US1543685A

US1543685A - Semiautomatic telephone system

Info

Publication number: US1543685A
Application number: US481747A
Authority: US
Inventors: Ray L Stokely
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1921-07-01
Filing date: 1921-07-01
Publication date: 1925-06-30
Anticipated expiration: 1942-06-30

Description

June 3Q. 1925. 1,543,685 R. L. STOKELY SEMIAUTOMATIC TELEPHONE SYSTEM Filed July 1, 1921 6 Sheets-Sheet 2,

June 30, 1925.

R. L. STOKELY SEMIAUTOMATIO TELEPHONE SYSTEM Filed July 1, 1921 6 Sheets-Sheet 3 Mrenfor Edy L. Sic/way June 30, 19254 1,543,685 R. L. STOKELY sEMIAumoMATIc mswvuous svsma Filed July 1, 1921 a Sheets-Sheet 4 1 "i 1 Mqrginal lnven/br:

Jun; 30, 1925.

R. L. ST OKELY SEIIAUTOMATIC TELEPNQNE SYSTEI Filed July 1. 1921 s Sheets-'Sheet s lnvenfol':

Bay L; dfolcey' June 30-, 19254 R. L. STOKELY SEMIAU'I' MA'I'TC TELEPHONE SYSTEM 6 Sheet-Sheet 5 Filed July 1, 1921 lrzvenfor: Bay A. fifokefy Patented June 39, 1925. i it I nun-ED STATE-5 PATENT oFFics.

nae L. streamer, on FLO RAL Penn; roan, 'ro' wnsrnnn nntccriarc corarnnr. INwRPoBn'rn-n, ornnw Ycnn, n. a conrcancriori on NEW YORK.

SEIv'IIAUillOMATIQ TELEIEH-QNE SYSTEM.

A ication "rila m 1,

To all whom it may concern. Be it known that I RiAY L. STOKELY, a citizen of the United States, residing at Floral Park, in the county of Nassau, State of New York have. invented certain new and useful Improvements in Semiautoma-tic Telephone Systems,"of which the following is a fulhjclear, concise and exactdescription.

This invention relates to semi-automatic telephone systems and more particularly to tell switching trunk circuits. 5 Theobject of the; inrent ion is to provide an improved arrangement for systems of this character. 7

One oglithe features of this invention is the provision of inanual means for associating a calling device with a trunk leading to an automatic ofti'ce,. and means for auto matically disconnecting. the calling device from thetrunk as soon as the. connector reaches the called line terminals whereby the calling device is immediately released for use in. other calls. i

Another feature is, the provision of means for automatically operating. a supervisory signal. before the operator as. soon as the calling device is disconnected, this means being controlled by thecondition of. the called I line, and. operating the; supervisory signal in one manner it the line is; idle and in another manner if it is busy.

'lniore specifically, a *dialingcordf circuit common to the toll position, is provided; a number of toll connecting circuits is also provided. for each. position. Then the toll operator desires to set up a toll call to an: automatic, office; she inserts the calling plugs oi both oi said circuits into a-Hpair of jacks. individual to the trunk. The trunk isthusextended illUOllgll contacts of a relay. in the trunk to thedialin the cord circuit. The operator now turns-the dial. to set the switches at the automatic oiiice'. hen the connector is set on the called line the relay switches the trunk from the dial cord circuit to the connecting; cir= (.'.-U.li' The line if idle causes the supervisory lamp in the connecting circuit to: light.,. and the busy conditiona oi the: line causes the signal to flash. The operator in the: former case by depressing; a key causes tlie cone Hector to apply ringing current to the selected line, Upon the: response oh the called party: the lampis extinguished.

Anothen feature is. the; provisionofmeans 192 Serial No. 481,747.

for automatically lighting a lamp in the cord circuit if any oi the selectors encounters a busy trunkgroupl vAnother feature is the provision of a pair of coin control keys associated with the cord circuit; and if the call is to or from. a pay station the operator after the response of the called party actuates the proper key to apply plus or minus cu'rrent to the trunk from her position. A relay atthe auto matic oi'iice relays this current to the'line tooperate the coin hox nagnet.

A further feature- ;is the provision of meansfor holding. the connector on the line if it is busy, for causing the same to F seize such line as soon as it becomes idle, the seizure of the line causing the calling supervisory lamp to cease flashing and re main steadily lighted as a ringing signal tothe; toll operator, who thereupon actua'tes her ringing key to start the automatic ringing. operation in the toll: connector, the ringing current being cut 0th and the talking circuit completed upon the response of the called party.

