contacts 554 and 555, a connection `between the line conductors C522 and C524V of the trunk 520 and the retarder coil 530 and the telephone apparatus 5I1 at the first A operator position 500. Accordingly, atthis time, one terminal of the retarder coil 530 is connected by way of the contacts 53| and 55| and by way of the contacts 542, 531 and 554 to the Vline conductors C52I and C522, respectively, of

the trunk 520; and the other terminal of the retarder coil 530 is connected by way of the contacts 533 and 552 and by way of the contacts 544, 538 and 555 to the line conductors C523 and C524, respectively, of the trunk 520. Also the telephone apparatus 5I1 at the rst A operator position 500 is connected by way of the contacts 5|| and 5|3 across th terminals of the retarder coil 530. Y

4Upon operating, the cut-in relay R310 completes, at the contacts 312 and 315, an alternative loop circuit extending between the retarder coil 530 at the rst A operator position 500 and the line relay R450 in the selector switch 400, this circuit extending from ground'by way of the lower winding of R450, the contacts 466, 433 and 428, C362, the contacts 315, the line conductor C324 in the cable 320 and the wiper 385 and engaged contact in the associated contact bank 386 of the sequence switch 380 to the line conductor C524 of the trunk 520, and from battery by way ofthe upper winding of R450, the contacts 463, v43| and 426, 036|, the contacts 312, the line conductor C322 in the cable 320 and the wiper 389 and engaged contact in the associated contact bank 390 of the sequence switch 380 to the line conductor C522 of the trunk 520, the line con' Vductors C522 and C524 of the trunk 520 being l 31| and 314, a connection between the subscriber substation T| and the line conductors C52I and C523 of the trunk 520. More particularly, the line 2,282,584 conductor C206 of the telephone line 205 is conwhile the line conductor C201 of the telephone line 205 is connected by way of the wiper 3 I 5, the contacts 332 and 314, the line conductor C323 in the cable 320 and the Wiper V383 and engaged contact in the associated contact bank 384 of the sequence-switch 330 to the line conductor C523 of the trunk 520. Finally, it is noted that a bridge at the subscriber substation TI is connected across the line conductors C205 and C201 of the telephone line-205; while the line con ductors C52I and C523 of the trunk 520 are connected to the retarder coil 530. Accordingly, at this time, a direct loop circuit is completed between the retarder coil 530 at the rst A operator position 500 and the line relay R450 in the selector switch 400; while an alternative loop circuit is completed between the subscriber substation TI and the line relay R450 in the selector switch 400 which includes the trunk circuit at the rst A operator position 500. Also when the telephone apparatus 5I1 at the first A operator position 500 is bridged across the retarder 'coil 530 a vconnection is completed between the calling subscriber substation TI and the telephone apparatus 5I1.

Further the cut-in relay R310 interrupts, at the contacts 313 and 315, the previously traced direct loop circuit between the subscriber substation TI and the line relay R450 in the selector switch 400, interrupts, at the contacts 310', a'point in a holding circuit traced hereinafter for energizing the winding of the call back relay R440 in the selector switch405, and interrupts, at the e the switching relay R330 andthe rotary magnetl M351, and'interrupts at the'contacts 313', the previously traced original holding circuit for energizing in series the lower winding of the switching relay R330 and the. rotary magnet M351. Accordingly, the operated-.cut-in relay R310 retains the switching relay R330 in its operated position independent of the selector switch 400, thereby to retain the iinder switch 300 in its operated .position independent of the selector switch 400. f

Also, upon operating, the disconnect relay R550 completes, at the contacts 55|', a circuit for energizing the Ywinding of the tone relay R5I0, this circuit extending from ground by way of the contacts 55|' and 528 and the winding of R5|0 to battery. When the winding of the tone relay R5|0 is thus energized this relay operates shortly thereafter, this relay being of the slow-to-operate type, to complete, at the contacts 5|5, an obvious circuit for energizing the winding of the tone relay R520. When thus energized the tonerclay R520. operates shortly thereafter, this relay being of the slow-to-operate type, to complete, at the contacts 523, an obvious circuit for energizing the winding ofthe tone relay R525. When thus energized the `tone relay R525 operates shortly thereafter, this relay being of the slow-tooperate type, to complete, at the contacts 521, an obvious holding circuit for energizingthe winding thereof and to interrupt, at the contacts 528, the previously traced circuit for energizing the winding of the tone relay R5I0. .The tone relay R5I0 then restores to interrupt, at the ccntacts 5|5, the previously mentioned circuit for energizing the winding ofthe tone relay R520', Y

thereby to cause the latter relay to restore.

