US1575272A - Telephone system - Google Patents

Description

' March 2,1926.

Filed Oct. 51. 1923 6 Sheets-Sheet 3 Match 2 1926;

H. w. NEZLL TLPHONE SYSTEM March 2 1926. V 1,575,272

H. w. ONEILL TE}LEPHONE SYSTE.M Filed 06%,. 31, 1923 6 Sheets-Sheet 5 H. W. ONEILL TELEPHONE SYSIEM March 2 1926.

Filed Oct. 31, 1923 6 Shets-Sheet 6 Patented Mar. 2, 1926.

TEIEBHONE SYSTEM.

Application filefl=0ctober*3l,"1923. Serial No. 671;871L

T0 aZZ w7mm it may conm:

Be it known that I,HENRY W. ON1LL, a citizen of the United States of Anherica, residingat B rooklyn, in;the oounty of Kings and. Stnteof New York, have invented:oer tain new and usefu1 Improvements in Telephone Systexns, of Whih the following is a full, clear, concise, and exact description,

This invention relates to :teleDhone systemsand more particulafly to' systems for autom utic a1ly establishihg -connections in the handling of to11 trafiid.i

'lheprincipal object .oi Lhis.invention:is to provide an improved system xvheneby machine switehing operations mayrbe more expeditiously, reliably and: :eoonomicaily carriod out overtransmissionlies Such as telephone toll circuits.

A featureof this invention relates :to rthe en1pioy1nent of one:or more;aiternating our- 1GDS to fo1m a single inipulse intenval for transmission over a line circuit to efcet control of switohing equipment on the xve]l known numericaiimpuise basis. 4

Anothen feature: of the invention resides in an interrelation ofequipment.at a nontrol o1* sending :point= relative to equipment ata distant switohing point, whereby successive impulses of alternating ouvrent ;may "be releasedw from the -sending pointonly fo]loving:1eeeption :of a;:revertive impulse ofi aiternating: ourrenh 1eieased ifrom zthe switching 01' translating point. A turther eature of this invention me- ]ates to the employment of alternatinggcur- Tents for-the control of supenvisonysigals on the somailed positive supervision -basis in a mannen to -render voies ourrents inefiectivo wi.th su ch signals,- and to: the+ urther employment. of.such ournents:in a manner-to place the breaking clown of a connection entireivunden-control of anoriginating operatmn: V

A sti1l Liuithententure.0f tho invention a manner that the first impulse (51 anveode of impuisosperformsa dualfiinmtion in that it first conditionsthei'eeeivingsystein :f'or the reception, of impulses, a ancLthen, :following such conditioning said first impulse and subsequentimpnlses are translated into impulses to control sWitohing-or soleotive opemtions.

m udditional featnre of the invention ment; in association with a t01l'onlong dis tance lino at a switchingpoit tnereon, may in eflect, be substitutedior an .automatic subscnibeis station associated with substantiallany fofm of automatiC switchihg equipment tocontrol said automatio switching equipmentl A further'adflitional feature of this invention relates .to provision for so+called two-way service 01 operationeiativoto the oompietwnof connections in either direction over a line circuit.

Another additionaifeaturo of the invention pnovides that a signal corresponding with rzso-oavlled dialing: tons must emanate from inward automatiosWitches 1:olldWing seizure theredf, bef'ore -waiting impuiss ma be released t0 efi'ct response -'o-f fsuoh switchs. 7

Other featureS of the invention WiH hareinafter ap13ear.

In-carrying out the present invention a system of keys commonly ,referred to numericai, or 'digitkeys is provided at an originacing tell position. Byactuating these: keys in any predetermined,jorder, a contre-1 operator may write or record any desired code whereby resultihg;opemtions automatically oarried ont,may extend-a con mention from ai1associated link or cord Circuit to any desireddistant point .01 telephone v station. 4

.iz;Lsystem of relays, coordinatod on the plan :commoniy referred to as conting relays,in association with the nu1ne1i8al keys, are controlled by revertive impulses 0f altenn ating 4 eurrent released from a switch ing point on a line circuitin such a manner thatimpulses 'formed of altmating entrent,

at single=frequenoy or prenmtntions of CUIIGDSVO ditferent freqnuoies, may have-been seleoted under controlof the nu- -merical keys,- may be released from an or1g1nahiig position to traverse a line o1rou 1t. At a sw1tchmgj or mwardpomt on a lino,

devises or eirouittuned fox; respective reoept1on-oi 1ncom1ng impuises of alternatmg ourrents of difl'erent frequenies, eflect se- ;leotionin a first;groupof relays to,' in turn,

establishrespective predetermined set-- t1ngs? on select1onsm a systemofcount1ng relaysfrom which oorresponding numbers of impu1ses may. be releasedflto cause entrent ohan;;esin aloo 7 circuit whereby thooontrol relates-te an arrangement winereb.*ejfl1p;-

In establishing a connection, the first impulse o alternating current from an originating point initiates switching operations to transfer a loop circuit extending to machine switching equipme'nt, from the toll line to paths under control of the lastmentioned counting relays. The first effect of such circuit transfcr is to close the loop circuit and thereby initiate preliminary ie sponses in the machineswitching equipment whereby such equipment will be conditioned for the recePtion of selective impulses. As concerns the machine switching equipment, the transfer operation, in eifect, may be said to correspond with the lifting of atelephone receiver from its switch hook on an instrument joined to an automatic ,system and equipped for automatically establishing tele phone connections with other local stations 01 points, and in which, at such instant as switches may have responded and moved to such point as may render them rezidy for the reception of impulses from a dial at the instrument, an alternating current common ly referred to as dialing-tone will be impressed on the loop and manifested in the telephone receiver. In the present systcm, such dialing-tone current istranslated by an alternating current relay in the switching paths already referred t0, to place the loop circuit under control of the counting relays as further controlled by a system of stepping relays. Following release of a last impulse efi'ct corresponding with any setting of the countingrelays, a momentary impulse of alternating current will be released from the inward point to cause the'counting relays associated with the distant numerical keys to release a next impulse of alternating current. Such cycle of operations may be repeated until the last impulse of a,code

series has been received from an originating point. Following this, the numerical keys and associated equipment will be automatically restored to normal and disconnected from the cord circuit, while the circuits at such point Will be switched to the normal or talking position.

