US1776570A - Telephone system - Google Patents

Description

Sept. 23, 1930. 1.. RUGGLES TELEPHONE SYSTEM Filed Oct. 21, 1927 5 Sheets-Sheet 2 Mob umqmm km QR IEEWWZQ E &

Imranlur' Lean-Laval LE 115125 Se t. 23, 1930. L. L. RUGGLES 1,776,570

TELEPHONE SYSTEM Filed Oct. 21, 1927 5 Sheets-Sheet 3 Q a a 3 i i q i E i F.

Inuenlur' Sept. 23, 1930. 1.. L. RUGGLES 1,776,570

TELEPHONE SYSTEM Filed Oct. 21, 1927 5 Sheets-Sheet 4 l" 3 Lu II- (r) [L I w Z 2 Sept; 23, 1,930. 1.. 'RUGGLES 1,775,570

TELEPHONE SYSTEM Filed Oct. 21, 1927 s Shets-Sheet 5 RUM ELSE.

RING BACK SWITCH Imam? v LEUFLEI'EI LRu Zes IIHr G HANG-UP mus arrangements whereby the callingjjline is Patented Sept. 23, 1930 UNITED STATES. ore-i es LEO ARD L. .EoGeLEs; or .wHEAToE, mu s AssiG-E R TO nEsEnvE Hon-nine. com} PANY, OF KANSAS CITY, MIssoUEI, A CORPORATION or DELAWARE TELEPHONE y SYSTEM Application filed October 21, 1927'. serial N6. 221673."

The present invention relates to telephone systems in general,butisconcerned more: particularly with semi-automatic telephone systems, especially those wherein anuniber of i smaltexchanges areinterconnected by trunk lines with an operating centerfrom which operators may control the automatic switching equipment in the various semi-automatic exchanges. 1-- a i The broad general object of the invention isthe production of suitable circuitiarrange the invention above stated, a number of 'de pendent objects and features are involved as follows: a g

@ne object is to provide c rcuit arrangements such that two-way trunk lines may i used between theoperating center and asemiautomatic exchange so asto increase the efliciency of the relatively small trunk group.-

Another object of the inventionis the pro vision of arrangements for seizing the semiautomatic exchange end of atwo way trunk line-when a'call 1s originated 1n a SGIIll-ZLLHLO:

lnatic exchangeand to automaticall signal the operator, atalkingcircuit being efiectlv-e between the calling subscriber and the operators switchboard when the operator respends; i

It is afurtlier' object of the invention to destroy thetalking'eircuit whenthe operator is operating the" automatic switches so as to prevent severe clic {S from being heard by the calling subscriber, this being done by short circuiting the calling line while the switches are being operated.

A feature oftheinvention is found in the switched through from a sele'ctor'to a confor use in reverting calls for operating the calling andcalled sub-station ringers a1ter-- nately. In carryingout this object -arr'angements have been provided for preventing a premature operation of the ringback switch by maintaining the calling line short circuitedat the first selector until the operator has withdrawn from the'connectionz A feature of this arrangement is found' in the ring-back switch wherein-suitable circuit arrangements are provided for preventingthe ringing operation from being started when the operator withdraws from the connection; such-ringing operation being heldup until the calling subscriber replacesh-isreceiver) Another object of-the=inventio1ris to make suitable provision for placingan out-'of-order tone on a calling line when an attempt is i 7 made to complete a? connection to a line-"tliat is outof order, the-outer order condition'be ingrt'r-ansmi'tted to*a connectorswitch t hibugh a separate wiper from-w separateconductor associated with "the called line terminals As i he most frequent out of-orde'r condition-- of aline is for theli ve side ofthe line to be grounded or forth'e two conductorsof a line to beinadvertently v connectedtogether, in

which case the lineswitch individual to the lineseizesa first selector and causes theoperator to be signalled, a certain level of the selector is-re'served'tor receiving out of-order calls and for'placing an out of-orderpoten tial on the out et-order conduetor individual to a defective line. a

In developing the system de eribed here'in, it has"been"assumed that local calls withina semiautomatic exchange are completed under the control of asp-called localoperator' in the operatingcen'ter, and-that incoming calls are completed through a toll board presided calling supervisory lamp is extinguished.

upon the operation of the ringing key. Now, when a'local operator'makes a call from a subscriber local to the operating center to a subscriber in a semi-automatic exchange, it is unnecessary for such operator to operate her ringing key. It is accordingly an object of the invention to provide circuit arrangements associated with the trunk line extending to the semi-automatic exchange to extinguish the calling supervisory lamp automatically without obliging the operator to -operate her ringing key, while the calling supervisory lamp in a toll cord circuit is not extinguished until the called subscriber in theautomatic exchange has responded.

Referring now to the accompanying drawings comprising Figs. 1-5, they show by means of the usual circuit diagrams a sufficient amount of apparatus 1n a semi-automatic telephonesystem embodying the features of the inventionto enable the invention to be understood. In order for the drawings to be understood best, Fig. 2 should be placed to the right of Fig. 1 with the inter-,

connecting lines in alignment; Fig. 5 should be placed beneath Fig. 2; Fig. 4 should be placed beneath Fig. 1; and Fig. 3. should be placed to the left of Fig. 4.

l/Vhen the drawings are laid out in the above manner, Figs. 1 and 2 show the switching equipment comprising a lineswitch, aselector, and a connector necessary to complete a connection from the line of-substation A, Fig. 1, to the line of the substation B, Fig. 2,

both lines terminating in the same semi-auto-.

matic exchange.

Fig. 5, shows a ring-back switch accessible to the selector shown inFig. 1 and arranged to signal alternately the callingandcalled stations on a party line.

Fig. 3 shows the operating-center end of a two-way trunk line connecting the operating center with the semi-automatic. exchange.

shown in Figs. 1, 2, 4, and 5. The equipment shown in Fig. 3 includes the trunk circuit TCl with the associated jacks at the toll. 1? board and at the local board, together with the dial cord DC at the local board for associating the dial type callingdevice CD with any of the trunk lines through dial jacks such as the dial jack DJ 2, associated with the trunk circuit TC.

Fig. 4 shows the semi-automatic exchange end of the trunk line comprising conductors 314 and 315, which trunk line terminatesiin the incoming selector. This drawing shows also the secondary switch SS, individual to tions of the apparatus shown-will now be given. For this purpose it will be assumed that the subscriber at substation A, Fig. 1, desires'to' converse with the subscriber at substation B, Fig. 2.

Local call in' the semi-automatic exchange lVhen the receiver is removed at substation A, line relay 1080f the lineswitch LS operatesover the calling'line and starts the lineswitch LS into operation by grounding the private normal conductor 104 and by connecting up test wiper 111 to the junction of switchingrelay 108 and stepping magnet 109. If the trunk line on which the wipers 110113 are standing is idle, no advance of the wipers takes place, and switching relay 107operates in series with magnet 109. If, however, the trunk line is busy, a ground potential is encountered by test wiper 111; switching relay 107 is short circuited; and the self-interrupting magnet 109 operates in a buzzer-like manner to advance the wipers,

. wiper 112 at its inner lower armature; opens a point in the test circuit and prepares the holding circuit for the lineswitch at its inner upper armature; and at its upper and lower armatures it disconnects the conductors of the calling line from line relay 108 and ground and extends them by way of wipers 110 and 1 13 and trunk conductors 114 and 117 to the line relay 121 of the local selector through contacts of switching relay 126. Line relay 121 now operates over the calling line and places a ground at its inner upper armature on release trunk conductor 115, thereby closing the usual holding circuit for the lineswitch LS before the slow-acting line relay 108 has fallen back.