Upon operating, the tone relay R5 I 0 interrupts, Y

at the contacts 5| I and 5I3, the previously traced connection between the telephone apparatus 5I1 and the retarder coil 530 and completes, at the contacts 5|2 and 5|ll, a circuit for conducting tone current over the telephone apparatus 5I1. Thelast-mentioned circuit extends from the ungrounded terminal ci a grounded source of tone current, not shown, by way of the tone conductor C581, the contacts 522 and 5|2, the 'telephone' for conducting tone current over the telephone apparatus 5I1. Upon operating, the'tone relay R525 completes, at the contacts 525, the previously mentioned alternative circuit for conducting tone current over the vtelephone apparatusr 5|1, this alternative circuit extending from tone potential appearing upon the tone conductor C581 by way of the contacts 523, 52| and 5|2, the telephone apparatus 5I1, the contacts 5M and the condenser 5|5 to ground. Upon restoring, the tone relay R5|0 interrupts, at the contacts 5|2 and 5I4, the previously traced alternative circuit for conducting tone'current over the telephone apparatus 5I1 and recompletes, at the contacts 5H and 5|3, the previously traced connection between the telephone apparatus 5I1 and the retarder coil 530. Finally, upon restoring,

the tone relay R520 interrupts, at the contacts 52 I, a further point in the previously traced alternative circuit for conducting. tone current over the telephone apparatus 5|-1 and prepares, at the contacts 522, the previously traced original circuit for conducting'tone current over the telephone apparatus 5|1. The'operation of the tone relays R5I0, R520 and R525 and the subsequent restoration of the tone lrelays R5|0 Vand R520 is effective to cause the receiver of the telephone instrument included in the telephone apparatus 5 I 1 to be operated alternately, whereupon a distinct zip-zip tone is produced thereby. The .produce tion of the zip-,Zip tone by the receiverV of the telephone instrument included in the'telephone apparatus 5|1 at the first A operator'position 500 indicates to the operator thereat that an incoming call hasbeen extended to her position by one y of the sequence switches. Y Y

Further, upon operating, the disconnectrelay R550 prepares; at the contacts 553', a point in a chain circuit traced hereinafter for energizing the winding of the busy relay R560, which chain circuit is completed in the event allor the A operator positions are busy at this time,.in a manner more fully explained hereinafter. Finally, the disconnect relay R550 completes, at the contacts 558, the previously mentioned circuit for energiz- 1 ing the lefthand winding of the position relay R640 corresponding to the second A operator-position, this circuit extending from ground byway of the contacts 558, 063|, the contacts S33 and the left-hand winding of R640 to battery.- VWhen thus energized, the position relay-R540 operates l to complete, at the contacts 644, a holdingcirV contacts 656 and 644 and the right-hand wind-l ing of R640 to battery. Also the position relay R640 interrupts, at the contacts 646, the previously traced holding circuit for energizing in series the winding of the hold relay R610 and the right-hand winding of the position relay R630, thereby to cause the latter relay to restore. Further the position relay R640 prepares, at the contacts 643, an obvious circuit for energizing the left-hand winding of the position relay R650 corresponding to the last A operator position, completes, at the contacts 642, an obvious path for applying battery potential to the control conductor C61| extending to the second A operator position and corresponding to the control conductor C682 extending to the iirst A operator position 500 and completes, at the contacts 64|, an obvious path for applying ground potential at the second A operator position to the control conductor C680, in a manner similar to that previously explained.

Accordingly, the operation of the position relay R640 in the main A operator position distributor 630 is effective to prepare the second A operator position to receive the next incoming call in the event the second A operator position is idle at this time. On the other hand, in the event the second A operator position is busy at this time, the previously mentioned circuit for energizing the left-hand winding of the position relay R650 is completed at the contacts `643 incident to the operation of the position relay R640, the disconnect relay at the second A operator position being operated at this time. Further it is noted that, upon restoring, the position relay R630 interrupts, at the contacts 634, a further point in the previously traced holding circuit for energizing in series the Winding of the hold relay R610 and the right-hand winding of the position relay R630. Also the position relay R630 interrupts, at the contacts 633, the previously traced circuit for energizing the left-hand winding of the position relay R649, interrupts, at the contacts 632, a further point in the previously traced circuit for energizing the winding of the answer relay R545 and interrupts, at the contacts 63|, the previously traced original circuit for ,applying ground potential at the first A operator position 500 to the control conductor C680.