During the release of the devices at the outward point, a momentary impulse of alternating currents is sent over the line to effect re-transfer of the main conductors in joining the line to a loop circuitas estab lished through machine switching equip ment to the line of a station or point under call. Such circuit re-transfer also causes a momentary impulse of alternating current t0 revert over the main line and eflect dis play of a supervisory signal to indicate to' sponse at a called station. an impulse of alternating current becomes effective t0 ext1ngurSh the superv1sory signal while disconnect or replacement of a rece1ver on its hook switch at a called point will cause the supervisory signal to be energized.

A connection may be retained until disconnection at an outward position takes place. This reSults in application of alternating current to the line for eiecting restoral of the devices at a distant inward point. Due to such restoral, an impulse of alternating current will revert over the line to clfect disconnection of the alternating current and rstoral of the cquipmcnt of the line circuit at the originating position.

A preferred form of recep tor or trans lator for the alternating currents employcd in the present system, may comprise an electromagn etic device tuned to respond to alternating currents of a particular frequency. The device may be of the type employing an inertia elemerit normally establishing a circuit in a manner to permit accelcration of this element under the influence of alternating current to disable the circuit, 'A dcvice of this nature is shown in copending appli. cation Serial No. 526,152 filed December 31, 1921, (H. W. ONeill), and for convenience, devices of this type have been shown and will be described-or use in the present system.

This invention is illustrated in the accompanying drawings, in such a manner that when Fig. 1 is positioned above Fig. 2, Fig. 3 to the right of Fig. l,Figs. 4: and 5 exten'ding to the right of Fig. 2, with Fig. 6 below Fig. 5, a complete arrangement for carrying out the features of this invention will be diagrammatically illustrated.

In detail, Fig. 1 shows a digit keyboard associated with an outward toll operators position;

Fig. 2 shows a group of counting relays associated with the digit keys of Fig. 1;

Fig. 3 shows a group of frequency selecting relays also associated with the digit keys of Fig. 1 'at the outward operators position;

Fig. 4 shows a portion of a cord circuit C at the outward operators position, a calling subscribers line A which may be associated with the operators cord circuit in any well known manner, and outward equipment D" of a toll line L;

Fig. 5 shows receiving equipment at the distant or incoming and of the toll line irom which a trunk line L extends to an automatic exchange of any well known type, and

Fig; 6 shows a systemof selectable relays E and a group of counting relays F ssociated with the receiving equipment of Fig. 7 is a diagrammatic showing of a complets system by means of which a connection between a calling and called sub scrfloer may be made in accordance with th1s invention. Th1s figure shows calling and callcd snl2scribefis lines an outgoing opcrators position a toll lino oonnectcd to an antomatic cxchango whcrc a trunk line is showntorminatingin antomatio switches whercbya called sabsclibcrs lino maybc machcd.

Dilicront freqnencies of tlxc altcrnatflg currcnts 1ncntioncd. aboveanay lo of oithcr 10W 01' high range, althongh definito freqncncics have l3con assigncd in tlxc drawings to tlio various sources ofaltornating ouvrent.

In a more dotailoddcscriptionof tho Systcn1 or'ca11 ing out the fcatnras of this invention let it* bc assurned that a tollop eracox at an ontward position (Figs- 1 4) has roceived aticket in any W611 lmownnwan nm, iridicaiiigflii a. connoction is desircd by a station A. (Fig. 4) with a distant point 01 station 01 an automatic systom (mot shown), which station, for convenicnco of dcscriptiom will b c designatcd as Sterling 1590.

The digit kcys (Fig. 1) have, foxcon vonienco, oeuf designatcd in accordance witha Well known systcin wl1c:*ob tl1c first th1e e iettoi's 01'" the name of an ofiicoand tl1c mnncrical"digits correspondingWith tho cxchange nnmloer of the called station may ho sat un. Inzaccordance With this systcn1 the code for. tho present assumed call willbc represontcd 1337 the digits S-TE 1590 winch maybe set np loy de prossing -koy 7 in the first or ATOW, key 8 in the second or B 10W, kcy 3 in the tlflild or C 1OW and keys l, 5, 9 and;0 in the fourth or T11 roW, fiftho1 H 1OW, s1xth 01' "'1 1OW and seventh or U 1OW, respectively. The lasttlnee rows cf keys correspond,- as indicated; with station hundreds 8H, station tons ST and station nnits SU, may be employod more pa1ticlarly. EOB rcaching extension stations in a private automatic oxchangc,- thcse kcys Will notbc cmployed and therefo1o may be disregarded in the pmscnt assnmcd cal]. For the sake of clearncss, the contact points of the keys assnmcd as now dep2essod have bccn shown in hcavy 01' shadd marking. The doprossed l eys Will look in their actnatodpositions nndo1 control of a1nagnet 115.

A plus; 4101may 110W ho inscrtcd into a jack 102 of a tol1 lino L. This complotcs a slccvc circuit f1om gtonndod batterv ovcr tl1c parallcl connoctod local contacts 01: 1cla vs 405 to 4108, l .ey 4:09. nppov contacts and np1 ort windin of a Polar; rclay 4-10; conductov l-l2. thcslocvc contacts of: the 1olug:- and jack to groxmd tlnough thc WindihgS of relays 420 and 425. The latter relays now opora. Rclay 425 .operatcsin advanceof 1clay 420which is slow-to-0Pcrace and also slowto-rcloaso. This prevents response of the rclay 430 at this time.