In addition to placing the ground potential on the release trunk conductor of the selector, line relay 121 closes at its inner lowlowervarmature, line relay 121 connects test wiper .403 of the switch: SS to the junction of the switching relay 401 and stepping magnet 405, thereby setting the switch into, operation.v The switch SS operates in the manner described in connection with the lineswitch LS, selecting-anidle trunk line for example, the trunk line comprising conductors 314 and 315, extending from the semi-automatic exchange to the manual exchange shown in Fig. 3. 1 When. this idle trunk line isreached, switching relay 401 operates and connects up the associated wipers 402404. When the wiper 403 is grounded by relay 401, a circuitis closed over the test conductor of the seized trunk'line and through normally closed con-' tacts of release relay 408 forfcuuofi relay 406. Relay 406 operates and disconnects the conductors 304 and 305 "from line relay 407 of the selector and connects them insteadto the V conductors extending to the bank of i the switch SS, thereby connecting impulse relay 122 ofithe local selector, Fig. 1, to the conductors 31.4 and 315. It will be noted that relay 407 is connected tothe conductors 314 and 315,

normally, so that there is a ground potential onconductor 315 and a negative-battery potential on conductor 314. It will be noted, further, that relay 1220f the local selector is now connected to conductors 314 and- 315 in V conductor 314'being supplied with ground potential throughv thelower winding of the said relay.

In the manual exchange, line relay 301 of the trunk circuit T61, which is normally connected between ground and conductor 315 and which normally remains non-operated due to the ground potential on conductor 315,.now operates due to the battery potential placed on conductor 315 throughthe 1 upper winding. ofrelay 122, Fig., 1. -Although 301 operates, relay 122 does not operate. due to the relatively high resistance of relay301. WVhen relay 301 operates itcloses a circuit for the associated call lamp at the local board. J

When the operator notes the lighted con dition of the call'lamp,she inserts the answering plug of an idle cord circuit into the ack J 2, whereupon the discriminating relay 303 of the trunk circuit TCl is operated through the upper spring contacts of'the jack J2, but its operation is of no particular utility in connection withan incomingcall. As a further result of the plugging-in operation, sleeve relay 302 placesgroundon conductor 321 at itsinn'er; armature, thereby closing a lighting circuit for'the busy lamp and preparing certain locking circuits-in trunk cir cuit. Relay 302 also. disconnects. the incomchange and a positive potential being sup 7 plied to the negative conductor. The impulsing relay 122, Fig. 1, is not operated at this time owing to the inclusion of the high, resistance 311 in thebrid'ge across the con-- ductors 314 and 315. It will be noted that a bridge exists. across the tipand ring conductors of the jack J 2 throughthe upper contacts of relay 304, lower winding of relay 308, and theinnerlower contacts of relay 310. Relay 308 operates in this bridge from the regular battery-feed circuit of the cord and closes a locking circuit for its upper winding at its upper armature, which locking circuit includes the inner upper contacts of the. non-.1 operated relay 304 and the inner upper contacts ofth'e operated relays 303 and302. Re I lay 308 also disconnects the lower terminal of relay 307, but this does not produce any particular vetl ecti. at this. time. Since the above mentioned bridge is across the tip and ring conductors of the jack J2, the current flow through the. usual supervisory relay of the cord sufiices to operate; this relay to extinguish the supervisory lamp so as to give I the operator answered supervision.

voice current passing through, the condensers at the local selector shown in Fig. 1. Upon learning that the. subscriber at substation A desires to converse with the subscriber at sub-.

station E, the operator proceeds to insert the plug P ofthe dial cord DC into the dial jack DJ 2 of the trunk line in use and to ,dial the digits.- in the desired number.

jack DJ2, the dialicircuit including the impulse springs of the calling device CD and relays304, 305, 309, and 310 in multiple, but I the operation of relays304, 305, and 309 is of no particular utility at this time. Relay 310 connects the tip and ring'conductorso-f the dialij ack to the trunk conductors 314 and 315, at the same time disconnecting-these trunk conductors from the talking conductors associated with theJjack'J2, Relay 310 also The operator nowconverses with the call- V .ing subscriber at substation A, Fig. 1, the

V When the plug P is inserted into the dial opens the tip andring supervisory bridge, whereupon unanswered supervisionnis indicated in the operators cordcircuit.

Impulse relay 122 of the local-selector, Fig.

1, now energizes over conductors 31 1 and .315'

and through the contacts of relay 313. Upon operating, relay '122 of the local selector closes a circuit. for release relay 123, Whereupon relay 123 operates and prepares a circuit for the vertical magnet 131 at its inner lower armature, at the same time opening a point in the release-magnet circuit at its lower armature and closing a short circuit across the talking circuit at its upper armature so as to prevent the calling subscriber from hearing the clicks as the digits are dialled.

After. havinginserted the plug P, Fig. 3,

into'the dial ack DJ 2, the operator dials the first digit 2 in thedesired number by-means of the calling device CD. When the calling sition, the circuit is interrupted twiceat-the impulse springs.

When the calling device reaches its normal position, relay 313 falls back and replaces the shunt across the impulse leads. Due to 1 this arrangement whereby the impulse circult of the calling device is shunted except whenthe -calling device is oil-normal, preliminary impulses are prevented when the plug is inserted into the jack and a momentary opening of the impulsecircuit is prevented when the plug is withdrawn from the jack. 7

Following the dialling of the first digit 3, the operator dials the two digits necessary to bring the Wipersot the connector into engagement with the terminals of the line of substation B, followed by'the party selecting digit 6 necessary to operate party selector tosignal the substation B as will be hereinafter explained. V

Having dialled the complete number, the operator removes the plug from the jack J2,

as well as removing the plug P from the jack 0J2, whereupon the various relays ot a the trunk circuit TC1fall back and relay 122 of the local selector, Fig. 1, falls back.

- The call lamp associated with the trunk circuit TGlis notagain operated because the switch SS, Fig. 6*, immediately releases and trees the trunk line in a manner to be pointed out hereinafter.

The setting of the switches in responseto the-digits dialled by the operator will now be explained. VV-hen the first digit 2 is dialled, impulse relay 122 of the local selector,

Fig. 1, falls back twice momentarily, closing, each time it falls back, a circuit through the innerlower armature of release relay 123,

inner lower armature, normal, of switchingrelay 126, and series. relay 124 for vertical magnet 131. By the operatlon of the vertical magnet the wipers 127.13O are raised.

step by step until they come to rest opposite the second level of bank contacts. Relay operates upon the delivery of the first impulse, and, being. slow-acting, remains operated throughout the digit. Relay 124 pre-.

and closes a self-lockingcircuit at its upper contacts, through the middle lower contacts of the, switching relay 126, and at its lower contacts it prepares thecircuit of the rotary magnet.