Other features will. be. pointed out-Yin coin nection. with the detailed descriptions Referring to the drawings, Fig. 1! shows a. combined. dialing. and coi-n cord circuit and. also apart 01- a connecting circuit;- Fig 2 showsa toll switching trunk circuit; Fig.3 shows an incoming selector ;1 Fig. l shows a toll transmissionselector repeater; Fig. o-shows a toll connector; Fig. 6 shows a toll rotary connector.

The inventioir willbe-more clcarl y understood from a detailed description of the operations involved insctting up a connection.

The toil-l. operator haying received the number of the desired substation from the recording, operator. or in any other suitable manner, touches the tip 0t her plug 100 toflthe tip oi her jack 101', to select" an idle. trunk leading to the automatic ofii'ce; and inserts: the'p'lug intov the jack. Relays 1'02; 200 thereupon operate over the" fol lowing circuit: free pole of battery, relays 102.103 condiicton 1051; sleeves of the=plug and jach re'iay 200,.to ground. Belay 1053 disconnects the busy test conductor and completes: the tip conductor,. and relay 200 prepares certain circuits Whichwill be described latter. Relay 103 is'marginal and does not operate in: this circuit, but only when the plug 100 is inserted into atoll line. of her dial cord into jack 107, which causes relays. 108 and 201 to operate, the latter connecting the

trunk conductors

202, 203 to the

conductors

204, 205 leading to the operators dial 109. Relay 201 removes the short circuit from about the right winding of relay 206, and this relay operates for a purpose which will appear.

' Impulse relay 300 of the incoming selector at the automatic office now operates over the following circuit: free pole of battery, lower winding of relay 300, armature 308, and normal contact of relay 307, conductors 306, 203, armature 209, and alternate contact of relay 201, conductor 205, ring of the jack 107, ring of the plug 106, normal'contact of key 120, conductor 121, relay 110, middle right armature and normal contact of relay 115, conductor 122, impulse contact 112 of the dial, conductor 123, outer right hand armature and normal contact of relay 115, normal contact of key 120, tip of the plug,

L tip of the jack, conductor 204, upper armature and alternate contact of relay 201,.

conductors

202, 305, armature 309, and normal 'contactof relay 307, upper winding of relay 300, normal contact of switch 304, to ground. Relays300 and 110 operate'in this circuit. Relay 110 operates slow relay 113 in a circuit including the innerright armature of relay 115, and relay 113 in attracting its inner right armature locks itself to ground at the armature and alternate contact of relay 108. The impulse relay 300 of the incoming selector in operating energizes the usual slow relay 301, which opens the circuit of release magnet 302, and prepares the circuit of vertical magnet 303 in the wellknown manner. The operator now turns the dial to transmitthe first digit of the desired number. Ofl-normal contact 114 on the dial operates relay 115 which locks through the armature and front contact of relay 108. At its middle armature relay 115 opens the original energizing circuit of relay 110, but this relay remains energized in a circuit including the leftarmature and front contact of slow relay 113. The dial restoring interrupts the loop including the impulse'relay 300 and the relay 110. The vertical magnet 303 receives impulsesfrom impulserelay 300 in the well-known manner and raises the .selectorto the desired level, which auto matically hunts for an idle trunk leading ,to a toll transmission selector (Fig. 4). The operation of the incoming selector (Fig. 3), will not be described in detail, since it is of the standard'type shown and described for example in Patent No. 1,377,225 issued May 10, 1921 to A. J. Seymour. Relay 113 in the dial cord being slow, does not release, as its circuit is intermittently opened by relay 1.10. If, howeve the incoming selector The operator now inserts the plug 106 right armature lights the all busy trunks lamp 116, whereupon the operator withdraws plugs 100 and 106, and waits and sets up the connection later.