The loft l1and contacts ofrclav 425 connect battery to a bnsy bus condnctor 433 to operate busy signals 131 and 182 which:1na.y bc assmncdato-boin association '\."ll1ll'lllfi* plo jacks at. othci* positions of thc switchboard not shown.

Battery. conncctcd tothe lca'd 4323 also causes relay 43510 opcratcin a circuit which may: be traced throngh contacts 480 of in ward cqnipmcnt .437 whichis not shown in dctail; Rolay135 in opcrating,'switchcs tl1c .toll: lino Lutronr ti1o inward oquipnxont 4137 to the tipa11dfring sprini; mcinbcrs of thojack 402 by way. of thc uppcnand iowcr inner normal contacts et 1ol ay 430.

The p1irpose o:t thc loft baud contacts of ti1o relay 4120 in parallcl with tise lclt hand contacts et relay: 425 is to momentarilycon: tinno tl1e busy signals 431, 432 operated; folloWing the rcn1oval of the ping 401 tron1 tho jack.402 as will be prosently doscribcd.

It wilLbc notcd that the winding o*t rclay 440 is shnntod-by a patln which may bo traccd Ton grounded: battery. ovc1: thc contacts of rclays t05to:408, key 409, and thc nppcn alternazte contacts of rolay 4:10. Thcrcfora, whcn:the plug 401 was inserted in the jack 402, zicircnit was alsocomploted f10111.

battery; ovon thc contacts oi rolay 440, tho winding ortrclay 445, lowcr winding olt' relay 4.10, tho sleovc contacts 01' the plug and jack to ground -tl1rough thc.windings ot rolays 4:20 aml425. "Rc1ay 4:4;50perates in this circuit as established in paralle1 with the appu windingofthe rclay410. Thc roistancc ot -rc1ay 445 =reduccs the ours-cent fiowing throngh the lower winding ofrelay 4510 to the tent:that thiS.current Will 'notbc sufiicicnt to:overcomctheactionof the strongc1 currentxin the upper winding of' the rclay. 410. Therefore,-.thearmatnrc of the latter relay 1nay continue on its uppor bias. Momentary depression of a koy 4m40 Will cause &' rclay 450 to oporate in an obvions circuiti Relay450 in operating,locksin a circuit from battcry,- ho winding and lowcT- 1nost= altelnate contaotsot 1*elay450, Condnctorst53 and254 tolground at tho normal "contacts of rclay 230.

Tho npper and 10Wcninnc* armatures ot inlay. 450 when attracted, switch tl1c 1'ight handsportionof tho C0id circuit. C f1on1 tho loft hand portion tobuscomluctors 4:22 and 4-239Wl1iCl1 extcnd ovcr condnotors 222 and to=a -1clay 2-1-0, Fig. 2,.and ovcr conductors 322 and 323 to :frcqncncy sclccting: 1:olays 301 to 310,.Fig. 3.'

Thcnppcmnost contacts ol i'clay 4:50 con ncctlmtto1ycvc1.* a lcad 451, to tl1c slccvo strand 0:1".- tho cord indepondontly:oi thc contacts ot'relays405 to 408 asa guardagiainst possib1e@rematnvecfiects on.tho signal 4A2. Thcse contacts also supply loattcry.ovor a lcad452and the normal contacts of relay 240 to gronndthrough-the winding of a relay 225. *The lattercre1ay operates and connects g1ound to a condnctor 24:2 thus oomploting a circuit to light a pilot or master lamp 120 in an obvious circuit. Ground on the ,lead 242 also causes a first relay 201 of a first pair of counting rolays 201 and 211 to operate in a circuit Which may be traced from battery, conductor 243, winding 01: relay 201, lower normal contacts of relay 211, lead 242 to ground -at the contacts of 1clay 225. Relay 201 in oporating connects ground from bus conductor 253 to operate a requency selecting relay 307 in a circuit which may be traced from battery, ovor conductor 333, the winding 01" relay 307, conductors 332 and 132, contacts of the digit koy of the first or A roW oi keys Fig. 1, the upper normal contacts et relay 211, the contacts of rclay 201, bus conductor 253 to ground at the 10W- ermost normal contacts 01 relay 230. By 1noans ot mochanism, not shown, depression 0:1 any digit koy in any one of the vertical rows A to Su, Fig. 1, automatically separatcs and retains separatod, the corresponding contacts in the horizontal row ot contacts 101 to 110, until the respectively associated koy may l restored. It will therotore be clear that for the assumod call, tho contacts 101 to 107 Will bo separatod, while the contacts 108 to 110 Will romain closcd due to the fact that no l eys have been operated in the associated rowsSh, St and Su.

Relay 307 operates in the circuit just traccd and connects alternating current of frequenc' f supplied through a transformer 311 to the toll lino L, to actuato correspondingly tuned relay 501, Fig. 5, at the distant end of the lino. The circuit for this may be traced from ground, secondary winding 0J transformer 311, upper alternate contacts ot rolay 307, upper normal contacts ot' rolays 306 to 301, c0nductors 322, and inner lower altcrnate contacts of relay 450, ring mombors cf plug 401 and jack 402, inner lower normal contacts of rola'y 430, righthand altornate contacts et rolay 435, contacts 536 ot a rolay not ully shown in the inward equipmont 500, which may correspond with the rclay 435 at the outward ond of the line, tlie inncr normal contacts ot relay 505, the Windings oituned rolays 501, 502, 503 and 504, conductor 521, uppern1ost normal contacts of rolay 505, contacts 537 at tl1o inward -equipmont 500, loft-hand altorrmto contacts ot rolay 435, upper normal contacts ot rolay 430, t ip mombers of the jack and plug, the second uppermost alternato contacts ot relay 450, conductors and 323, lower normal contacts o-f relays 301, to 306, thenco to ground through the lowcr altornate contacts of the relay 307 and a resistance 317. Relay 501 is the only one of the above group of four relays which 'may respond to'the frequency 01 source 7. Theroiore, While relay 501 reapond to scparate its normaly closod con- Tecoption of impulscs.

tacts, the rclays 502 to 504 romain at rest With the1r respective contacts closod.