At the end of the vertical movement, the

series relay 124 falls. back and opens the initialcircuit of the stepping relay, leaving the stepping relay energized over its locking circuit, at the same time completing a circuit from the grounded release trunk conductor 115 for the rotary magnet 132. When the rotary .magnet' operates it advances the wipers 127-130 one step in a horizontal direction, whereupon they encounter thefirst set of bank contacts in the second level. Near the end of its stroke, magnet 132 disconnects stepping relay 125, whereupon-relay 125 falls back and closes its interrupter contacts again. The further operation of the selector depends upon whether or not the first trunk line is idle. If this trunk line is idle, switching relay 126 now operates, seizing the trunk. Assuming that the trunk line is busy, a ground potential is encountered on the test contact thereof by test wiper 128, and relay 125 reoperates, shunting relay 1'26 and cansing the rotary magnet to reoperate and advance the wipers another step.

This alternate operation of the stepping relay and the rotary magnet continues until an idle trunk is reached, which'trunk it will be assumed is the one comprising conductors 14514c8. lVhen this trunk is reached, relay 125 does not operate again owing to the fact that no ground potential is encountered by wiper 128, and switching relay 126 operates from the grounded release trunk conductor 115 in series with relay 125, through the asso ciated off-normal and the interrupter contacts. Relay 125 does not operate in series with relay 126 owing to the relatively high resistance of the latter. Upon operating, relay 126 opens a further point in the circuit of release magnet 133'at its middle lower armature, disconnects impulse conductor 139 from the vertical magnet 131 and sends it to impulse wiper 129 at-its inner lower armatu-re; opens a point in the test circuit" and connectstest wiper 128.t the grounded release trunk concluctorlli at itsinner upper armature; and at its upper and lowers armatures it disconnects the incoming conductors- 1 1 4 and ill? from line relay 121 Aand'extends; them by u'ayoi wipersl27 and 1.30 to icon cluce tors, 1&5 and 14:8,oi the connector shown in Eig. 2. Line relay 1 21 of'the localselector, having been diseonn ected fron the talkingcoi'iduetors 11 iandll'iywould ordinarilyfall back and cause the connection tofbe; released ifitsvere not: for thei'act that. its circuitis held closed at the upper contacts of release relay 128.

y In the connector, 2, linerelay203 now energizes over the calling l ne and-oyerconr' ductors 145 and 148 and through contacts of relays 201 and202 and closes a circuit for re: lease. relay 2,04, V'Belay 204' operates and prepares the switch'ioroperation.

lWhenthe operator dials the seconddigit in the number, impulse relay-122 ofthe local selector again responds, butthe impulses are this tune transinltted over mpulse conductor,

139. and through impulse wiper 129 by'way of the inner lower armature of the operated switching relay. 126.v The inipulses'are transmitted further over impulseconductor 147 Q test winding of switchin relay 20,9 tot'he;

to the connector and then to vertical magnet 21"5. p'lhe circuit o'fthe vertical magnet ineludes, at the timejofits first closure, the lower armature,operated, of; release relay 2%, normally-closed olt-normal contacts, and serites relay 205, Y the operation of thew-ver tical magnet, the wipers 211-214 are raised opposite the desired leyelof bank contacts.

Slow-actingrelay 205 respondstojthe current fiowthrou hthe vertical ma net and re:

mains operated throughout the digit, 1 This relay maintains its own circuit and that or off-nor the i'ertical magnet intact after the mal contacts have shiftedr At'the end f the vertical movementyrelay 205 falls back and transfers the impulsing conductor from the vertical magnetite the rotary magnet 216.

When the next digit is dialled, the impulses; of current passthrough the restored arma 0 circuit at the time of its first closure 111ClL1Cl ture or". relay205 to the rotary: magnetythe ing contactsof busy relay. 207 and the inner? lower armature ofswitchingrelay 209. Re lay 208 operatesin multiple with the'ro'tary magnet andtransfers test wiper 2'12f-ron1 the winding of busy relay 207 at its upper arnia ture, and at itsinner lower armature it shunts the corresponding contacts ofbusyrelays20'? so as to maintain the operatingcircuit intact in case relay 207 operates during therotary movement of the switch.

The operation taking pends-upon Whethe the 1 12 01 i llb tetie 3- place at, the end of the rotary movement of the connector deis busy or idle. Assuming 'first that the line is busy, busy relay 20'] is operated through test wiper 212-whenthe wiperszcoine torest in. engagement with thebank contacts of the called line.

p .Then whenslow-acting relay 208'iallsbacl it completes a locking circuit 1 forthe busy re ay "froinlthe grounded release 1- trunk conductor' 1461 through the inner upper l armature of thebusy relayv and through con taste of relays 2Q' 8zand 20 9 In vthis' case, no

further impulses can be delivered over the iln pulse concluctor owing to the factthat this i conductoris open at the contacts of relays 207, and208. A busy toneis now placed onthe lower talking conductor and is transmitted to the calling subscriber as soon as the oper ator has finished dialingQr'The automatic switches are released as soon the calling;

subscriber replaces his receiver.

r A ssuming now that the lineis idle the busy;

relay 207 isflnotoplerated when the wipers land on the contacts of called line and switching relay 20.9 operates fromground on -releasegtrunk conductor 146 torbattery en-V countered on the private normal conductor by test wiper 212, its circuit including the s perarmature, normal, of relay 20,8, thelower winding" of relay 209, and the inner upper armatureynorinal, of busy relay 2 07.

e rs ofthe switch. a i

In the connector, relay upon operating,

places ground directly, at its upper armature,

upontest wiper 212 independent of its own lower windin opens a point in the circuit of busy relay 20( at its'middleupper armature so as to prevent the operation ofthe busy relay during the setting of the party selector; l

closes a locking circuit for its uppergwinding atlts nner upper armature opens a point 1n the busy-tone circuit and closes a point in the i ring-back-tone circuit at its lower armature; and at its inner lower armature it disconnects the impulsing conductor from rotary magn 1 n x nds t t he'ppe ti magnet of the party selector. a

' When the'party-selecting digitis dialled,

the digit6 in thiscase, the impulses of current are delivered to the operating magnet of the party s'elec'tonwith the result that the wipers 221 and'2 22 are advanced step by step until they come to rest on the sixth set of bank contacts, The oif norinal contacts of the party selector closea point in a new circuit for busy ,relay 207, but this circuit is main-.2 tained open at the contacts of relay 2 08 until this relay falls backat the end of the party'- a selecting" digit. When relayQOZ reoperatesit 7 planes ri g back ton 9! he lever. talk n conductor throughits own lower armature and through the lower ar1nature,-operated,of

switching relay 209. Relay 207 at its inner.

lower armature opens the impulse conductor so, as to prevent further operation of the operating magnet of the party selector in case theimpulse conductor is grounded again; it prepa'resa circuit for the release magnet of the party selector at its middle upper armature; and at its upper and lower armatures it disconnects the talking wipers 211 and 214 from the auxiliary backbridge'r'elay 202 and connects them instead to the wipers 221 and 222 of the party selector. At this time, wiper 221' is standing on its sixth associated bank contact which is connected through the equipment shown in Fig.5 to battery directly, or to battery through the 66-cycle generator, depending upon the positionof the relay controlled bythe interrupter 12. Accordingly,

ringing current from the 66-cycle generator is transmitted intermittently over wiper 222 of the party selector and through wiper 214 of the connector'to the lower conductor of 1' the called'line, operating the ringer at substation B.