Assuming however that the incoming se le'ctor (Fig. 3),'finds an idle trunk, relay 307 operates and extends the trunk conductors 305 and 306through to thetoll selector (Fig. 4), whereupon the impulse relay 400 thereof operates over the following circuit: free pole of battery, left winding of relay 400, outer right armature and normal con" tact of relay 401, normal left contact of relay 402, lower left-hand winding of the repeating coil RC to the lower talking conductor, over the path traced to the dial cord,"returning over the upper talking conductor through the upper left-hand winding of repeating coil RC right normal contact of relay 402, inner right armature and normal contact of relay 401, right winding of relay 400, switch 404 to ground. The impulse relay of the toll transmission selector and therelay 110 are energized in this circuit, the latter maintaining the slow relay 113 energized to prevent the lighting of the all trunks busy lamp 116, and the former operating'the usual slow relay 405 to interpose a break in the circuit of the release magnet 420 and prepare the circuit of the vertical magnet 407. Relay 405 in attracting its inner right armature, grounds tlie release wire 406 leading back to the incoming selec- Ltor to hold up the relay 307 after the slow relay, 301 releases in the wellknown manner. This ground also causes the seized toll transmission selector to test busy. to other incoming selectors. The operator now turns thedial for the next digit and upon the restoration of the dial, relay 400 transmits impulses to the vertical magnet 407 to raise the toll selector to the desired level. The slow relay 412 in series with the vertical magnet 407 operates a relay 421, this'eircuit including off-normal contact 422 and the outer right armature and alternate contact of relay 405. Relay 421 in attracting its left armature, locks itself over a circuit including the armature and normaleontact of magnet 423, and the inner armature and. the normal contact of slow relay 424. Relay 412 also operates a relay 411, this circuit also including the outer right armature and nor mal contact of relay 405. This relay locks up in a circuit includingits armature 413 and the outer right armature of relay 405. .VVhen slow relay 412 releases upon the termination of the vertical impulses the rotary magnet 423 is operated over a circuit in- ,i'llG first trunk, and at the end of its stroke 1 opens the locking circuit or relay 421 which releases, opening the circuit of the rotary magnet in the \vel leknomn manner.

grounded and: relay. r21 again operates over a circuit includingthe. oil? nor-meal switch 4:22, arinature and normal contact of the rotary magnet, conductor 426, armature 4:17, outer right armature of relay 4-24,, conductor 416. to the grounded-test multiple 425. Relay l21 againv closesthe circuit of the rotary magnet and locks, up in the circuit pro-yr. ,ously traced. The rotary mag-net steps the brushes to, the nezgt trunk.

This interaction between the relay 4-21 and magnet 423 co tinues; until an. ungrounded test multiple is reached, whereupon. the relay 5:98 operates over a, circuit includingrelay 42-1, swi h. 22, normal on ac o mag-n t 4 23, conductor 4,26, relay 4,055, to ground at .the outer right a mat and m o t ofrelay 405, Relay 408 extends the con,- gluctors 4.09, 410. to. the in' pulse relay 500 of the toll connectorwhich iia op rates oyer the f ll "11;; circui pole f bat ery,

, M lne w o: conductor 5 12, arInatu 51-3 andynornral contact relay 59 lower talking concluo tors (Figs. 5 and; 1), lower right winding ojfi repeating coil EC, left armaflrre anal trout contact 015 relay-all, left W ling of relay 4e18, upper right wh rling oli the repeating coil RG, -upper talking. coudtrcto-rs l and 5);, arnrature 51:4 and normal contact of relay 5 5. left winding of r c 5.00,, to, gr und. Rel y 1:1. is n eased. clue to the seizure of the toll connector since Contact ll l isI a IRQkBrbQillOIEwblfGfilfi cont-act. Relay 411 is; thus held; up oyer the. tel-lowing circuit: free polev of battery, relay l11, augngat-ure ll -3 vand its front; contac contact ll t, c n r l: l ad 1 c nduc 0, arm-rat-ure 515311161 normal cont-actor relay 505, sleeve conductors 5,06, 416', armaturell/Z, and altern Contact of relay 108- to, ground at the outer right armature of relay 1305. Then the loop circuit was closed including t e letlt winding:- of

relay

418, 1 circuit was s1; iultaneously closed, through the right winding. 015 sa d relay at the lower-most arinat e and; front coutact 0t relay 408. These rind ings neutralize. each otherand consequently relay 4:18 remains inert. Relay 500 operates slowrelay- 591' over a circuit including thevupper winding of said relay and the lowerm st armature and back contact of relay 505. Relay 50]: in attrac ing its uppermost armature locks. itself to the. sleeve Willj. 506 by Way of the armature 51 51 ofthe. relay 5.05, and connects the terlli the, first trunk is busy, its test. multiple 425 is,

tical magnet 502 to. the hack contact of the impulse relay 5.90, and opens the circuit of release magnet 503. lfhe operalornorv turns the dial tor-the tens digit, and the relay lOO, the circuitof which; has been preyigously traced repeats the impulses to relay 5,00 which transmits impulses to the ertical n egnct 502 to .l'ilh: the connecdesrrctl level. The usual sloiv relay. is in series with the rertical 711mg The first impulse tor the Yer-tical net passes lay way of contact 517 of t ell-normal switch 516, and; the succeeding inrpul scs pass lay way of contact 5118, and the armature and front Contact 01 slow relay 4307..

