US2288789A - Telephone system - Google Patents

Description

July 7, 1942- T. F. cRocKr-:R 2,288,789

TELEPHONE SYSTEM Filed March 29, 1940 7 Sheets-Sheet l A, .mmv .mul if mmw wml@ m QN zw 45,3

INVENTOR THOMAS F. CROCKER ATTORNEYS T. F. cRocKER TELEPHONE SYSTEM Filed March 29, 1940 July 7, 1942.

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T. F. CROCKER TELEPHONE SYSTEM Filed March 29. 1940 `7 sheets-sheet 5 July 7, 1942.

T. F. CROCKER l1"ELEPHONE SYSTEMl Filed March 29, 1940 7 Sheets-Sheet, 6

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I ollakmmb INVENTOR' THOMAS F. CROCKER ,am BY al M l l ATTORNEYS Patented July 7, 1942 1 'Thomas Crocker, Chicago, Ill., assgnor 4to As- Isociated 'Electric Laboratories, `In'ci, Chica-go,

'IlL, -a corporation of Delaware Application March 2.9, 1940, Serial o..32li6l9 erom-rms; (ci-risate) The present invention relates totelephonel systems and moreparticularly to improved semiautomatic telephone systems-ofl the character of that disclosed and claimed in the copending application `of Thomas F. Crocker; Serial No. 311,1551, led December 29, 11939.

In a 4conventional telephone system of the semi-'automatic typ-e, the various manual telephonev lines terminate, injackswat the A and lB operator positions; and an automatic switch train provided with a distributin'gfsystem is in.-

'terposed between the A operatorpositions and theB operator positions. Ina telephone system of this type, calls son theV telephone :lines are answered directly by the operators at the A operator positions and :routed by way of the switch train underthe lcontrol of the distributing'system to the s-B operatorpositions to be completed.

Hence, in a'telephone's'ystemof this type, the

`traflic between the Agoperator positions and the Boperator'positionsis governedby the rdistributing system. However, the traffic betweenthe calling .telephone lines `of tlievarious A operator positionszis'not` governed butz'remains under thez'manual control of the-operatorsat .tlie. A operatorpositions," rendering the number of 'calls on the telephone linesfanswered by' anioper'ator at a given A operator position `and. routed therefrom tothe Boperator `positions to 'be completed entirely within the discretion of` the operator attlie given A operator position.

Accordinglyitis an object ofthe present invention toprov'i'de in aitelephonesystem f Vthe type deScribedVimpoved `apparatus .for distribting calls -on telephone lines to "a number of A .operatorrpositions to be answered.

vAnother"object of the invention 'isl to iprovide in a telephone system including anumbe of A operator :Lp'ositionsiand .a number of..Boperatorpositionsgan `improved arrangement for fdistributing incoming calls on telephone lin'es'to` the Aoperatorpositions toi be answered.` and.' for distributing 1 recalls on established connections to the Aoperatorlpositions to be answered.

Another i object `of `.the invention 'is'V to provide in a telephone `:system including a number of A operator "positions and va .number ofB operator positions and apparatus under` .the control ing recalls on the established connections to- -the -A operator positions to :be answered and `for .governing coin Acollection V and i refund "mechanism and message re'gistermechanism associated with the telephone lines.

-A'furthery object of jthe A invention'is to i provide in `a telephone rsystem including an operator position provided with facilities -for "answering 4a callback'upon-an established-connection, improvedswitcliing lapparatus included -in the establish'ed connection' and embodying control apparatus selectively 'governable over thel estab- 'lished connection forjcreating-agcall-back upon .the-established connection rand for governing coin-col-lectionand refund mechanism or yrnes- `sagere'gister mechanism associated witha* calling line 'included in theestablished connection. The features ofV the present invention are 4illustrated .as being incorporated in -atelephone system comprising an exchange terminating v a apluralityof manual telephone lines and includring -anumberjof Aoperator'positions; a numiber of B "operatorv positionsand a number of switching links.A The switching links-have acfcfess to Vthegltelephone lines, Vto the A operator .positions-andito the Bioperatorfpositions; while the B operator positions have access to the' tele- :phone'linesp The ltelephone lines comprisetwo `classesvvhich 'are i rendered correspondingI classes of servioe consisting f of Ymessage. register service :lo and prep-ay*service.` c. i

' In accordance with; one feature'4 of the invention, thetelephonesystem comprises aplura'lity` of telephone lines, a i plurality; of VA operator -positi'ons andfsa Bf operator jposition.V -Also the gli-system-compris'es"means for-1outing'a call on -any-one of .the telephone 'lines to an idle-one of thel 'A'folserator positions to be answered, vmeans" for routing `a call from the one A'oper- 1ator position to Ithe -B operator position, and

o means for` establishing a connection between' the fonetelephone -line` and 'the -B operator position "-indepennent `of the one A operator position,

` -thereby to route acallfromgthecne telephone line to the B operator position- V Furtheruthe system comprises `means for routing a recall by particularly, the "system comprises Va switchingA 5o `.link including an answer switch fhaving l'access to the telephone lines, va nderswitch having za'ccessto the A operator positions and a call s'witcnhaving access to the 'B operator VApositions, and lmeans controlled i by 4the presence `of a callionone .ofthetelephone lines forinitiating operations of the answer switch and the nder switch of the switching link, the operation of the answer switch being arrested when it finds a calling one of the telephone lines and the operation of the finder switch being arrested when it finds an idle one of the A operator positions. Also, each one of the A operator positions has an identity unit individually associated therewith which is controllable from the one A operator position to indicate the particular character identifying a calling telephone line seized by the finder switch of the link, each of the telephone lines being identified by a particular multi-symbol character.

In accordance with a further feature of the invention, 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 governing 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 operative under the control lof 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 in the established connection, and additional means controlled 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 receiving 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.

Further features of the invention pertain to the particular arrangement of the circuit elements thereof, 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 and advantages thereof, will best be understood by reference to the following speciiication taken in connection 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, illust/rate the details of a system having incorporated therein the features of the invention, as brieiiy outlined above.

Description of the 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 28, a distant exchange 3l) 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 265 and 245, respectively, extend to the subscriber substation Tl and to the paystation T2. Also, it is noted that each telephone line in the local exchange 20 is identified by a particular multi-symbol character constituting a directory number in a manner more fully explained subsequently. The message rate line circuit 200 is individually associated with the telephone line 205; and the prepay line circuit 240 is individually associated with the telephone line 245. Each of the subscriber substations and paystations in the local exchange 20 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 29 comprises a number of A operator positions, including the first A operation position 500, and a number of B operator positions, including the first B operator position 484. Also a group of toll lines, including the toll line 499, terminates at the local exchange 2i) and extends to a remote exchange, not shown. Each A operator position has a trunk individually extending thereto, the trunk 528 individually extending to the first A operator position '560; 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 operator position 494. Each trunk extending to each B operator position is provided with a trunk line circuit individual thereto, the trunk line circuit 445 being individual to the trunk line 49) extending to the first B operator position 494. Each toll line terminated at the local exchange 2li is provided With a toll line circuit individual thereto, the toll line circuit 491 being individual to the toll line 499. Also each trunk line extending between the local exchange 29 and the B operator position 498 in the distant exchange 30 is provided with a trunk line circuit individual thereto, the trunk line circuit 412 being individual to the trunk line 410 extending between the local exchange 20 and the B operator position 498 in the distant exchange 39.