;When the subscriber at substation B responds by removing his receiver, he opens his 7 ringer circuit and closes a direct-current br dge across the talking conductors, whereupon the'ring-cut-ofilrelay-206, which is connected between the grounded conductor 2'18 and the-bank contact on which wiper 221 of p the party selector is now standing, operates through wiper 211 of the connector and over the upper conductor of the called line. Upon operating, relay 206' closes a locking circuit for its upper winding at itsinner upper armature; and at its upper and lower armatures'it disconnects the wipers 211 and214 from the wipers" of the Z-party selector and connects them instead to the windings of back-bridge relay 201, thereby completing the talking circuit. The ring-back-tone circuit is opened at the normally-closed contacts controlled by the lower armature of relay 206.

Back-bridge relay 201 now operates and reverses the connection between the incoming conductors 145 and 148 and the windings of line relay 203, but this reversal is of no par ticular utility in this connection.

Considering now the effect produced in the semi-automatic exchange when the operator removes the plugs from the jacks DJ 2 and J 2,

Fig. 3,;when this occurs, impulse relay 122,

Fig.1, falls back and delivers another i1n pulsethrough wiper 129 and over conductor 147 to the connector, but no harm results. because the impulse circuit is open at the inner 1 lower contacts of relay207 and 208.

:- ciiit "of line" relay 121, whereupon line relay 121 falls back and removes ground at its inner upperuarmature from the trunk conductor 115, leaving conductor 115 grounded from the grounded release trunk conductor 146 of the'connector, Fig; 2, through wiper 128and the bank contact on which it is standing. At its middle lower armature, line relay 121 opens a point in the test circuitof the secondary switch SS, and at its inner lower armature it opens the circuit ofswitching relay 401, whereupon relay 401 falls back, freeing thetrunk line comprising conductor 314 and 315.- When the trunk line is freed and the local release trunk conductor 450 thereof is ungrounded at the contacts ofrelay 401, slow-acting relay 406 of the incoming selector falls back and reconnects the conductors 314 and 315 to the wind-' ings of line relay 407. Since the polarity of the connection made through impulse relay 122 to the conductors'314 and 315 is opposite to'the polarity of the connection made,

exchange'that prevents a reoperation of the call lamp, Fig. 3, w hen the operator pulls down her plug after having dialled up the number desired in the semi-automatic ex- 7 change.

Regarding the established connection, the two subscrlbers are able to converse with each otheras soon as the ring cut-ofi' relay 206 of the connector-operates as abovedescribed. When theconversation is over, the two subscribers replace their receivers, and the back-bridge relay 201, Fig. 2, falls back and reverses the current flow in the incoming conductors to normal, when the receiver Z is replaced at substation B.

When the receiver is replaced at substation A, line relay 203 of the connector falls back and opens the circuit of the associated release relay 204. Belay 204 falls back afters a slight lnterval and removes ground from release trunk conductor 146 at its upper armature, whereupon switching relay 126 of the local selector and switching relay 107 of the line switch LS both fall back. 126 of the local selector falls back, it completes at its middle-lower armature a circuit through contacts of relays 121 and 123 for release magnet 133 through the associated off-normal contacts. tor releases in the usual manner, the release magnet circuit being opened again when the normal position is attained.

' As a further result of the deenergization of release relay 204 of the connector, ground hen rel As a result, the selec:

1 moves his receiver, the lineswitchpperaates.

[its middle upper armature. The release magnet 217 of the connectoroperates through the associated off-normal contacts and through the lower. a rrnatures oiirelays 203 and-204i, restoring the connectorato nor mal in the usual manner. 1 I

'ThGJGHtlIG connection isnowreleased and the apparatus involved therein may be used in setting up a subsequent connection. 7

It Will now be assumed that the subscriber at substation A desires to converse with an- \othersnbscriber on the same line, for example the subscriber who "has. the 50 cycle ringer connectedbetween the npper line con duct-or and ground. I I

p p Rewriting call When the subscriber atsubstation A rein the hereinbefore described lnannerpand seizes a loeal selector, the one-shown. in Fig. 1, ton-example. VVhen the localselectoris seized line relay 121 operates-over theca-lh line in r the 'hereinbefore described man ner and causes the secondary switch SS to select an idle trunk, for example the trunk comprising conductors 314iand 7 When this trunk is seized, the operator is signalled as before described and she respondsan'd converses with the calling subscriber. Upon learning that the call is for another station on the same lineas the calling-linathe operator associates her alling device with the trunk line over which the call was received. after whiehshe dials the ring-back digit followed by the two digits necessary toset the ring-back switch such as the one shown in 5, into .the correct position ta signal the. and called stations alternately: The subscribers areinstructed'to leave their receivers oitthehoolr until they hear a hang uptone, which is placed on -the calling line at the propertiine as will be hereinafter explained. Then, afterthe calling subscriber hangs up his receiver,ina'esponse to this hang-up tone the ringersof the two substations operate alternately until the called subscriberresponds. j v When the operator has inserted the plug Pinto the dial jack DJ2 3, and has dialled the digit 1, the local selector, 1 raises its wipers 1 27 130,o pposite the first level of bank contacts in the usual manner and selects an idle trunk, for example the one comprising conductors 141'144- and extendingto the ring-back switch shown in Fig. 5. When thistrunk llne 1s reached, switchlng relay 126 operates and extends the-nicomlng conductors 114 and 117 to wipers 127 and 180 to the conductors 14:1 and 1 14. The line relay 121 of the local selector is maintained energized through the upper contacts of release relay 123 after switch relay 126 operates; Itwill be noted that there is a local bridge across conductors llt and117' in this case through the upper contacts o'f line relay 121'and through the first-level shaft springs. This local circuit 'is established inorder that the z lijne relay 503, Fig. 5, ctth ring-back switch will remain "operated until the connections to the operating center has been released upon the disconnectoperation of the operator in case the calling subscriber replaces "his receiver prematurely.

lWhn the ring-back switchis seized, its liner'elay 503 energizes overfconductors 1'41 and lift and through *the bridgeacross the conductors 114jand 117.5ofthe -local selector, Fig. 1, andclos'es atits inner lower armature a circuit for release relay 504. Relay 504,

operates and prepares the impulse circuit at amowe armature; prepares a locking circuitfor relays 505 and 507 at its inner upper.

armature and at itsupper armature it places ground on therelease trunk conductorl l2 so asto maintain the local selector and the callingjlineswitch operated. When releasetrnnk conductor 142 is first groiinded, which. occurs when the ring-back switch is seizedg'a circuit is "closed througlrthe associated off-normal contactsfor the "combination change-over and reversing relay502. Relay 502 operatesand V preparesat its inner upper armature a locklng circuit for tself, and at lts lnner lower armature it disconnects the rotaryanagnet and connects up the vertical magnet.

