US1559269A - Telephone-exchange system - Google Patents

Description

0a. 27,1925. 1,559,269 W. H. MATTHIES ET AL TELEPHONE EXCHANGE SYSTEM Fild Nov. 30. 1 2 4 Sheets-Sheet 1 //1ven/0 m: W////'am lilfaff/llei Wa/fer P Alba/f y W f'y Oct. 27, 1925- 1,559,269

w. H MATTHIES ET AL TELEPHONE EXCHANGE SYSTEM Filed Nov. 30, 1923 4 Sheets-Sheet 2 /n venfom: VW/mm/i 170/7/7/66 \Ah/fer P/I/ber/ Oct. 27, 1925' 1,559,269

w. H. MATTHIES ET AL TELEPHONE EXCHANGE SYSTEM Filed Nov. 50. B25 4 Sheets-Sheet 5 Oct. 27, 1925 1,559,269

W. H. MATTHIES ET AL TELEPHONE EXCHANGE SYSTEM Filed Nov. 30. 19215 4 Sheets-Sheet 4 pm y Patented 2?, 1925.

1 UNITED sures PATENTTOFHCE.

W LLIAM H. MATTHIES, 0E HAcKENsAcK, AND WALTER P. ALBERT, OF EAST ORANGE, NEW JERSEY, ASSIGNORS TO WESTERN ELECTRIC COMPANY, INCORPORATED, or NEW YORK, N. Y., A con-rona'rlonor NEW YORK.

v TELEPHONE-EXCHANGE SYSTEM.

Application filed. November 30 1923; Serial No. 677,834.

To. all whom it m concern:

Be it known that we illman H. MAT time. and VALTER P. ALBERT, citizens ofthe United States of America residing atI-Iack onsack, in the county of Bergen and State otiNew Jersey, and East Orange, in the, county otEssex and State of New Jersey, respective y, haveinvented certain new and useful Improvements in Telephone-Exchange- Systems, of which the following is a full, clear, concise, and exact descrip'tion.

,This invention, relates to telephone exchange systems and especiallyfto systems employing automatic swit-ches for the establishment of connections.

, The invention has for its object an i1nprovement in the means of connecting a calling subscribers line with. any one of a plurality of called subscribers lines.

A feature or" the invention relates .to a small telephone system wherein each line may be paired with every other line and trunk, and a connecting device, such' as a relay, which .isindividual to each pair is used for connecting them together.

' Further features. and advantages will be.- come apparent from a detailed description of theinvention. j

.The drawings, when arranged in the order illustrated in Fig. 5 discloses apreferred method of using the invention. Q

Fig. 1 shows .in connection with a subscribers line. circuit, a register switch for recording the designation of called lines, and a number of transfer relays. In addi tion a portion of the startcircuit tor'causing the association of the calling line with an idle central oflice trunk is shown, as also are a viumber of individual connecting relays. V i

' Fig. 2 illustrates substantiallysimilarcircuits and apparatus to those shown in Fig. 1.

Fig.3 disclosesa central oiiice trunk with the. controlling apparatus thereforfor ale lowing calls to be madeto a central ofiice; and also a line for co-n'ipleting calls to an at tend-ant whose talking and coni'iecting apparatus is shown in that portion of thefigure within the broken line.

Fig. 4 illustrates .in schematic form an outline of the plan or" using the invention.

Referring to Fig. 4 there are shown a pliirality of subscribers lines with dialing apparatus and register switches. each individual to one of said lines. In conjunction with the register switch there are a number of connecting relays associated with each.

subscribers line and intended to be operated according to the position assumed by the individual registerswitch which is controlled or set by impulses transmitted by the calling subscriber. Inthis figure is also shown an arrangement for interconnecting any two subscribers lines by means of a connecting relay which is individual to both .of said lines.

A call from one local station to another is accomplished bythe calling. subscriber dialing the numerical designation of thedesired line. Calls to the central oflice are completed by dialing a special code which causes the association of the calling sub: scribers line with an idle one of a number. of centraloflice trunks, at the same time releasing the line circuit. with its associated controlling apparatus and registering mechanism, and vallowingbattery .to be supplied from the central oiiice. Provision is made for placingthe release of the connectionjunder the control of the central office operatorl An incoming call from a central ofliceis received by the attendant and may be extended'to any desired station by simply op-.

crating the proper stations key whereupon she receives asignal notifying her whether.

the. local .subscribers line is busy or idle. If the called party is connected with another local subscriber the attendant by means of a notest key can break in on the established connection and notify the. local called. snb-.

or more calling parties to become connected with the same central ofi ice trunk.