Further the local exchange 2l! comprises a number of finder-selector links, including the finder-selector link illustrated, and a link distributor 30| for assigning idle ones of the links to the use of the telephone stations. For example, the link illustrated includes a finder switch 330 and a selector switch 439. Also a sequence switch is individually associated with each of the links, the sequence switch 380 being individually associated with the link illustrated. Further the local exchange 20 comprises a main A operator position distributor B30 and an auxiliary A operator position distributor 695, each of the A assensoo'perator positiondistributors beingV operative Ato assignidle ones of! the- AK operatory positions to receive incoming calls or recalls to the local exchangeA 20 in a-predetermined order- Finally the local exchange 20-` comprises a call storage-unit w `and anumber of identity units individually associated with theY A. operator positions, the first identity unit libeingindividually associ-` ated withthefirst- A operator positionl Eachoflthe finder switches, such, for example, as. the finder switch3ll0, constitutes an answer switchl having access. to.each-of the telephone lines .in the local exchange.; each ofthe selector switches, such, forexample, as the selector switch itil.; constitutes a. call. switchfhaving access to eachof the trunkscextending to .the Boperator. positions andto the` toll.lines and .to `each ofthe trunk` lines; extending., tothe distant exchange 3B.; andeachof the sequence switches, such, for example, asthesequence. switch 380, constitutes a positionandlstorage` finder switch having access toeach of the trunks individually extending to the. Apperatorpositions. and .tothe call storage unit S. Also it is noted that each B operator position in the local exchange 2E has` access to each .telephone4 linev therein.

The distant exchange 33 comprises a number of A operator positions, not shown, and a number of B operator positions including the B operator position 438, previously mentioned. It is noted that the trunk line 4.1i) extending between the local exchange 2|)v and the distant exchange Sliis terminated at the B operator position lied in the distant exchange 3i).

Preferably, each of the lnder-selector links is identicalto the link illustrated which comprises a iinder switchSil anda selector switch lifll, as previouslynoted. The finder switch 365, as best shown in Fig. 3, comprises a switching mechanism 3H! of the 20D-point Strowger type including a carriage provided with a first wiper set, including the wipers 3M, 3I5 and 3|5, a second wiper set including the wipers 3| I, 3|2 and 3|3 and a control wiper 3H.

wipers 3| I, 3I2 and 3|3 of the second wiper set are capable of both Vertical and rotary movements; while the control wiper 3|l' is capable of vertical movement. Further the mechanism 3H) comprises a circumferentially disposed `main conu tact bank provided with two sections respectively associated with the first and second wiper sets and a vertical control contact bank associated with the control wiper 3|1. Accordingly, in the mechanism 3|il, the rst and second wiper sets respectively have access to the first and second groups of one hundred lines each, respectively terminated by the first and second sections of the main contact bank. Also the mechanism 3H) is provided with a vertical magnet M365 for moving the iirst 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 and a release magnet M339 for releasing the rst and second wiper sets thereof and for causing these wiper sets to be returned to their normal positions. Finally, the mechanism 3|0 has two sets of switch springs S352 and S356 operatively associated'therewith, which are controlled in accordance with the movements of the first and second wiper sets thereof, in a manner more fully described subsequently.

Also the nder switch 300 comprises a number of relays including two switching relays R320 and R330, a startrelay R340, a stop relay R350, an

It is noted that the wipers 3|4, SI5 and 346 of the first wiper set and the identity relay R301and aout-in relay-,R313 connected' and arranged; ina.- manner more fully` described hereinafter.`

The selectos switchil, as bestshownin Fig.. 4, comprisesa-switching mechanism 4100i the point Strowger type including a .carriage .provided witha vwiper set includingthe wipers 4| I, 4 2 and M3. Itis noted thatthewipersi I, M2 and4|3 of the-wiper sets-are capable ofboth vertical and rotary movements. Further. the .mechanism i I i) comprises a.circumferentially.disposed maincon-Y tactbank associated: with the.wiper` set. Accordingly, the wiper. setthas aocessto a group. of one hundred. lines terminated` by. the contact bank. Also the mechanismA I Uilisprovided .with a vertical magnet ,MMA for moving the` wiper set thereoffin the. vertical direction, arotarymagnet M418.. for. moving thewiper.. set thereof in the rotary direction, and areleasev magnet Mlilfor releasing the wiper setrthereof and forV causing the wiper set tobe returnedto itsynormal position. Finally the mechanism 4| has a number of switch springsSIS, S42,.,Sfl2|S422, Sf-i23 andzSsi/ `operatively associated therewith, which are `controlled in accordance with `the movements of the wiperset thereof, ,inf a manner more fully described subsequently.

Also the selector switch .4M comprises anumber ofrelays includingv a control relay RME, a coin and register relay R43|la call pack` relay Rfi, twoholdrelays R445; and R480, 4aline relay R453, a switch-.through relay Rlha battery supply relay Rolo, atransfer relay R485 and a switching relay Riso connected-aand, arranged in a manner more fully describedsubsequently.

Preferably, each of the sequenceswitches is identical to the sequence switch 33E! individually associated with the link illustrated. The sequence switch 3.8i! is of the rotary type and comprises, as best shown in Fig. 3, six rotary wipers Sti, 383, 3&5, 337, 339 and 39| provided with individually associated rotary contact banks 382, 33d, 3%, 383, 3% and 392. Also the sequence switch 339 is provided with a rotary magnet M393 for moving the wipers noted in the rotary direction.

Thelink distributor 39| illustrated in Fig. 3 has;` access to each of the links in the local exchange 2S 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` 2i). The details of the connection and arrangement of the link distributor 30| are not disclosed as they form no part of the present invention. However, for reference purpose, it is noted rthat the connection and arrangement of a link distributor of the type of the link distributor 30| is shown in the copending application of Edward S. Peterson, Serial No. 233,021, filed October 3, 1938. Also a marking network 283, shown inFig 2, is associated with the link distributor Sill `in order to initiate operation thereof when a call is initiated on one of the telephone lines extending to a telephone station inzthe local exchange 2li. Also the marking network 283 comprises a busy relay R285; associatedwith the link distributor Sill and a tone transformer 29D commonly associated with the various line circuits, in a manner more fully described hereinafter. i

Preferably, each of the message rate line circuits is identical to the messagey rate line circuit 230 individually associated-with the telephone line 265 extending to the subscriber substation TI, shown in Fig. 2, which .comprises a line relay RMO, a cutoff relay R220. and alockoutrelay R230 connected and arranged in a manner more fully described subsequently. Also, a signal lamp LZES 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 cutoi 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 with 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 R463 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 first B operator position 494, shown in Figs. 4 and 2. The first B operator position 494 comprises conventional answering equipment, not shown; conventional calling equipment including a number of call jacks J20l and J202 respectively terminating the telephone lines 205 and 245; and a number of conventional cord circuits, not shown.

