US2249475A - Telephone system - Google Patents

Description

July l5, 1941-. F. KEs-sLER TELEPHONE SYSTEM Filed Deo. 29, 1,939

8 Sheets-Sheet 1 July 15, 1941. F, KESSLER 2,249,475

'TELEPHONE- SYSTEM Filed Dec. 29, 1959 8 Sheets-'Sheet 2 Order @06m/0f Posfon 2] 623 y f c5747 nos@ i C658 Figa Ffg. 4 H95 ng 6 lNvENToR Fran/f Kessler ATTORNEYS July 15, 1941.. l F, KEssLER 2,249,475

TELEPHONE SYSTEM Filed Dec. 29, 1959 la sheets-sheet s F 1g. 3 0353 -c359 c3602 I 118@` C358) Y Genf/a1 4 Office IO v C3592 e36/Z C3622 c3632 REX. Operalor POS, 35 30! I 3 112 4 C3`4 l 4 IL-Q- k PBX. Tru/7 y 34 Cfr'cul 221( Open 17 v l@ f R 3X.' Tra/7S er' Cord me v Tru/7k 33' CI'ICUIT Finde/"34 Answer CIPGL/[ 33 F434/ nog H i955@ 36 1- I 9351 P5310 NP/134? 303 R320 @43432-1- MH-"- @4344 T V352 U* F4322 U dx -C363x n H: Tru/7k C- 357 `C'LrcL/IZ 6 37 304@ 27 zf C37 C372 C373 03m-C367 *c0369 Cam.' A l INVENTOR Fra/7k Kessler BY ,I g Z C ATTORNEYS l July 15, 1941. F. KESSLER 2,249,475 I TELEPHONE SYSTEM vFiled Dec. 29, 1959 8 Shelet-s-Sheet 5' Oper Pos Ender l R455/ F456/ C574 C575 049/7 4 L il C574J 505 MIMO] R455/ I q' 5 P4552 P4562 9\- 0576 C4 04, 507 L @457/7 WML frA503 C495; 50e "1"; Q 05777 ,#504 C57 056i Vc586 MU C300 C367 058/ -c58z E 26 INVENTOR Fran/f Kass/ek BY ATTORNEYS July 15,` 1941. F. KEssLl-:R y 2,249,475

'TELEPHoNEsYsTEM Filed Deo. 29, 1959 .V8 Sheets-Sheet 6 w l L cae@ T im 7/6 -v--f INVENToR Frank Kessler @Miky MM ATTORNEYS July 151941- l F. KEssLER l A 2,249,475

TELEPHONE SYSTEM Filed Dep. 29, 1939 9 '8 Sheets-Sheet 8 Fg 9' 26m.

` Y 7 J 117/1942 C640 .JQ-LJ m 900 H92 j' I y Q 29492/ 9963 C642) 969 o/ pil 946 INVENTOR Frank Kessler A TORNEYS Patented July 15, 1941 UNITED STATES "PATENT'QFFICE TELEPHONE SYSTM Frank Kessler, Villa Park, Ill., assignorto Associated Electric Laboratories, Inc., Chicago, Ill., a corporation of Delaware Application December 29, 1939, Serial No. 311,527

16 Claims.

Y The present invention relates to telephone systems and more particularly to improvements in syste ms of the character disclosed and claimed in copending application Serial 311,546, led Dec. 29, 1939, Imre Molnar.

A As explained in the above-referred toY copending' application, in certain' branch Vexchange installations a large part of the calls routed to the branch exchange area from the central exchange "are of a special character. For example, in large department stores a major portion of the incoming cails are for the purpose of placing orders,

or represent inquiries concerning the price of the merchandise on sale. In order more expeditiously to handle the calls incoming to a branch (dlin'g, special calls of the character just mentioned, the arrangement being such that so long as any of the special operators positions are idle the calls of specialcharacter are routed directly to idle ones thereof, but when all of the special operators positions become busy the excess calls are stored and are then released from storage to the special operators positions in the same order as they were stored. i

It is an object of the present invention, therefore, to provide in atelephone system, improved special call handling facilities of the character described which is of simple and economical arrangement and operates in a positive and reliable manner rapidly to route the special calls to the special operators positions in the order of their initiation under all operating conditions.

It is another object of the invention to provide, in a telephone system, special Ycall handling facilities of the character described wherein an improved Vand exceedingly simple arrangement,

Yrequiring a minimum of circuit equipment, is pro- I vided for transferring the calls of special char-` acter'incoming over the special call trunks from the special operators positions to an operators position located at the regular branch exchange switchboard.

' It is a further object of the invention to provide, in a telephone system, specialr call handling facilities of the character described wherein an improved and exceedingly simple arrangement, requiring a minimum of control apparatus order.

` circuit.

at the special operators positions, is provided for transferringv the special calls from the special operators` positions to the regular branch exchange switchboard and for splitting the-threeway talking circuits thus established to exclude eitherrthe calling or the called ends of such connections from the talking circuits.

In the illustrated embodiment of the invention there is provided atelephone system which comprises a central exchangev and a branch exchange area including regular branch exchange facilities. These facilities comprise a branch exchange switchboard at which are terminated a plurality of trunks which extend to the central exchange. Additional facilities are provided for handling calls of special character routed from the cenvtral exchange to the branch exchange area.

associated with the various trunk circuits andY Y includes a call storage position distributor and a call release distributor. In accordance with the present invention there is also provided, for the purpose of transferring special Vcalls to answer circuits located at the branch exchange switchboard, transfer trunks which are individually associated with the trunk circuits, and automatic switching means controllable from the special operators positions for transferring calls Y present on the special call trunks over the transfer trunks to idle ones of the answer circuits.V

More particularly, each answer circuit has associated therewith a finder' switch which has ac- A cess to all of the transfer trunks, distributor means being provided for assigning idle ones of the answer'circuits and associated finders to the use Vof the transfer trunks in a predetermined This 'distributor means comprises control apparatus controllable from any one of the special operators positions for routing a call present on one of the special call trunks over the associated transfer trunk and through'an assigned one of the nder switches to the assigned answer Additional apparatus comprising positionfinders having access to the special operinV the appended claims.

tions from the established talking circuits. In

accordance with a further feature of the .invention, apparatus comprising a lslow-acting device embodied in the call storage circuitV is provided for causing a predetermined time delay between the release of a special operators position and the release of a call from storage, thereby to prevent the possibility of calls in storage being -assigned operators positions ahead of an earlier initiated4 call. l

HlFurther features of theinvention-pertain -to vthe -particular arrangement` of l the. circuit elements, whereby'the -above and additional operat kving facilities-are attained. I

The novel features believed tobe characteristic of the inventionare set-forth with particularity The invention, both as to its organization-and method-of operation, to-

gether V*withY further `objects -and advantages- "thereof-Will best be understoodby Vreference to ithe speciiication taken in connection with Athe accompanying drawings in which VFigure 1 sche- `matically illustrates atelephone system `having `incorporated thereinthe features ofthe invention Vas briefly outlined above; Fig. 2` illustrates themode of assemblying the remaining iigures of the drawings-to form a unied'system; andvFigs. 3 to l0, inclusive, illustrate the details of the apparatus schematically shown in Fig. 1.

'Referring Vnow more particularly to'Fig. l Vof the drawings, 'the telephone system there schematically illustrated-comprises a central exchange It and a branch exchange area -20 within which are located the of a department store, or the like. The central exchange IU may be'of any desired'type;

kthat is,'it may be of themanual-type in 'which "case'the subscribers and trunk lines extending thereto'are terminated in line multiples at Vthe operatorsswitchboard inthe usual manner. 'Alternatively, the exchange IUI may beoi anyi'desired automatic type, in whichv caseconnections are established between the lines extending thereto through the provision of dial controlled automatic switching apparatus. This exchange is arranged 'to serve a large numberof central oiiice subscribers lines, one of which is indicated at II asextending to the central office subscribe'rs substation A. For the purpose of routing regular substation calls between the central oice andthe'b-ranch exchange area-20, there areprovided a plurality of branch exchangeftrulnks one of which is indicated at I2. 'The trunk I2 has .a

- trunk circuit. I 3 of conventional arrangement kAa's- -sociated therewith and terminates'atV a jack4 I4 which is provided at AonefofY the operators positions formillglavpart f the branchY exchange operators switchboard. Thisswitchboard is.pro -videdto serve the regularbranch Xchange ysub- Y,stations located within y.the area" 26, one' 'such substation. B being I connected4 to [the substation line. I5which .terminates at the` branch-exchange .switchboard .in .a jack VIl and'lhas associated 60 which all of vthe transfer trunksterminate.

which calls involving the line I5 may be supervised.