The general description of how a call is completed letween local subscribers will now be given, reference being had to Fig. 4, wherein are illustrated a number of subscribers stations 401, 402, 403, etc, and a number of subscribers lines 420, 421, 422,

etc. Ass ciated with each calling line and individual thereto is controlling apparatus 430 represented scl'iematically and also a register switch. The register switch 410 for instance is associated with line 420. The register switch comprises a plurality of mul tiple banks and cooperating wipers. The terminals of the multiple banks are Connected by means of conductors 431 to the windings of connecting relays 412, 413, 414, etc., the )articular one of which, when operated, connects the calling subscriber-s line directly with the called subscribei"s line, which connection is independent of the register switch.

The calling subscriber, upon removing his receiver closes a circuit for operating the individual register switch 410 under control of his sending dial, and depending upon the value of the first digit dialed one or a number of transfer relays is operated. Upon the completion of the dialing of the second digit, the register switch is set upon the terminals corresponding to the called line and thereupon a circuit is closed to operate the proper one of the connecting relays 412, 413, 414, etc. For example, assume that the subscriber of line 420 desires to converse with the subscriber of line 422. W'hen the calling subscriber has completed his dialing and the register switch individual to his line has been set upon the terminal corresponding to line 422 a circuit is closed to operate the connecting relay 413 which is individual to lines 420-and 422, thereby connecting line 420 directly with line 422, through the front contacts of this connecting relay.

For the purpose of allowing each of the local subscribers to communicate with the central otfice 445, .each line is provided with a duplicate set of connecting relays 417, 418, etc., corresponding to relays 412, 413, etc. In this case, the connecting relays are each individual to a line and a central office trunk. For example, assuming that there are ten central office trunks, then each subscribers line is equipped with ten relays similar to relay 417. WVhen the central oflice code is dialed by a local subscriber, the register switch 410 is correspondingly positioned and causes a connecting relay, for example, relay 418 to operate. Relay 418 is individual to the pair formed by the calling line 420 and the first available ofiice trunk, in this case trunk 44?. Similarly, each of the other local lines has associated therewith sets of relays such as relays 442, 443, 444, etc.

Local call.

A detailed description of the method of connecting two local lines will now be given. For this purpose, let it be assumed that the subscriber of line 101, Fig. 1, whose numher is 16, desires to talk with the subscriber at line 202, whose number is 15. hen the calling subscriber removes his receiver from the switchhook, a circuit is closed to operate relay 102 from battery through the right-hand winding of said relay, inner right back contact of relay 103, middle right back contact of relay 104, over the ring side of the calling line through the subscribers set, thence over the tip side of the line, through the inner right back contact of relay 104 to ground through the left winding of relay 102. Relay 102 becomes energized and closes a circuit for the slow-releasing relay 105 from battery through the winding of the said relay, front contact and armature of relay 102, conductor 150, normal terminal and brush 140 of register switch 100, conductor 151 to ground at the left inner armature and back contact of relay 106. The operation of relay 105 closes an obvious operating circuit for relay 106. Relay 106 upon attracting its armatures closes a substitute holding circuit for relay 105 which circuit is independent (of register switch 100 and may be traced as follows: from battery through the winding of relay 105, right front contact and armature of relay 102, left back contact and armature 'of relay 104 to ground at the left inner armature and front contact of relay 106. The circuit is now in condition to receive the first set of impulses.