Preferably, each f 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 K565, an error release key K510, an identity key K515, a trunk disconnect key K580 and an A operator position distributor key K590. Also the trunk circuit at the first A operator position 500 comprises telephone apparatus 5I1 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 R5I0, 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 L583. 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 iirst 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.

The call storage unit 600, shown in Fig. 6, comprises six marking relays IM to 6M, inclusive, a control relay R6i0 and a release relay R620 connected and arranged in a manner more fully described subsequently. Also, six storage lamps Lll to L606, inclusive, are associated with the call storage unit 600 and commonly associated with each of the A operator positions.

Preferably, both the main A operator position distributor 630 and the auxiliary A operator position distributor 695 are identical; the main A operator position distributor 630 comprising,

as shown in Fig. 6, a hold relay R610 and a number of position relays R630, R640, R650, 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 rst identity unit individually associated with the first A operator position 500 which comprises, as shown in Fig. '1, a first test switch 'H0 individually associated with the rst group of one hundred lines 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 vaccessible 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 "III, H3, 1I5, 1I1, 1l9 and 12| provided with individually associated rotary contact banks 112, "H4, H6, 118, and 122. Also the test switch 'Ht is provided with a rotary magnet M123 for moving the wipers noted in the rotary direction.

Further, the first identity unit "il comprises a iirst start relay R and a first stop relay R140 individually associated with the first test switch and a second start relay and a second stop relay, not shown, individually associated with the second test switch. Also the first identity unit includes a test transfonner 155, a lockout relay R'i, a switching relay R160, five testing relays l'ZU, SMU, 56U`, 16U and @0U and ten marking relays iD to 10D, inclusive. Finally, the first identity unit W0 comprises a group of identity lamps including a thousand-digit lamp MLI, two hundred-digit lamps CLI and CL2, ten tendigit lamps DLI to DLli, inclusive, and ten unit-digit lamps ULi to ULM?, inclusive. The first identity unit 'E63 is so connected and arranged that, when the identity key X515 at the first A operator position 595 is operated, the rst identity unit 160 operates in a 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 iinder 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. l of the drawings, it is noted that, when a 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 t0 initiate operation of the link distributor 35|. The link distributor 36! 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 30! 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 tele* phone station; whereupon the nder switch 306 thereof operates to seize the telephone line ex tending to the callingtelephone station, andoperation of the sequence lSwitch Sindividually associated with the link illustrated is initiated. When the nder switch 300 seizes the telephone line extending to-the calling telephone station, such, for example, asthe telephone line 2Ii5'extending to the subscriber substation'll, the link distributor Stil is releasedV and operatesto pre-` select another idle link, as previously. noted.

TheiA operator position distributor 33t preselects one of the idle Aoperator positions for use; and when a preselected one ofv theA operator positions is taken for use the A operator position distributor E30 operates to. preselect another idle one of the A operator positionsfor use. Upon operating, the sequence switch 33S seizes the trunk extending to the previously selected A operator position, such, for example, as the trunk 520` extending to the first A operator position de, thereby-to extend the call from the calling subscriber substation Tl tothe selected first A operator position 59B. The operator at the rst A operator position 5to answers'the call andthen operates the key sender ather position, thereby to control the operation of the selector switch liet in order to extend the call to its destination. In this connection it is noted that the selector switch 453i) may beselectively conH trolled to extend the call to any idle B operator position in the localexchange 20, to the B operator position 49% in the distant exchange 3! or over a toll line, such,. forv example, as the toll line i599.

In the event the call is to be routed to a telephone station inthe local exchange Zi, the selecto;` switchlll is controlledin order to route the call to an idle B operator` position inthe local exchange 2Q. The operator` atA the idle B operator position in the local exchange 23 answers the call and then extends the call to the called telephone stationv in the local exchange 2i), in the usual manner. In the event the call is to be routed to a telephone station in the distant` exchange-Sil, the selector switch 4&8 is controlled in order to route the call totheB operator position i313` in the' distant exchange 3Q. The .operator at the Bi operator position 498 in the distant exchange 3Q answers the call and then extends the call to the called telephone station in the distant exchange. in the usual manner. In the event the call is to be Arouted toll, the selector switch 45H3 is controlled in order to route the call to an` idle one of the toll lines, such, for example, as the toll line tti); 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 iirst A operator position 5G!! in the local exchange 2G to an idle one of the B operator positions in the localexchange 2i), to the B operator position A498 in the distant exchange 3i! or over one of the tolllines, and the informationconcerning the extension of the call has been conveyed to the called operator, the operator at thev rst A operator position 5M releases the connection between her position and the ynder-selector link, whereupon a direct connection is completed between the finder switch and the selector switchl of the link excluding the rst A operator position Beil.

It is not that the called operator at a B operatcr position in the local exchange Eil or `at the B operator position 498 in the distant exchange Sil, to which the call is routed-by the selector switcl 400, may recall the operator at an idle one o'EV the A operator positions in the local exchange 20v 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 eventY the connection includes a telephone line in the local exchange 2i) rendered prepay4 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 apaystation associated with a line included in a con-- nection may be controlled from the-rst A operator position 500, thereby to causeit to, refund the coin deposited, therein.

Also itis noted that, when a connection. is routed to the first A operator position 50E),l the operator thereat may initiateoperation of the rst identity unit 10i), thereby'to cause the firstv identity unit 'l'llilV to operate. andidentify the directory number of the calling telephone line in the local exchange 2.0 includedin the connection, as determined-by the operation of the nder switch 300 of theplink. illustrated. to seizethe calling telephone linein the localexchange 20.

In'the event all of` the` A operator positions in the local-exchange 20 are busy when operation of the seque-nce switchli).` is initiated, the sequence switch 38|] seizes the call storage unit 60B. More particularly, the sequence switches` individually associated with the links inthe local exchange 20 seize the respective positions of the call storage unit lill()k 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 inthe local exchange 20-are busy. At this time,` when a number of calls and recalls--ona number of the links are stored in the callstorage unit E00 and one of the A- operator positionsin thelocal exchange 20 `becomes idle, the A operator position distributor 63E! operates to assign the idle A operator position for use and causes ythe callstorage unit M9 to initiate operation of the sequence switch corresponding to the-first stored call or recall in the call storage unit 603. The sequence switch corresponding to the first storedV callV or recall in the call storage unit 60E) 'then operates to rind the assigned A operator position. The call storage unit 609 then operates-to causeeach of the remainder of the sequenceA switches to be advanced one position, thereby tov advance,` by one position, thecalls and recalls stored in the call storage unit-600. Accordingly, the call storage unit Gill) operates to cause incoming calls and recalls to be stored in a predetermined order when allof the A operatorpositions 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 2i) become idle.