When the operator dials the next cligihthe f impulses of current-are delivered through the impulse wiper 129 ofthe local selectorand oiier'j conductorf to the vertical magnet 516,"through the lower armature, operated, of relay 504 middle lower .armaturanornial, of .relayf505gand the inner lower armature, operated, oi. relay 5021 vBythe operation of the vertical magnet, thewipers 510 513 are raised step by step opposite the desired level of contacts; which level it will be assumed is the one shown in the drawings... Belay 506 is operated in multiple withthe vertical inagnetancl it remains eperated throughout the dig-it. .U pon ope-rating, relay 506 completes at its upper armature the locking circuit for relay 502 through the inner, upper contacts the said relay. This locking circuit maintains relay 502 operated after: its inititalcircuit is opened at the associated .ofllnormal contacts upon the initial upward movement of the switch.

hen the impulses have ceased, relay 500 falls back and opens the locking circuit of 5 relay 502, and relay502 falls back and disit mainrelay 509 is placed under thecontr'ol of the interrupter I1 through bank contact 515 and wiper 511, and a. circuit is closed from battery over oneof-the ringing leads andthrough bank contact 516 or 517 and wiper 512 or 513 for the lower winding of relay 505. The path over which this circuit becomes eiiective de pends upon whether or not the relay 509 is operated immediately by the interrupter I1. When relay 505 operates,.-it closes a locking circuit for itself at its, upper armature through 1 contacts of relay 504; opens its initial circuit at its inner lower armature; and at its lower armature disconnects the impulse conductor from the magnet circuit and prepares a circuit for operating the hang-up relay 501 as will be described subsequently. The circuit of relay 501, when completed,.includes thelower contacts. of line relay 503. Therefore, this .circuiticannot be completed until line relay 503 is permitted tofall back.

When the operator initiates the operatordisconnect operationby removing the plugs from the jacks J2 and DJ 2,Fig. 3, impulse relay 122, Fig. 1, falls back and opens the circuit of release relay 123, whereupon relay 123 falls back and-opens the circuit of line relay 121. Line relay 121 falls back and causes the secondary switch SS, Fig. 4, to freethe trunk line extending to the manual office. Line relay 121 opens at its upper armaturethe holding circuit across conductors 114 and 117 thereby placingthe line relay 503 ofthe ring-back switch, Fig. 5, under the direct control'of the calling substation. During the interval requiredfor release relay 123 to fall back after line relay 1 22 has fallen back, a ground potential is placed on impulse conductor 143 through impulse wiper 149, but this impulse of current does not operate the hang-up. relay 501, due to the fact that line relay 502 of the ring-back switch is still operated due to the bridge across conductors 114 and 117 at the local selector, which bridge holds the line relay of the ring-back switch operated regardless of whether the'calling subscriberhas hung up or not.

Referring now to the ring back switch, it

Relay 506 is operated .falls back and at its inner lower armature closes 'a circuit through the lower armature, operated, of release relay 504, middle-lower armature, operated, of relay 505, lower con-- tacts of line relay 503, and the lower armature, normal, of ring-cut-ofl' relay 507 for hang-up relay 501. Relay501 operates and closes'at its inn er lower armature a circuit for relay 504 so as to maintain the release relay operated for the time being. At its upper and lower armatures, relay 501 disconnects the incoming conductors 141 and 144 from the windings of the line relay and connects them instead to the ringing circuit and to ground through the contacts of the reversing relay 502. The reversing relay 502 and the generator-switching relay 509 are controlled by the interrupter I1, through wipers 510and 511. When the ringing current is placed on the ringing conductors with relays 509 and 502 restored, current from the -cycle source passes out to the ringing circuit through bank contact 517, wiper 513, armature of relay 509, contacts of relay 507, winding of relay 508, and the upper contacts of relays 502 and 501 to the upper conductor 141. This ringing current passes back over the connection to theupper conductor of the calling line and operates the 50-cyc1e ringer connected between the upper line conductor and ground. Now, when the interrupter I1 moves into its alternate position and operates relay 502 through bank contact 514 and wiper 510 and operates relay 509 through bank contact 515 and wiper 511, the ringing circuit is switched from wiper 513 to wiper 512 at one end and is switched at the other end from conductor 141 to conductor 144. The result is that the next application of ringing current is made from the 66-cycle generator through bank contact 516 and wiper 512 to conductor 144. This ringing current passes back over the established connection to the lower talking conductor 102 of the calling'line, operating the 66-cycle ringer at the calling substation A.

This operation continues, the calling and called ringers being operated alternately, until the calling subscriber removes his receiver again or until the called subscriber responds. Assuming now thatthe calling subscriber re.- spondsto the ringing of his hell by removing his receiver, a direct-current bridge is placed across the conductors of the line, whereupon the ring-cut-ofi-control relay 508 in the ringback switch operates from battery through either wiper 512' or wiper 513, depending upon the position of relay 509, to ground over conductors 141 and 144 in series to either the lower resting contact or the upper working contact of relay 502, depending upon the position of this relay at this time. Upon operating, relay 508 closes a circuit for relay 507 through the associated contacts, whereupon relay 507 operates and locks itself; opens the ringing circuit at its lower armature; and at its middle armature it opens the circuit of the hang-up relay 501 and closes a circuit through the associated off-normal contacts for the release magnet 520. Release magnet 520, operates and restores the switch to its normal position in theusual manner. The circuit of the release magnet is opened when the normal position is reached.

After a slight interval, the slow-relay 501 falls back and shifts the conductors 141 and 144 back to line relay 503 again, whereupon line relay 503 reoperatesand closes a circuit for the release'relay 504 so as to maintain the release relay operated.

Asa result of the restoration to normal of the ring-back switch, relay 502 operates again through the associated oft-normal contacts from conductor 142, and the hang-up tone is disconnected from the line at o it-normal contacts 521.

The two subscribers on the same line may now converse with each other in the usual manner. 7

When both subscribers replace their receivers at the end of the conversation, line relay 503 falls back and opens the circuit of the release relay. A moment later the release relay falls back and unlocks relays 505 and 507 at its upper armature,atthe same time removing ground from release-trunk conductor 142 at its inner upper armature, whereupon relay 502 falls back. At the same time, the local selector and the lineswitch shown in Fig. 1 both are released responsive to the removal of the ground potential from conductor 142.

Semi-automatic to manual call It will now be assumed that the subscriber at substation A desires toconverse with a subscriber whose line terminates in the manual office shown in Fig. 3, or in some nearby ofiice. It will be assumed, as before, that the local selector shown in Fig. 1 is seized when the lineswitch LS operates in response to the removal of the receiver at substation A and that the trunk line incoming to the trunk circuit T61, Fig. 3, is seized by the secondary switch SS, Fig. 4. The operator is signalled in the hereinbefore described manner by the operation of line relay 301, Fig. 3, over conductor 315. When the operator responds, the hereinbefore described bridge is placed across the tip and ring conductors of the jack J2 through the lower winding of relay 308 to extinguish the supervisory lamp in the cord circuit,

After inquiring as to the destination of the call, the operator completes the connection through the other end of thecord circuit used.

After the conversation has terminated, the.

in the current flow through the polarized relay 306, Fig. 3, whereupon the polarized relay operates and at its upper armature opens the bridge across the tip and ring conductors of the ack J2, thereby giving the operator a disconnect signal. Upon perceiving this disconnect signal, the operator pulls down the connection, restoring conditions in the trunk circuit TCl to normal.