The subscriber upon manipulating his dial for the tens digit, which in this case. is represented by one impulse, releases relay 102 thereupon closing a circuit to operate stepping magnet 108 as follows: battery through the winding of slow releasing relay 107, winding of stepping magnet 108, conductor 152, left back contact and armature of relay 109, outer left armature and front contact of relay 106, right armature and back contact of relay 102, left back contact and armature of relay 104 to ground at the left inner armature and front contact of relay 106. \Vhere the line circuit is reclosed stepping magnet 108 having received one impulse, positions brushes 140, 141, 142 upon the number one set of terminals. Following the transmission of the tens series of impulses, the slow to release relay 107 releases closing a circuit as follows: from ground through the left inner ari'nature and front contact of relay 106, left winding of relay 109, conductor 153, back contact and arma ture of relay 107, conductor 154, brush 141 and No. 1 right'hand terminal of register switch 100, conductor155 to battery through relay that ifthe called .line had '2 as its tens digit the; register switch 100 would have been positioned on the N o. 2 set-of terminals, and

instead ofoperating asinglexrecording :relay as 113,'a set of recording-relays as 110, 111:;w0uld' have been .operated.

The calling subscriber next transmits the f r set 'of impulses corresponding to theiumts digit of the called line. In this casegsi nce the called number has a :units digitof5zthej line circuit will be opened 'five-timesand relay 102 will release accordingly stepping rgister switch '100 to the set of terminals ing current 213" through winding of relay 161,162 corresponding to the units digit of the calldline... If the number of the called linewas 24 instead of 15, the brushes of the register switch 100 at the end of the units dialing would-be resting on. the same set of terminals 'w-hiclriwereused in the case of the called line 15, butin this .c'asefrecording' relays 110 and 111 operate in place of recordingrelay 1'13.

Relay 107 releases a second time when the subscriber has dialed the units digit of the' called line designation. Should the line which'is being'called be busy, relay 206will be iii-an operated condition andth'e'calling subscriber will receive a busy signal the following circuit: from atone source 222,

through .the right armature and front contact of'relay 206, conductor 1, lowermrddle armature and back" contactoffrelay 111, 1 terminal 162 of .registerswitch 100, brush 1 11, *armature and back contact-of relay 107,

conductor153, left inner armature and'back.

' contact of relay 109, condenser 112 to the ringside of the line, thence through the substation loop, returning over the tip side offtlie' lineyto ground through the-left winding of. relay 102. 4

If," however, the called line is idle a cir- 'cuit is closedfwhen relay 107 releases the second time, for operating relay 203 which is individual to the called line. This cir cuitmay be traced from ground through the left inner armature and frOntcontactof relay 106, left Winding of relay- 109, con-- ductor 153, armatrirennd back contact of relay107, brush 141, terminall 162 of m ister switch'100, the lower middle armature and back contact of relay 111, conductor'254c, right armature and back contact of relay 206, through the winding of relay 2032to battery. :Relays 109and 203operate inthis circuit. At the same time a circuit isclosed to ioperatethe connecting relay 220 which isicolnmon to' lines 15'and 16. as follows:

from battery.throughthe: winding of relay 220, conductor 255, lower niddle armature and baclc-contactof relay 110, terminal 161 .of: register switch 100, brush 142, conductor 158,:tright armature andxfront contact of relay 109, through the Tight hand winding 7 of said relayto ground at the left inner armature. and front contact ofrelay 106.

relay directly to' the called subscribers line.

The operation-of relay 220 also provides a lockingci-rcuitx for relay 203 as 2 follows: battery through the JW-inding of. relay; 203,-

left innerzarmature.and front-contact of said relay,a-ar -n1ature and contact ofrelay 214: to

The operation of'relay:220.connects thecalling 1 subscribers lin through the contacts of'said g ound at theJlower-inner armature and front contact of'relay:220.-i

iWhen; relay x203 operates scribens bell is: rung from. a "source of= ringtu'rns operates relay 206 rtoirenjder' this line busyto other callingi -statio ns." 1

WVhen the called subscriber removes his o f the-circuit including relay 214 is reduced so that the latter now operates and breaks the. locking :circuit for relay-5203Whichf-re-f leases anddisconnects ringing current from the icalled-linei. The calling subscriber. can with subscriber of now hold :co nversation linef202. f

number containedfa tens digit2,f it connect:-' mg relay-other than 220 would have been operated, through: a f'1'ont=1.contactof. trans-- ferrelays 11 0 and lll inst e-a'd-of:through back: contacts of these relays. Thus by :dis-. criminatingas to the ,tens digit and thereby operating certain-of'thetransfer relays109,

110 a nd 111; a.' limited numberof contacts on the register switchw-100:can serve for connecting with a greater numberof called lines.- I I I iFollowingconversation when the calling.

subscriber replaces his-receive'r on the switchhook, "line relay 102 releases, .thus opening-the operating circuit. of slow 're leasing irelay- 105. hen relay 105 releases, it-in turnreleasesrelay 106 and relay 113.