After'a call from a calling telephone station has been extended from one .of the A operator positions to one ofthe B operatorV positions in either the locall exchange or the distant exchange 30, the release-of the established connection is primarily under the control of the operator at the calledoperator position. On the other hand, afterY acall from a calling telephone station has been extended from one of the A operatorA 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.

` Message rate subscriber substation call A call from a message rate subscriber substation, such, for example, as the subscriber substation TI, is initiated by removing the receiver of the telephone instrument thereat from its associated switchhook. AWhen the receiver of the telephone instrumentat the subscriber substation TI Vis removed from its associated switchhook, a bridgepath is completed between the line conductorsCZE'and C201of the telephone line 205V extending to thesubscriber substation TI. When this bridge path is completed between the line conductors ofthe telephone line 205, a circuit is completed for, energizing in series the upper and Ylower windings of the line. relay R2|0;Y 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 T|, C206, theY contacts 22| and the upperwinding of R2|0 to battery. When energizedoverthe above-traced circuit the line relay R2|0 operates to complete, at the contacts. 2 |73, Van Vobvious path for applying ground potential to the control conductor C209 of the telephone line Y20,5 terminating in the `iack .120|

at the first B operator position 494, thereby to I ing 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 nder switches having access thereto. Furtherthe line relay R2|0 completes, at the contacts 2||, a path for applying resistance ground potential to the start conductor C-8 extending tothe link distributor 30|, this path extending from ground by way of the contacts 2|| 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 obviouspath for applying direct ground potential by way of the marking conductor C283 to the rst contacts in the vertical control contact banks of the nder 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 iinder switches marks the telephone line 205 as terminating in the first level of the main contact banks of the i'lnder switches.

The link distributor 30| is of the preselective type and operates to select another idle link as soon as the nder switch of a previously selected link operates to find 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 C392, thereby to complete an obvious circuit for energizing the winding of the start relay R340 in the finder 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-link-busy conductor C309 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 C309. Also the start relay R340 prepares, at the contacts 34|, obvious multiple circuits for 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 hereinafter for energizing the rotary magnet M361.

The link distributor 30| then operates to cause ground potential to be applied to the vertical conductor C305, thereby to complete the previously mentioned circuit for energizing the vertical magnet 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 abovetraced 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 interruptor conductor C306 causes the link distributor 30| to interrupt the application of ground potential to the vertical conductor C305; whereupon the vertical magnet M305 restores to interrupt, at the contacts 366, the previously mentioned path for applying ground potential to the interruptor 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 30|. 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 engag-es 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 30| to operate, thereby to interrupt the application of ground potential to the vertical conductor C305 and to applygrcund potential to the rotary conductor C304.

The application of ground potential to the rotary conductor C304 completes the previously mentioned .circuit for energizing the 'rotary 4magnet M361, .this circuit extending "from lthe grounded rotary vconductor C304 4by Way `of the contacts344, :336 and` 328 and'the rotarymagnet M361 to battery. When energized `over the `above-traced. circuit the rotary magnet "M361 operatesto drive the first andsecond `wipersets o'flthe mechanism3 |10 one step Ainthe rotaryfdirection-andito complete, at Ithe contacts A366,an

`obvious path for applying ground .potential to the interrupt-er l.conductorC366- 'This applica- Vtionof ground potential'toithe interrupter-conductor C366 causes the `link -distributor 130| to operatel and removethefapplication o'f ground potential -to 'the vrotary conductor C304; whereupon the rotary Y.magnet M361 yrestores to finterrupt,

at the contacts 366, the 'previously 'mentioned path for applying Aground `potential to the interrupter 4conductor C366. Accordingly, the rotary ymagnet M361 operates intermittently, thereby to driveftherstand second wiper sets'of the mechanism -3 I 6- step bystep infthe rotary direction until either the control wiper "316 or the `control Wiper "3 3 of the respective first and second wiper conductor ofy acalling telephoneline having bat- `tery lpotential thereon.

Inthe present example,thetelephonefline 265 is'includedinthe first section of -the main contact bank-ofithe mechanism `316. Accordingly, when C the-control wiper i6 of the rst wiper set ofthe mechanism`3|`6 engages the contact of the'contact set in the first-section of the main Contact bank of the-mechanism3l0 Vterminating the control conductor C268 of lthe telephone line 1205, a circuit is completed Zfor energizing `the upper winding of the switching relay R336. This circuit extends from the grounded marking "conductor C263 gbylway ofthe -vertical'control wiper 3 I1 of the `mechanism 3|6, the upper winding of R330, thecontacts-324 and the control wiper 3|6 of the iirst wiper set of the mechanism 3|0 to the control conductor C206 of the telephone'line 265, the vcontrol conductor C268of thetelephone `line 5265 -h'aving battery potential thereon. When ltion due to vrthehigh series resistance of this holding circuit. Accordingly, further operation `of the mechanism -3|6 is arrested. -Also the switching relay R330interrupts, atthecontacts 334, `a'point in an obvious circuit for energizing the upper Winding of the switching relay R326, thereby positively to prevent operation of the latter relay at this time. 'Further the switching relay R336 interrupts, atthecontacts l339, a point in a circuit 'traced hereinafter for energizing the release magnetMB-S and completes,at the contacts 336, a connection between the rotaryconductor C364 `and the .guard conductor "C363, this connection extending 'from vthe rotary conductor C304 by `way of the contacts i344, 336 and r34'2 to theguard conductor C303. When the rotary conductor C364 Lis connected to fthe guard `conductor-C363,

'sets engages a contact terminating the-control `125 `signal "lamp L2 |56.

Ioperation `of fthe link :distributor .36| to 'control the finder switch i366 istarrested,"whereupon the `link distributor 36| operates automaticallyto select foruse Lanotheridle ione of the links.

'Alsolit is 'noted that, Awhenrthe carriageof the lmechanism 1'3`|0 is driven onestep .in the Verti- .caldirection, the setsorswitch springs S352 and C356 4are actuated. `More.partic1'ilarly,the"con- `tacts '35'1 .and`358 of lthe set ofswitch springs rS356 are yactuated. respectively into engagement land disengagement, thereby to prepare a Vfurther point inthe .previously mentioned circuit `for energizing "the lrelease `magnet M369 and 'to interrupt afurther point in the .previouslyitrace'd path for applyingground potential in the nder switch ,3`0`0`rto the all-link-.busy conductorC309. "Finally, `the ` contacts 364 and 353 of `the setfof switch springsS352 are 'actuated respectively into Adisengagement "and engagement, thereby to interrup't the connection betweenthe controlconductor C364 of thetrunk 366 andthe guard conduc- `tor C363land to vprepare a `path traced .hereina'fterfor applying ground potential to `the guard lconductor C363. Finally, upon foperating, the