In order to handle calls of special character routed from the central oice subscribers sub- 5 station through the central exchange I0 to the branch exchange area 20, a plurality of special call trunks, one of which is indicated at I8, are provided. Assuming that the central exchange ID is `of the manual type, these trunks extend from the operators switchboard in the central exchange I0 to the lbranch exchange area 20 where they terminate in trunk circuits individual thereto. These trunk circuits have access to a .group of special operators positions. In the caseunder consideration wherein it is assumed,

lfor .purposes of explanation, that the branch exchange area 29 constitutes a department store or -othermerchandise establishment, the special operatorsn positions may be provided for the purpose of taking orders from the central ofce subscribers. -For convenience describing^ the ap- --paratus, thespecial call trunkswill-be referredfto hereinafter asorder trunks,-the--trunk circuit `associated therewith-will be referred to-as-order trunk circuits, and the special-oper'a-torsl positionswill be referred to-as orderoperators-positions. -More specically, theorder trunk 4I8 terminates in -'the-branch exchange La-rea V20l in an Y- ordertr-unkcircuit I9 which has access toa group of order operators positions including theposition-2 I Under ycertain circumstances andrmore 1 particularly whenall =of the order operatorspositionsare not staiied;A thevolume of traiiicL over *the-order trunks# may-be -in `rexcess of the Ycall handling capacity' of theV staled order operators positions. For the `purpose of-holding such excess calls -untilY suchV time as-A an lorder operators A'position is--released or otherwise-made available for service, there' isprovided, `in common 'asso- 32E() ciation' with -the several order trunk circuits, -a

" call storage circuitd '3 I which -functions to'store the lexcess-calls inthe' orderof ltheir initiation and to *release the` stored calls fromv storage -in n m the same'- order-,as the order operators positions sub stations @become idle; To enable -the order operators to -f transfer calls `fromy their-positions to'r the branch exchange svfitchboard'fwhereby they may be extendedto the regular branch'exchange substa- -tion-orto the central oIiice, there is provided a group `Yof transfer trunks one 'of "which isindi- -cated at22as .being individualto' the order-trunk circuit IS. These transfer trunks are'accessible toa` plurality Aof answer circuits provided at the *branch exchange switchboard, each 'answer circuit having associatedtherewith a' transfer trunk trunksiand associated 'answer circuitscan only f be .used for Acall 'transfer purposes. Accordingly, `Aadditionalmeans comprising a second group of trunks; including the` trunk 26, 'are provided for enabling the order operators to route Ycalls .di-

rectly` from their positions 4to the' branch exchange' switchboard. AMore Aspeciiioally, these y additional trunks terminate 1in' positionfnders which have access tothe various .orderoperatorsjpositions and have .associated therewith a therewith a line circuitY I'through operationf 75 position"nder"distributor'30 whichfunctions to part.

allot the additional trunks and associated position nders for use in a predetermined order. More specifically, the trunk 26 terminates at the branch exchange switchboard in a trunk circuit 21 which includes an answer jack 28, and extends to a position finder 29 having access to all of the order operators positions. For the purpose of supervising calls routed by Way of the order trunks to the order operators positions, there is provided a supervisory operators position r32 at which are located signal lamps for indicating whether or not the order operators positions are staffed and, if staffed, whether idle or busy, and also for indicating the idle or busy condition of the various trunks and trunk circuits.

Neglecting for the present the particular arrangement of the circuit elements embodied in the apparatus schematically illustrated in Fig. 1 and considering the operation of the system generally, it will be apparent that interexchange traiiic between the central omce subscribers substations and the substations provided at the branch exchange area 20 are handled by the regular branch exchange facilities including the branch exchange operators switchboard and the group of trunks of which the trunk |2 forms a To this end, the branch exchange operators switchboard is assigned a particular directory number which is different from the directory number assigned to the order operators positions. By virtue of this directory numbering scheme, the special or order trunk calls may be segregated in the central exchange and routed by Way of the order trunks to idle ones of the order operators positions. For example, a call routed over the order trunk |8 may, through operation of the order trunk circuit |9, be routed to the order operators position 2|. If the order operator attending this position is unable to give the calling subscriber the desired information, she may cause the call to be transferred to one of the regular substations provided at the branch exchange area 20 by operating a transfer key-located at her position. In response to this operation, the answer circuit distributor 35 operates to initiate the operation of a transfer trunk finder associated with a previously selected idle one of the answer circuits. For example, operation of the transfer trunk nder 34 may be initiated in response to operation of the transfer key provided at the order operators position 2|.. When this transfer trunk finder finds the calling transfer trunk 22 individual to the order trunk circuit I9, a talking circuit is completed between the order operators position 2| and the answer circuit 33 and the call signal lamp provided in the answer circuit 33 is energized. The branch exchange operator may, after answering the transferred call, route the call to the desired substation, such, for example, as the substation B. After a call transfer of this character is made, the operator attending the order operators position 2| may remain connected to the established three-way connection or she may retire from the connection and release her position for use in handling of additional calls. If an operator atstations, she may secure the desired connection Vby seizing one of the trunks assigned for use by the position finder distributor 30, such, for example, as the trunk 26, thereby to route a connection from her position to the branch exchange switchboard. rFrom this switchboard the call may be routed over one of the regular branch exchange trunks and through the central exchange I0 to the desired substation. In a similar manner the order operators may route calls directly from their positions to the substations located in the branch exchange area 20, such calls being handled by the operator or operators attending the branch exchange switchboard. 'Ihe arrangement is such that calls may be routed over the additional trunks just mentioned from the order operators positions at times when the order operators positions are engaged in handling order trunk calls. More specifically, the order operators may establish three-way connections including the order trunks extending to the central office and the additional trunks extending to the branch exchange switchboard, and may split such connections to exclude either the calling or the called ends thereof from the established three- Way talking circuits. In the event all of the order operators positions become busy at the same time and special calls routed over the order trunks continue to arrive, operation of the call storage -circuit 3| is initiated whereby the excess calls are stored in the order of their initiation. As the order operators positions are thereafter released and rendered available for use in handling other calls the call storage circuit, in cooperation with the associated trunk circuits, functions to release the stored calls from storage in the same order as they are stored. Supervision of the order operators positions and of the calls handled at these positions is under the control of a supervisory operator attending the position 32.

ReferringY now in greater detail to the circuit arrangement of the apparatus schematically illustrated in Fig. -1 and considering first the order trunk circuit |9, this circuit is illustrated in Figs. 4 and 5 as comprising an operators position finder switch 500, a storage position nder switch A 400 and a plurality of associated control relays and control circuits. are of the well-known rotary type and may be of any desired commercial construction. The number of contact points provided in the position finder switch 500 is determined by the number of available order operators positions, each setting of this switch being individual to a particular order operators position. Similarly, the number of contact points provided in the storage position finder switch 480 is determined by the number of storage positions available in the call storage circuit 3|. In the arrangement illustrated twenty-four call storage positions are available in this circuit and, hence, twenty-five sets of contact points are provided in the rotary switch 480, the rst set of contact points being reserved as the normal or home position of the switch. The control equipment associated with the two switches `480 and 500 comprises a line relay R440 which is normally bridged across the conductors of the order trunk I8 in series with a condenser 421 and is arranged to operate when energized kwith either alternating or direct current. This equipment furthercomprises a slow-to-operate position finder start relay R460, a slow-to-operate control relay R420, a pair of call storage control relays R400 andv R4l0, a combined-call transfer and trunk release relay R430 which is provided with two operating positions in addition to its normal released position, anda combined position nder stop and line switching relay R410.