\Vhen relay '106lr eleases, a circuit is closed to a-estore register switch 100' to'sits 'n'ormal position as follows: Battery through the Winding of relay 107, winding ofstepping magnet 108, armature and contact thereof, conducting segment 160, brush 140,. conductor 151 to ground at the leftsinner armature and. back contactiof relay-.1106. :"Svvitclr100v subsetluent to the: completion of-=..dia'ling,: the called :-'sub-- receiver from the switchhook the resistance thus steps itself by means of its interrupter contacts to its normal position. The release of relay 106 caused the successive release of relay 109 and connecting relay 220, thus disestablishing connection between the two stations. When the called subscriber hangs uphis receiver he releases the remainder of the connection by releasing relays 201, 205 and 206 in succession.

From the foregoing description it will be clear that if the subscriber of line 202 had initiated the call for the purpose'of connecting with subscribers line 101, the register switch 200 would operate. In this case the same connecting relay 220 would be energized since this is the only one of all theconnecting relays which is common to lines and 16. In a similar manner another connecting relay as 221 would serve to interi connect lines having numbers 15 and 22 regardless whether line 15 was originating or terminatlng the call.

Trzmlc circuit originating calls. Should a local subscriber desire connection with the central oflice the procedure is similar for that described for a 'local call as far as the point where the register switch is set corresponding to the units digit. However, in this case, a special code is dialed for associating the calling line with a central oflice trunk. In the case illustrated, this code is represented bythe number 11. When, therefore, a subscriber as the subscriber of line 202 dials the code 11, the register switch 200, at the completion of dialing has its brushes 241 and 242 positioned upon terminals 261 and 262. Since the tens digit of the special ofiice code is 1, transfer relay 212 alone will be operated. The operation of relay 212 closes acircuit for trunk relay 216, traceable from battery at the armature and back contact of relay 217, left winding of relay 216, left armature and front contact of relay 212, brush 242, conductor 259, right armature and front contact of relay 209 and right hand winding thereof to ground at armature of relay 206. Relay 216 operates and closes a locking'circuit for itself as follows: from battery through the right hand winding, right inner armature and front contact of said relay, to ground at the armature and front contact of relay 205. The operation of relay 216 also closes an obvious operating circuit for relay 217. Re-

lay 217 which is common to a number of central oflice trunks, upon operating removes battery from conductor 258 thus preventing any other trunk relay similar to relay 216 from operating and associating another calling line with this particular trunk. Assuming that trunk 355 is idle, starting relay 301 individual. thereto is operated, over a circuit traceable from battery through its winding, left inner armature and back contact of relay 302, conductor 341, to ground 7 at the left outer armature and front contact of relay 216. If, however, trunk 350 had been busy relay 302 individual thereto,

would be operated and the starting wire 341 would be extended through the locking contacts of relay 302 to the next starting relay similar to relay 301 associated with the next idle trunk. Should all the central ofiice trunks be busy, relay 303 will operate from battery through its winding, left inner front contacts of intermediate relays similar to relay 302, to ground at the left outer arma ture and front contact of relay 216. The operation of relay 303 therefore, will cause a distinctive tone to be sent back to thecalling subscriber from a source of tone 314 through the armature and front contact of relay 303, conductor 342, right outer armature and front contact of relay 212, terminal 262 of register switch 200, brush 241, armature and back contact of relay 207, left inner armature and back contact of relay 209, condenser 210 to the ring side of the calling line, thence through apparatus at station 202, notifying the calling subscriber that all the central office trunks are busy.