Upon the cessation of the vert' pulses, relay 50?; release, connec V. N in let 508' to the back contact of tire impi: so relay 5G0; 'l-he operatornom t the dial for theunits digit to rotate the brushes into contact with the desired line. The slow relay 509 in series with the rotary magnet upon its operation energizes slow relay 511(Jlfl-011'1 the ground on the sleeae wire 5.06:. Relay 509 in attracting; its left armature operates relay 519 which loclts up to the sleeve Wire 506.- When relay 509 releases, its right ari-rrat-ui'e connects relay 5-11 over the inner right armature of relay 510 which if the selected line is busy, locks up to, the ground at its. test multiple. Relay 5111 operates from this ground and reverses the direction of the current flow in, the trunk leading back to the relay 418. in, the toll transmission selector (Fig. ll which causes the polarizecr relayllS. to GP! crate. Relay 18 at its armature 431,9- op" operates relay 402 fronr the ground at the lowermost armature of relay 1508. lie-lay e02 reverses the direction oli' current flow in the trunk leading back to: the dial and coin cord circuit. This causes the polarized relay 111 to. operate, and ren oycs the short-circuit from about relay 117, wherer upon the marginal relay 201, releases, d;is connecting the trunk; 202, 2-03 from the dial cord and extending it to the connecting cord. Relay 4:37, being marginal does not operate at this time. Relay :1 in releasing locks up relay 206. and novides a circuit for relay 208 which operates and closes. a break in, the ring conductor; The supervisory lamp 119 in the connecting circuit now flashes. to in.- dicate the busy conditionv of the desired line. This is brought about in, the. 't'ollom 'ingrnianner: Relay 4:18 in attracting its innermost left armature, connects an interrupter 1-27 to. the lower Winding of relay 128, the circuit being as. follows:- innerimst armature of relay 4B8, lower-Winding o f the relay 4-28, armature 4:29, liront contact of relay all]; to ground at the left armature and: front contact 0:1 relay 4,00. Relay 228 in intermittently attract ng its armat re app ies a i it) wire 506. Relay 505 in attracting its arma ture 515 opens the circuit previouslytraced for the relay 411. Relay 411 in retracting its armature 429, opens the circuit including the interrupter 427 and relay 428, relay 428 remaining inert, causing the supervisory lamp 119 to remain steadily lighted. This serves as a ringing signal to 'the toll oper ator, who thereupon depresses her ringing key RK to impress ringing current on the trunk to operate'relay 432 over the trunk conductors in series. Relay 432 in attracting itsarmature operates relay 428 over a circuit including the armature 433, lower winding of relay 428, armature 429 of relay 411, and armature 434 of relay 413. Relay 42Siu attracting its armature 430 opens the circuit previously traced for the relay 501 which releases and applies ringing current to the selected line. Upon the response of the called party, relay 501 operates in the wellknown manner and again locks up to the grounded control lead 504 and completes the talking circuit. Relay 435 now operates in series with the called line over the following circuit: free pole of battery, le'tt winding of relay 435, relay 436, left-hand armature and back contact of relay 411, lower right-hand windings of the repeating coil, lower talking conductor, returning over the inner right armature of relay 411 to ground at the right winding of relay 435. Relay 436 operates relay 401 which in attracting its right armatures removes battery from the trunk conductors leading back to the connecting cord, and the outer right armature closing a bridge to hold relay 400 operated. The removal of battery from the trunk leading to the connecting cord, releases the supervisory relay 118 1 which extinguishes the lamp 119 indicatingto the operator that the called party has responded. Talking current is fed to the calling line over the windings of the repeating coil at the distant otfice (not shown).