At this point it is noted that the main A operator position distributor 630 is operated, thereby to cause one of the position relays to operate and condition a corresponding one of the A perator positions to receive the next incoming call, such, for example, as the second A operator position, only in the event one of the A operator positions is idle at this time. More particularly, in the event all of the A operator positions are busy when the disconnect relay R550 is operated, the previously mentioned chain circuit for energizing the winding of the busy relay R560 is completed at the contacts 553' incident to the operation .of the disconnect relay R550. This circuit extends from ground by way of the chain conductor C549, the contacts of the disconnect relays at the other A operator positions, the contacts 553' of the disconnect relay R550'at the rst A operator position 500 and the winding of R560 to battery. When thus energized the busy relay R560 operates to interrupt, at the contacts 56|, the previously traced holding circuit for energizing the winding of the hold relay R610 in series with the right-hand winding of one of the position relays R630, R640, R650, etc., thereby to cause the hold relay R610 to restore and all of the position relays R630, R640, R650, etc., to remain in their restored positions. Also, upon operating, the busy relay R560 interrupts, at the contacts 562a point in an alternative circuit for s energizing the left-hand Winding of the position relay R630. Upon restoring, the hold relay R610 prepares,1a,t the contacts 61|, a point in the previously mentioned alternative circuit for energizing the left-hand winding of the position relay R630. Accordingly, the operation of the busy relay R560 is eiective to prevent further operation of the main A operator position distributor 630 until one of the A operator positions becomes idle.

When one of the A operator positions becomes idle the disconnect relay thereat is restored, thereby to interrupt the previously traced circuit for energizing the winding of the busy relay R560,'whereupon the latter relay restores. Upon restoring, the busy relay R560 prepares, at the contacts 56|, the previously traced holding circuit for energizing the winding of the hold relay R610 in series with one of the position relays R630, R640, R650, etc., and completes, at the contacts 652, the previously mentioned alternative circuit for energizing the left-hand Winding oi the position relay R630, this circuit extending from ground by Way of the contacts 562, C502, the contacts 595 of the A operator position distributor key K590, C684, the contacts 61| and the left-hand winding of R630 to battery. When this circuit is completed the position relay R630 operates, thereby to initiate further operation of the main A operator position distributor 630; whereupon the main A operator position distributor 630 operates in order to cause the particular one of the position relays R630, R640, R650, etc., to remain operated, which corresponds `to the idle A operator position, thereby to conditributor 630, previously explained. In the event the main A operator position distributor 630 becomes defective, the operator at the rst A operator position 500 may substitute the auxiliary A operator position distributor 695 for the main A operator position distributor 630 by operating the A operator position distributor key K590. When the A operator position distributor key K590 is thus operated the previously traced connections between the control conductors C684, C683 and C685 extending to the main A operator position distributor 630 and the common control conductors C502, C50| and C680 are respectively interrupted at the contacts 595, 594 and 592 of the A operator position distributor key K590; and obvious alternative connections are completed, at the contacts 596, 593 and 59| of the A operator position distributor key K590, be-

tween the' common control conductors C502, 050| and C680 and the control conductors C693,

C692 vand C69|, respectively, extending to the auxiliary A operator position distributor 695.