Returningto the point where startingrelay 301 was operated in connection with the first idle central office trunk, connecting relay 218,which is common to this trunk and calling line 15, was operated as follows: from battery at the left armature and contact of relay 301, conductor 343, upper winding of relay 218 to ground at the left inner armature and front contact of relay 216. Relay 301 connects direct ground at its right armature and front contact to the tip side of the trunk which serves to signal the central office operator. At the same time the low resistance bridge 327 was placed across the trunk. The central otfice operator upon observing the signal plugs in on this trunk and in a well known manner places battery on the tip side, and ground on the ring side of the trunk as a result of which relay 306 operates. Relay 306 closes an obvious operating circuit for slow releasing relay 307 which in turn closes an obvious circuit for relay 308. Relay 308 closes an obvious operating circuit for relay. 309.

Relay 309 at its right armature and front contact lights busy lamp 310 in parallel with the right hand winding of relay 302 which operates and transfers the starting circuit to the next idle trunk. The lighting of lamp 310 serves as a signal to the attendant that the'associated central ofiice trunk is busy. Relay 309 at its left armature and front c011- tact also closes a locking circuit for connecting relay 218 as follows: from ground through the left armature and contact of relay 309, normal contacts f relay 335, left armature and back contact of relay 338, conductor 344, inner armature and front contact of relay 218,-. through the lower. winding ofi said relay in series-With the-winding of relay 204 to battery. Relay 204: loperates in this circuit and disconnectsthesubscribers line from'the P. BagXgli'nk and its associated relays and register mechanism. The calling line is now connected directly wiam central office trunk, and since relay313 is bridged across the trunk,-it operates in series with the .subscribers 'set. Subsequent to answering by the central oilice operator, relay 323 operates from battery through its winding, leftouter armature and back contact of, relay 335, right'armature and front contact of relay 313 to ground. at the left armature and front contact ofrelay 308. Relay 323 also looks in a circuit from-battery through its Winding, right outer." armature "and front contact to' ground at relay308.

Relay 323 in operating, connects the calling subscribefis line through the inner *arrna tures and front contactsv of said relay directly with the central ofiice trunk, and the calling subscriber may either-give thenumber of the desired line to the central office operator in the case of aimanual office, or dial the central oilice number inc-the case of a mechanical office. s

' Disconnection. I

Following conversation, when thecalling subscriber replaces his receiver, supervisory relay 306releases, and after an, interval relays307 and 308 release. Relay:3( )9,however, being slow to release is, held IOperated from ground atzth'e armature-ofirelay' 316 which is bridged across" thetrunk upon the release of relay 308. The complete release of the connection, therefore, is under the controlof relay 31.6 which in turn is controlled by the central oflice operator.

Incoming calls.

hen, a central ofiice operator plugs in on a trunk with a cord circuit, relay 316:operates from a source of battery atfthe ceritral office over the tip side of the-trunk, left normal contact of key 330, right normal contact of key 332, the right outer armature and back contact of relay 308 through-both windings of relay 316 in series to the ring 7 side of thetrunk, right normal; contact of key 330 and thence over the ringside of the trunk to a source of ground at the central oflice. The operation of relay 316 closes an obvious operating circuit for relayr309 which in turn lights the busy lamp 310 asvh'erein-- before described. Relay 3021 also operates in'thi's circuit and renders the. associated trunk busy by extending the start. wire 341 to the'nelxt idle trunk.

Vhen the central oflice operator applies ringing current; to: the trunk, a circuit is closed for ringing relay 315. whichoperates',

since its left hand winding isb'ridged across the trunk. Relay 315 locks -over a circuit traceable from battery through the right hand winding, right armature and front contact of 'said irelay, right; armature and 315 looks. The lighting of lamp 312 serves as a signal to the attendant that a central office call is awaiting connection. The talk key 331 is thereupon operated closing an obvious" operating circuit for relay 318 which locks through its rightarmature and front contact through the left normal contacts' of relay 320, to ground at the right armature and front contact; ofv relay 309. The operation of relay 318, extinguishes the lamp3l2iand: releases relay 315'. The operation of-relay3l8 also places retardation coil 31-9 in parallel with. theright hand winding'of relay 316 whichis bridged across the trunk.

