US1777049A

US1777049A - Telephone system

Info

Publication number: US1777049A
Application number: US171113A
Authority: US
Inventors: Ostline John Ellis
Original assignee: Associated Telephone and Telegraph Co
Current assignee: Associated Telephone and Telegraph Co
Priority date: 1926-03-22
Filing date: 1927-02-26
Publication date: 1930-09-30
Anticipated expiration: 1947-09-30
Also published as: GB272628A; DE534092C; FR629974A

Description

P 1930- J.E. OSTLINE TELEPHONE SYSTEM Original Filed Feb. 26, 1927 2 Sheets-Sheet. 1

Adm

Inuen U1" John Ellis [35111115 Sept. 30, 1930. J. E. OSTLINE 1,777,049

TELEPHONE sirs'rzm Original Filed Feb: 26, 1927 V 2 sheets-Sheet 2 Imfim John El is UETZin:

Patented Sept. 30, 1930 Y UN ED STATES BATENT} oF FlcE[ j JOHN ELLIS QSTL NEiOF ILLlN A I NQRTO ;A, SQCIA, ED;

[6t TELEGRAPH COMBANY, OF KANSAS CI'IFY, 51311530111311, .AJQOBBOBAEIQH ,QF DEI AF I TELEPHONE-SYSTEM Application fi1edFebruarj2 6; 1927, ,Serial no. 171, 1iae a' nre at t in natal 32,1925. {aen'w 'd i f January 31,4939.

The present invention relates to telephone systems, and though some of its tea tures are capable of wider application, it is more particularlyconcerned with systems 1neluding both automatic and manual exchanges, so that someprovision has to be made for completing calls; originated by an automatic subscriber and intended fora man'-v ual subscriber, It is usualin thesecircum-i stances to provide [for so-called call indicator working, that is tosay,thejimpulses di- V alled by the calling 'party operate registering apparatus by means of which thewanted umb s d splaye o: an op ato o n stance on a lamp panel,andfthefoperator then completes the call bylinserting a plug in the multiple jack associated with the Wanted Pa tyi lin It ha h- 1 usu fo the junctions incoming to the manual exang o in e in Pl g and s n equ ntlywhen a call received over a certain Junci i f a tha th op rat r mus 1 ploy the plug associated with that junction. In the case ,ofheavy trafficahowever, a 'difliculty tends to arise in that, the cords become interlacedand this involves additional wear on the cords and slowing down of the. oper-j ation generally. It is oneobjectofthe presto speed up the operation, while at the same time permitting increasedreliabi'lity of op erat-ion and economy of apparatus.

It i c y u c n c terms i ea se of registering and dis'play control apparatus associated wlth each trunk relay group at the manual exchange and theusual arrangement is toprovide a limited number, forfinstance 7 and to arrange thatwhen a trunk relay group is taken intouse for an incomcall, a r e et .Q reg s er n c p ra u 1s assoc ated therew th over ahunt ngswitch.

In View of the fact that at leastitwo hunting I operations are thus involved betweensu'cceeding sets of impulses dialled" the calling party, it may happenin extreme cases that he will dial thenext'digit, whichhasto be routed to the registering apparatus, before this apparatus has actually been seized, It,

has already been suggested to .dealwith this contingency by giving the subscriber the busy According to one feature-0f-'theinvention,

inatelephone system having a register set :adaptedfto be associated with a conrlection over a' hunting switch, Speaking connections to an 'operator s position are also adapted to be extended over the hunting'swith;

According to another feature ofithe invention, in a system including both manual and automatic exchanges an'd'having numbers re quired'on calls from automatic to manual exchanges displayed at call indicatorpositions, the impulses dialled by the calling party'are repeatedto the call indicator apparatus in a circuit having the source -of-energy at the autom-aticexchange. I

LA further-featured the invention is that in system in which impulses transmitted over a trunk line by a'calling subscriber serve to effect a display of the corresponding num beron call indicator apparatus at a manual exchangeyeach cord circuit at the callindieator operatorsposition has associated with it a tinderswitch which is set in operationwhen the corresponding plug is inserted in a jack to connect the plug with the line over which the number displayed istransmitted.

"These features "will be "better understood from the following description of one embodiment of the invei tionwl ich should be taken inconjunction with the accompanying drawings. 7 It will" be'funderstood', however, that the arrangement shown is given by Way of example only, and that. various, modifications could be made 'inthe circuit details without exceeding the scope'ot the. invention. Referring, now to the drawings, the'upper Par are. 1 w summi epeatera heault ma i cha ge, W il 'th lower part shows the 'trunkrelay group at the incoming end, and also a cord circuit together with its associated finder switch. Fig. 2 shows the common apparatus at the operators position and also one of the register sets for recording the number dialled by the calling party and controlling the corresponding display 011 the indicating lamps. The sequence of opera tions is briefly that when the repeater shown in Fig. 1 is seized from a selector level, the trunk relay group at the incoming end is prepared for operation and the switch RS starts hunting to associate a free register set with the partly-established connection. It

may happen in some cases, particularly if secondary line switches are employed at the automatic exchange, that the subscriber will commence to dial the numerical digits of the wanted number before a register set has been associated with the trunk relay group taken into use, and it is clear that if the switch RS should subsequently seize a register set, a mutilated number would be set up and the subscriber would not get his connection. Ac cording to the arrangement about to be described therefore if the subscriber dials prematurely, the call is switched through to an operators position and when dialling ceases, the operator will ask the subscriber for the number which he has dialled and may then complete it in the usual way. It is convenient to arrange for the operators position to be reached over certain contacts in the bank of the switch used for selecting anidle register, and in the present instance two test wipers are used, one of which is only used for hunting for a free line leading to the operators position, while the other is only used for hunting for a free register set, the switchover from one to the other taking place as soon as the subscriber starts dialling in case a register set has not then been taken into use. The number of register sets usually found suitable is seven, and if the switch ED is a 25-point switch, as it probably would be, the lines leading to the registers are multipled three times round the bank and the four remaining points are connected to lines leading to the operators position. A set-up control switch is also provided, in this case in duplicate, arranged to control the order in which numbers set up on the register sets are displayed on the lamp panel.