In the normal position of the rece1vmg circuits, Fig. 5, the following four circuits may. be traced. A first path extonds from battery, the loft-hand winding of relay 510, loft-hand winding of relay 511, and contacts of relay 501 to ground. A second path from battery, middle winding of relay 510, loft-baud Winding of relay 512, righthand winding; of relay 511, and the contacts 01- rolay 502 to ground. A third path r0m battery, right-hand winding of relay 510, righbhand winding of relay 512, loft-baud winding of relay 513, contacts 01. relay 503 to ground, while a fourth path extends from hatterg, rcsistanco 514, right-hand winding 0f rclay 513, and the contacts of rolay 504 to ground. As indicated, the windings of relay 510 are connected accumulativoly and therofore. this relay is normally oporated, wheroas the windings ot relays 511, 512 and are diflerentially connected, therefore, these rolays will be normally unoperated. Rolay 510 in its operated position connocts battery to a bus conductor 516. VVhen rolay 501 respondod to the impulse of frequoncy f proviously montioned, it openod its contacts and thus permitted relay 511 to operato nndor the current flowing in its righthand winding as previously tracod. While relay 511 is operatod, a circuit for the operation cf relay 520 may be traced from battery, left-hand alternate contact of relay 510, right-hand alternate contacts 01 rolay 511, conductor 517, upper middlc, normal contacts ot relay 51.5, lower inner normal contacts of relay 520 and the winding of relay 520 to ground. Relay 520 operatos and looks up in a circuit Which may be traced frombattery, lefthand alternato contacts cf rolay 510, conductor 516, inner lower alternate contacts of relay 520 and winding ot' relay 520 to ground. The two uppermost sets of contacts et the rolay 520 trams for the coriductors 0L1 trunk L from the lino L to a bridge consisting of the winding 01: alternating current relay 525 and the normal. contacts of a relay 530. Direct current trom automatic oquipment, not shown, but which may be assumed as con nectcd to tl1o distant end of the trunk 100p L may now flow in the completed circuit throngh the winding 01. the relay 525 and normal contacts of the rolay 530 to initiate, at the distant machine switching office, the operation 01 equipment to result in the application to the trunk 100p L of alternating current, usuallyreferred to as dialing toue. This is the usual signal to indicate that the automatic equipment is positioned for the VVhile the direct cur ront flowing bacl over the 1001) L may be inetoctive to oporate u1teri1ating currentrm when the relay 611 of the first or left-hand pair of counting relays, has responded the relay 530 Will have been operated and re: leased to eiiect seven impulses or momentary interruptionsin the tr1ink loop L As Will be understood by those familiar With automatic telephone systems, a first register or selector switch of an automatic exchange in which the trunk L may terminate, ma consequently have been advanced t0 a predetermined position. The operation of counting rela'y 611 at'the conclusion of the seventh impulse to the line L connects ground over conductor 631 through the windings of relays 550{ and 505 to battery. Relay 505 operates in the above circuit and transfei*s the Conductors of lino L from the receiving circuit which inchides the serially connected receiving relays 501 to 504, to a source of alternating current f supplied through a transformer 55l and the contactsof relay 550, Which rela operated in unison With relay 505. At the outward end of the line L, Figs. l, 2, 3 and 4, this current may complets circuit through the windings of relay 240 over'a previously traced circuit including theupper and lower innr alternate contacts :of relay 450. Relay 240 in responding to this alternating current froni the Source f opens the circuit of relay 225 which'releases and di Sconnects gr0und from lead 242, thereby extinguishing the lamp120 and in breaking the shunt path around relay 211 of the first pair of counting relays, permits'this relay to operate in series with the winding of its mate relay 201. This circuit may be traced from battery, over conductor 243, Winding'of relays 201 and. 211, contact et relay 201, conductor 253 to ground atthe normal contacts of relay 230.

Attention Will be returned for a moment to the distant or incoming end of the line and an instant Will be assumed as when relay 505 operated, to disconnect at its normal contacts, the relays 501 to 504 thus deenergizing relay 501 Which was under vibration due to alternating currentfrom source 7 as already described. ThiS reestablishe's the circuit from battertl1rough the left hand Windings of relays 510 and 511 'to ground through the normally closed contacts 01 relay 501. Relay 511 due to the fact that its two windings are differentially connected now releases and disconnects battery from conductors 517, 518, 632 and 633. Removal of battery froni conductor. 632 permits relays62l to 626, 628 to 630, 601 to 607 and 611 to 617 to release.- Relay 611, in releasing, opens the Previously traced circuit for eneigizing relays 550 and 505, thereby disconnecting the source of alternatin; 'current 7 from the toll lino L while reconnecting the line to the receiving relays Cessation of the impulse cf alternating current supplied from source 7* over the toll lime L to actuate relay 240 permits this relay to corne to rest, thus closing its contacts t0 effect reoperation of the relay 225. Response of relay 225 restores ground to the lead 242, whereupon pilot lamp 120 Will again be lighted, and this ground may 110W extend over the alternate contacts of relay 211 to the lower armature of relay 212. The relay 202 of the second pair of counting relays may now respond over a circuit from battery, on lead 243 through the windmg of relay 202, the lower normal contacts of relay 212, and lower alternate contacts et relay 211, to ground over the lead 242 and the alternate contacts et relay 225. Relay 211 in disconnecting the lead to the first or A row of digit keys efiects release of the frequency selecting relay 307 (Fig. 3). Relay 202 in operating, also completes a circuit in conjunction With the eighth digit key of the B row corresponding to the second letter T of the call being described, for the operation of a frequency selecting relay 308. This circuit extends from battery, Winding of relay308, cOnductors 234 and 134, key 8 of the B row, upper normal contacts of relay 212, the contacts of relay 202, conductor 253 to ground over the lowermost normal contacts of relay 230; Relay 308 operates in this circuit and connects alternating current fro1n source f through a transformer 312, to the toll line L to operate the corresponding tuned relay 502 at the other end of the line, in a similar manner to that already described for the operation of relay 501 in connection with the impulse from source 7.