AThere is also provided in the trunk circuit.V I9` a The switches 500 and 48|)V control relay R400' which is serially includedin one side ofthe transfer trunk-'22, and a position l finder stop relay R450 which is individual to the Atransfer trunk 22 and is arranged to cooperate with the distributor 35 to control the operation of an assigned transfer trunk finder when-a call is transferred over thetrunk; 22 to the branch exchange switchboard.

'The order operatorsposition 2| has associated therewith a position circuit which is illustrated in Figs. and 6 as comprising an induction coil 504 `having line terminals connected to the talking conductorsCSlll` and C515. This induction coil has connected thereto transmitter and receiver jacks 602 and 003, respectively, which are arranged to receive the contacts of a multiple plug 602. The contacts ci this plug are connected in the usual manner to a transmitter 500 and a receiver 60| forming an operators head set. The position circuit individual to the order operators position 2| also includes a group of control relays, these relays. comprising a position marking relay R510, a tone start relay R560, a slow-to-operate tone cut-off relay R530 and a rel-ay R550 which is operative to release the position finder distributor 30 in response to seizure of the order operators position 2| by one of the position iinders in the group including the iinder 29. The enumerated relays are-also operative to perform additional control functions referred to more specifically hereinafter'.v For the purpose of enabling an attendant at the rorder operators position 2| toperform various control operations -incident to the handling of calls involving this position, various keys or switches are embodied in the position circuit individual tothis operators position. These keys-comprise a combined talk and split key 605, a combined call transfer and trunk release key S20, a flashing recall key 623 and a key 024 which is operative to disconnect the transmitter 600 from the .induction coil 304. A call lamp B25-is also provided at the order operators position 2|, this lamp being connected for energization in response to operation of the relay R550 to indicate that a special call has been routed to the position 2|.

As illustrated in Fig. 9 and in the right-hand portion of Fig. 6, the position finder 29, which is individual to the trunk 26 extending to the branch exchange switchboard, comprises-.a nder switch of the well-known rotary type and ay to the'branch exchange switchboard is under the control of the finder distributor 30' whi-ch is illustrated in Fig.Y 9 as comprising a distributor switch 060, also of the well-known rotary type and having positions individually corresponding to the number. of positionnnders available. This `distributor .also includes a plurality of' control relays which may Ybelidentified asa slow-to-ope erate start relay RSID, a pulsing relay/R930, a relay R920 for controlling the line switching relays of the respectiveassociated positionlnders, and. a slow-to-release relay R900 Awhich is oper- `ative to delay the trunk' hunting operation ofthe distributor switch ..950 .for a .short time interval after a previously selected position :finder switch is. operated "toy seize a calling .one of. the'. order operators positions. vThe distributor.- 30 Y also includesf-an 'all-trunks-busy 4relay yR950 which is -operativewhenall ofthe trunks of the Vgroup invided at'one of the" branch exchange operators positions-forming a part of the branch exchange switchboard comprises-the jacks I4, |1 and 28 at which the lines |21, |5 and 20 respectively terminate. These lines have individually associated therewithvcall signal Alamps-30|, 302 and 304 respectively. There is also provided at this branch exchange operators-position an operators cord circuit 33 which may be of any conventional arrangement. This cord circuit is connected to call and answer plugs V30 and 31, respectively, and includes a transmitter 34 and a receiver 35. -The jack 23 individual to the answer circuit 33 is also located at this branch exchange operators position. vMore( specically, the answer circuit 33 is illustrated in Fig. 3 .as comprising a call lamp 303, a repeating coil 305, and four control relays R3|0, R320, R330 and R340, respectively. The transfer trunk nder 34, which is individual to the answer circuit 33, is illustrated in Figs. 3 and 7 as comprising a rotary iinder switch having access to all of the transfer trunks and a busy marking relay R1|0. Operation of the finder 34 and of the other similar finders individually associated with the other answer circuits is under the control of the :answer circuit distributor 35 which is illustrated in Fig. '1 .as comprising a distributor switch |50 also of the well-known rotary type and having positions corresponding to the number or answer circuits available. This distributor also includes a plurality of control relays which may be identified as a slow-to-operate start relay R100, a pulsing relay R120, a relay R .for controlling the busy marking relays corresponding to and including the relay R1|0 individual to the transfer trunk finders, and aslow-torelease relay R which is operative to delay the trunk hunting operation of the distributor switch for a short time interval after a previously selected transfer trunk nder is operated to seize a calling one of the transfer trunks. This distributor also includes an all-trunks-busy relay R100 which is normally operated and is connected andrarranged to be released when all of the answerzcircuits are busy to cause the energization of an all-busy lamp provided at the supervisory operators position 32.

The call` storage circuit 3| is illustrated in Fig. S as comprising a call-storage distributor switch 860 and a call release switch 810each of which is of the well-known rotary type and includes twenty-ve sets of contact points, respectively representing twenty-four diiferent call storage positions and a blank or unused position. The

Yoperation of these switches. is under the control .pair of relays R825 and RSIS, the last of which is of the slow-to-operate type.

A pulsing.- network comprising the relayvRSGO and the slow-.to- .operate relay -RB 0 is provided .for controlling the operation of the calll .storage position distributor switch 800, Vanda similar network including `therelays R320, R835 and "R845 is. provided .for vcontrolling the-operation of the call release switch the abandonment of stored calls to be lled up w 810. The relay equipment also includes a stop relay R840 which functions as a test relay and also to prevent the rotary switch 810 from operating to a storage position in advance of that occupied by the distributor switch 860, all in the manner more fully explained hereinafter. For the purpose of indicating an all-busy condition of the order trunks, there is also provided in the call storage circuit 3| lan all-trunks-busy meter 801 which is arranged to be controlled by an all-trunks-busy relay R805.

The apparatus provided at the supervisory operators position 32 is illustratedY in Fig. 10 as comprising a plurality of jacks individual to the order trunks and additionaljacks individual to the order operators positions. Thus, a pair ofV jacks |002 and |003 are provided which are respectively connected to the conductors of the order trunk I8 and to the talking conductors C514 and C515 individual to the order operators position 2|. The apparatus located at the supervisory operators position 32 also includes a cord circuit |000 having embodied therein a transmitter |00| and a receiver |002. This cord circuit may be of any conventional arrangement and is arranged to be connected to any desiredl one of the line and position jacks through the provision of a connecting plug |004. There are also provided at the supervisory operators position 32 a plurality of signal lamps which enable the supervisory operator to check at all times the condition of the order operatorsvpositions and of the with ladditional calls initiated on the order trunks.