The operation of setting up a call from the automatic exchange to the manual eX- change in question will now be considered in detail and it will be assumed that the wanted subscribers number is 3456. When the repeater is taken into use from a preceding group selector, a circuit is completed over the line conductors 1 and 2 and the.

normally closed springs controlled by armatures 32 and 33 for line relay 5 which thereupon operates and at armature 6 completes a circuit for release relay 12. The latter at armature 9 connects earth to the release trunk conductor 3 so as to maintain the preceding switches operated, at armature 10 energizes the polarizing winding of relay 24, at armature 11 prepares a circuit for relay 13 and at armature 8 completes a circuit for relay 62 of the trunk relay group which extends follows: battery, upper winding of relay 62, back contact and armature 72, back contact and armature 82, armature 95 and its back contact, lead 50,-front contact and armature 7, armature 14 and its back contact,

lower winding of relay 24, normally closed springs controlled by armature 34, upper winding'of relay 28,:irmature 8 and its front contact, lead 51, back contact and armature 98, armature 84 and its back contact, armature 73 and its back contact, lower winding of relay 62, normally closed springs controlled by armature65, armature 86 and its back contact, lead 156, armature 261 and its back contact to earth (assuming that the operators position is in use at this time). Belay 24 is not operated in this circuit owing to the fact that its two windings now produce flux in opposite directions, but relay 62 operates and at armature 63 completes a circuit for relay 64. This relay thereupon at armature 65 connects direct earth to the lower winding of relay 62 so that this relay shall not be de-energized on the subsequent operation of relay 85, at armature 66 prepares a circuit for relay 71, at armature 68 prepares a locking circuit for relays 52 and 58 and at armature 67 completes a circuit for starting the hunting of the switch RS, which circuit extends as follows: battery through the low resistance upper winding of relay 58, armature 59 and its back contact, armature 83 and its back contact, front contact and armature 67, lead 157, armature 208 and its back contact, winding of relay 200 to earth. Owing to the high resistance of relay 200, relay 58 is not operated at this time, but relay 200 operates fully and at armature 202 completes a circuit for switching relay 204 and magnet 203 in series and at armature 201 connects test wiper 211 to the junction of magnet 203 and relay 204, the circuit for the test wiper extending over back contact and armature 206, lead 152, armature 56 and its back contact and lead 154. The switch RS thereupon commences hunting, and it will be noted that the contacts in the bank of wiper 211 corresponding to lines leading to the op erators position such as 322 have earth permanently connected to them so that at this time the switch cannot come to rest with its wipers in engagement with such a line. When a free register set is found as indicated by the absence of earth on the contact engaged by wiper 211, relay 204-is no longer short-circuited and operates, thereupon at armatures 205 and 209 connecting up wipers 212 and 214, at armature 206 connecting earth to lead 152 so as to busy the seized register, at armature 207 completing a locking circuit for itself and at armature 208 opening the circuit of relay 200. Belay- 200 is slow to release, however, and during the instant that it holds up, earth is connected back over lead 157 and relay 58 is then able to operate. It thereupon completes a look ing circuit including its lower winding for itself at armature 60 and at armature 61 closes a point in the impulsing circuit so that the next series of impulses dialled by the calling party shall be transmitted to thescriber dials the next digit, and it will be assumed in the present case that all the above operations have already fore he does so.

When he dials the digit 3, three interruptions are produced in the circuit of line relay been completed beand. it deenergizes accordingly. When relay 5 firstfalls away, it opens. the circuit of relay 62 at armature 7 and thisrelay ac-v cordingly de-energizes. Moreover at armature 6 a c rcuit is completed by way of armature l1 and its front contact for relay 13 and this relay at armatures-H and 15 prepares for the connection of battery and earth respectively toleads and. 51, at armature 16 short-clrcuits the lower winding of relay 2 1 and at armature 17 closes apoint in a chain circuit over leads 18 and 19 for a purpose which will be described later. When relay 62 de-energizes, a circuitis completed at. armature 63 for relay 71 andthis upon o-p-v erating, at armatures 72 and 73 connects up relay 78 andopens further points in the circuit of relay 62. lVhenrelay 5 energizes on the termination-of this lmpulse, a circuit is completed over l3l1&]1l l'10i31011- for relay 78 and it energizes,thereupon at armature 8O trans-.