'switching relay 'R330 completes, at the contacts 33|, 332 and '333,.connections`between the conductors of the trunk360 extending between the iinderr switch 366 andthe selector switch 466 v and .thei'irst wiper seto'fithe mechanism 316. More particularly, a circuit isfcorn'pleted, at the convtacts 333, for energizing-the windingoflthe cutoi relay R220, this rcircuit extending from the grounded control conductor C364 di the trunk the wiper 3|6, the=control conductor C268-off the A telephone line 205, thecontacts'/ZIIZ and i236 yand the winding of R226to` battery. When-the winding of `the cutoff relay R220-is thus energized this relay operates toin'terrupt at the contacts 4225, the `previously meritionedpath for applying lbattery potential by -Waycf `'the resistor 2|6 to the control conductor l'C266 -fof the telephone "line 265 and-to complete, at the contacts v224, `a holding vcircuit for energizing the Winding of the cutoff relay R220, this yholding circuit extending from the grounded control-conductorCZfS of the telephone line l265 by-way of Ethe contacts A'224 and vthe winding 0612.226 Ate battery. Also the cutoil relay'R226 interrupts, atthe contacts "226, a point in an obvious circuit 1for illuminating the vsignal lamp L2 |8an`d completes,fat the contacts 223, an obvious circuit :for energizingthe winding ofthe lockout relay R236, thereby l"to cause the Llatter relay to operate. Finally, -theoutoi relay R226 interruptsyat the contacts I2| and 222 the previously 'traced circuit `for `energizing .the .winding of theline relay R2l0, .thereby to `clear the tele- ,phone line 265 of impedance ,elements and to cause .the latter relay to restore.

,Upon operating, the .lockout Jrelay R233 .pre-

pares, at `the contacts 232,-a pointua holding `circuit traced thereinafter' tfor energizing the winding thereof, completes, Vat thecc-ntacts 233,

.-an obvious alternative path for'applying ground potential `to `the control conductor `C266 of 'the telephone line 205,'thereby'to'markthe telephone -line 265 .as-busy .tothefB operator positions inthe ilocal exchange A26 havingaccessthereto.'and prefpares, at the contacts 235, a `further point .in the previously mentioned -circuit for lillurninating the Upon restoring, the line relay R2|`6 interrupts, at the contacts 2H, the previously A'traced 'paths for lapplying direct `ground c potential to the Vmarking conductor 4C263 and Yresistance ground potential to the start conductor C306 extending to the link distributor 30|.

Further it is 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 finder switch of at least one of the links, groundv potential being removed from the alllink-busy conductor C309 in the inder 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 39| 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 start relay 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 350 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 Vmagnet M361 and the vertical magnet M395.

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 369 in the selector switch 400 at this time.

When the trunk 350 is connected to the telephone line 205 due to the operation of the switching relay R330 in the finder 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 423, C362, the contacts 316 and 332, and the wiper 3| 5 to the line conductor C201 of the telephone line 295, and from battery by way of the upper winding of R450, the contacts 463, 43| and 426, 030|, 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 telephoneA line 295 being connected together by way of the bridge path at the subscriber substation 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 403, the previously mentioned path for applying ground potential to the control conductor C364 of the trunk 360, as previously noted. Also the hold relay R400 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 432, a point in a circuit traced hereinafter for energizing the lower winding of the switching relay R460 and prepares, at the contacts 484, a circuit traced hereinafter for energizing in multiple the lower winding of the transfer relay R405 and the vertical magnet M4|4.

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 R435 prepares, at the contacts 403, a further point in the previously mentioned circuit for energizing in multiple the lower winding of the transfer relay R485 and the vertical magnet M4|4 and completes, at Athe contacts 486, an obvious path for applying ground potential to the control conductor C363 of the trunk 350. 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 nder 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 380 extends from the grounded control conductor C353 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 the 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 300 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 M393 operates intermittently, thereby to drive the wipers noted of the sequence switch 380 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 the use of the calling subscriber substation T|, operations of the iinder 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 300 to find an assigned one of the A operator positions or to find a storage position in the call storage unit 600 is initiated prior to the seizure of the telephone line 205 extending to the calling subscriber substation Tl by the finder switch 309.

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 330. Assuming that the iirst A operator position590 has been preselected by the main A operator position distributor 630 to be seized by the sequence switch 380 at this time, a holding circuit is completed for energizing in series the winding of the hold relay R610 and `the `right-hand winding of the Aposition relay R630, -the position relay R630 corresponding to the rst A operator "position 500. This holding circuit extends from ground by Way ofthe contacts 55|, C50|, the contacts 534 of the Azoperator position distributor key K530, C653, the winding of R610, the contacts 646 and 634 and the right-hand winding of R630 to battery. The operated position -relay R530iretains interrupted, at the contacts 635 a `holding circuit traced hereinafter for energizing the winding of the hold lrelay R610 in series with the right-hand winding and the contacts 559 to the control conductor C525 of the trunk 520 extending to the iirst A operator position 5150 and completes, at the contacts 53|, a path for applying ground potential to the control conductor C630, for a purpose more fully described hereinafter. The path for applying ground potential to the control conductor C680 extends from ground by way of the contacts 545, C656, the contacts 63|, C635 and the contacts 592 of the A operator position distributor key K530 to the control conductor C500. Further it is noted that no potential Whatever appears upon the marking conductor C530 to C535, inclusive; while battery potentialappears upon the marking conductor C535. The path for applying battery potential to the marking conductor C536 extends from battery by way of the winding of the, rst marking relay` IM and the contacts 62| to the marking conductor C535.

Continuing .now with the operation of the sequence sWl/Qh 350, the rotary magnet M393A continues to operate intermittently in order to drive the wipers noted of the sequence switch 350 step by step in the clockwise direction until the wiper 30| engages the seventh contact in the associated contact bank 352 terminatingv the marking conductor C536; whereupona circuit is, completed forenergizllg, inr series the winding of the stop relay R350 and the winding of the marking relay IM. This circuit extendsfrom the grounded control` conductor C363 of the trunk 360 by way of the windingof R350, the contacts 311, the control conductor C325 in the cable 32,0,.the wiper 39| and engaged seventh contacty in the associated contact bank 332 of the sequence switch 380, the marking conductor C536, the contacts 62|` and the winding off IM tor battery. When the winding of the stop relay R3501is thus energized, this relay operatesto interrupt, at the contacts 35|, the previously traced circuit for energizing the rotary magnet M393, thereby positively to arrest further operation of the sequence switch 385;

When thewinding ofthe marking relay |M` is thus energizedthis relay operates shortly thereafter, this Vrelay being ofthe slow-to-operate type,

' to complete, at the contacts |M2, a circuitfor energizing the winding ofV theY release relay R625,V

`Also the release relay'R62`0 completes, at the contacts 623, an obvious circuit for energizing the winding of the control relay REID, thereby Yto cause the latter relay to operat'eshortly thereafter, the `latter relay being of the slow-to-operate type. Further the release relay R`620 inte`r rupts, at the contacts 62|, the previously ytraced circuit for energizing in series the winding of the stop relay R355 and the winding of the niarking :relay IM. Upon operating, the control'relay R5|0 completes, at the contacts 6| I, an obvious path for applying battery potential by way of the Winding of the marking relay IM to the marking conductor C536. Y