`V Interexchange traffic between central office and` branch exchange switchboard f vReferring now more particularly tothe operation of the apparatus illustrated in Figs.,3 to 10,

inclusive, lif a call routed from'one of the central f cnice subscribers lines to an operators position vin the central oice .I0 is to be extended to asubstation line terminating at thebranch exchangeV switchboard, the central ofdce operator handling the call may seize the trunk I2 and by operation of the ringing key embodied in her cord circuit 2Q upon observing the lighted condition of the lamp,

may answer the call by inserting the plug 36 in the jack I4. e In response to this operation, a talking circuit is completed between the calling central oiiice subscribers substation and the cord circuit 33'. The branch exchangeoperator may l now converse with Athe calling subscriber andasvarious trunks associated therewith. More particularly, there is provided a position lamp IOII individual to the order operators position 2| which is arranged to be energized under control of the relay R510 when this order operators position is attended. A second lamp |0I0 is provided for the purpose of indicating when the order operators position 2| is engaged in handling a call. A third lamp I 009 is provided for indicating seizure of the trunk circuit I9.` The signal lamps provided at the supervisory operators position 32 also include a lamp |006 which is operative to indicate the idle or busy condition of the answer circuit 33, a lamp I 001 which is operative to indicate an all-busy condition of the answer circuits, a lamp |0|3 which is operative to indicate an all-busy condition of the order trunks, a lamp |0I2 which is operative to indicate an all-busy' condition of the trunks forming the group including the trunk 26, and a lampV |008 which is individually associated with the trunk circuit I9 and is operative to indicate that the associated order trunk is occupied with a call which has been placed in storage. k'Ihere is also provided at the supervisory operators position 32 an alarm device |005 which is arranged to be controlled by a slow-acting device comprising a dashpot relay 540 and associated control relay R520, and functions to indicate undue delay in routing an order trunk call to an order operators position or to storage. In order to enable the supervisory operator to control the call storage circuit 3| in accordance with the conditions indicated by the energized and deenergized conditions of the associated trunk call storage lamps, there are provided two keys IOI4 and |0-I5, the rst of which is operative to render the call storage circuit 3| totally inactive. The key I0 I 5, on the other hand, is provided for the purpose of enabling the lstorage distributor switch 860 to operate through a position occupied by the call release switch 810, thereby to permit those call storage positions in the switch 060 which have been vacated through usual manner.

certain the identity of the desired branchexchange substation. When the plug 30 is inserted in the jack I4, battery or ground potential is im- .pressed upon the-ring vcontact of this jack to. cause the energization and operation of one of the relays'includedin the trunk circuit I3. The resulting operation ofthe last-mentioned relay causes the deenergization of the lamp 30| in the current bridge between the tip and sleeve contacts of this jack, thereby to cause the operation of a Vsupervisory relay embodied in the cord circuit in use by the operator handling the call in the central oiiice`V I0. Operation of this supervisory relay causes the operation of a supervisory lamp individual to the cord circuit in use in over the line I5 and throughthe winding of the ringerl conventionally provided at the substaf tionB. When the call is answered at .the called substation, the branch exchange operator'm'ay 4 retire from the connection and rely upon the su.-

pervisorylamps embodied in lthe cord circuit 33|.v

to indicate when the connection is ready to bey released, When either of the two supervisory lamps individual to the calling and called ends `.of the connection is illuminated, indicating that, the vconnection has been released at one endk thereof, the branch exchange operator may clear.y

out the connection. For example, if the called party at the substation B hangs up prior to the release of the connection ai; the calling -end Y thereof, the supervisory lamp of the cord circuit Y, 3.3,.which is individual to the called. end of theconnection, is energized to inform the branch ex-Y change operator handling the call that the connectionmay be cleared out. 'I'he operator may..

nowrelease the apparatus in use by withdrawingthe plugs30 and 31 from the jacks I4and I1 re-VVV spectively. In response to this operation, the trunk circuitv I3 and the line circuit I0 are,re

stored to normalin the-usual manner, and the Insertion of the plug 36 in the y jack I4 also results in the completion of a direct bridging path established acrossthe conductors off the trunk I2 is opened to causetheenergization of the disconnect lamp associated with the trunk I2 and embodied in the cord circuit in use in the A necti'on at herposition. In response to this operation,. a disconnect signal is transmitted over ther conductors of the trunk line I2 to cause the energization of; thesupervisory lamp in the operators cord circuit 33' which is individual to the calling end of the connection. Energization ofthis lamp serves to inform the branch exchange operator that the .connection has been released vat'the callingend..thereof and may be cleared out at her switchboard. To clear out the connection, the branch exchange operator handling .the calliwithdraws the plugs 36 and 31 from the jacks I4 'and I1 respectively, whereby the trunk' circuit I3 and the line circuit I6 are restored .to normal in the usual manner.

The branch exchange trunk I2 Vand the .other similar trunks may also be used in routing a call from. the branch .exchange operators switchboard to thesubscribers lines terminating at the central "oiice I0.. Forexample, if a call is initiated at the branch exchange substation B through removal of the receiver provided at this substation from its associated hook or cradle, the

associated hook or cradle switch operates .to establish a direct current path between the conductors of theline I5. As aconsequence, certain vof the relays embodied in the line circuit I6 are operated 'to complete a circuit for energizing the call lamp, 302 individual. to .the line, I5. The

branch exchange operator,. upon observing the` lighted .condition of .this lamp, may answer the callbyinserting the plug 36 in the jack I1. In response to this yoperation atalking circuit is establishedbetween theoperatorscord circuit 33.

and the subset in use at the substation B. InA

addition, battery or ground potential is impressed upon the ringcontact of the` jack I1 to complete a circuit fory energizing the signal. lamp cut-01T. relay conventionally embodied in the.line...cir cuit' I6; causes .the deenergizationof the call lamp 302. Uponascertaining Ithat ,a .central office. call has been initiated at the substation IB'r the branch.

exchange operator handlingthe call...may for.- ward the.,connection. to the operators. switchboard in. the. central oilice` I0. by.inserting the plug 31'in the jack III4 and operating .the ringing. keyembodied.in the cord. circuit 33. toproject.

the manner conventionally followedl in manualy oflice practice. After the .connection has been established,` the supervision and release thereof The resulting operation of. this relayA Vaccess thereto.

are exactly thesameas set -forth above with reference` to a call' routedv from a central ofce sub'- scribers substation to one of the branch exchange Y'telephone stations.

Call to order operators position Each of the several order operators, when on duty, maintainsthe telephone set at her position connected to the position circuit apparatus provided at her position. For example, when an operator is on duty at the order operators position 2|, the terminals of. the multiple plug 602' are. respectively insertedinto the jacks 602 'and 603 so thatthe transmitter 600 is bridged across one winding of the induction coil 604 in series with a condenser and the contacts of the key 624, and the receiver is bridged across a portion of the other induction coil Vwindingin series with a` second condenser. With the transmitter 600 connected to the terminals of the jack 602, a circuit is completed for supplying energizing current to the transmitter and for energizing the relay R510, this circuit extending from ground by'way of the transmitter 600, C568 and the -winding of' R510V to battery. This relay, in its operated position, holds completed, at RA51I, a battery marking path for identifying the operators position 2| 'as idle in the bank contacts of all of the position inder switches having As explained more in detail hereinafter, when the position 2| is occupied With a call this idle marking is removed and a busy ground marking; is substituted therefor. Thus, under normal conditions certain of the order operators positions are marked as idle in the bank contacts of the position finder switches, while those engagedin handling calls are marked as busy. When an operator is in attendance at the position 2|, the combined talk and split key S05-'fis maintained in its normal position such that-'the contact springs 606 are disengaged, the springs 601 and 608 are disengaged, the springs 601 and 609'are engaged and the springs 6I0 are engaged. With the key 605 occupying this position an operating circuit is prepared for the tone start relay R560. With the relay R510 operated, a'circuit is also completed for energizing the position lamp I 0I I located at the supervisory Y operators position, this circuit extending from *ground by way of RA513, C586 and the lament of the lamp IOII to battery. The energized condition of this lamp serves to inform the supervisory operator that the order operators position 2| is attended.

Assuming that certain of the order operators positions are conditioned in the manner explained above to receive incoming calls, if the order trunk I8 is seized at the central oiiice and ringing current is projected thereover the relay R440 is venergized by the ringing current traversing its 'and the winding of the magnet 50S to battery.