initting an impulse over the following circuit earth, armature 80 and its front contact, armature 61 andits front contact, back con tact and armature 93, back contact andarma; ture 57, lead 153, armature 205 and its front contact, wiper 212 and the contact on which it is standing, front contact and armature 222, winding of relay 227, wiper 25 i and the first contact inits bank, winding of magnet 255 to battery. Magnet 255 accordingly operates and advances. the wiper256 of the first digit registerswitchlVl one step. Relayv 78-also at armature 79 completes a circuit for relay 7 1 and this relay,-on operating, at armature 77 completesanadditional circuit for relay7 1, at armature 7 5 completes a circuit for the upper windingof relay 62 so that this relay nowa-gain operates, and at armature 76 completes a circuit for relay 69. Relay 69 at armature 70 then opens a fur ther pointin the initial energizing circuit relay 71 so as to prevent this relay energizing prematurely after the termination of the series of impulses. Relay 227 in the reg ister is energized over the circu1t 111st traced for magnet 255 and being slow to release holds up throughout the subsequent train of impulses. Relay 227 at armature 228 completes a circuit for relay 239 and this relay at armature 24:0 prepares a circuit for the magnet 250 of the digit distributor M and at armature 241 opens a point in the circuit of relay 229. When relay 5 de-energizes at the commencement of the next impulse, the, circuit of relay 7 8 is opened and-1t de-energizes also, thus terminating the impulse tothe magnet 255. hen relay 5 again pulls up, relay 78 again operates and transmits a second impulse to magnet 255 and in a similar way a third impulse is subsequently transmitted. Since this is the end of the first series of; impulses, relay 5 now remains operated and consequently the circuit for relay 13 is opened for a longer time and it decnergizes after a slight interval, thereupon at armatures 1 1 and 15 opening thecircuit for relay 78. Thisrelay ole-energizes and op is the circuit of relay 7 4 for a longer time so that it de-energizes and at armatures 75, 76 and 77 opens the circuits for relays 62, 69 and 71. respectively. When relay 71 falls away, a circuit is again completed for relay .62 and since relay 69 is slightly slow it maintains the circuit of relay 71 open at armature 70 until relay 62 is again energized. Relay 227 also (ls-energizes at the end of the series of impulses and at armature 228 opens the circuit of relay 239. This relay, however, 18 slow,

and while it holds up a circuit is completed from earth, armature 228 and its back contact, armature 240 and its front contact,

winding of magnet 250 to battery, whereupon the wipers 253 and 254 ofthe digit (ilS- tributor M are advanced one step so that the next train of impulses shall be transmitted to the magnet of the switch M rather than to that of the switch M Whenthe next digit i is dialled, the se quence of operations takingplace at the repeater and at the trunk relay group is similar to that previously described, and the swicth M is accordingly advanced four steps. Upon the termination ofthe series of impulses, relay 13 de-energizes and hence relay 7 8 also and non-dialling conditions therefore are restored in the trunk relay group. Moreover the wipers of'the switch M are advanced a further'step so as to routethe next series of impulses to the third digit register 1 This switch is accordingly moved five steps when the next train of im pulses is dialled and the switch M then advances so as to connect up the fourth digit register 1 When the final digit has been dialled, the switch M is advanced as before and when relay 239 falls away a circuit is completed as follows: earth, wiper 253 and the fifth contact in its bank, back contact and armature 241, winding of relay 229 to battery. Relay 229 thereupon operates and at armature 233 disconnects the interrupter 2341 and at armature 232 disconnects earth from the associated contact 311 in the bank of the display control switch DS and instead connects up battery through relay 235. Moreover, at armature 230 a circuit is completed for the pilot lamps 257 and 258 to indicate to the operator that a call is waiting to be displayed, and at arn'iature 231 a circuit is completed for relay 300 by way of armature 267 and its back contact. Belay 300 upon operating, at armature 301 completes a circuit for relay 303 and at armature 302 connects up wiper 310 of the switch D8 The operation of relay 303 completes a circuit for relay 307 and magnet 306 in series at armature 305 and at armature 30% connects wiper 310 to the unction of magnet 306 and relay 307. Assuming in the present instance that the call under consideration is the only one awaiting attention, wiper 310 will now be advanced by magnet 306 until it engages the contact 311 from which earth has been removed by the operation of armature 232, it being understood that earth will be normally connected to contacts associated with registers not in use. When wiper 310 engages contact 311, relay 307 is no longer short-circuited and therefore operates, at armature 308 opens the circuit of relay 303 and at armature 309 completes a circuit which is maintained as lon as relay 303 holds up as follows: earth, front contact and armature 305, front contact and armature 309, armature 302 and its front contact, wiper 310, contact 311, armature 232 and its front contact, winding of relay 235 to battery. Relay 235 thereupon operates, at armature ..36 locks itself up to earth on wiper at armature 238 completes a circuit for relay 242, and at armature 237 completes a circuit which extends as follows earth, front contact and armature 237, contact and wiper 21 1, front contact and armature 209, lead 151, armature 53 and its back contact, upper winding of relay 85 to battery. Relay 85 operates, and at armature 86 opens the initial energizing circuit of relay (32, at the same time preparing a circuit for busying the trunk line as will presently be described in case the operator should delay to answer the call and the subscriber should hang up in the meantime. Moreover relay 85 at armature 87 prepares a circuit for relay 9-1, at armature 88 removes earth from test contact 100, at armature 89 completes a locking circuit for itself, at armature 90 completes an alternative circuit for applying holding earth to lead 157, at armature 91 prepares a circuit for busy relay 81, at armature 92 propares for the connection of earth to lead by way of the busy key and at armature 93 opens the pulsing circuit so that any further operation of the dial by the calling party shall be without effect. Returning now to the register set, the operation of relay 242 extends earth to the wipers of the digit registers M M M and M whence it is extended over contacts of relay 270 and similar relays to the appropriate indicating lamps in the panel L and thence by way of the call register relay 287 to battery. The lamps indicating the wanted number are therefore lighted and relay 287 operates, thereby at armature 289 completing a circuit for the meter 290 which operates to register the call.