The attendant by operating the talking key .331 connects. the talking set. 350. through the normalcontacts of relay 337 across the trunk, for the purpose of receiving thenumber of the desiredfstation. Upon receiving the designationoffthe station, the operator throws key'260 which is individual thereto. It will be observed that when key s'260an'd 331 are thrown, relays 335 and" 337 operate from battery through the windings of said relays in parallel, left'outer' contact of key 331, to ground at the left contact ofstations key 260. If the desired'station be lousyv the attendant will receive abusy tone as follows: from source of tone 222, right armature and! front contact of relay 206; right contact of key"26 0,:conductor 345", left outer armature and {back -c'ontact of relay 336, condenser 351', rightarmature andbac k contact of relay 338, ring'si'de'of the trunk, middle front contactso'f relay 337 through the attendants talking set, through the inner contacts of relay 337, right normal contactsof relay 323, to tery through the right winding of relay 313. In'this case, the attendant may break in on the established connection to irifiirnrth'c subscriber at station 202 that-"a centrall o'ffice' call is waiting. For this purpose the attendant operates the key 361, and relay 338 operates from battery through i'tsiviiid ing', left outer armature and front contact of relay 337 to groun-d at key 361. The operation of relay -338 cuts oft' the' busy tone from the attendants set and with eta tion key 260 operated, 'a circuit is'fclosed to operate connecting relay 2 l8 associated with the subscribefsgline asfjfollows: from ground at the contact of 'key 3'60, right outer armature and front contact of relay 335,1e'ft armature "and front contact of relay 338;

conductor 347, middle contact ofkey 260, I

upper winding of relay 218 to battery at the left inner armature and front contact of relay 335. The operation of relay 218 therefore connects the attendants talking set directly with the subscribers set at station 202. It will be observed that when relay 337 operated, the attendants talking set 350 was transferred from the central office end of the trunk to the local end of the same trunk. The attendant may now inform subscriber 202 that a call is awaiting him from the central office.

If, when the attendant operated key 260, the associated station had been idle, relay 206 would be normal and a circuit would be closed from battery through the winding of relay 203, right armature and back contact of relay 206, right contact of key 260, to ground through the left hand winding of relay 336. Relay 336 operates and closes a locking circuit from battery through its right hand winding, right armature and front contact, right outer armature and front contact of relay 335 to ground at key 360. The operation of relay 336 closes the following circuit: from ground at the left armature and front contact of relay 309, left inner armature and front contact of relay 336, conductor 347, middle contact of key 260, upper winding of relay 218 to battery at the left inner armature and contact of relay 335. Relay 218 locks in a circuit from battery through the winding of relay 204, lower winding, inner armature and front contact of relay 218, conductor 344, left armature and back contact of relay 338, right outer armature and front contact of relay 335 to ground at key 360. The attendant is now in direct communication with the called station, ringing current having been applied to the called line when relay 203 operated and locked, in the manner already described for a local call. The attendant may new release the talk key 331, and station key 260. The release of these two keys releases relays 337, 335, and'relay 313. l Vhen relay 335 releases, guard lamp 311 is lighted from battery through the lamp 311, left outer armature and front contact of relay 318, right inner arn'iature and back contact of relay 320, right inner armature and back contact of relay to ground at the left armature and front contact of relay 309. The lamp 311 remains lighted in this circuit until the called subscriber has answered.

When the called subscriber removes his receiver from the switchhook, relay 313 reoperates as hereinbefore described. The operation of relay 313 causes the operation of relay 323, in a circuit traceable from battery through the winding of relay 323, left outer armature and back contact: of relay left armature and front contact of relay 313 to ground at the armature and contact of relay 316. Relay 323 closes a look-- ing circuit for itself, from battery through its winding, right outer armature and front contact to ground at the armature of relay 316, at the same time releasing relay 313. The release of relay 313 closes the following circuit: from battery through the winding of relay 320, left middle armature and front contact of relay 318, left outer arma v ture and front contact of relay 323, right armature and back contact of relay'313 to ground at the armature of relay 316. Relay 320 operates and locks to ground at the left armature and frontcontact of relay 309. Relay 320 also causes guard lamp 311 to be extinguished which serves as a signal. to the attendant that the called party has answered. Ringing current was cut off when relay 214 operated subsequent to the called subscriber removing his receiver from the switchhook. YVhen relay 203 operates as above described it closes an obvious circuit for slow releasing relay 205 which in turn operates relay 206 thus rendering this line busy to any other calling station.