The ,branch circuit for energizing the upper winding of the relay R410 extends from ground at RA44I. by way of RA4I4, RA4I3, RA423,.the resistor .418 and the upperwinding of R410 to battery. Due to the relatively high resistance of the resistor 418, the relay R410 does not operate when energized over the circuit just traced, but is rendered exceedingly fast to operate when its lower winding is subsequently energized in the manner described hereinafter. Due to the circuit interrupting action of the armature |0 included in the circuit for energizing the magnet 509, this magnet operates buzzer fashion and in cooperation with its associated ratchet and pawl mech-'1 anism'functions to drive the wipers 505 to 508, inclusive, over the contacts of the respective associated contact sets 50| to 504, inclusive. The relay R460 operates, after an interval, 'to complete, at RA46I, a circuit extending from ground at RA413 and through the resistor 4|9 for energizing the upper winding of the relay R4|0. 'I'he resistance value of `the resistor 4|9 is such that the relay R4! 0 does not operate when this circuit is completed. At RA46I, the relay R460 also completes a circuit for energizing the relay R520 in series with the signal lamp |009, this circuit extending from groundby way of RA413, RA46I, RA4I2, C364, the winding of R520, C585 and the filament of the lamp |009 to battery. Energization'of the lamp |009 serves to indicate to the supervisory operator that the trunk circuit I9 is operating to`extend a call to one of the order operators positions. The relay R520 upon operating completes, at RA52I, an obvious circuit for energizing the dashpot relay 540 whereby operation of the last-mentioned relay is initiated.

At RA4E4, the relay R400 opens one of the multiple paths for impressing ground potential upon the all-trunks-busy conductor C444, this conductor being maintained grounded over similar paths individual to the various order trunk circuits so long as any of these trunk circuits are idle. At RA463, the relay R460 prepares a circuit, traced hereinafter, for energizing the storage start relay R400, this circuit now being open due to the ungrounded condition of the start conductor C442. At RA462, the relay R460 completes a circuit extending by way of RA405 for energizing the slow-to-operate relay R420. The latter relay operates, after an interval, to open, at RA423, the initially completed circuit for energizing the'winding of the magnet 509 and the upper winding of R410 in parallel and at this same armature completes an obvious circuit. for energizing these two windings. At RA424,

the relay R420 prepares a test circuit, traced hereinafter, for energizing the lower winding of the relay R410. At RA425, the relay R420 opens a point in the prepared operating circuit for the; relay R400. At RA422 and its associated resting Contact, the relay R420 opens the path normally short-circuiting the resistor 428. At RA42| and RA422, the relay R420 completes an obvious path for short-circuiting the condenser 421, thereby to establish a direct current path including the winding of the relay R440 and extending between the conductors C358Y and C359 of the trunk I8. The completion of this path results in the energization of the relay R440 over the established R420 being greater than the period during which an electrical disturbance may persist.y

-Assuming that 'the order operators position 2| i is the rst'idle position tested bythe WipersV of the switch 500 following the operation of the relay R420, the previously mentioned test circuit is completedfor energizing the relay R410 when the wipers 505 to 508, inclusive, are 4advanced into engagement withvthev-contacts terminating the position circuit' conductors individual to the orderoperators position. 2|; More specifi-cally, when the wiper 501' engages the associated contact individual to the position 2| a. circuit is completed for energizing the lower winding of the stop relay R410 in series 'with the winding `of the tone-start relay R560, this circuitf'extending from ground by way of RA424, the lower winding of 'R410, C494, the wiper 501, RA51'I, C516, the switch springs 6|0 and 6|9, C588 and the winding of' At RA415, the relay R410 completesl an obvious path for Vshort-circuiting its lower winding,'there f by to render itself vslow to release and tocomplete a path extending directly from ground at RA424 for impressing, over the conductorC49l and the wiper 501, busying ground potential :upon the guard conductor individual to the operators position 2| and multipled between correspon-ding contacts of all of the position iinder switches. At RA413, the relay R410 interrupts the previously traced circuit for energizing the upper winding ofthe relay R4|0. At RA413, the relay R410 alsol interrupts the previouslyv traced circuit for energizing the relay R520 in series with the signal lamp |009, thereby to cause the deenergization of these two circuit elements. Deenergizationl of thelarnp |009 serves to informthesupervisory operator that the trunk circuit 9 has been successful in its operation to nd an idle one of the order operators positions and to switch the calling order trunk through to this position. The relay R520, upon releasing, interrupts the operating .circuit lfor the dashpot relay 540.`

At RA416, the relay R410 prepares a circuit traced hereinafter, for energizing the combined call transfer and trunk releaserelay R430. At l RA411, the relay R410 disconnects the wiper 488 of the storage position nder switch 480 from ground. At RA41|1and lRA`412, the relay R410 connects the trunk conductors AC358 and C359 to the link conductors C49| and C492 preparatory to the establishment of a talking circuit between the calling central `oil'lce subscribers'substation and the order operators position 2|.

As indicated-previously, the purpose of providing the signal lamp |009 and the alarm device |005 is to bring in analarm to the supervisory operator in case one of the trunk circuits for some reason fails to iind an idle order operators position within a reasonable time interval "after operation thereof is initiated. Thus, in the' case just considered if the position finder switch 500 fails to iind an idle order operators position, the relay VR410 remains in its restored position and the nder switch 590 continues to operate. After a predetermined time interval, determined by the setting of the dashpotv relay V540, this relay trunk circ-uits is either defectiveror for some other reasonhasfailedto ndan' idle order operators position;

As indicated above, the relay R560 is energized in series with the lower winding of R410 immediatelythe Wipers of the position rfinder `switch 500 are operated to=the setting corresponding to the order voperators `position 2|. When' the relay R410 operates to short-'circuit its lower winding the 'relay R560 is energized over a circuit extending gdirectly-fromrground and is therefore fully energized. The relay R560 operating, completes, atV RA564,- a circuit for energizing the Vcall signal lamp; 625, this circuit extending from ground at the'switch spring 601 by way of the spring |309,- C519,RA564; C518 'and the lament of the lamp 625 to battery. Energization of this lamp serves to inform the operator attending the position 2| that an incoming call should be answered.' This visual-signal is supplemented by an audible signalwhich is reproduced .byV thev receiver 60|.' More specifically, therelay R560 upon operating completes, at RA56|'andRA562, a circuit'for connecting :a zip-zip-tone source, not shown, by way ofthe restored armatures RA53| and RA532 to "thetalking 'conductors' C514 and C515 individua'l-to-l the operators position 2|. The resulting currentowing'from this source through the windings ofthe induction coil 604 is reproduced by the receiverx60| audibly to inform the operator attendingathe-position 2| that an incoming call should be answered.. At RA555, the relay R560 vopens the multiple'path individual to the order operators position 2| over which ground potentialis normally impressed upon the storage start conductorC58l. Ground potential is maintained-on the last-mentioned conductor over similar paths individual to the other order operators positions so=long as any of the positions'are idle. At RA566,` theV re1ayR560 -completes a circuit for energizing the "positionbusy lamp ||0,Y this circuit extending 'from lground by way of RA566, C585 andthefilament of the lamp I0 0 to battery. The resulting illumination of theilamp I0 0 serves to inform the-operator attending the'position 32 that the call routed'by wayiof the trunk circuit IBhas been extended to the order operators position 2|. At-RA5S3, the relay R560' completes an obvious circuit. forenergizing the slow-'tooperatetone -cut-oif and line switching relay R530. The rel-ay R530 operating, disconnects the talking conductors C514 Y and'C515 from the zipzip tonecurrent source, Athereby to terminate the audiblefsignal being reproduced by the receiver 60|',--and completes the desiredtalking circuit between the calling central oflice subscribers substation and the operator-s position 2 Following. the operation ofthe relay R530 to establish a talllzingcircuit between the calling subscribersfsubstation and the orderoperators position f2|', the order operator attending this position may converse with the calling subscriber andf'give the calling subscriber the information desired. In order to initiate the release of the connection after the Iconversation is terminated, the operator attending the position 2| momentarily actuates thel combined call transfer and trunkL release key 620 to the off-normal position required toppen the springs 6|!)` and to close thea-springs 620. Inresponse to this operation.v