Accordingly, the marking -relay IM and the stop relay R355 restore when the previously traced circuit for energizing iin series the windings thereof is interrupted incident to the operation of the release relay R520. Upon restoring, the stop relay R550 completes, at the contacts 35|, the previously traced circuit for energizing the rotary magnet M593 of the sequence switch 350, thereby to cause the rotary magnet M353 again to operate intermittently. In the present instance, the rotary magnet M353 operates and restores only once; whereupon the wiper 33| thereof engages the eighth Contact in the associated contact bank 332 of the sequence switch 380 terminating the control conductor C525 of the trunk 525, thereby to complete a series circuit for energizing the winding of the answer relay R555 and the winding of the stop relay R353; This circuit extends from the grounded control conductor C353 of the trunk 355 by way of the winding of R355, the contacts 311, the control conductor C325 in the cable 325, the wiper 375| and engaged eighth contact in the associated contact bank 392 of the sequence switch 380, the control conductor C525 of the trunk 520, the contacts 555, the winding of R555, C532, the contacts 532 and the resistor 5|2 to battery. When this series circuit is completed the windingsof the stop relay R353 and the answer relay R555 are energized, thereby to cause these relays to operate. Upon operating, the stop relay R355 again interrupts, at the contacts 35|, the previously traced circuit for energizing the rotary magnet M355 of the' sequence switch: 355, thereby again to arrest operation of the sequence switch :5 335. Upon operating, the answer relay R545 interrupts, at the contacts 556, the previously traced holding circuit for energizing the winding of the release relay R523, thereby to cause the latter relay to restore and interrupt, at the contacts 523, the previously mentioned circuit for energizing the winding of the control relay RSIEI, thereby to cause the latter relay to restore. Also the answer relay R555'completes, at the contacts 551, an obvious circuit for energizing the winding of the disconnect relay R555, thereby to cause the latter relay to operate.

Upon operating, the disconnect relay R555 completes, at the contacts 552', a holding circuit for energizing the winding thereof, this circuit extending from ground by way of the contacts 55'i of the trunk disconnect key K550, the contacts 552 and the winding of R553 to battery. Also, the Adisconnect relay R555 interrupts, at the contacts 555, the previously traced circuit for energizing in series the winding of the stop relay R555and the winding of the answer relay R555 and completes, at the contacts 557, a circuit for energizing the winding of the cut-in relay R310, this circuit extending fromground by way of the contacts 551, the control-conductor C525 of the trunk 520, the wiper 38| and 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 en ergizing 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 313, a further point in the previously traced circuit for energizing the rotary magnet M303 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 rst A operator position 500.

Further, the disconnect relay R550 interrupts, at the contacts 553, an obvious connection between the line conductors C521 and C523 of the trunk 520, interrupts, at the contacts 555, 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 C521 and C523 of the trunk 520 and the retarder coil 530 and the telephone apparatus 511 at the first A operator position 500, and completes, at the contacts 554 and 555, a connection between the line conductors C522 and C524 of the trunk 520 and the retarder coil 530 and the telephone apparatus 511 at the rst A operator position 500. Accordingly, at this time, one terminal of the retarder coil 530 is connected by way of the contacts 531 and 551 and by way of the contacts 542, 531 and 554 to the line conductors C521 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 511 at the rst A operator position 500 is connected by way of the contacts 511 and 513 across the terminals of the retarder coil 530.

Upon 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 335 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 of the upper winding of R450, the contacts 463, 431 and 426, C361, the contacts 312, the line conductor C332 in the cable 320 and the wiper 380 and engaged contact in the associated contact bank 330 of the sequence switch 300 to the line conductor C522 of the trunk 520, the line conductors C522 and C524 of the trunk 525 being connected together by way of the previously traced path including the retarder coil 530. Also the cut-in relay R510 completes, at the conta/cts 31| and 314, a connection between the subscriber substation T1 and the line conductors C521 and C523 of the trunk 520. More particularly, the line conductor C206 of the telephone line 205 is connected by way of the wiper 314, the contacts 331 and 311, the line conductor C321 in the cable 320, and the wiper 331 and engaged contact in the associated contact bank 383 of the sequence switch 330 to the line conductor C521 of the trunk 520; while the line conductor C201 of the telephone line 205 is connected by way of the wiper 315, the contacts 332 and 314, the line conductor C323 in the cable 320 and the wiper 383 and engaged contact in the associated contact bank 334 of the sequence switch 360 to the line conductor C523 of the trunk 520. Finally, it is noted that a bridge at the subscriber substation T1 is connected across the line conductors C206 and C201 of the telephone line 205; while the line conductors C521 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 511 at the first A operator position 500 is bridged across the retarder coil 530 a connection is completed between the calling subscriber substation T1 and the telephone apparatus 511.

Further the cut-in relay R310 interrupts, at the contacts 313 and 316, the previously traced direct loop circuit between the subscriber substation T1 and the line relay R450 in the selector switch 400, interrupts, at the contacts 3'10, a point in a holding circuit traced hereinafter for energizing the winding of the call back relay R440 in the selector switch 430, and interrupts, at the contacts 311', a point in a circuit traced hereinafter for energizing the winding of the coin and register relay R430 in the selector switch 400. Finally the cut-in relay R310 completes, at the contacts 312', an obvious alternative holding circuit for energizing in series the lower winding of the switching relay R330 and the rotary magnet M301, 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 finder switch 300 in its operated position independent of the selector switch 400.

Also, upon operating, the disconnect relay R550 completes, at the contacts 551', a circuit for energizing the winding of the tone relay R510, this circuit extending from ground by way of the contacts 551 and 528 and the winding of R510 to battery. When the winding of the tone relay R510 is thus energized this relay operates shortly thereafter, this relay being of the slow-to-operate type, to complete, at the contacts 515, an obvious circuit for energizing the winding of the tone relay R520. When thus energized the tone relay 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 of the tone relay R525. When thus energized the tone relay R525 operates shortly thereafter, this relay being of the slow-to-operate type, to complete, at the contacts 521, an obvious holding circuit for energizing the winding thereof and to interrupt, at the contacts 523, the previously traced circuit for energizing the winding of the tone relay R|0 The One relarlillihen restores t0 interrupt,

circuit for f energizing the `Winding of Y the ,tone

relay R520, therebyto restore. K -f g ,1

. 4Upon operating, the tone relay R5l0 interrupts, at the contacts, 5I I and 5l3, thepreviously traced connection between, the telephone apparatus 5|1 andthe retarder coil 530 and cornpletes, at thecontacts 512 and 5I4,.,a -circuit for conducting tone,I current ,over` theA telephone apparatus 5|1i 'Ihe last-.mentioned circuit extends `from the, ungroundedgterminal of a grounded sourceof tone` current, not shown,.by Way` of the causeA `the latter, relay to tone conductor C581, thev contacts 522 and 5I2,