V H cradling toll connections Regarding the handling of toll connections that are completed to distant points, it may be pointed out that the toll connections in the semi-automatic exchange are handled through the toll board shown in Fig.3. jA toll connection originated by a subscriber in the semi-automatic exchange, for example, the subscriber at substation A,'Fig. 1, is recorded by the operator at the local board, Fig. 3, which operator passes a ticket describing the desired connection to the operator at the toll board. After making the necessary ticket regarding the connection, the local operator requests the calling sub-- scriber in the semi-automatic exchange to replace his receiver, and the connection to the operating center is released as soon as he does so. The operator pulls down the connection when she gets the disconnect signal.

\Vhen the operator at the toll board is ready to complete the connection, she inserts the plug of a cord circuit into the jack J1, whereupon sleeve relay 302 operates through the sleeve of the jack and the sleeve of the plug in series and disconnects line relay 301, at the same time bridging the polarized relay 306 across the trunk conductors. Relay 302 also grounds conductor 321 so as to light the busy lamp. Since the line relay 407 of the incoming selector, Fig. 4, is connected to the conductors 314 and-315 in the normal direction, as contrasted with the reversed connections between these conductors and an impulse relay such as relay 122, Fig. 1, the

polarized relay 306, operates when it is bridged, across the conductors 314 and 315 by relay 302, and it opens the bridge across the tip and ring conductors of the jack J2, thereby giving the operator unanswered supervision. The discriminating relay 303 is not operated in this case.

lVhen the toll operator inserts the plug of her dial cord (corresponding to the plug P ofthe dial cord DC) into the dial jack DJ 1,

the upper spring contacts of the dial jack close a circuit for relays 305, 309, and 310, whereupon these relays operate. A locking circuit for the upper winding of relay 305 is closed from conductor 321. When relay 310 operates, it places a bridge across conductors 314 and 315 including contacts of relay 313, whereupon line relay 407 of the incoming selector, Fig. 4, operates over conductors 314 and 315 and prepares the selector for operation by operating release relay 408.

Now, when the toll operator dials the first digit in the number of the subscriber at substation A, the digit 2, for example, line relay 407 .iialls baclr twice momentarily, each time closing a circuit through emitscts of release relay 408 and series relay 409 for .the vertical magnet 412. By the operation of the vertical magnet the wipers 415 and'417 of the selectors are raised. opposite the second level of bani-I contacts. The series relay 409 operates in the manner described in connection with the series relay 124 of the local selector and initiates the trunk-hunting operation of the selector at the end of the vertical movement, this trunk hunting operation being effected by the action of rotary magnet 413 in connection with stepping relay 410.

When an idle trunk line is reached, switching relay 411 energizes in series with stepping relay 410 and disconnects 'round from the operating and release circuit at its inner lower armature; shifts wiper 416 from the test circuit to the holding circuit at its inner upper armature; and at its upper and lower armatures it disconnects conductors 314 and 315 from the line relay 407 and extends them by way or wipers 415 and 417 to the talking conductors of the seized trunk line, for example, conductors 145 and 148 of thetrunk line extending to the connector shown in Fig. 2. The line relay 203 and the release relay 204 of the connector, Fig. 2, now operate and the latter places ground on conductor 146 so as to furnish a holding circuit for relay 411 of the incoming selector before re lease relay 403 of such selector has had time to fall back.

W hen the operator dials the next digit in the number, the line relay 203 of the connector, Fig. 2, responds and brings about the operation of vertical magnet 215 in the hereinbetore described manner.

' When the next digit is dialled, rotary ma net 216 responds as described hereinbefore and brin the wipers 211214 into engage ment with the terminals of the line of substation A, Fig. 1. Assuming that the line is idle, switching relay 209 operates through the cut-olt'relay 107 of the lineswitch LS and transfers the impulse circuit from the rotary magnet 216 to the operating magnet of the party selector.

Having established the connection to the line, the toll operator now removes the plug of the dial cord from the jack DJ 1, leaving the connection in this condition until she has completed the connection to the desired distant line.

When the plug is removed from the dial acl; D31, relays 305, 309. and 310 fall back, whereupon the connection is transferred from the tip and ring conductors of the dial jack through he normally closed contacts controlled by the upper and lower armatures of relay 310 to the temporary bridge including resistance 312 and the contacts of the slot acting relay 309. A moment later relay 309 falls back and leaves the connection held up through the bridge including the upper armature, operated, of relay 302, polarized relay 306, and the lower contacts of relays 305. Relay 306 operates in this bridge and opens the bridge across the tip and ring conductors of the jack J1, discriminating relay 303 being non-operated in this case, whereupon the calling supervisory lamp in the operators cord becomes lighted.

It will now be assumed that a subscribe on the line of substation A removes his receiver, possibly to make a call, while the connection is in this condition. lVhen this occurs, the auxiliary back-bridge relay 302 operates through wipers 211 and 214, upper and lower armatures. normal, of ring-cut-otl relay 206, and the upper and lower arma tures, normal, of relay 207. Relay 202 closes local. holding circuit for line relay 203 and disconnects the said line relay 203 from conductors 145 and 148. *When this is done, relay 203 remains operated in the local circuit, but the polarized relay 306, Fig. 3, Falls back and recloses the bridge across the tip and ring conductors of the. cord circuit, giving the operator answered supervision. The operator responds by throwing her listening lrey and conversing with the subscriber on the line, telling him to withdraw temporarily until the toll connection has been completed. lVhen the subscriber on the line of substation A replaces his receiver, the auxiliary backbridge relay 202 falls back and reestablishes the circuit of line relay 203 over conductors 145 and 14-8 in series with the polarized relay 306, Fig. 3. Relay 203, which relay may fall back momentarily if it is placed in series with the polaried relay 306, Fig. 3, when it has previously been energized through a resistance such as the resistance of the trunk line from the manual office to the semi-auto- 'matic exchange, does not fall back momentarily at this time because it has been energized in a local circuit of practically no'eX- ternal resistance. It may be pointed out that this is the reason why the contacts of the auxiliary back-bridge relay 202 are arranged to discontinue the flow of current over the conductors 145 and 148 in order to give supervision rather than reversing the current flow through the conductors to give supervision, asthe line relay would momentarily fall bag; and advance the party selector if the connection to the conductors were merely reversed.

Assuming now that the operator has completed the connection to the distant called subscriber and is ready to call the subscriber at substation A, the operator re-inserts the plug of her dialcord into the dial jack DJ 1,

whereupon relays 309 and 310 again operate,

preparing e circuit for dialing.

When the operator dials the stations digit 6, six impulses of current are transmitted over the circuit previously traced to the operating magnet of the party selector, Fig.

'whereupon the wipers 221 and 222 are brought into engagement with the sixth set of associated bank contacts. is operated in the hereinbefore described manner at the end of the operation of the party selector, and it completes the ringing circuit, whereupon the current from the 66 cycle source is sent out through wipers 222 and 214 to the lower conductor 102 of the line of substation A so as to signal the subscriber thereat. It will be remembered that relay 207 opens .the impulse circuit at its inner lower armature so that no further op-.

eration of the operating magnet of the party selector will take place until'the connection has been released.