the'previously traced-'circuit for energizing the lower winding of R410 and the winding of R560 in series is broken, thereby to cause the sequential release of the relays R560 and R530 in the order named. The relay R560 upon restoring interrupts, at RA564, the previously traced circuit for energizing the call signal lamp 625, and recompletes, `at RA565, the path individual to the order operators position 2| over which ground :potential is impressed upon the storage start conductor C58| so long as this order operators position is idle. At RA566, the relay R560 opens the previously traced circuit for energizing the signal lamp |0|0 provided at the supervisory ioperators position 32, thereby to inform the supervisory operator that the'call being handled at the order operators position 2| has been released. When the springs 620' are moved into engagement, the above-mentioned circuit is corn--` f l-ipleted for energizingV the combined call transfer and trunk release relay R430, this circuit extending from groundl by way-of the resistor 625, the springs 620', C511,'the wiper 508, C495, RA416 and the winding of R430 to battery. Due to the relatively high resistance of the resistor 626, the relay R430-only partially operates to open the'X contacts associated with RA434 in response'toits energizationover the circuit just traced. When these X contacts are disengaged,

the operating circuit for the relay R460 is interrupted causing this' relay, the relay R420 and the relay R410 to restore in the order named; The relay R420, upon restoring, opens, at RA424,'a further point in the previously traced circuit for ;energizing the relays R410 and-R560 in series, thereby to prevent the reoperation' of these two relays when the combinedcall transfer and'trunk release key 620 is rele'asedand permitted to return to its normal position.- At RA42| the relay `R420 opens the established loop circuit including the winding of R440 and'extendingto the' central oice |0, whereby the line relay R440 is permitted torelease'and a disconnect signal is transmitted to the operator. handling the call in tice.U Following the relayoperations just de scribed, the order-trunk circuit I9 and the position circuit individual to the order operator-s position 2| are fully restoredto-normal.

If the connection routed' overthe trunk line I8 'to the order operators position 2| is'released at the positionof the operator handling the call in" the central oice |0 prior to actuation of the" combined call transfer and trunkY release key 4A520, in the "manner set forth in the preceding paragraph, the relay R440restores to openthe operating circuit forl the relay R460, wherebyY the relays R460,- R420 and R410- are causedV` sequentially to" restore` in the order named;

*.When the relay AR420 restores, the-circuit overwhich the relay R560-V is being held energized 'isinterrupted causing this latter relay and the relay R530 to restore inthe order named. Thus, in the case where the connection is rst cleared out 'at the position of the operator handling the' call in the central' oihce |0, the trunk circuit I9 and the position circuit individual to the order operators position 2|"are fully released'without any operation on the part of the operator attend- 'iing the order operators position 2|.

Transfer of order trunk call to branch exchange switchboard Y In the event the order operator attending the position 2| nds it necessary to converse with a party located at one of the branch exchange telephones in order to obtain the infomation desired by the calling central office subscriber or to connect the calling central cnice subscriber directly with one of the branch exchange substations, she may route the call to the .branch exchange Y operators switchboard by operating the'combined call transfer and trunk release key 620 to the off-normal position required to cause engagement of the transfer springs 62|. In respenseV to this operation the relay R430 is energized over a circuit extending from ground by way of the springs 62|, C511, the wiper 508, C495, RA416 and the winding of R430 to battery. It will be noted that the resistor 626 is excluded from this circuit and, accordingly, the relay R430 is fully energized. Hence, this relay assumes its fully operated position. At RA434, the relay R430momentarily opens and then recompletes the operating circuit for the relay R460. At RA43| and RA432, the relay R430 disconnects the conductors of the order trunk I8 Yfrom the line wipers 505 and 506 of the position finder 500, thereby to interrupt the talking circuit established to the order operators position 2|. At RA433, the relay R430 prepares a circuit, traced hereinafter, for energizing the relay R450 when an assigned one of the transfer trunk iinders'has operated to seize the transfer trunk 22. At RA435, the relay R430 completes an obvious path for impressing ground potentialv upon the distributor start conductor C445, thereby to initiate operation of the control relays embodied in the answer circuit distributor 35. As previously indicated, the distributor 35 is so connected and arranged that the, wipers of the distributor switch 160 normally stand in engagement with contacts corresponding to an idle one ofY the answer circuits. Assuming, for example, that the answer circuit 33 and associated transfer trunk nder 34 have previously been selected for use by the distributor switch 160, operation of the nder 34 to search for the transfer trunk 22 is initiated in response to operation of the combined call transfer and trunk release relay R430. More particularly, when ground potential is impressed upon the conductor C445, the distributor start relay R140 is energized over a' circuit extending by way of this conductor, the winding of R140, RA14I, the armature 112 and the winding of the magnet 11| to battery. Due to the relatively high resistance of the winding of R140, the magnet 11| is insuiiiciently energized over the circuit just traced to attract its associated operating armature. The relay R140, o'n the other hand, is suilciently energized to operate and, upon operating, opens, at RA14|, thepath normally short-circuiting the resistor 113, thereby further to increase the resistance of the circuit serially including its own Winding and the winding of the magnet 11|. At RA143, the relay R140 opens a point in the operating circuit/for the magnet 11| and completes an obvious circuit for energizing the slow-to-release relay R150. 'Ihe relay R150 now operates to prepare, at RA15I, the operating circuit for the magnet 11|. At RA142, the relay R140 prepares atest circuit, traced hereinafter, and serially including the winding of R450 and the respective upper windings of the two relays R120 and R130. At RA144,

the relay R140 completes a circuit for energizing the operating magnet 356 of the transfer trunk finder 34, this circuit extending from ground at RA13| by way of RA144, RA12I, the wiper 169, RA1|3, C312 and the winding of the magnet 356 to battery. When energized over this circuit, the magnet 356 attracts its associated armature 351 to complete a circuit for energizing the lower winding of the pulsing relay R120, this circuit extending from ground by way of the armature 351, C313, the Wiper 168 and the lower winding of R120 to battery. The relay R120 operating, opens, at RA12|, the above-traced operating circuit for the magnet 356, causing this magnet to retract its associated armature 351 to open the above-traced operating circuit for the relay R120, whereby this relay releases to recomplete the operating circuit for the magnet 356. The interrelated operation of the relay R120 and the magnet 356 continues until the wipers of the finder 34Vare positioned in engagement with the contacts terminating the conductors of the transfer trunk 22.- More specifically, when the wiper 355 engages the associated contact terminating the test conductor C362 individual to the transfer trunk 22, the above-mentioned circuit is completed flor energizing the relay R450 in series with the respective upper windings of the relays R120 and R130, this circuit extending from ground by way of VRA142, the upper winding of R130, the upper winding of-R120, the wiper 161, RA1|2, C31|, the wiper 355, C362,.RA433 and the winding of R450 to battery. When its upper winding is energized over this circuit, the relay R120 immediately operates to open, atRA12I, the abovetraced v operating circuit for the magnet 356, whereby further operation of the finder 34 is prevented and the wipers of this nder are left standing in engagement with the contacts terminating the conductors of the trunk 22. The relay R130, upon operating, completes, at RA132, an obvious locking circuit for itself and opens, at RA13I a further point in the operating circuit for the magnet 356. At RA13| and its associated working contact, the `relay R130 completes a circuit extending by way of the wipers for energizing the lower winding of the relay R1|0. The relay R1|0 now operates to complete a locking circuit for itself and the relay R450, this circuit extending from ground at RA1|4 by way of the upper winding of R1|0, C31|, the wiper 355, C362,RA433 and the Winding of R450 to battery. At RA1I3, the relay R1|0 opens a further point in the vabove-traced operating circuit for the magnet 356. At RA1|5, the relay R1|0 prepares an alternative locking circuit for itself. At RA1| the relay R1|0 opens the circuit individual to the answer circuit 33 over which the al1-busy relay R100 is normally energized. At RA1| the -relay R1|0k also completes a path including the wiper 166 for short-circuiting the winding of the distributor start relay R140, thereby to cause the latter relay to restore. At RAlfi,` the relay R1|0 completes a circuit for energizing the signal lamp control relay R310, this circuit extending from ground by way of RA1I6, C368, RA33I and the winding of R310 to battery. The relay R3|0, upon operating, completes an obvious circuit for energizing the call signal lamp 303, whereby the branch exchange operator is informed that an incoming call routed to the answer circuit 33 should be answered. Finally, at RA1|2, the relay R1|0 opens the circuit` over which the respective upper windings of the relays R and R130 are being held energized in series causing the relay R120 immediatelyvto restore and conditioning the relayR130 to release in response to release of the relay R140. TheV relay R450 included in the trunk circuit I9 and energized in series -with the vtwo relays R120 and R130 and the relay R1I0 inthe manner pointed out above, upon operating, opens, at RAI, the path over which ground potential was impressed upon the distributor start conductor C445. n Following the relay operations just described, operation of the answer circuit distributor switch is initiated to select another idle answer circuit. Thus, when the relay R140 restores, it opens, at RA143, -the operating and locking circuits for the relays R150 and R130,respectively. At RAM! and RA143, the relay R140 simultaneously completes two parallel operating circuits for the magnet 11|, one of these-circuits extending from ground at RATII by way-of the wiper 136, RA14 I the armature 112 and the winding of the magnet 11| to battery; and the other extending from ground atV RA143 by way of RA15I and the winding of the magnet 11| to battery. At RA142, the relay R140 opens a further pointV in the above-traced circuit serially including the windings of the relays R and R130. At RA144, the relay R opens a. further point in the previously traced operating circuit for the magnet 356. When `the two operating circuits traced above for the magnet 11 I` are completed, this magnet attracts its associatedarmaa ture 112 to open the first-traced circuit'. Shortly thereafter, the relay R restores to open the other operating circuit and thus permit the-magnet 11 I, in cooperation with its associated ratchet and pawl mechanism, to step theA wipersl 166lto 110 inclusive, into engagement with'the set of contacts terminatingthe circuitV conductors individual to the next answer circuit. If the answer circuit thus selected-is busy, ground potential is maintained on Vthe test wiper 166 because ofA- the operated condition of the test relay corresponding to the relay R1I0 and individual to lthe selected answer circuit. Accordingly-,the operating circuit for the-magnet 11| is again completed at the` armature 112 and this magnet -is caused to step the wipers 106 to 110, inclusive, a second step. The step by step operation of the'distributor switch continues until such time as the wipers thereof are positioned on the contacts corresponding to an idle answer circuit, at which time the wiper 163 is disconnected from ground and no further circuit is available for energizing the magnet 11 I. Thus, operation of the distributor switch 160 is arrested with the wipers of this switch standing in engagement with the contacts terminating the circuit conductors individual to an idle one of the answer circuits.