If the substation A to which connection has been made is a pay station the operator will communicate with the called party and inform him of the coins 'to be deposited. She checks this by the sound frpm the gongs which the coins strike in passing through the chutes ot the coin box in the line.

well-known manner. The operator now lfeinserts. the plug 106 into thewjack 107. Since relay does not operate until the dial is moved 003 normal, relaylll is short circuited'and does not operate, consequently relay 117 does not operate. Relay 201 however, operates to extend the tip and ring of the trunk to the cord circuit. The operator then 'actuates key 120, which connects a 110 volt source of currentto the ring of the trunk to operate relay 437 in the transmission selector. The circuit for relay 437 is as iollows: i'rec pole of battery, contact of key 120, ring of the plug 106, ring of the jack 107, ari'nature 209 of relay 201., ring conductors 203, 306, armature 308, alternate contact of relay 307, ring conductors Figs. 3 and 4), lower left winding of the repeating coil RC, conductor 438,

left armature and alternate contact of relay 402, relay 437 and itsnormal contact,c0nductor 439, inner right armature and front contact of relay 401, conductor 440, right arm ature and front contact of relay 402, conductor 403, upper left winding of the re peating coil RC, upper talking conductor (Figs. 4, 3 and 2), upper armature and alternate contact of relay 201, conductor 204, tips of the jack and plug, contact of key 120,

conductors

124, 125, normal contact of key 126, conductor 127, normal contact of key 128 to ground. Relay 437 in attracting its armature 441 locks itself to ground, and in attracting its armature 442 transfers the tip of the trunk from its normal connections to the tip and ring of the called It the called subcribers receiver is on the switchhook, the operating circuit for relay 437 leads through the right winding of relay 400 to ground. Key 120 while actuated remains in its actuated position until released by the operator. The operator now depresses one of the coin keys 126 or 128, which will impress plus or minus 110 volts upon the tip of the trunk. Relay 437 being operated, permits this current to flow over the talking conductors in parallel to ground, through the polarized magnet in the coin box. This coin box may be of the type shown and described in Patent No. 1,043,219, issued Nov. 5, 1912 to O. F. Forsberg. The deposit of the minor coins connects the polarized magnet to ground. this ground is present, relay 130 in the cord circuit will operate, lighting the lamp 131 to indicate to the operator the condition of the circuit; that is to say, if no coins have been deposited, relay 130 will not operate and the lamp 131 will not glow. The "release of the coin key in releasing the magnet causes the magnet to disconnect itself from ground, thus opening the circuit of relay 130, which extinguishes the lamp 131. The operator new releases the key120, whereupon the relay 437 restoresand completes the talking circuit in the transmission selector.

The operator now withdraws the plug 106 whereupon the relay 201 releases, completing the talking circuit at the trunk (Fig. 2). The subscriber at substation A by actuating his receiver hook causes relay $36 to intermittently operate relay 401, which applies and removes battery from the trunk, thus intermittently operating the relay 118 to-flash the lamp 119. Inasmuch as relay 1-00 is holdup either through the bridge in eluding the resistance when. the receiver hook is up, or over the trunk leading back to the connecting cord when the receiver hook is down, relay 105 is maintained energized to prevent release.

l Vhen the party at substation A restores the receiver, relay 436 releases, releasing relay 401 which replaces battery on the trunk operating relay 118 to light the lamp 119. When the operator desiresto break down the connection she withdraws the plug from jack 101 which places relay 210across the trunk by the release of the left armature of relay 20.0. Thus, and if the subscriber's receiver is still off the hook, there will be no battery on the trunk, and relay 210 will not operate, Relay 208 remains operated to apply battery through its outer armature and the inner right armature of relay 200, to the sleeveof the jack 101 to cause, this trunk to test; busy. lVhen the subscriber hangs up. his receiver, battery is applied to the trunk as described, which auses rel-a 210 to operate to open the looking circuit of relay 208, whereupon relay 208 releases, opening the loop circuit including relay 210 which releases relay 400, and since the relay an is at thistimev inert due to the subscriber having replaced his receivcr,-relay 105 is released. Relayl05 at its inner right armature removes ground from the sleeve wire 4106 to deenergize switching relay 307. This relay at its uppermost armature closes the circuit of release .niagnet 302 to restore the incoming selector. The retraction of the left armatures of relays 4-05 and Q00 operates the release magnet 420 of the transmission selector. The release of the transmission selector releases relays 505, 501 and 519. Release of the relays 505 and 501 completes the circuit for the release magnet 503 of the connector from. free pole of battery, magnet 503, off-normal switch 516, lower- ;iost armature, and normal contact of relay 601, left armature and back cont-act of relay 500, lowermost armature and normal contact of relay 505 to ground.