When the subscriber at substationA removes hisreceiver, ring-cut-ofi relay 206 of the connector, Fig. 2, operates and completes the talking circuit, whereupon back-bridge relay 201 operates and reverses the connection between line relay 203 and conductors 145 and 148. Line relay 203 momentarily falls back when this reversal takes place, but no particular ettect is produced owing to the fact that the impulse circuit is open.

In the trunk circuit TCl, polarized relay 306 restores when the current flow through its winding is reversed, again completing the bridge through the lower winding of relay 308 across the tip and ring conductors of the jack J 1. This gives the operator answered supervision. l

The conversation'now takes place in the usual manner. 3 V

When the conversation is over, the subscribers replace their receivers. l/Vhen the receiver is replaced at substation A, backbridge relay 201 of the connector falls back and reverses the current flow in the conductors 145 and 148 to normal, whereupon the The relay 207] polarized relay 307, Fig. 3, reoperates and and 315 through relay 306 and reconnects relay301 to conductor 315.

Line relay 203 of the connector, Fig. 2, now falls back and brings about the release of the connector and the incoming selector in the usual manner.

Incoming non-toll connection Assuming now that the operator at the local board receives a call from a subscriber local to the manual exchange in which her switchboard is located, which call is intended a for 'a subscriber of the semiautomatic exchange, the subscriber at substation A,- for example, the operator at the local board completes this connection through a trunk line such as. the one comprising conductors 314 and 315. r

Assuming that this trunk line is idle, as evidenced by the unlighted condition of the busy lamp associated with the jack J2, the operator inserts the calling plug ofthe cord circuit in use into the jack J2, whereupon sleeve relay 302 and discriminating relay 303 both operate and relay 306 operates to give unanswered supervision. I

The operator now inserts the plug P of the dial cord DC into the jack DJ 2 andproceeds to dial thedigits in the-number of the called station. WVhen this plug is inserted, relays 305, 309, and 310 operate as before, and relay 394 operates through contacts of discriminating relay 303 and unlocks relay 308.

The operator now dials the digits in the number of the subscriber at substation A, whereupon the incoming selector, Fig. 4, a connector, and a party selector, the connector and party selector shown in Fig. 2, for example, are operated to complete the connection. When the operator withdraws the plug P from the dial jack DJ2, relays310, 309, and 304 fall back. Relay 310 reconnects conductors 314 and 315, whereupon the temporary holding bridge through resistance312 becomes effective and a parallel bridge through relay 306 becomes effective. Before relays 309 and 304 fall back, relay 306 receives suflicient current in multiple with the resistance 312 to operate and transfer the tip conductor from the lower winding of relay 308 to a new bridge including impedance 307. This new bridge is completed when relay 304 falls back and it includes the upper'contacts of relay 304, armature of relay 306, operated, upper contacts of relays 305 and 303, impedance 307, lower contacts of relay 308, and the inner-lower contacts of relay310. When this bridge is closed, the

calling supervisory lamp in the local operators cord circuit is extinguished, giving her dark-shelf supervision without the necessity of the pressing on the ringing key by the operator.

When the called subscriber responds, the current flow is reversed in the conductors 314 and 315 whereupon relay 306 restores, shifting the bridge across the tip and ring conductors from impedance 307 to the lower winding of relay 308. Relay 308 operates in this bridge and locks itself at its upper armature to conductor 321 through contacts of relays 303 and 304. At its lower armature, relay 308 opens a further point in the bridge including the impedance 307. The answered state of the supervision in the calling end of the cord is maintained now through the bridge including the lower winding of relay 308. y I

When the called subscriber at substation A replaces his receiver at the end of the conversation, the current flow in conductors. 314 and 315 is reversed to normal, whereupon polarized relay 306 again opera-tesand opens the bridge across the tip and ring conductors of the jack through the lower winding of relay 308, at the same time closing a point in the bridge including impedance 307. This bridge is not efiective at this time due to the fact that relay 308 is operated andremains locked up. The operator, therefore, is given disconnect supervision and she pulls down the connection with the here1nbefore'described results.

Out-of-orcier equipment nalled in the hereinbeiore described manner.

When the operator responds to the call and attempts to converse, she, of course, gets no answer and she knows that the line is still in a calling condition from the state of supervision in her cord circuit as controlled by the reversed current flow from the impulse relay 122 of the local selector.

In order to dispose of the connection and free the interoiiice trunk line, the operator connects her calling device with the trunk line and dials the digit 3, the third level of the local selector beingset aside for maintaining out-of-order connections.

hen the digit 3 is dialled, the local selector in use raises its wipers opposite its third level of bank contacts and rotates them in search of an idle out-or-order trunk circuit. Upon finding such circuit, for example, the trunk circuit T02, shown in the drawing, the trunk line comprising conductors 149152 leading to such trunk circuit is seized and the line relay thereof operates to place ground on the release trunk conductor 150 so as to maintain the local selector and lineswitch LS in an operated position. The line relay of the trunk circuit also places ground on the outof-order conductor 151, extending a ground potential back through wiper 129, conductor 116, wiper 112 of the lineswitch LS, and contacts of the switching relay 107 to the outof-order normal conductor 105.

Having dialled the out-ofiorder digit 3, the operator withdraws from the connection, whereupon the interoifice trunk line is released in the usual manner.

Assuming now that a calling subscriber uses theconnector shown in Fig. 2 to extend a connection to the line of substation A, the line tests busy because of the ground potential on private normal conductor 104, and the busy relay 207 is accordingly operated when connection is made to the line. However, the busy tone is not transmitted back to the calling line owing to the fact that the out-otorder relay 210 is energized over the correspoi'iding wiper 213 and the out-of-order normal conductor to shift the tone circuit from the busy tone lead release to the out-oforder-tone lead.

Upon hearing this distinctive tone indicative of an out-of-order condition, the calling subscriber replaces his receiver, whereupon the attempted connection is released in the usual manner.

When the out-of-order condition of the line of substation A is remedied, the line relay of the trunk circuit TC2 falls back, permitting the lineswitch LS and the local selector to release.

What is claimed is:

1. In a telephone system, a semi-automatic exchange, a manual exchange, two-way trunk lines connecting said exchanges, equipment at said manual exchange for sending digits over said trunk lines to control the setting up of connections by the switching mechanism in said semi-automatic exchange, a group of local selectors responsive to the first digit of numbers in calls between two lines in the semi-automatic exchange, and a separate group of incoming selectors responsive to the first digit in calls incoming from the manual exchange to the semi-automatic exchange.