In the event all of the answer circuits VareV busy l at the time the hunting operation of the distributor switch 160 is initiated, the wipers of this switch are operated to engage their associated eleventh contacts at which the operating circuit for the magnet 11| is opened and further opera- Cil at RA10I by way of-C335 andthe lament of the lamp |001 to battery. The resulting energization of the lamp |001 serves to inform thevsupervisory operator'that all of the answer circuits provided at the branch, exchange switchboard are occupied with 'calls which have been transferred from the order operators lpositions to the branch exchange switchboard. At RA10I, the all-busy relay R100 also vdisconnects ground` from the eleventh contact associated with the wiper 166. Hence, when the wipers of the distributor switch 160 have been Yoperated to engage their respective associated eleventh contacts, the voperating circuit for the magnet 1 1.I'is interrupted and no further operation `of the distributor switch wipers occurs. Thereafter and when one of the answer circuits, such, forlexample, as the circuit 33 is released, the holding circuitfor the test relay R1I0 individualfthereto is interrupted in the manner hereinafter explained, causing this relay to restore and rec'omplete, at RA1|I, the operating circuitfor theall-'busy relay R100. Reoperation of the relay R100 results in the deenergization of the lampl |001 and in the connection of ground tothe eleventh contact of the contact set associatedwith the wiper'166. As a result, the magnet- 11| is again energized and operation of the distributors'witch 130is initiated. The hunting operation Yof vthis switch continues until such timefas the wipers thereof are positioned in engagement with. the contacts terminating the conductors individual y to the answer circuit which has beenvacated or released. When these contacts are: located, the operating circuit for the magnet 11| is interrupted and operation of the distributorswitch 160 is arrested.

i The branch 'exchange operator may answer the call routed to the answer circuit 33 in the manner`,just described by inserting the answer plug 36" in the vjack 23. In response to this operation, battery potential is impressed upon the 'ringcontact of the jack 23 in the usual'manner to complete anobvious circuit for energizing the relayQ'R320. The relay R320 operating, completes', at RA322, an obvious circuit for energizing therela'y' R330. At RA32I, .the relay R320 completes an obvious circuit for energizing the line switching' relay'R34'0. The relay R330, upon operating', opens, at RA33I, the previously traced 'operating circuitjfor the relay R3I0, causing the latterV relay 4to restore and open the circuit for energizing the signal lamp 303. At RA33I, the relay R330 also completes a locking circuit for itself, this circuit extending from ground at l RA1|0, by way of' C368, RA33I and the winding of the relay R330 to battery. At its armatures RA34I' and RA342, the relay R340, upon operating, connects the line terminals of the repeating coil 305 to the line wipers 353 and 354 ofthe transfer trunk finder 34, thereby to establish a talking circuit extending between the operators cord circuit 33 and the head set in use at the order operators position 2|, this talking' circuit including the transfer trunk 22. In completing this talking circuit, the relay R340 also prepares a circuit, traced hereinafter, for energizing the relay R400'. uAt RA343, the relay R340 completes a circuit for energizing the signal 'lamp |000 4individual to the answer circuit 33, this circuit extending from ground at RA343 by-way of -G309'and the lament of the lamp l|006 to battery. The resultingk illumination of the lamp |006 `serve sto inform the supervisory operator attending the position 32 that the answer circuit 3371s occupied with a call. At RA344,

the relay R340 completes the previously mentioned alternative locking circuit for the test relay R1I0, this circuit extending from ground by way of RA344, C310, RA1I5 and the lower winding of R1I0 to battery.

Following the relay operations just described, the operator attending the order operators position 2| may converse with the branch exchange operator and direct the latter operator to extend the connection to the desired line. Assuming, for example, that the substation B is desired by the order operator, the branch exchange operator may route the connection to this substation by inserting the call plug 31 in the jack I1 and operating the ringing key provided in the cord circuit 33 to cause ringing current to be projected over the line I and through the windings of the ringer provided at the substation B. When the call is answered at the substation B, the desired talking circuit may be established through the operators cord circuit 33' between this substation and the head set in use at the order operators position 2|. Following the completion of this talking circuit the operator attending the position 2| may converse with the answering party at the substation B to obtain the desired information and during the course of this conversation the calling centraloice subscriber is excluded from the connection because of the operated position occupied by the call transfer and trunk release relay R430.

If the operator attending the position 2| desires, she may establish a three-way talling circuit between her substation, the central office subscribers substation and the substation B. y To this end, the combined call transfer and trunk release key E is restored to its normal position. In response to this operation the call transfer and trunk release relay R430 restores to open the completed holding circuit for the relay R400 and to recomplete the operating circuit ior this relay. At RA433, the relay R430 opens the holding circuit for the relay R450 causing the latter relay to restore. At RA435, the relay R430 opens a further point in the path, individual to the trunk circuit I9, for impressing ground potential upon the distributor start conductor C445, this path being prepared at RA45| in response to the release of the relay R450.

At RA43I and RA432, the relay R430 connects f the conductors of the order trunk I8 to the talking conductors of the transfer trunk 22, thereby to establish a three-way talking circuit between the calling central oiiice subscribers substation, the order operators position 2| and the substation B. In response to the completion of this three-way talking circuit, the relay R400 is energized in parallel with the line relay R440 over a circuit extending by way of the order trunk I8 to the terminals of the exchange battery provided in the central oice I0. More specically, the relay R400 is bridged across the conductors of the order trunk I'S over a path extending from the conductor C358 by way of RA43I, the winding of R400', C360, the wiper 353, RA34I, the resistor 345, RA342, the wiper 354, C36I, RA432 and the resistor 428 to the opposite conductor C359 of the order trunk I8. The resistance of this path is such that the series relay R400' does not operate at this time.