The operator upon noting the number displayed on the lamp panel will select a free cord which is most suitable for completing the wanted conection, for instance that terminating in the plug P, and will test by touching the tip of the plug against the bush of the wan ted subscribers multiple jack. Assuming in the first instance that he is busy at this time, there will be battery on the bush of the jack, and a circuit will then be completed by way of the tip of plug P, normally closed springs controlled by armature 137, lead 100, armature 280 and its front contact, primary winding of the induction coil to earth. Consequently this current will induce a similar current in the secondary winding of the induction coil and this will produce a click in the operators receiver 291. The operator then knows that the wanted party is busy and accordingly momentarily presses the common busy key 276, thereby connecting earth to leads 158 and 159. When earth is connected to lead 158 it is extended to lead 157 and serves to prevent the release of the register set as long as the operator keeps the key pressed so that the busy signal shall not be given in respect of the next display also. The connection of earth to lead 159 completes a circuit for the relay 81 and this at armature 83 removes the normal holding earth from lead 157 and at armatures 82 and 8d disconnects relay 62 and connects itself in a locking circuit across the

loads

50 and 51. The lower wind ing of relay 81 extends by way of lead 99 to a busy tone source so that the calling party now hears the busy tone and realizes that he cannot obtain his connection. Vhen the operator releases the busy key, earth is removed from lead 157 and the release of the register set is initiated and takes place as about to be described. Moreover relays 58, 61 and 85 now have their circuits opened and release, so that all the apparatus in the trunk relay group exceptrelaytfil is restoredto' normal. When the calling party replaces his receiver, relay is de-energized and at armature 6 opens the circuit of relay 12. When'relay 12 releases, at armature 9 it removes earth from release trunk conductor 3 so that the'prececling selector switches and subsc'ribers line switch are released. Relay 5 also at ar1nature7 opensthe circuit of relay 81which then releases,f-thus completing therestoration of all tlieapparatus employedto normal. v,

Considering" now the circuit changes in the registerset, when earth is removed from lead 157, relay 204 ole-energizes andrestores'co'nditions to normal in'the register selector RS. Moreover, relay 221 is .de ene'rgi'zed at this time and at armature 223 opens the circuit of relay 225 which after a short interval sulficient to permit'the register to restore to normal, removes earth fronflead 154: at'armature 226 thus rendering the register again selectable. The release of relay 221 also closes a circuit from earth over armature 223 and its back contact, pilot relay 24:7 and by way of the off-normal contacts such as 252 andrelease magnets such as 251 of the switches M, M M ,l\1 ,M to battery so that all these switches are accordingly restored to normal. When Wiper 253 leaves the contact on which it has been standing, the locking circuit for relays 229 and 235 is openedand they accordingly ole-energize, whereupon at armature 231 the circuit for relay 300 is opened unless there are any other calls awaiting attention, in which case the circuit of this relay will be maintained at the armature similar to 231 in theoperated register set. Moreover at armature 232 the circuit for relay 307 is opened and earth is replaced on the contacts in the "banks of the switches DS and DS corresponding to the register set shown. Hence all the apparatus in this register set is restored to normal and it may be taken into use for completing another 'call'if any other calls are awaiting p attention. The switch DS will beset inoperation as soon as relay 307 de-energizes, and

in a manner similar to that just described it will bring about the display of the next number in order on thelamp panel; J} N Consider now the casein whichthe wanted subscriber is found'to be idle whenthe oper ator tests his line, that is to say when she touches the tip of the plug againstthe bush of hisfinultiple jack she hears'no click. She

accordingly inserts the plug and earthis then fed through the cut-off relay associated With the subscribers line over the bush of the jack, sleeve of the plug, sleeve relay 136, supervisory lamp 140 to battery; Sleeve relay 136 however is operated, thereupon at.

armature 137 disconnecting lead 160 extending to the operators headset and closing a point in the upper speaking conductor. Moreover at armature 139 a circuit is pre:

pared for initiating ringing and at armaand relay 105. The 'iinder switch F is-thus started in 'operationand continues to rotate until the wiper l09 engages the contact 100 from wh ch earth was removed on theoperation of relay neiayios isthe'n no longer ShOrt ircuitedand "operates, thereupon at armature 106p nr1eting earth; to test wiper 109, whence it is extended over contact and armature 87 "and its" front contact a relay 94, Relay 94 thereupon operates and at armatures 95 and 98 disconnects relay 62 from thespeaking conductors, at armature 96 completes a locking circuit for itself, and at armature 97 preparesthe release of relay 85, and the removal of earth'froin lead 157. When relay 62 falls away, at armature 63 it opens the circuit or relay 64, and the latter upon releasing after a short interval, at armature 67 opens thelocking circuit of relay 85 and removes earth from lead 157, Accordingly all the apparatus in the register set is released irithe manner previously described and relay 85 will "also restore to normal. As a further result of'the operation of relay associated with the finder switch, at armature 107 the circuitoflt relay 101, is 0pened, and a locking circuit isprepar'ed for relay 105. Moreover at armatures 106 and 107 relay 105 connects the speaking leads through so that,-sassiiiningthe calling; party.

is still on the line, a circuit is now completed for-line relay 120, which operates and completes a'circ'uit for relay 115 at armature 121. v

Relay 115 thereupon at armature 116 preares a circuit for initiating ringing, at armature 117 prepares a circuit which will not be operative in the present case for flashing the supervisory lamp, at armature 118 crinipletes a locking circuit forrelay 105 and at armature 119 co'nipletesa circuit for relay 112. This relay upon operating in its turn, at armature 11 1 completes a locking circuit for itselfindependent of armature 119 and at armature 113 opens the flashing circuit justreferred to. When relay 101 falls away, as it does shortly after its circuit is opened, it disconnects interrupterand completes the following circuit: earth,'winding of the wanted suhscribers cut-off relay, bushof the jack, sleeve of the plugP, sleeve relay-136,

armature 104 and its back c'ontact, armature 116 and its front contact, front contact and armature 139, armature 133 and its back contact, normally closed springs controlled by armature 135, winding of relay 127 to battery. may 1 27 now operatesandeat arms,

tures 128 and 129 connects up ringing current from lead 132 by way of the winding of the ringin trip relay 131 to the wanted line. The small condenser 130 is inserted in order to allow acertain amount of ringing current to leak back and give a ringing tone to the calling party to indicate that the wanted partys bell is being rung.