During the interval between the disconnection from the receiving circuit, Fig. 5, of the first application of alternatirg C111- rent and reception of the second impulse, the trunk 100p L Will remain closed through the upper normal contacts 01: relay 530, and it Will be assumed that during this iutcrval apparatus at the ,automatic. office (net shown), Will. functionin a well known manner to transfer the trunk 100p L? to the next following registr or to a next selcctor switch depending on the type of system With Which the distant end ofithe trnk L may be connected.

Operation of the relay 502 in response to the second impulse of current opens the circuit through the right-hand winding of the cliflerentially connected relay 511, thereby permitting this relay t0 again operate and connectbattery over its alternate contacts to the conductors 517, 518, 632 and 633. VVith battery connected to conduct-n: 633, a circuit is completed for the operation of r elays 621 to 627 and 629 to 630, the circuits for Which are obvious and Will not be described in detail. The operation of relays 029 and 630perform no usful tunctionat this tin1c since the ground lead 641 is opened at the alternate contacts et relay 628 due to the factthat relay 502 is 110W euergiZed in response tothe impulse of alternaiing current frozn source f Therefore, tl1e circuit for relay 628 is noW open at tire contacts f 1clay 502. lVith relays 621 to 627 operated, and relay 028 released the operation of rela3 608 ofthe eighth pair of oount1ng relays is efi'ected in a circuit from battery, alternate contacts et relays 510, and511, conductors 517, 518,032, 633, winding ol relay 608, normal contacts of relays 618 and 628, alternate contacts ofrelays 62? to 621, conductors 6 11 and 541,upper normal contacts-cf relay 540 to'ground at the. altcrnate contacts or relay 585J WVhen relay 511 open ated andconnected battery to' conductors 517 and 518, repetition of a cycleof operation similar tothat already descrioed may take place relative to successive responee and release of stepping relays 545, 530 and 540 in rcndering eight impulscs efiectivewith the loop circuit D. The counting relays 601618, 611618 performing their part in theseoperations in a manner sin1ilar to t-bat already described inconnection witlrthe reception and translation otE the fifst impulse of current over the line L relative to setting up' impulsesin the trunk circuit L At the instant the relay 611 Will have rcsponded relays 550 and 505 Will be operated t0 agsiin connect the source of alternating current f" to the line L. Tire operation of relay 505 again disconnectsthe rclays 501 to 50 1 from the line L andtherebypermits. relay 502 to restore and eiect release of diff'eren tially connected relay 511. Relay 511 in rcleasing, disconnects relays 621 to 627, 629 and 630, 601 and 608, 611 and 028, in a manner similar to that already described in connection with translation of the first assu1ned impulse. Tire eight impulses transmitted intothe trunl: 100p L ma v in a well known 1nanner, serve t0 advance tire assumed antomatic equipment anotlmr stage.

At the outgoing end of the tell lino, the arrival of the impulse of alterna.tingcurrent returned over the line from source 7 on completion of the above cycle:ot op raations, causes relay 2&0 to loe opezztod as before descril ed tu disconnect the rolay 225 wlrich releases and removes ground from lead 242. Re1noval of grouncl-fmxn lead 24:2 extinguislres the la1np 120 and also opens the shuntcirouit around the wiuding of rela v 212 01 the second pair of counting relays, and llilS relay 1nay therefore operate in series with its mate relay- 202 in a circuit similar to that previously described for tlie first pair of counting relays.- Relay 212 in operating disconnects at:its upper normal contacts the circuit previously tweed for .the relay 308 and transfers lead 242 contacts et relay 801.

through tothe lower armatureof rel9v 213. Cessationoftheimpulse of alternating current from source f due to release 031 the relays 550 and 505 permits relay 240 to come to rest, thereby closingthe circuit to reoperate relay 225. Relay 225 again connects ground to lead 242, to relighttlm pilot lamp 120 and also efi'ect response of relay 208 in initiating a cycle et operations sinv ilar to those above described.

The third key in the C 10W of digit keys isnow inits actuated position for transmit ting thethird letter E et the assumcd code, and closes an obvious circuit for energizing i*elay 303. Relay 303 in operating, simultaneously conn cts alternating current front sources 7 and f Over thepreviously traced paths including the upper and lower alternate contacts oi rela; 450 to thetoll lino L. From the description already given it Wlil loe clear that following the reception, at tire sending station, et the next revertive innpulse of alternating current transmittcd back over the toll linetroxn the source aiter' direct currentimpulses corresponding to the digit E 013 the assumed call, have been sent into the t1 unk L tire counting relays, Fig. 2, Will again advance tire controlcircuits t0 permit -alternating currerrts 1rom sources 7 and f to loe s1multancously .con

nected tothe tell lino L over the alternate lhis impulse will correspond withthe depressed key 1 of the thousands Th row of the digit l cys. In turn, key 5 of the hundreds row o1 digit keys and relay 305 govrn tire sinmtaneous application et alternating currents fronr sources 7 and to; the toll lino. Key 0013 tlie tons T row oi' digit l oys and relay 309 apply current fron1 source 7"' t0 the:toll line, and key 10 o.f tl1e units U row oi digits keys and relay 310 govern the application ozl current fronrthe source f* to the line L.