After the connection is established between the substation B and the substation of the calling central oice subscriber in the manner just explained, the operator handling the call vat the order operators position 2| may retire from the connection and release the trunk circuit ap- Vis short-circuited at the armature RA422 and its associated resting contact, thereby to exclude this resistor from the above-traced series path including the winding of the relay R400. In response to this operation the relay YR400' is sufciently energized to operate and, upon operating, opens, at RA40I, the path individual to the trunk circuit I9 over which ground potential is normally impressed upon the all-trunks-busy lead C444. Following the release of the trunk circuit I9 and the position circuit individual to the order operators position 2|, supervision of the call as extended through the operators cord circuit 33 to the substation B is under the control of the operator handling the call at the branch exchange switchboard, supervisory lamps provided in the cord circuit 33 being utilized to indicate'when'the connection is no longer desired. More specifically, when the operator handling the call at the branch exchange switchboard receives a disconnect signal caused by the release of the connection at the central oice or the substation B, she may clear out the connection by withdrawing the call and answer plugs 31 and 3B, respectively, from the jacks I1 and 23, respectively. In response to this operation battery potential is removed from the ring contact of the jack 23 to cause the deenergization and release of the relay R320. This relay releasing opens, at RA32I, the established circuit for energizing the relay R340 and interrupts, at RA322, the operating circuit for the relay R330. The relay R340 releasing interrupts, at RA34I and `RA342, the established loop circuit extending through the winding of the relay R400 and over the order trunk I8 to the central oice switchboard. Interruption of this loop circuit also results indeenergization of the relay R400', which relay releasing recompletes, at RA40I',v-the path individual to the trunk circuit I9 over which ground potential is normally impressed upon the all-trunks-busy lead C444. At RA343, the relay R340 opens the above-traced circuit for energizing the signal lamp |006 whereby the supervisory operator is informed that the answer circuit Y33 has been released. AtRA344, the relay R340 opens the previously traced holding circuit for the relay R1I0. 'Ihe relay R1|0 restoring opens, at RA1 I6, the locking circuit for the relay R330, causing the latter relay to restore. Following the release of the relay R330 the answer circuit 33 and associated transfer trunk finder 34 are fully restored to normal.

Call from` order operators position to branch exchange switchboard If, for any reason,the operator attending the branch exchange operators switchboard by operating the key 605 to the oi-normal position required to cause engagement of the springs 606,

disengagement of the springs 601 and 609, engagement oi the springs 601 and 608 and disengagement of the springs 6|0. When the springs 6|0 are disengaged the marking path including the winding of the relay R560 and over which battery potential is normally impressed on the contact associated with the wiper 501 for marking the position 2| as idle in the position finder switch 599, is interrupted. When the springs 601 and 669 are disengagedthe path individual to the order operators position 2| over which ground potential is normally impressed upon the storage start conductor C58I, is interrupted. At the springs 996 a circuit is prepared for energizing the relay R550 when an assigned one of the position nder switches is operated to the position corresponding to the order operators position 2|. At the springs 601 and 603 a path is completed for impressing ground potential upon the distributor start conductor C582, thereby to energize the distributor start relay R9|0. More specifically, the operating circuit for the relay R9|9 extends from ground by way of the springs 601 and 609, C586, RA553, C532, the winding of R9|0, RAGI i, the armature 912 and the winding of the magnet 91| to battery. Due to the relatively high resistance of the winding of the relay R9|0, the magnet 91| is insufficiently energized to operat-e when the circuit just traced is cornpleted. The relay R9|0, however, operates to initiate operation of a previously selected idle one of the position finder switches. Assuming, for example, that the wipers of the distributor switch 960 are standing in engagement with the contacts individual to the trunk 26, operation of the position finder 29 is initiated'. More specifically, the relay R959, upon operating opens, at RA9| the path normally short-circuiting the resistor 923, thereby further to increase the resistance of the circuit serially including its own Winding and the winding of the magnet 91|. At RA9|2, the relay RBI@ prepares a circuit for energizing the winding of R550 in series with the respective upper windings of R920 and R930. At RA9l3, the relay R9|0 completes an obvious operating circuit for the slow-to-release relay R900 and opens a point .in the operating circuit for the magnet 91|. The relay R900 operating, prepares, at RA90 the circuit for energizing the magnet 91|. At RA9I4, the relay R9|0 completes a circuit for energizing the operating magnet 636 of the position finder 29, this circuit extending from ground by way of RA922, RA9l4, RA93I, the wiper 969, RA945, C64! and the winding of the magnet 636 to battery. When energized over this circuit, the magnet 636 completes, at its armature 631, a circuit for energizing the pulsing relay R930. This circuit extends from ground by way of the armature 631, C642, the wiper 968` and the lower winding of R930 to battery. The relay R930 operating, opens, at RA93I, the above-traced operating circuit for the magnet 636, causing this magnet to retract its armature 631 and thus open the operating circuit for the pulsing relay R930. When the magnet 636 is deenergized it also opcrates, in cooperation with its associated ratchet and pawl mechanism, to advance the wipers 633 to 635, inclusive, one step. The interrelated operation of the pulsing relay R930 and the magnet 636 continues until such time as the wipers of the finder 29 are positioned in engagement with the contacts terminating the circuit conductors individual to the calling order operators position 2 More speciiically, when the wiper 633 is advanced into engagement with the test contact individual to the position 2|, the above-mentioned circuit is completed for energizing the relay R550 in series with the respective upper windings of the two relays R920 and R930. This circuit extends from ground by way of RASIZ, the upper winding of R920, the upper winding of R930, the wiper 961, RA944, C638, the wiper 633, the springs 606, C581 and the winding of R550 to battery. When this circuit is completed the relay R930 immediately operates to open, at RA93|, the above-traced operating circuit for the magnet 636, thereby to arrest operation of the position iinder 29 with lthe wipers of this finder standing in engagement with the contacts individual to the order operators position 2|. The relay R920 also operates when its upper winding is energized in the circuit traced-above and, upon operating, completes, at RA92I, an obvious locking circuit for itself. At RA922, the relay R920 opens a further point in the above-traced operating circuit for the magnet 636 and completes. a circuit extending by way of the wiper 910 for energizing the lower winding of the line switching relay R940.

The line switching relay R940, upon operating, opens, at RA943, the circuit, individual to the trunk 26, for energizing the all-trunks-busy relay R950. At RA945, the relay R940 opens a further point in the above-traced operating circuit for the magnet 636. At RA946, the relay R940 completes a locking circit for itself, this locking circuit extending from ground by way of RA946, the upper winding of R940, C638, the wiper 633, the contact springs 696, C581 and the winding of R550 to battery. At RA943, the relay R940 also marks the trunk 26 as busy in the contacts of the distributor switch 960. At RA944, the relay R940 opens the above-traced circuit for energizing the respective upper windings of the relays R920 and R930 in series, causing the relay R930 immediately to restore and the relay R920 to restore in response to the release of the distributor start relay R9|0. At RA94| and RA942, the relay R94D connects the talking conductors C639 and C640 to the talking conductors C361 and C366, respectively, thereby to establish a loop circuit between the order operators position 2| and the trunk circuit 21. When this loop circuit is established one of the relays embodied in the trunk circuit 21 is caused to operate to complete a circuit for energizing the signal lamp 304, whereby the branch exchange operator is informed that a call present on the trunk 26 should be answered. The relay R550, upon operating, opens, at RA55| and RA552, two points in the above-traced circuit for transmitting zip-zip tone current to the receiver 60| provided at the order operators position 2 l At RA553, the relay R550 disconnects ground from the distributor start conductor C582. At RA554, the relay R550 completes the previously traced circuit for energizing the position signal lamp I0 0 individual to the order operators position 2|, there to inform the supervisory operator attending the position 32 that the order operators position 2| is busy.

As indicated above, the distributor start relay R9|0 is deenergized in response to operation of the two relays R550 and R940. This relay restoring,'initiates the operation of the distributor switch 960 to search for an idle one of the trunks forming the group including the trunk 26, pro-

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