Vhen he replies by removing his receiver. a direct current path is completed over the loop and the current flow is then sufiicientto operate the ringing trip relay 131. This accordingly at armature 133 removes .the short-circuit from relay 134 so that this relay is now able to operate and at armature 135 connects up battery to maintain itself operated and to short out relay 127 which then de-energizes and completes the speaking circuit at armatures 128 and 129. When these contacts close, relay 125 included in the lower speaking lead is operated and at armature 126 it completes a circuit for the reversing relay 122. Thereupon at armatures 123 and 124 current flow is reversed back over leads 50 and 51 and is now in the proper direction to operate the polarized relay 24 in the repeater. At armature 26 a circuit is now completed for the reversing relay 30, and this relay at armature 31 connects earth to the metering lead 1, at armatures 32 and 33 reverses current back over leads 1 and 2 and at armature 34c inserts the whole of the impedance 28 in the line circuit so as to improve transmission.

The desired conversation will now be carried on and when it is completed the called party will replace his receiver whereupon relay 125 de-energizes. The effect of this is to open the circuit of relay 122 which accordingly reverses the current flow over leads 50 and 51 back to normaLthereby restoring polarized relay 24; this operation, however, is without any particular effect. When the calling party replaces his receiver, line relay 120 is de-energized and at armature 121 opens the circuit of relay 115. Consequently this relay de-energizes after its slow period and at armature 118 opens the locking circuit for relay 105 so that this relay also falls away. The circuit for relay 94 is then opened and this relay also de-energizes, thereupon restoring all the apparatus in the trunk relay group to normal. As a further result of the de-energization of relay 115 the circuit previously completed through relay 131 which is of suii'iciently low resistance to short out lamp 14-0 is now opened, so that the lamp lights to indicate to the operator that the connection may be taken down. Relay 112, however, remains energized over its armature 114 until the operator removes the plug, whereupon the sleeve relay 136 de-energizes and all the apparatus in the cord circuit is restored to normal. y

As regardsthe operation of the supervisory lamp 140, it will be seen that as long as re lay 101 is up, that is to say while the finder switch F is hunting, a circuit will be completed from battery by Way of the interrupter 110, front contact and armature 104i to the junction of sleeve relay 136 and supervisory lamp 1 10, so that during this period the lamp will be intermittently shorted out and will accordingly flash. Since however, the hunting time of the switch F is very short this circuit does not normally become operative. In case however, for any reason the switch F fails to find the trunk circuit in use, the lamp 140 will indicate the trouble to the operator. The interrupter 111 is provided to take care of the case in which the operator erroneously withdraws the plug over which an existing connection is set up. In this case, since sleeve relay 136 ale-energizes, the locking circuit for relay 112 is opened and it de-energizes also, thereupon at armature 113 connecting earth intermittently by way of front contact and armature 117, back contact and armature 101 to lamp 140 so as to flash the lamp and warn the operator of her mistake.

A description will now be given of the circuit changes which take place in case the calling subscriber continues dialling before the trunk relay group taken into use has been associated with a free register set. It will be remembered from the previous description that as long as the register selector BS is hunting, relay 58 is not operated but as soon as earth is connected back over lead 157 when the switch RS comes to rest, relay 58 operates; in the case under consideration, therefore, since RS has not found a free register set, relay 58 will not be operated. Accordingly when the next series of impulses is dialled, relay 7 8 will energize a corresponding number of times in the manner previously described. 'l/Vhen it first energizes the following circuit will be completed: earth, armature 80 and its front contact, armature 61 and its back contact, armature 55 and its back contact, up er winding of relay 52 to battery. Relay 52 is a two-step relay and at this time only operates its light armature 54 thereupon preparing a locking circuit for itself over armature 68. When relay 78 next falls away, the short-circuit is removed from the lower winding of relay 52 and it then operates fully, thereupon at armature 55 opening its initial energizing circuit, at armatures 53 and 5'? connecting the speaking leads 50 and 51 through to leads 151 and 153 rosnectively, and at armature 56 disconnecting test wiper 211 and connecting up test wiper 210 in its place. As previously mentioned it is assumed in the arrangement under con sideration that seven register sets are provided and that the contacts associated with them are multipled three times round the bank so as to occupy 21 contacts, while each of the remainlng four contacts glves access sets of contacts giving access to register sets are also permanently connected to earth, as for example contact 320. It will be seen therefore, that on the operation of relay 52, the furtherhunting operation is under the control of test wiper 210 and that as all the contacts-in the bank of this wiper associated with the register sets are permanentl'y connected to earth, it will be impossible for the switch to seize a-register seteven supposing one should become idle at this instant. Consequently the switch will continue to hunt until wiper 2-10 engages a contact to which earth is not connected. Suppose that the line shown in the drawings is the first idle one encountered, relay 20d will operate as in the previous cas'e,thereupon at armature 206 connecting earth to wiper 210 to busy this line, at armatures 205 and 209 closing points in the speaking circuit and at armature 207 completing a circuit which extends as follows: earth, armature 202 and itsfront contact, front contact and armature 207, armature 208 and its front contact, wiper 213, contact 324, winding of relay 326to battery. It may be mentioned that this circuit is only completed as long as relay 200 holds up,but that since in the meantime relay 58 has operated fully, a holding earth is now fed back over lead 157 as in the normal case; "Relay.