Referring now to Fig. 6, it shows a toll rotary connector, that is to say, a connector wherein private branch exchange lines terminate. This circuit isso arranged that if all thetrunks correspoi'iding to the, called number are busy, the switch will wait in front of the trunkgrou a and cause the supervisory lamp 119 to flash. When one of these trunks becomes idlethe switch will move along the bank and seize this. trunk automatically, and upon the seizure of such trunk will cause the lamp 119 to remain steadily lighted as a ringing signal. The operator will then depress her ringing key and-cause a ringing operation to start. The remaining operations are the same as those traced in connection with the toll connector. The operations involved in raising the toll rotary connector to the desired level are exactly the same as those described in. the case of thetoll connector, the relay 600 trans, mitting iinpulses to the vertical magnet 602 and the relay 607 Onthe termination of these impulses closing the circuit of rotary magnet 608. The rotary magnet then in response to impulses from the impulse. relay 600 rotates the brushes to the first trunk. Slow relay 609 energizes upon the first ro- ,tary impulse and operates relays 610, 620, and 619. Relay 619 looks up to the. sleeve wire 606. If all trunksare busy, a series of chain relays 621, 622 etc. extends the ground on the last test multiples 628, 624 to the multiple 626. Relay 610 at its. inner left armature locks up to ground at multiple 625, and at itsinner right armature holds relay 620 operated from the ground on testmultiple 626 to prevent the switch from stepping. Relay 610 at its. outer right armature operates relay 611 over the following circuit, free pole of battery, relay 611, left armature and front contact of relay 620, outer armature and front contact of relay 610, lower armature and front contact of relay 6.19, left armature of relay 609 to ground on the sleeve wire 606. Relay 611 reverses, the direction of current flow in the trunk leading back to the relay e18, just as in the case of a busy ordinary line, whichrelay 4-18- in operating, connects the interrupter in. circuit with the relay 128, which intermittently applies ground in shunt of the supervisory relay 118 to flash the lamp 119 before the toll operator. As soonas one of the trunks becomes idle a chain relay releases disconnecting the ground from test multiple 626. which causes the release of relay 620. If this idle trunk is the one upon which the switch is resting the removal of the ground from its test multiple 625 releases the slow relay 610, whereupon the relay 605 operates over the following circuits: free pole of battery, relay 605, outer right armature of relay 610, lower armature and front contact of relay 619, left armature and back contact of relay 609 to ground on the sleeve wire 606. Relay 605 in attracting its uppermost armature releases relay 4111 of the toll transmission selector which in retracting its outermost right armature holds relay 402 operated independently of relay 118, and in 620 to the relay 627, relay 610 remaining locked up on this ground over its left winding. Relay 627 in attracting its left armature locks up over the backcontact of the rotary magnet 608, and at its right armature transmits an impulse to this magnet; The

rotary magnet at the end of its stroke-opens the locking circuit ofrelay 627, which in releasing its right armature, opens the circuit of the rotary magnet; This interaction continues, and the rotary magnet steps the switch aroundnntil it reaches the ungrounded test multiple 628, whereupon relay 610 releases, operating relay 605, with the results described. The operator in re sponse to the lighting of the lamp operates her ringing key, which energizes relay 432 to operate relay 428, which'in attracting its armature 430, releases relay 601 to start the automatic ringing operation. The remaining operations are the same as those described in the case of the toll connector.

hat is claimed'is:

1. In a telephone system, a trunk terminating at one end in a pair of jacks and at the other end in an automatic switch, other automatic switches, a cord circuit and a connecting circuit for connection with said jacks respectively, a dial associated with said cord circuit for-settingsaid switches, means for automatically disconnecting said trunk conductors from the cord circuit and con necting the same to the connecting circuit upon the selection of the called line, and means for maintaining the setting of the switches after said transfer from the cord circuit to the connecting circuit has'taken place. p

2. In a telephone system, atrunk terminat ing at one end in a pair of jacks and at the other end in an automatic switch, other automatic switches, a cord circuit and a connecting circuit for connection with said jacks respectively, a dial associated with said cord circuit for setting said switches, means for automatically disconnecting said trunk conductors from the cord circuit and connecting the same to the connecting circuit upon the selection of the called line, means for maintaining the setting of the switches if the called line is in busy condition, a supervisory; signal, a supervisory relay in the connecting circuit, and means controlled :by the idle condition of the called line for operating said relay to control said signal.