Disconnect-ion is substantially the same as before described'in connection with a local subscriber calling the central office, the release of the connection being under the con trol of the central oflice operator who can keep relay 316 operated and in turn control the locking circuit of connecting relay 218. In order that the attendant may be called by a subscriber at any local station, she is provided with a line circuit 349, which has controlling and registering mechanism similar to that shown in the line circuits illustrated in Figs. 1 and 2. hen ringing current is applied to the line 349 as a result of such call, relay 353 operates to light the lamp 352 as a signal that a local subscriber desires to converse with the attendant. She answers by operating the key 356 which causes her talking set to be placed in direct connection with the calling'subscribers line. The attendant at the station is provided with dialing apparatus which she manipulates when she wishes to initiate a call to any local subscriber. Should the attendant desire to leave the position, key 362 is actuated. Accordingly, when relay 353 operates upon theapplication of ringing current to the line 349, lamp 352- lights and relay 364 operates in narallel with the right hand locking winding of relay 353 to ground at the contacts of key 356. Relay 364 closes a circuit through the contacts of key 362 and the buzzer 363 to battery. The buzzer 363 gives an audible signal for the purpose of attracting the attention of the attendant. It should also be noted that re-- lay 366 operates in parallel with the right hand locking winding of relay 315. Relay 366 performs similar functions to relay 364- and is operated when the attendant is away from the position when an incoming call is extended thereto.

The attendant'may also originate calls to the central oflice by operating the talk key 331 and central oiiice key 332. The operation of both these keys places ground on the tip side of the trunk for signaling purposes at the central office as described in connection with a local subscribers call to the central oiiice. Having obtained connection with the central o'fiice the attendant may extend connection to any local station in the manner descr1bed for an 1ncom1ng call.

lVh-at is claimed is:

1. In a telephone system, telephone lines, a plurality of connecting means each individual to a dii'l'erent pair of said lines, registering mechanism comprising switch and relay recording devices, and means responsive to the joint setting of said switch and relay recording devices for operating one of said connecting means to interconnect the corresponding telephone lines.

2. In a telephone system, calling lines, a. plurality of called lines, a plurality of concordance with impulses transmitted over said calling line and a relay recording device, and means responsive to the joint setting of said switch and relay devices for operating said connecting means to thereby establish a direct talking circuit between said calling line and said one of said called lines.

4-. in a telephone system, a plurality of 7 subscribers lines, a plurality of switch recording devices each individual to one of said lines, discriminatingmeans individual to said one of said lines and comprisingrelays tor'recording a portion of a numerical designation, connecting means individual to a pair of said plurality of subscribers lines, and means operable in accordance with the 'oint'settin of a switch recordin device b b and said discriminating means for causing the operation of a particular one of said connecting means to establish a direct tall;- ing circuit between said pair of lines.

5. In a telephone system, a calling line, a called line, registering mechanism set in accordance with the complete designation of said called line, discriminating means individual to said calling line and operable in accordance with a portion of said designation of the called line, and connecting means individual to said calling line and to said called line and operable in accordance with the oint setting of said registeringand discriminating means.

6. In a telephone system, a plurality of central office trunks, asubscribers line circuit, controlling and registering mechanism associated with said line circuit, means operable in accordance with a special code dialled for associating said linecircuit with an idle one of said central office trunks, and a plurality of connecting means each individual to a calling line and a central otfice trunk for connecting said'line circuit directly with one of said trunks and for releasing the registering and controlling apparatusassociated with said line circuit.

7. In a telephone system, a plurality of central otiice trunks, a plurality of called lines, a plurality of testing means. each individual to a called line, a plurality of connecting means each individual to a central office trunk and a called line,and.1neans operable upon the actuation of one of said testing means for testing the condition of a called line prior to the actuation of said connecting means.

8. In a telephone system, a plurality of calling lines, a plurality oi? called lines, a plurality of connecting means each individual to a calling and a called line, a plurality of testing means each individual to a calling line, a plurality of registering mech anisms, and means operable upon the setting of one of said registering mechanisms for causing the actuation of said testing means prior to the actuation of said connecting means.

'In witness whereof, we hereunto subscribe our names this 27th day of November A. D..

1923. \VILLIAM I-I. MATTHIES.

IVALTER P. ALBERT.

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