326 upon operating, at armature 327: completes a circuit vtor the lamp-332 associated with the jack J at the operators position. The operator upon noting the lighting of the lamp 332 will insert the answering plug or a cord circuit of known type in the ack J thereupon. completing a circuit for the sleeve relay 328. This accordingly operates in turn and at armature 330 'extingulshes the "lamp 332 and at armature 329 connects the imped-g ance 333 across the tip and ring conductors of the jack. The operator may-now throw her listening key and communicate with the calling party, waiting it necessary until he has finished dialling the. wanted numberl.

She willthen inform him that the difliculty.

has arisen because he has dialled his nuinber rather toooq'uickly and that he must replace his receiver and dial. the number again at a slower rate. Alternatively the operator could actuallycorcplete the connectionto the wanted party with the calling plugor the cord circuit. '5

When the calling party hangs up, in accordance with the operatorsinstructionsor at the end of the conversation, relay 5 is deenergized and initiates. the release of the repeater as previouslydescribed; Owingtothe opening ofits circuit at armature 7, relay 62 is now de-energized and opens the circuit of relay 64 so that it removes the holding earth from lead 157 at armature 67. Thereupon relay 20 i falls away and opens the circuit for relay 326 at armature 208. Accordingly relay 326 releases in its turn and at armature 327 again lights the supervisory lamp 322 thus giving the operator disconnectsupervision. She thereupon draws the plug from the jack J, thus releasing the sleeve relay 328 whereupon all the operated apparatus is re stored in known manner. It will be noted that though the initial busying earth is removed at armature 206 when relay 2041cleases, the line to the operators position is not again rendered selectable until earth is removed at armature 331 when the operator withdraws the plug. v e V Consideration may nowbe given to the operation of the various keys provided at the operators position for taking careof special conditions which may arise. It will be seen that the operators headset 291 is attached to a plug, and over the upper and lower=con 1 and ready to deal with calls relay 278 will be operated. When relay 278 is de-energized, however, owing to the withdrawal of the plug, a circuit is completed from battery throu h relay 260, backcontact and armature 279 andover the right hand contacts of the key 277 to earth, so that relay 260 is operated. Thereupon at its armature 261 it connects up battery-in place of earth to lead 156, whence it is extended over back contact and aramature 86, normally closed springs controlled by armature 65, lower winding of relay 62, back contact and armature 73, back contact and armature 84, armature 98 and its back contact, lead'51, winding of relay 21,

back contact and armature 11 back contact Y and armature 6 to earth. As pointed fout previously, a similar circuit for busying'the trunkline is completed when relay is operated but relay 64 is not. Relay 21 is Operated over this circuit, and at armature 22 connects earth to release trunk conductor 3 soas to prevent the repeater associated with this particular trunk relay group being taken" into use. Moreover at armature'2 3 an addi-' tional point is closed in the chaln circult over ble warning in case a call should come to the particular position while the operator is absent. This circuit will be completed owing .tojthe factthatpilot relay 287 iseiier-i gized when a number is displayed on the call indicator lamps, and at armature 288 closes a point in the circuit which is completed if the key 283 is operated) for relay 284. This relay which may be common to the whole exchange is then operated and at armature 285 connects earth to lead 286 so as to operate an alarm. Moreover, at armature 280 the connection of test lead 160 is transferred from the operators headset to the headset of the operator at the next position so as to enable her to deal with the call. Key 277 is operated when it is required to busy the position Without the operator leaving it and effects the operation of relay 260 as before. Key 269 is operated when it is desired to bring into use the duplicate set of lamps which is provided to guard against any failure of the lamps normally used. It will be understood that a suflicient number of relays corresponding to relay 270 are provided to enable all the connections extended from the banks of the switches M to M to be transferred to the other set of lamps. It will be seen also that the switches DS and DS and their controlling relays are identical and that one or other is used according to the position of the key 265 which when in an operated position completes an energizing circuit for relay 266, and this at armature 267 effects the necessary change-over.

The operation of the time control switch TC shown on the right of Fig. 2 will now be considered. It will be seen that when relay 221 operates on a register set being seized, the interrupter 234 is connected up and accordingly sends pulses to the magnet 312 of the switch TC. As already pointed out this circuit is opened at armature 233 when relay 229 is operated upon the completion of the sending of the digits of the wanted number so that normally the switch TU is not fully operated. Suppose, however, that for any reason the calling party fails to finish dialling, in order that the register set shall not be held up indefinitely it is arranged that after the switch TC has made 10 steps it completes a circuit over its up er wiper for relay 229 similar to that which would normally be completed over wiper 253 and the fifth contact in its bank so that the digits which have been dialled are displayed in due course under the control of the switch DS If the operator then finds that the number dis played is incomplete she may clear it out of her position by pressing the busy key, and the subscriber will then receive the busv tone and will realize that he has set up the number wrongly.

It will be seen that when a register set is taken into use, a multiple earth is removed from lead 334 at armature 226. Consequently if all the register sets at a position are in use, there willbe no earth on lead 334 and the all registers busy relay 335 will accordingly operate. Thereupon at armature 336 it completes a circuit for the position busy relay 260, which by operating its armature 261 busies all the trunk lines incoming to the position so that for the time no further calls can be received. In order to take care of the case in which switches such as RS are actually hunting at this time, it may be arranged that certain dead positions are provided in the bank of the RS switches which positions are rendered accessible by relay 335 when it operates. In these positions the busy tone is connected up to warn the subscriber that he cannot for the moment obtain his connection and must hang up and try again later. In the arrangement of bank wiring outlined above, no provision is made for this, but it could be readily modified to give 7 busy positions, the leads to the registers being then multipled only twice round the bank. Alternatively it could be arranged that if all the registers were busy, relay 335 rendered the special operators position accessible in the same manner as on premature dialling, though perhaps this arrangement would be less satis factory from an operating point of View.