the telephone apparatus 5|1, the contacts 514 and the condenseny 516 to ground. vUpon. operating, the Atone relay R520` interrupts, at the contacts 522,` the previously `traced :circuit for conducting tone current 'over the telephone aptive circuit for conducting tone current over the telephoneapparatus 5|1, this alternativecircuit extending from toneA potential-appearing upon the tone conductor C581 by way of the contacts 526, 52|` and 5|2, `the telephone apparatus 5H,

the contacts 5i 4 and the condenser 5 l 6 to ground. Upon restoring, the tonerelay R5i0 interrupts, at the contacts 512 and 5|4, the previously traced alternative. circuit for conducting tone current over the telephone apparatus 5I1 and recompletes, at the contacts 5H and 5i3, the previously traced connectionbetvveen the telephone apparatus 5H and theretarder coil 53,0. Finally, upon restoring, the tone-'relayR520 interrupts, at the contacts 521, a furtherpoint in the Apre- Viously tracedalternativeprcuit for conducting tonev current over the telephoneapparatus 5I1 and prepares, at- Ithe contacts 522, the previously `*traced original circuit for conducting tone currentovertheutelephone apparatus 531. The o'per-'ation-ofY the tone relays R5l0, R520 and R525 andthe Vsubsequent restoration of thetone relays R5I0 and R520 is eiective to cause the receiver of the telephoneinstrument,included in the telephone apparatus 511 to be operated alternately,` Whereupona distinct zip-zip tone is produced thereby. lThe production of the zip-ziptone by the receiver of the telephone instruinentl included in themtelephone apparatus iilfi'A at the first A operator position k550,indicates to the operator thereat that an incoming call has been extended to herpovsition by one of the sequence switches. j

Further, upon operating, the disconnect relay R550 prepares, `attire, contacts 555?, a` point in chain circuit.tracedhereinafter for energizing the Winding of 'thebusy relayv R550,V which chain circuit is. completed-in the event all of the A" to battery;vl When thus` energized;` the. position lil A operator position 500 tothe Vcontrol conductorrelay R640 operates to complete, at the contacts 64.4, aholding circuit for.4 energizing in, series the windingotfthehold relay R610 and the righthandi.,winding of thefposition relay R640,this `circuit iextending vfrom ground by Way of the contacts. 56I,C50I, the contacts 5940i the A .operator position distributorkey K500, C683, the Winding of R610,\thecontacts 656' and 644 and the right-hand Winding of R640 4to battery. Alsothe position relayiR640 interrupts, at the ,contacts 646, the previously. traced holding circuit for energizing in series thel winding of the hold relay. R610 and the-right-hand Winding of thepositiony relayfR630, thereloyv to cause f-the latter relay to. restore. Further the position relay R640 prepares, at the contacts 643, anobvious .circuit forenergizing `the left-hand Windingof the positionrelay R650 corresponding to the last A operator position,l completes, at the contacts 642,Y 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 rst` A operator position 500 and completes, at the contacts 64|, an obvious* path forrapplying ground-potential at the second A"A operator position to the'control conductor C680, in `a'manner similar to lthatfpreviousl-y explained. Accordingly,rthe operation of the position relay R540--inthe fmain ',Aoperator-'position distributor'si is effective toprepare the secondiA operator positionitoreceive the next incoming call vin` theevent the second -A operator position is idle atA this time. On the other hand, in the ev'ent theseoond A operator position is busy at this ttime, theprev-iouslymentioned circuit for energizing the left-hand Winding of the position relay R650 is completed at the contacts 653 incident tothe operation ofthe position relay R540, the disconnect relay at: the second A operator position being operated at this time. Further it isfnoted that, upon restoring, the position relay :R630 interruptaat the contacts 634, a further pointin thev previously traced holding circuit for energizing in series rthe Winding-of the hold relay R5`1ElandV the `right-hand winding of the -positionirelay R530.V Also the position relay R530 interrupts, at the contacts 633, the previouslytraced circuit for energizing the lefthand Winding of theposition relay R50,"int`eri rupts, at the contacts 532,1a further point inr the previously traced circuit'for energizing the Winding offthe answer relay R545-and interruptsg'at the contacts G3i; thepreviusly traced original circuit for applying groundpotential at the first v "At this point it is noted that the main A operatori position l distributor 630- is` operated, thereby to causetone of the position relays to operate and condition a corresponding oneof` the A operator positionszto receive the next incoming call, such, forexample, asthe second Aoperator position, only yinl-the event oney of` the A operator positions is idle atthis time; 1 More particularly, Vin

t the event all of the-A operator positions are busy When thedisco'nnect relay'R550 is operated, Athe previously mentioned-chain circuit for energizing the Winding-fof the busy: relay R560l is completed at thecontactsv 553 incident to the operation of the'disconnect-=relay1R550. This circuit'extendsfrom ground 'by way of the chain conductor C519,-the contacts ofA the disconnect relaysY atcth'e other A operator positions, the

contacts 553 ofthe disconnectfrelay 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, R540, R650, etc., to remain in their restored positions. Also, upon operating, the busy relay R560 interrupts, at the contacts 552, a point in an alternative circuit for energizing the left-hand winding of the position relay R630. Upon restoring, the hold relay R010 prepares, at the contacts 61|, a point in the previously mentioned alternative circuit for energizing the left-hand winding of the position relay R635. Accordingly, the operation of the busy relay R560 is effective 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 R500, whereupon the latter relay restores. Upon restoring, the busy relay R560 prepares, at the contacts 55|, 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 lefthand winding of the position relay R630, this circuit extending from ground by way of the contacts 502, C502, the contacts 595 of the A operator position distributor key E590, 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, R540, R650, etc., to remain operated, which corresponds to the idle A operator position, thereby to condition the idle A operator position to receive the next incoming call.

Further it is noted that the operation of the auxiliary A operator position distributor 605 is the same as the main A operator position distributor 630, previously explained. In the event the main A operator position distributor 630 becomes defective, the operator at the first 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, C603 and C655 extending to the main A operator position distributor 650 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 K595i); and obvious alternative connections are completed, at the contacts 596, 503 and 59| of the A operator position distributor key K590, between the common control conductors C502, C50| and C680 and the control conductors C693, C692 and C09I, respectively, extending to the auxiliary A operator position distributor 695.

Accordingly, at this time, after the sequence switch 389 seizes the trunk 520 extending to the rst A operator position 500 and both the apparatus at the iirst A operator position 500 and the main A operator position distributor 630 operate in the manner previously explained, a connection is established between the calling subscriber substation TI and the telephone apparatus 5|? at the first 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 telephone instrument included in the telephone apparatus 5|1 are operatively connected to the subscriber substation Ti. Accordingly, the operator at the rst A operator position 500 may converse with the subscriber at the calling subscriber substation T| and ascertain the destination of the call. After learning the destination of the call, the operator at the rst A operator position 500 initiates the extension of the call by operating the key sender K520 in order appropriately to control the selector switch 400 in a manner more fully described hereinafter.