For tlie pressent assmned cal], no keys were clepressed inthe last three rows 0' digit keys, theretore, following the recoption et a revert1ve nnpulse from the source t0 permit of the units impulse et the assu1ned number and the disposal at the in' ward point, response et the counting relay 217 for .advancing thecontrol to the next pair of counting relays 208, 218, a circuit W1ll loe prepared for tireenergization et re lay 230. This circuit may l e traced from battcry, winding of relay 2230, key group contacts 110, 109, 108, lower alternate contacts et relays 217 to 211 to conductor 212. On cessation et the inco1ning impulse tro1n source 7" in aimanner sin1ilarto tl1at already dcscribed, re-

storal of relay 20and reoperationoi relav 225t0 apply ground tothe lead 2 12 Will re sult in response of the relay 230. The upper contacts of the latter relay apply ground over a load2lltoefiect energization of a relay 320, Fig. 3. Rolay 320 in operating, simultaneously connects current from sources f and f through the respective normal contacts et relays 301 to 310 and conductors 322, 422 and 323, 423 to the line L over the upper and lower inner alter-mate contacts et relay 450. Respdnse of the relay 230 also disconnects ground from the leads 253 to reloase the counting rolays 201207 and 211217 andthe relay 4:50. Due to the slow-to-releaso charactenshcs 01" the relay 450 as indicated in the drawing,

net 115 which releases all the depressed keys and permits them to return to their normal positions. Final release of the relay 230 disconnects tho relay 320 and the equipment of Figs. 1, 2 and 3 Will thon be at rest in normal positions. Tlre releaseof relay 450 also transfers the tip and ring conductors 01 the toll lino L from the bus conductors 322 and 323 of the frequency Selocting relays 301 to 310 to the main conductors 4:56, 157 of the cord circuit.

Directing attention to the incoming end of the toll lino L, and assuming an instant when the pulse of current consisting of the combined frequencies 01 source 7 and 7 corresponding with the setting of the third digit key in the row C, was received at the inward point, the correspondingly tunod relays 501 and 5501 were actuated and opened the circuits through the lefthand and righthand windings respectively of the relays 511 and 513, thus permitting these diiorential relays to be onergized by the current fiowing in their other windings. Relays 511 and 513 in operating,connect battery from conductor 516 to conductor 517, in energizing leads632 and 633. Relays 621,

623, 62 1, 625, 628 and 629respond in circuits which W1ll bo obvious from tho foregoing descriptions. Relays 623 and 627 and 630 Will romain deenergized due to the fact that their energizing circuits are open at the contacts of relays 501 or 50 1, which relays are now under response to the frequencies 7 or incoming over the toll lino. This combination 01 energized and deenergized relays of the group E permits' counting re. lays 603, 613, 602, 612 and 601, 611 to be sequentially operated to transmit a series of three impulses into the trunk 100p L following which, the usual impulse of current from source f Will be transmitted back over the toll line L t0 release the thousands impulse formed of requencies 7 and f to operate relays 501 and 502. The operation of relay 502 opens the circuit through the left-hand winding of relay 512, whiclrrelay thon operates due to current flowing in its right-hand winding to ground over the contacts of relay 503. Relay 511 is not operated at this time as the contacts et both relays 501 and 502 are now open. Relay 512 in operating connects battery at its left hand contacts over lads 517, 518, 632 and 633. Relays 629, 630. and 622 to may now operato while relays 627, 628 and 621 romain deonergized as their circuits are open at the contacts et the relays501 and 502, respectively. Relays 601 and 611 operate in succession as before, wlrereby a single impulse is transmitted over the trun k 100p L Current from the Source 7 again transmitted over the toll line in the same manner as beiore to release the setting of the hundreds digit of the called number, which is represented by a combined impulse of current consisting of frequencies and 7 simultaneously applied to the toll lino, thus causing relays 502 and 50:: to respond. \Vith relays 502 and 50l0perated, and relays 501 and 503 at rest, relays 511 and 513 Wlll be operated to cause relays 621 to 624-, 626, 627 and 629 to operate. Relays 625, 628 and 630 continue doenergized due to the fact that their energizing circuits are open at the contacts of relays 502-50at, respectively. In this combination, relay 625 is the first effective relay relative to tl1e counting relays F and, therefore, relays 605, 615; 601, 614; 603, 613; 602, 612 and 601, 611, will in cOunting dwnwardly transmit live impulses into the trunk 100p L After this an impulse reverts over the toll lino rom source to cause the transmission of an alternating current impulse corresponding to the tons digit of the called member. This impulse of current being supplied fronr the source f causes relay 503 at the incoming end of the toll line to be actuated, where upon relay 513 Will operate. Relay 513 in operating, causes relays 621 to 628 and 630 to be oporated while relay 620 Will romain inert as its circuit is now open at the con' tacts of relay 503. In this combination, counting relays 601609, 611619 Will se quentially operate to transmit nine impulses over the 100p L The impulse of current reverting from source over 'the toll lino after transmission of the mine impulses Will release the last or units digit 10 or zero digit of the assumed call. This selection is is efiected by the transmission of an impulse of current frequency f* applied to the toll lino over the contacts et relay 310. At the incoming end of the toll lino, relay 501 responds to this current and causes relay 513 to operato. Relay 513 connects battery over its alternate contacts and . conductors 517, 518, 632 and 633, whereby relays 621 to 629 Will be operated, the relay 630 re mainingr deenergized due to the fact that its energizing circuit is now open at the contacts of relay 504. In this combination, the entire series of counting relays 601620 become etlective t0 release tan inuoulses into the trunk 100p L This brings the operatiens to the point where the impulse of current reverted over the toll line from the so1n:ce :tollowing the last or units series et impulses in the present assumed call, and which resulted, as already described, in resterai of the sending -cquipment at the outward position.