Another arrangement which could be employed with advantage in the present scheme would be to make use of rotary line switches at the incoming end of the trunk lines under the control of a load distributing switch for distributing calls to each position in turn. Such an arrangement is described in detail in the British Patent No. 229,371 which discloses a system of the same general type as the present specification but somewhat more complicated. The use of such rotary line switches will, of course, slighlty increase the hunting time but in view of the arrangement for trunking calls in which premature dialling takes place to an operator, this is not of such serious importance as it otherwise might be.

It should be mentioned that though in the arrangement described the repeater is assumed to be reached directly from a selector level, it would clearly be possible to make use of secondary line switches in known manner. These should preferably be of the pre-' selecting type, for instance as shown in Patent No. 1,474,648, issued Nov. 11, 1923, to A. B. Smith, to avoid a still further increase in hunting time, as it would clearly not be desirable that an undue number of calls should be uncompleted owing to premature dialling, though some of the objections would vanish if the calls were actually completed by the special operator, instead of the subscriber being merely warned of the cause of the failure to complete the connection. It may he mentioned also that the operator reached over the banks of the switches RS would ordinarily be a special operator, but that if necessary arrangements could be made for the ordinary call indicator operator rto handle this class of call.

I claim r 1. In a telephone system, trunk lines extending from .an automatic exchange to a manual exchange tor handling automatic to manual calls, an automatic switch individual to each oi said trunk lines, a -pl;urality of registersets accessible to said switchand controlled by calling automatic subscribers for registering the numbers o f'the wanted'manual subscribers, speaking-connections to an operators position also accessible to saidswitches, 1

and means for operating one of" said switches when its correspondingitrunk line is taken into use for connecting the trunk 1 l1116 with either an idle 'one of said-register sets or with one oi-said speaking connectlons.

2. In a-telephone systemytrunk llIlGSQX 2o t8IlCll11g trom'an automaticexchange to a manual exchange lor handling automatic to manual calls, an automatic switclrindividual to each of 'said'trunk lines, apluralityiot" register sets accessible-to said switches and 5' controlled by calling automatic subscribers for registering the 'numbersof the wanted manual subscribers, speakingconnections 'to an operatorsposition also accessible to-said switches,*means -ior 'operatingone of said switches to hunt for an idle one ofsaidregister sets responsivetothe seizureo'f its corresponding trunk line, and ;means {or causing said switch to hunt only for one of said speaking connections in' case thecalling subscriber commences to dial be'foresaid-switch has seized an idle one of said register sets.

A telephone system as claimed in claim 1' including a call-indicator 'ope-rator7s positionin which the-numbers dialled by the call- 4o ing subscriber are lGCOI'dQCl Ollf the register set and are subsequently displayed on a lamp panel at the call indicator operatorspositi-on,

i. In a telephone syste'm as claimed in claim 1 in which a register Setisonlytemporarily associated withtheconnection-overthe hunting switch during the setting-up Oftl16 connection and in case aconnection is made to one of said speaking connectionssuch-'con- Y nection is maintained over said'switchttor the duration of the connection.

5. In a telephone system,-atrunk line extendingfrom an automatic exchange to a manual exchange for handling iaIll'JOIIiatIciO .manrial calls, an automatic hunting switch individual to said trunk 11116, a plural ty of register sets accessible to said switch-and controlled,by calling automatic subscribers for registering the numbers of 'the-wanted man-- ual subscribers, speaking connections'to'an "operators position also accessible to said switch, two'test wipers in said switch, means for operating said switch to hunt tor an idle one of said register sets respons ve to the seizure of said trunkline, saidhunting operation being controlledby'thefirst of saldtest wipers and means operative llIl case the 1 callingasubscriber commences diallingzbeioreian idle-register set-is seizedrforrsubstitnting the second wiperiforthe firstJwiperito causesaid switchto hunt only for an idleone iofsaid speaking connections.

6. In a telephone system,an automaticiand 6 including an impulse responding irelaycxin the* incoming end of said trunk line inawhich a number of I interruptions i in the loop circuit at the outgoing end are converted into acorresponding number=of energi zations of said relay at the incoming end.

18; In a telephone system, an a manual exchange, a call indicatorposition in said -manualexchange for displaying 1 the calledmanual telephone numberto anioperator thereat, a trunk line extending sfrom -said automatic exchange and terminating in said position at the manualexchange, a first relay having windings connected respectively :;to

battery and ground and normallyiconnected across i the trunk line atthe incoming end, :a second relayin-said trunkline atithe incoming-end neans in said trunk line :responsive to the calling automatic subscriber dialling the number 'of the wantedimanual subscriber for repeating the impulses yoveri said trunk line to said position over :a'loop :circuit .in which' the source of energy'for repeating; said impulsesis-located in the outgoingrend of: the trunk line at the "automatic exchange, sand means eflective during impulse? transmission for disconnecting said first =relay from :said

trunk and "for connecting said second relay directly across said trunk line in place of saidfirst relay.

-9. In a telephone systemytrunk llIlESJBX- tending from an automatic exchange: andrterminating in acall indicator position in'a manual exchange for'ha'ndling automatic-to inanual calls, -Ineans= control-ledbyzascallinga automatic subscriber for seizing one of said trunk lines, a line relay in said seized I trunk line at the automatic exchange directly con-trolled bythe' calling subscriber for transmitting-impulses 'oversaid seized trunk line to "cause the number of the called manual subsoriberto be displayed on the call indicator apparatus at "said position, a plurality of cord circuits automatic and at said position common to said trunk lines, a finder switch individual to each cord circuit, and means responsive to the insertion of a plug of one of said cord circuits in the ack of a wanted manual subscriber for connecting the associated cord circuit with the trunk in use by the calling subscriber.