2. In a telephone system, a semi-automatic exchange, a manual exchange, a two-way trunk line connecting said exchanges and terminating at the semi-automatic exchange in an incoming selector, a local selector in said semi-automatic exchange, means responsive to a call on a semi-automatic line for extending a connection to said local selector and for connecting said local selector to said trunk line instead of said incoming selector, and means controlled by the operator over said trunk line from the manual'exchange for 0p- Hui lHi

' said trunk line.

crating either selector which is connected to 3. In a telephone system containing a semi automatic exchange and a manual exchange from which the automatic switches in the semi-automatic exchange are controlled,'local selectors in said semi-automatic exchange, each selector having an impulse relay, means responsive to a call on a semi automatic'line for seizing one of. said local selectors and for automatically extending a connection from said local selector to said manual exchange,

said means including a line relay in said local selector controlled over the calling semi-auto: matic line, operator-controlled means including said impulse relay for controlling said local selector and other switching mechanism .to complete the connectio'n to a semiautomatic line, and means controlled by the impulse relay for-maintaining the line relay operatedin a local circuit after the selector has been set. i

4. In a telephone system, an operators switchboard, a trunk line comprising two inductively coupled sections, automatic switch-' ing mechanism controlled from said switchboard to set up a connection over both sections of said trunk line to'a party line, party-selecting means subsequently operated from said switchboard to select and bring about the signalling of the desired station on the party line, a supervisory relay operated over the second section of'said trunk line to give supervision to the operator over the second sections in case a subscriber on the called line responds before said party-selecting means is operated, and a second supervisory-relay operated instead of the first to give supervision when a subscriber on the called line responds after said-party selecting mechanismhas been operated;

5. In a party-line telephone system, an

operators I switchboard, a trunk line, automatic switching mechanism controlled over said trunk line to set up a connection to a called party line, party-selecting means operated subsequently over said trunk line to select and bring about the signalling of the 'de-' sired station on the party line, and means controllable fromthe calledline before said party selecting means has been operated to place a given distinctive supervisory condi tion on the first section of saidtrunk line and controllable from the called lineaiter said party selecting means hasbeen operated to place a difl erent distinctive supervisory con- :dition on the said first section.

6. In a telephone system including a manual oflice and a semi-automaticofice, trunk lines connecting said ofiices','means -1"ior set ting up a connection from a calling se1ni autoinatic line to said manualoifice over one of said trunk lines, meansfor thereupon closing a a direct current-signalling circuit over said trunk line to signal the operator in said manual exchange, automatic switches in said semi-automatic oltice, operator controlled means for opening the signal circuit and for closing a loop supervisory circuitincluding the two conductors of said trunk line in series, an impulserelay included in said supervisory circuit at the semiautomatic exchange nonresponsive to the flow of current over said circuit, and operator-controlled means for Closing a setting circuit over the two conductors of said trunk line in series, said impulse relay being responsive to the closure of the. latter circuit. r V

, 7. In a telephone system, a manual office and a semi-automatic oflice, trunk lines interconnecting said oflices, means for setting up a connection from a semi-automatic line to said manual oflice over one of said trunk lines and said connection exclusive of said high resist ance supervisory device to operate said impulse relay, and automatic switching mechanism in the semi-automatic ot'fice, operative undercoiitrol of said impulse relay to extend a connection from the calling line to a called line.

8. In a telephone system including a semiautomatic ollice and a manual oflice, trunk lines connecting sa d offices, means'for set-' ting up a talking connection from a calling line in said semi-automatic oilice to said manual'oilice including one of said trunk lines, a supervisory circuit including "said trunk line, a high resistance supervisory device in said circuit in the manual oflice, an impulse relay in said circuit in the semiautomatic oflice, means wherebythe operator in the manual office can set up a dialling circuit over said connection by by-passing said high resistance supervisory device whereby said impulse relay is operated, and

means responsive to the said operation of said impulse relay for nullifying said talking circuit;v

9. In atelep hone system, a semi-automatic exchange, a manual exchange, [automatic switches in said semi-automatic exchange operable from said manual exchange to complete local connections and to complete conexchange from said manual exchange, each *of said automatic switches havingtwo talkcourse of setting up anincoming connection,

'nections incoming to said semi-automatic conductor, means for seizing said switch and for closing a switch control circuit over said talking conductors, and means tor operating saidv switch to extend the connectionresponsive either to interruptions in said control circuit or to the transmission of impulses over said impulse conductor while said control circuit remains closed.

11. In-a semi-automatic telephone system, a party line, a ring back circuit for signalling two sub-stations on said party line alternately, switching mechanism controlled over a connection from an operators switchboard for extending a connection from a calling line to said ring-back apparatus, and means for delaying the ring back operation until the calling party has replaced his receiver and until the connection to the operators switchboard has been broken.

12. In a telephone system, subscribers lines, talking conductors,a busy-test conductor, and an out-of-order conductor associated with each line, means for extending a connection to a line, means controlled over the busy-test conductor to inform the call ing subscriber of the busy condition in case the line is busy, and means controlled over the out-of-or der conductor for informing the calling subscriber of the condition of the line in case lt'is out of order.

18. In a telephone system, subscribers lines, automatic switches, for extending c011- nections trom said lines, a group of out-otorder circuits, and means inoperative in case one of said switches is seized responsive to an out-of-order' condition on a subscribers line for operatingsa-id switch to extend the connection to one of said out-of-order circuits, and means responsive to such extension for placing an out-of-order test con dition on the line. 7

14;. In a telephone system, an inter-exchange trunlr line, means'for completing a connection to said trunk line in either exchange,means in the first exchange for sending impulses over said trunk line to the second exchange, two impulse receiving. de vices in-the second exchange, means roicausing one of said receiving devices to receive said impulses in case the trunk line was initially connected within the second exchange and for causing the other receivingdevice to receive said impulses in case the trunk line was initially connected with in the first exchange. I

15. In a telephone system, subscribers lines, automatic switching mechanism for extending connections to said lines, means for signalling the calling subscriber and for denying the connection in case a called line is busy, and means for denying the connection and for-signalling the calling subscriber in a distinctly different manner in case the calledline is out of order.

16. In a telephone system, an automatic switching device having access to subscribers lines to complete connections thereto from calling lines, said switching device including abusy relay arranged to prevent connection to a busy line'and to bring about the application of a busy tone to the calling line when the called line is busy, said device containing also an out-of-order relay arranged to operate when the line is out of order to substitute an out-of-order tone for the busy tone, while the busy relay operates as before to deny the connection and prepare the tone circuit. 17. In a telephone system, a connector switch having access to called lines, said connector having a pair of talking wipers, a busy test wiper, and an out-of-order test wiper, means controlled over said busy test wiper for placing a busy tone on one of the incomingtalking conductors of the connector when the called line is busy, and means controlled over the out-of-order test wiper for placing an out-of-order tone on one of the incoming talking conductors when the called line is out of order.

18. In a telephone system, a plurality of lines, a plurality of selectors, regular trunks accessible to the said selectors, special trunks accessible to the said selectors, means responsive to a call on one of said lines for effecting a connection between the calling line and an idle selector, whereby the selector may be operated to set up a connection to one of the regular trunks, said call-responsive means being also responsive to an out-of-order condition on a calling line for effecting a connection between the ont-of-order line and the selector, means effective in the latter case for operating said selector to extend a connection to one of said special trunks, the connection between the line and the special trunk comprising a plurality of conductors, and means in the special trunk for placing a special out-of-order condition on the out-oforder line by placing-a distinctive potential .on one of said conductors.

19. In a telephone system, a line having two test conductors, switching apparatus for extending two classes of connections from said line,- means effective in case the connection extended is of one classfor placing a dlstmctlve potential on only one of said two ,test conductors, and means effective in case 21. In a telephone system wherein connec-e tions are extended through an automatic switching device from a calling line to a called line, a relay associated with the automatic switching device and operable responsive to an out-of-order condition on the called line, and means including said relay for placing an indicative out-of-order tone on the calling line.

In witness whereof, I hereunto subscribe my name this 19th day of October, A. D. 1927.

LEONARD L. RUGGLES.

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