Assuming now the condition already de scribed whereby the relay 320 may be operated in qpplying the composite impulse formed of the requencies 7, 7 and 7' to the toll line, response .of the relays 501, 502 and 503, Will ;be had. The relays 501, 502 and 503 disconnect the thr.ee windings of relay 510 which Will release, while, due to disconnection of the circuit through the left-hand winding et relay 5'13, this relay may respond to battery, through rcsistance 5141 and its right-hand winding to ground over the closed contacts 01 relay 50 1. XVith relays 510 and 511 released, relay- 515 -may respond in a circuit from battery, winding cf rela- 585, winding and lowermost normal contacts et relay 515, the normal contacts 01 rclays 511 and 510 to ground. Relay 585 being marginal, does not operate in series with the high resistance winding of relay 515. Relay 515, however, responds and looks up to ground at its lowermost alternate contacts, atthe same time disconnecting the ground supplied over the normal contacts 01 relays 510 and 511. uppcr and lower inner alternate contacts 01 relay 515 complete a circuit to connect the polarized rela; 565 in bridge on the conductors of the trunl: lime L and in attracting its upper middle armature, it opens the con nection betwcen conductors 517 and 518 to prcvent Eurther application of battery to the leads 632 and 633 and the relays of group E, Fig. 6. The purpose of the uppermost contacts et relay 15 Will be described later.

lVhcn relay 510 releascd and removed batgtcry from conductor 516, disconnection of the rclays 520 and 535 took place. Relay 520,1mwcver, is slowtorelease in order that polarized relay 565 may be connected across the trunk before relay 525 is removed thereircm b the release of this relay 520. Such nondnterruption of the 1001) circuit ofthe trunk lino L insrires rctaining 01 the assumed automatic switchesat the distant end 01 the trunk, as Well understood in the art. lVhen relay 52.0 releases, however, it con ncets the trunk L through to the toll line L. ;1t this tim, tl1e polarit of the direct In its operatedposition, the

be ebvious, a composite impulse gformed of frequencies 7, 7, f and 7 over the contacts et relays 575, and 505 to the toll line L. Relay 505 in operating, connectsgrounded battery -over its lower contacts, the lower winding of relay 570thence over the circuit previously trace'd to ground at the left-hand contactsof relay 585. Relay 570 is of polarized type and the direction of this current is such that its armatme Wlll :be moved out of engagement with its lower contacts andinto engagement with its upper contacts. Separation .of the lowcr contacts of relay 570 opens the energizing circuit previously traced for relays 505 and 575 and these relays now release and disconnect the alternating current of sources 7, 7, j' and f* :from the toll line, and at the same time reestablisliing the connection between the line L and the trunk L which was broken during the interval that relay 505 was operated. At the outwand position, Figs. 1130 4, this impulse of current causes relays 405, 406,

407, 108 bridged across the cord condnctors 456, 457 to be operated. These relays in opening -their contacts disconnect battery from thearmature ofrelay 4-10 and thereb discontinue the current through the upper windingof this relay as already traced. The current in the lower winding of relay 410 by way of the winding of relay 445, may now move the armatureof this relay 410 against the action of the spring 111 out of engagement with its uppei* contacts and into engagement With its loWer contacts. sation of the incoming impulse formed of four trequencies, permitsrestoral of relays 4054108 to ieconnect battery to the armar.

turc of the relay 410. This results, in the shunting of relay 4415 which on releasing establishes a circuit from grounded battery, normal contacts 01 relay 4:45, winding of relay 4A0, upper winding of relay 410, sleeve contacts 01 the, jack and plug to .ground through the windings of relays 420 and 425.

Relay 44:0 operates in thiscircuit and closes at its altrnate contacts an obvious circuit 1 for lighting supervisory lamp 442. strength of the current in the circuit through the upper winding of relay 410 is insufiicient t0 attract its armature against the greater strength of current floWing in the ,lower -w,vinding et relay 410. It may be pointed The 1' out that the slow-to-release characteristics of the relay 530 in delaying closure of its lower normal contacts, insures that the revertive impulse of four frequencies will be present following release of the relay 450 and inclusion of the relays 405408 with the line Circuit.

Display of the signal 442 indicates that the assumed automatic equipment at the distant end of the trunk loop L has now extended the connection to the line of the called station, and, urther, thatsuch station is being signalled in a well known manner by ringing equipment located at the automatic office.

When the called station answers, the ringing current may be disconnected and the direct current in the trunk loop L reversed in well known manner. Such reversal of current causes the armature of polar relay 565 to be moved to its opposite bias, that is, to the bias shown in the drawing. With the armature of relay 565 in engagement with its lower contact stop, a circuit for the 0peration of: relays 505 and 575 may be traced from battery through the windings of relay 505 and 575, armature and upper contact stop of polar1zed relay 570, lower contact stop and armature or relay 565, lower normal contacts et relay 520, to ground ,at the left-hand normal contacts of relay 585. Relays 505 and 575 in operating, disconnect the inward equipment and apply current from the four sources 7' t0 7 to the toll line as previously described.

At the outward position, relays 405 to 408 respond to this current to seParate their contacts thereby disconnecting batter from the armature of relay 410,'Whi0h is now on its lower bias, tliat is, with its armature in engagement with its lower contact.The armature of relay 410 may now move out of engagement with its 10We1 Contacts and into 7 pulse of alternating currents ceases due to rclease of the relays 505 and 575 at the incoming end ofthe toll line as previously described, relays 405 to 408 Will come to rest, andin closing their contacts reapply battery to the armature of relay 410. This shunt-s the relay 440 and efl'ects its release, thereby extinguishing the supervisory lamp 442 and closing at the normal contacts of this relay a circuit to energize relay 445. This circuit extends through the lower winding of rela 410 as already traced. Relay 445 Operates in this circuit but the current fiowing in the lower winding of relay 410 is not suflicient to overcome the effect of current in its uppcr winding. Disconnection of the lamp 442 indicates to the operator that the called station-has answored.