Paystatz'on call A call from a paystation, such, for 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 bridge path 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, the contacts 262, C241, the bridge path between the line conv ductors C241 and C246 of the telephone line 245 253, 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 position 494 and the other B operator positions in the local exchange 20. I'he last-mentioned path extends from ground by way of the contacts 281, C294 and the contacts 253 and 214 to the control conductor C249 of the telephone line 245. Also the line relay R250 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 C248 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 25|, an obvious path for applying direct ground potential to the marking conductor C284 terminated by the i'ifth contacts in the vertical control Contact banks of the finder switches, thereby to mark the telephone line 245 as terminating in the fifth level of the main contact banks of the finder switches. Finally, the line relay R250 cornpletes, the contacts 25|, 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 theentacts" and 2f|l,`C234, the resister and the`-contacts288 to the start conductor C308, Theapplication of ground potential-to the start conductor C308 initiates operation of the link distributor in the manner previously explained.- A

`The-link distributor 33| then operates `to cause the previously selected link to be assigned to thei'iise of the calling paystation T2 in the pre- Viouslydescribed manner. Assuming that the linkdistributor 30| operates to assign the link illustrated to the use of the calling paystation T2, the finder switch 303 operates in the manner previously explained toseize the" telephone liner 245 extending to the calling paystationT2, Also the 'selector switch' 490 and the sequence switeh 380 operate in the manners-previously described.`

Assuming that the main A operator position dis-` tributor" G30 has previously selected the LfirstAf operator position 500 at this time, the'sequence switch`380 operates to seize the trunk 5205 extending to the iirst A operator position 538m themanner previously explained. l'

When the first `A operator position 500 seizedvb'y the sequence switch 380 the cut-in re-l lay R328 operates in order tocompletefat the contacts 372 and 325, the previously traced`loop circuit between the line relay R450 inn the selector switch 400 and the retarder coil 530 at the first A operator position 508, and to completeat` the contacts 3l| and 314, a loop circuit between the calling paystation T2l and the retarder coil 533 at the rst A operator position 530.

way of the wiper 3|4, the contacts 33| rand 31|, the line conductor C32| in the cable 328, the

wiper 331 and engaged contact in the associated contact bank 338 of the sequence switch 380,

the line conductor (252| of the trunk 520, the

contacts and 53|; the retarder coil 530, the contacts 533 and 552, the lin'conductor`C523 of the trunk 520, the wiper 383 and engaged contactin thel associated contact bank 384 of the sequence switch 338, the line conductor C323 in the cable 320, the contacts `3"|4 and 332 'and the Wiper 3|5 to the line conductor C2llll'cf`tl'1ey telephone line 245, the line conductors C245 and C24? ofthe telephone line 245 being connected together by Way of the bridgepath at the calling paystation T2.

Also; when the finder switch 300 seizes the telephone line 245, directground potential is applied by way'of the wiper'3l6 tothe control conductor C248 of the telephone line 245, there# by Vto complete a circuit for energizing the Winding "ofl the cutoff relay R250,`this circuit extending from the grounded control conductor 0248er the? telephone line 245 `by Way `of the contacts 252`and 26 and the Winding of R260 to battery. When thus energized the cutoff relay R260 opcrates to complete, at the contacts 204, an obvious The last-'f mentioned loop circuit extends from the line conductor C240 of the telephone line 245 by` circuit v,for energizing inV series ,th'ejupper and lcnyerl ,windings of` the line` relay, R258, thereby ,to caus'ethe' latter lrelayito restore, andjfree the telephoneline 245 of impedance elements.` ,Upon rest ng, theliner relay R250 interrupts; at the contacts25h'the previouslyA mentioned path for applying" direct groundpotential to the `markmg conductor o 'zaa and the previouslyl tracedf path" 'applying resistance lground potential to eifstart conductor C308; in order tov remove the ",n'iarking from the telephone line 245V and to stmfnrther operation ofA the" link distributor e lvUnpon operating,` the lockout relay R210 s, at the contacts 212, a point in aholding circuit traced hereinafter forenergizing the winding thereof and co,npletes,`V at thecontacts a 223, an obvious 'alternatiVeU path for, ,applying ground potential to the control'onductor C249 of tlietelephone `line 245, 'therebyto mark the `telephone'line 245 as busy tothe `Boperator positionsA in the local nexchange V20 having access thereto. Finally, ,thelockout relay` R2l0pre- Iparesatithe contacts 215, a further point in the previously mentioned circuit for illuminating the signal lamp L258. l I

The'operator at thev first A operator position 4"ll0` tl'ien answers the eall'andis advised con- "cernirig' the extension of 'the call by the subing ground potential tothe, control` Conductor holding circuit for energizing the winding thereof by way of the :control conductor C248 of the telephoneline 245, to interrupt, at the contacts 265, the previously traced path for applying bat-Y tery potential by Way of the resistor 201 tothe control conductor C248 of the telephone line`4245,

and to interrupt, at the contacts 266, a pointin a circuit traced hereinafter for illuminating the Also the cutoff relay R260 signal lamp L2$8. l K completes, at the contacts 283, an obviousV circuit for'energizing the winding of the lockout `relay Ril, thereby to Vcause the latter relay to operate. Finally the cutoi relay R260 interrupts, at

scriberat the calling paystation T2. After learning,*thedestination.ofA the call the operator` atV thefirrstuA operatorposition 530 initiates 'the extensionof the call by operating the keysender IIZ52f0in order appropriately to control thesein a manner more fully denetwork'ZBQ, whereupon the latter relay restores; Upon restoring, theabusy` relay R285 interrupts,

atvthefcontacts 231,l an obviousp'ath for` apply C2544 andan olfmjeus-- patnfcr ,short-`ciicuitingA the secondary winding 292er thetone trans-` former 4290, the primaryuwindinglj of thetone trans'rfomer 200 being eonnectedjtova suitable` ,tonejfcurrent not shown.' f Hence, wat, this` time,

the, (intacts A25| 2,32, thew'previously,tracedground` 'potential isA removed :from ,thefcontrol` conductorl C2 9 4 andtonefpotentilal appears there'- on. \Alsoupon restoring, the busy. relay` R205 intrruptscat the comme 235,1. a'jnoint `in the prevliously4 'traced Vpathv `forapplyin'g' resistance ground potential to'the start, conductorv'Ca y extending to 'tne link 'distributor t35a] 5 e ln the"e`vet a callw is initiatedat fone of the "siibscrilierv substatiisfqr paystauons at this tirri'e a' circuit is` completed'fer pr(')jecting busy tone rentto the subsrbef Subst'atien or paystatiqgilver -theassqeiated telephone une, For

subsane subsanar a therme@ .circuit is completed for projecting busy tone current over the telephone line 205 to the subscriber substa-

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