Accordingly, at this time, after the sequence switch 380 seizes the trunk 520 extending to the first Aoperator position 500 'and both the apparatus at the rst lA operator position 500 and the main A operator position distributor 630 operate in the manner previously explained, a connection is estabilshed between the calling subscriber substation TI and the telephone japparatus 1 at the rst A operator position 500 and the second A operator position is conditioned to receive the next incoming call. More particularly, both the receiver and the transmitter at the Paystation call A call from a paystation, such, forv example, as the paystation T2, is initiated by removing the receiver of the telephone instrument thereat from its associated switchhook and depositing a coin in the coin slot of the coin collect and refund mechanism thereat. When the receiver of the telephone instrument at the paystation T2 is removed from its switchhook and the coin is deposited in the coin slot of the coin collect and refund mechanism thereat, a bridgepath is completed between the line conductors C246 and C241 of the telephone line 245 extending to the paystation T2, thereby to complete a circuit for energizing in series the upper and lower windings of the line relay R250. This circuit extends from ground by way of the contacts 281, C294, the lower winding of R250, lthe contacts 262, C241, the bridgepath between the line kconductors C241 and C246 of thev telephone line 245 at the paystation T2, C246, the contacts 26| and the upper winding of R250 to battery. 'When energized over the above-traced circuitA the line relay R250 operates to complete, at the contacts 253, a path for applying ground potential to the control conductor C249 of the telephone line 245, thereby to mark the telephone line 245 as busy to the rst B operator Yposition 494 and the other B operator positions in the local exchange 20. The last-mentioned path extends from ground by way of the contacts 281, C294 and the contacts 253 and 214 to the control conductors C249 of the telephone line 245. Also the line relay R256 completes, at the contacts 252, an obvious multiple path for applying battery potential by way of the winding of the cutoff relay R260 and the resistor 261 to the control conductor C246 of the telephone line 245, thereby to mark the telephone line 245 as a calling line. Further the line relay R250 completes, at the contacts an obvious path for applying direct ground potential to the marking conductor C284 terminated by the ith contactsin the vertical control contact banks of the nder switches, thereby to mark the telephone line 245 as terminating in the fth level of the Ymain contact banks of the nder switches. Finally, the* line relay R256 completes, at the contacts 25|, a path for applying resistance ground potential to the start conductor C308 extending to the link-distributorv this path extending from ground by way of the contacts 25| and 21|, C264, the re sistor 28| and the contacts 288 tothe start conu ductor C308.` The application of ground potential tothe start conductor C308 initiates operation ofthe link distributor 30| in the manner previously explained.

The link distributor 30| then operates to cause'V the previously selected'linkto be assigned to the use of the calling vpaystation YT2 in the previously described manner. Assuming that the link distributor 30| operates to assign the link illus-` trated to the use of the calling paystation T2, the finder switch 300 operates in the manner previously explained toseize the telephone line 245 extending to the calling paystation T2. Also the selector switch 400fand the sequence switch 380 operate in themanners previously described, y Assuming that the main A operator position distributor 630 has previously selected the rst A operator position 500 at this time, the sequence switch 380 operates to seize the trunk 520 extending to the rst A operator position 500 in the 4Vmanner previously explained.

kWhen the rst A operator position 500 is seized by the sequence switch 380 the cut-in relay R310 operates in order to complete, vat the contacts 312 and 315, the previously traced loop circuit between the line relayR450 in the selector switch 460 and the retarder coil 530 at the first IA operator position 500, and to complete, at the contacts 31| and 314, a loop circuit between the calling paystation T2 Vand the retarder-.coil 530 at the rstA operator position 500. Thelast-mentioned loop circuit extends from the liner conductor C246 of the telephone line 2,45 by way of the wiper 3|4, the contacts 33| and 31|, the line conductor C32| in the cable 320,- the wiper 381 and engaged contact in the associated contact telephone line ,245 being connected together by l `way of the bridge path at the calling paysta-y bank 388 of the sequence switch 380, the line conductor C52| of the trunk 520, the` contacts 55| and 53|, the retarder coil 530,'the contacts 533 and 552, the line conductor C523Yof thetrunk 520, the wiper 363 and engaged contact in the associated contact bank 384 of the sequence switch 380, the line conductor C323 in the cable 320, the contacts 314 and 332 and the wiper` 3|5 to the line conductor C241 of the telephone line 245, the` line-conductors C246vand C241 of the tion T2.

Also, when the finder switch 300 seizes the telephone line 245, direct ground potential is applied by way of the wiper 3|6 to the control `r`conductor C248 of the telephone line 245, thereby to complete a circuit for energizing the winding of the'cutol relay R260, this circuit extending from the grounded control conductor C246 of the telephone line 245 by .way of the contacts 252 and 216 and the winding of R260 to battery. When .thus energized the cutoi relay R260 operates toY complete, at the contacts 264, an obvious holding circuit for energizing the Winding thereof by way of. the control conductor C248 of thetelephone line 245, to interrupt, at the contacts 264, the previously traced path for applying battery potential by way of ,the resistor 261 to the control conductor C248 of the telephone line 245, and to thereby to cause the latter relay to operate.

Finally the cutoffrelay R260 interrupts, at the contacts` 26| and 262, the previously traced circuit for energizing in series the upper and lower

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