3. In a telephone system, a trunk terminating at one end'in a pair of jacks and at the other end in an automatic switch, other automatic switches, a cord circuit and a connecting circ'uitfor connection with said jacks respectively, a dial associated with said cord circuitfor setting said switches, means for automatically disconnecting said trunk con ductors from the cord circuit and connecting the same to the connecting circuit upon the selection of the called line, a supervisory signal, a supervisory relay in the connecting circuit, means actuated bythe busy condition of the called line for causing said supervisory relay to operate said signal in one manner, means actuated by the idle condition of the called line for causing said supervisory relay to operate said signal in another manner and means for maintaining the set ting of the switches regardless of the busy or idle condition of the called line.

4. In a telephone system, a trunk terminating at one end in a pair of jacks and at the other end in an automatic switch, other automatic switches, a cord circuit and a connecting circuit for connection with said jacksrespectively, a dial associated with said cord circuit for setting said switches, means for automatically disconnecting said trunk conductors from the cord circuit and connecting the same to the connecting circuit upon the selection of the called line, a supervisory lamp, a supervisory relay in the connecting circuit, means actuated by the busy condition of the called line for causing said supervisory relay to flash said lamp, and means actuated by-the idle condition of the called line for causing said supervisory relay to steadily light said lamp. 5. In a telephone system, a trunk terminating at one end in a pair of jacks and at the other end in an automatic switch, other automatic switches, a cord circuit and a connecting circuit for connection with said jacks respectively, a dial associated with said cord circuit for setting said switches, means for automatically disconnecting said trunk conductors from the cord circuit and connect ing the same to the connecting circuit upon the selection of the called line, a supervisory lamp, a supervisory relay in the connecting circuit, means actuated by the busy condition of the called line for causing said super visory relay to flash said lamp, means actuated by the idle condition of the called line for causing said supervisory relay to steadily light said lamp, and manual means in said connecting circuit adapted when actuated to cause ringing current to be applied to the called line from said connector.

6. In a telephone exchange system, a toll board, an automatic office, a trunk having two conductors only terminating at said board in a pair of jacks, and at said automatic ofiice in a selector, other automatic switches, a cord circuit and a connecting circuit at said toll board for connection with the jacks respeccuit, a supervisory lamp, means controlled by the busy condition of the desired line for causing said relay to flash said lamp, means controlled by the idle condition of the selected line for causing said relay to steadily light said lamp means actuated by the operator to cause ringing current to be applied to the selected line, and means actuated by the response of the called party for disconnecting said ringing current. and extinguishing said lamp. g

13. In a telephone system, an operator's position, a trunk terminating thereat in a jack and at its other end in a selector, other automatic switches, a cord circuit and a connecting circuit for connection with said jacks respectively, a dial associated with the cord circuit for setting said switches, a relay in the trunk-operated upon the connection of the cord circuit to the trunk to connect the trunk conductors to the dial, a resistance in the cord circuit normally short-eircuited, a relay operated upon the selection of the desired line to remove the short circuit from about said resistance to cause said relay to release and connect said trunk conductors to said-connecting circuit, a supervisory relay in said connecting circuit, a supervisory lamp, means 'controlled'by the busy condition of the desired line for causing said relay to flash said lamp, means controlled by the idle condition of the selected line for causing said relay to steadily light said lamp, means actuated by the operator to cause ringing current to be applied to the selected line, nieans actuated by the response of the called party for disconnecting said ringing current and extinguishing said lamp and-means c011- trolled by replacement of the receiver by the called party. for lighting said lamp.

14. In a telephone system, an operators position, a trunk terminating thereat in a jack and at its other end in a selector, other automatic switches, a cord circuit and a connecting circuit for connection with said jacks respectively, a dial associated with the cord circuit for setting said switches, a relay in the trunk ope-rated upon the connection of the cord circuit to the trunk to connect the trunk conductors to the dial, a resistance in the cord circuit normally short-circuited, a polarized relay in said cord circuit controlling said short circuit, and means actuated by the selection of the called line for reversing thecurrent flow through said relay to operate the same to remove said short circuit from about said resistance to cause said relay in the trunk to release and connect said trunk conductors to said connecting circuit.

15. In a telephone system, a trunk terminating at one end in a manual switch and at its other end in an automatic switch, other automatic switches, a cord circuit ter:

' place.

minating in a manual switch for connection with the manual switch of the trunk, a

associated with said trunk after thetrausfer oi the trunk from thecord circuit to the connecting circuit.