10. In a telephone system as claimed in claim 9 including a busy key common to said cord circuits at said position, and means responsive to the operation of said key for causing the busy signal to be transmitted to the calling subscriber over the said trunk line in use.

11. In a telephone system, a group of trunk lines, means for connecting a calling line to an idle one of said trunk lines, a plug ending cord circuit common to said trunk lines, an automatic hunting switch for selecting the trunk line in use and connecting the same to said cord circuit when the plug thereof is inserted in the jack of a called line, a supervisory signal individual to said cord circuit, and means for flashing said signal during the time said switch is hunting for said trunk line in use.

12. In a telephone system, a group of trunk lines, means for connecting a calling line to an idle one'of said trunk lines, a plug ending cord circuit common to said trunk lines, an automatic hunting switch for selecting the trunk line in use and connecting the same to said cord circuit when the plug thereof is inserted in the jack of a called line, a supervisory signal individual to said cord circuit, means for flashing said signal during the time said switch is hunting for said trunk line in use, and means for disconnecting said flashing means when said hunting switch connects said cord circuit with said trunk line in use.

13. In a call indicator telephone system, a plurality of registers for registering the called number of called subsribers lines, an operators position, an automatic hunting switch, means normally responsive to a call for causing said switch to select and seize an idle one of said registers, and means operative in case all said registers are busy to cause said switch to automatically complete a talking connection to said operators position.

14;. In a call indicator telephone system, a plurality of registers for registering the called number of called subscribers lines, an operators position, an automatic hunting switch, means normally responsive to a call for causing said switch to select and seize an idle one of said registers, and means operative in case a calling subscriber commences to dial before said switch has seized an idle register to cause said switch to automatically complete a talking connection to said operators position.

15. The combination, with a non-numerical. hunting switch, of a single set of wipers for said switch including two test wipers, a set of bank contacts for each of said wipers, a plurality of register sets for registering called telephone numbers having conductors terminating in each set of bank contacts except the set of bank contacts accessible to the second test wiper, a plurality of talking connections extending to an operators position having conductors terminating in each set of bank contacts except the set of bank contacts accessible to the first test wiper, permanent connections to ground from the bank contacts accessible to the two test wipers which are not connected to either the register sets or the said talking connections, and means for substituting one test wiper for the other.

16. In a telephone system, a trunk line having a battery feed bridge normally connected to one end, means for seizing the trunk line at the other end and for transmitting a series of impulses thereover, and means for disconnecting said first bridge and for connecting battery feed bridge to the trunk line at said other end during the transmission of said series of impulses.

17 In a telephone system, a trunk line comprising two conductors, a source of current normally bridged across the conductors at one end of the trunk line, means for transmitting a series of impulses over the trunk line, and means for bridging a source of current across the conductors at theother end of the trunk line and for disconnecting said first bridge during the transmission of said series of impulses.

18. In a telephone system, a trunk line comprising two conductors, a source of current normally bridged across the conductors at one end of the trunk line, means for transmitting a series of impulses over the trunk line, means for bridging a source of current across the conductors at the other end of the trunk line and for disconnecting said first bridge during the transmission of said series of impulses, and means for reconnecting said first bridge and for disconnecting said second bridge after said series of impulses has been transmitted.

19. In a telephone system, a trunk line, means for seizing the trunk line at one end and for transmitting a series of impulses thereover, a loop circuit including conductors of the trunk line to which battery and ground are connected at the other end completed responsive to the seizure of the trunk line, and a loop circuit including the same conductors of the trunk line to which battery and ground are connected at said one end completed during the transmission of said series of impulses.

20. In a telephone system, a trunk line normally having battery and ground connections at one end, means for substituting battery and ground connections at the other end for said normal connections, and means for interrupting said second connections to transmit impulses over the trunk line.

21. In a telephone system, a trunk line which may be in waiting condition, dialing condition or talking condition, means for feeding battery back over the trunk when the same is in waiting or talking condition, and means for feeding battery forward over the trunk when the same is in dialing condition.

22. In a telephone system, a two conductor trunk line connecting said exchanges, a relay at the second exchange energized over a circuit including the two conductors of the trunk line in series and a source of current at the second exchange responsive to the seizure of the trunk line at the first exchange, and a relay at the second exchange energized over a circuit including the two conductors of the trunk line in series and a source of current at the first exchange responsive to the interruption of said first circuit. 7

23. In a telephone system, trunk lines comprising only two talking conductors extending from an automatic exchange to a manual exchange, a relay in each of said trunk lines at the automatic exchange for marking its associated trunk line busy, a second relay at the manual exchange for energizing all of said first relays of idle trunk lines over only one conductor of the associated trunk line, and a manually operated key for energizing said second relay.

24. In a telephone system, an automatic exchange and a manual exchange, trunk lines comprising two conductors connecting said exchanges, a relay associated with each trunk at the automatic exchange for marking the trunk engaged, an operators position at the manual exchange, link circuits at said position for connecting the trunks to called'lines, an operators telephone set normally connected to said link circuits, and means responsive when the operator disconnects said telephone set from said link circuits for operating the relays associated with idle trunk lines over only one conductor of the associated trunk line.

25. In a telephone system, an automatic exchange and a manual exchange, a two conductor trunk line connecting said exchanges, a relay in the trunk line at the automatic exchange normally connected to one conductor of the trunk line, call register sets at the manual exchange accessible to the trunk line, an automatic switch associated with the trunk line at the manual exchange operative responsive to the extension of a call over the trunk line for selecting an idle one of said register sets, and means responsive when all register sets are in use for operating said relay to busy the trunk line at the automatic exchange.

In testimony whereof I hereunto afiix my 7 signature.

JOHN ELLIS OSTLINE.