16. In a semi-automatic telephone system, telephone lines, a cord circuit, trunk lines accessible thereto, a calling device adapted to be associated with said trunlccircuit by meansof said cord circuit, a connecting circuit, and means controlled by the selection of the called line for auton'iatically disconnecting said calling device from said trunk circuit, and for connecting said trunk circuit. to said connecting circuit and for maintaining the called line connected to saidtrunk after the transfer from the cord circuit to the connecting circuit has taken 17. In a semi-automatic telephone system, telephonelines, a cord circuit, a trunkcircuit, a dial, manual means for associating said dial with said trunk, automatic switches controlled by said dial for extending the trunk circuit to a telephone line, a connecting circuit having a supervisory signal,

a means controlled by the idle condition of the called line for automatically disconnecting sa d dial from said trunk and operating said supervisory signal and means controlled by the busy condition of the connected telephone line for automatically disconnecting said dial and maintaining the telephone line connected to said trunk.

18. In a semi-automatic telephone system, telephone lines, a cord circuit, a. trunk cir cuit, a dial, manual means for, associating said dial with said trunk, automatic switches controlled by said dial for connecting a trunk circuit to a telephone line, a connect-- ing circuit having a supervisory lamp, means controlled by the busy condition of the ltll) llO called line'for automatically disconnecting said dial from said trunk and flashing said lamp and maintaining the called line con nected to said trunk.

19. In a telephone system, a toll trunk terminating at one end in a manual switch and at its other end in an automatic switch, other automatic switches including a 0011-. nector, private branch exchange trunks terminating in said connector, a cord circuit terminating in a manual switch for connection to the manual switch of the trunk, a connecting circuit, a. dial associated with said cord circuit, and means for automatically disconnecting the trunk conductors from the manual switch of the trunk and for connecting the trunk conductors to said connecting circuit upon the selection of the first private branch exchange trunks.

20. In a telephone system,atrunk terminating at one end in a manual switch and at its other end in an automatic switch, other automatic switches including a connector, private branch exchange trunks terminating in said connector, a cord circuit terminating in a manual switch for connection to the manual switch of the trunk, a connecting circuit, a dial associated with said cord circuit, means for automatically disconnecting the trunk conductors from the manual switch of the trunk and for connecting the trunk conductors to said connecting circuitupon the selection of the first private branch exchange trunks, a supervisory lamp in said connecting circuit means whereby said connector automatically tests said private branch exchange trunks, and means operated upon the selection of an idle private branch exchangetrunk for lighting said supervisory lamp.

' 21. In a telephone system, a trunk terminating at one end in a manual switch and at its other end in an automatic switch, other automatic switches including a connector, private branch exchange trunks terminating in said connector, a cord circuit terminating in a manual switch for connection to the manual switch of the trunk, a connecting circuit, a dial associated with said cord circuit, means for automatically disconnecting the trunk conductors from the manual switch of the trunk and for connecting the trunk conductors to said connecting circuit upon the selection of the first private branch exchange trunk, a supervisory lamp in said connecting circuit, means whereby said conneetor automatically tests said private branch exchange trunks, means operated upon the selection of an idle private branch exchange trunk for lighting said supervisory lamp, and means automatically operated if all the private branch exchange trunks are busy for flashing said supervisory lamp.

22. In a telephone system, a trunk terminating at one end in a manual switch and at its other end in an automatic switch, other automatic switches including a connector, private branch exchange trunks terminating in said connector, a cord circuit terminating in a manual switch for connection to the manual switch of the trunk, a connecting circuit, a dial associated with said cord circuit for setting said switches means for automatically disconnecting the trunk conductors from the manual switch of the trunk and for connecting the trunk conductors to said connecting circuit upon the selection of the first private branch exchange trunk a supervisory lamp in said connecting circuit, means whereby said connector tests said private branch exchange trunks, means operated upon the selection of an idle private branch exchange trunk for lighting said supervisory lamp, means automatically operated if all the private branch exchange trunks are busy for holding the connector set on the first trunk and for flashing said supervisory lamp, and means operated when one of the private branch exchange trunks becomes idle for causing the connector to select and seize the same and for steadily lighting said lamp.

In witness whereof, I hereunto subscribe my name this 28th day of June A. D., 1921.

RAY L. STOKELY.