\Vhen 'relay 505 opcrated to connect the impulse of current from the sources ;f* to the toll line, the lower contacts of this relay connected battery through the upper winding of relay 570 to ground at relay 585 over the circuit previously traced from the armature of relay 565. The direction of this current through relay 570 causes its armature to move to its opposite bias, that is, with its armature in contact with the lower contact stop, which is the position shown in the drawing. This opens the previously traced circuit through relays 505 and 575 and these relays thercfore relcase to disconnect the alternating current from the toll line L and reconnect the toll line to the trunk loop L extending to the called station.

As shown in the drawingthe left-hand end of the cord circuit C is provided with a plug 454- adapted to be inserted into a jack 458 for the purpose Of connecting the line of a czilling subscriber as the line to the station A, which may now be considered as joined for conversation over the cord circuit with the assumed called station reached, as described, over the toll or long distance line L. A key 455 serves for joining an op erators talking set (not shown) with the cord circuit.

lVhen the conversation has been completed andthe called subscriber replaces his receiver on its switchhook, the current in the trunk loop L is again reversed, whereupon relay 565is operated to open its lower contacts and close its upper contacts, thereby initiating another cycle of operations, whereby amomentar operation of relays 575 and 505 is effecte to apply an impulse -of current from the sources f to 7 to the toll line L. Relays 405 to 408 associated with the cord circuit at the outgoing position respond to the currents of this impulse and momentarily remove battery from thearmature of relay 410, thereby permitting this relay to move its armature in the opposite direction to close its lower contacts due to the current flowing through its lower winding in series with the relay 445. \Vhen the alternating current impulse ceases and relays 405 to 408 come to rest, battery will again be applied to the armature of relay 410, thercby shunting the relay 445, which relay thon releases and at its upper normal switchhook may have been in its upward position thesupervisory lamp 442 would be extinguished and when the switchhook may have been in its downward position, the lanip Will have been 'lighted.

Assuming 110W that the lamp 442 is steadily lighted, thereby indicating that the called subscriber has replaced the receiver on its switchhook thereby indicating that the conversation has been completed, the operator- 1nay remove the plug 401 from the jack 402, thus opening the circuit for relays 440, 410, 420 and 425. Relays 440 and 425 immediately release and after a short interval, the slow-to-rclease relay 420 also releases. Relay 410 in deenergizing, permits the retractile spring 411 to move its armature to its normal position which is the position shown in the drawings.

During the interval between the release of relays 425 and 420 a circuit is completed to operaterclays 430 and 340. This circuit may be traced from battery over the normally closed contacts 01 alternating current relay 465, rightlmndalternate contacts of relay 420, right-hand normal contacts of relay 425, lowermost normal contacts and windng of relay 430, and the winding of relay 340 to ground. 'This efiects response of the relays 430 and 340. Current from grounded battery over the contacts et relay 465 and the lower alternate contacts et relay 430, looks the relays 430 and 340 independently of the relays 420 and 425, uncler :controlflof the relay 465. The contacts 419 of relay 430 also apply this battery to the lead 433 fo1retaining the switching relay 435 and the busy sig nals 431 and 432 while a so-called click busy test condition Will be maintained on the sleeve or shell member of the jack 402 due to the presence of the condenser 471. Relay 430 in operating, opens its contacts 413 and 414 to disconnect the jack springs from the toll line L, at its contacts 415, 416, it connects the toll line L to the windings cf alternating current relay 465 and at its contacts 417 and 418 connects alternating currents .ir0m sources 7, 7", 7" and f'* as present over the contacts of relay 340 to the toll line. At the inward equipmcnt, Fig. 5, this impulse of currents causes the operationoi relays 501 to 504, which in turn permits relay 510 to releasedue to the factthatthe circuits th rough the three windings of this relay are opened at the contacts et relays 501, 502 and 503. The operated condition of the relay 504 prevents response of the diferential relay 513 at this time. Relay 510 in releasing, connects ground over its normal contacts andthe normal contacts of relay 513 to short circuit the inlay 515, which relay may now release. 'lhis g;round also forms a direct path for the rela v and perinits it to operate. Relay 535 in orating, disconnects ground at its Ie"l-l1and normal contacts from the armature cf relay 565, and at its right-hand contacts connects ground to Operaterelays 550 and 505 in anobvious circuit. Relay 550 in operating, connects a mo neutary impulse of alternating crirrent from the source f to the toll line in the same manner as :befoie de scribed, to efi'ect operation of the relay 465 110W connected to the toll line at the -outward position. Response of relay 505 disconnects the relays 501 to 504 from the toll line, and these relays therefore come to rest and close their contacts. This permits relay 510 to reoperate and disconnect -g ground and there. by deenergize relay .585. As shown by the drawing, this relay 585 is 01 slow-to-release type and, therefore, relays 505 and 550 Will be retained operated t0 permit theiinpulse otcurrent frein the source f to be effective for a sulcient interval with the toll line L. When relay 585 releascs, it disconnects groundat itsright-hand contacts, thereby disconnecting the relays 550 and 505, which. relays may now rclease to disconnect the source of current f from the toll line L and reconnect the line through to the trunk L When relay 465 at the outgoing positron responded to the impulse of current from source f-,'its contactsseparated thereby releasing the relays 430, 340 and 435 the busy signals 431 and 432 and also removed the click busy test condition from the shell mem ber of the jack 402. Restoral of the relays 430 and 340 disconnects the four lrequencics f f and f and also the -relay 465 frem the toll line. It may be noted that the operating circuit for the relays 430 and 340 normally stands open at the right hand contacts cf relay 420.

Thg-retractile springs of the polar relays 410 and 565 insure that :the armatures of these relays Will normally be biased in the positions in which they are shown in the drawings, to insure so-called positive supervision -by means of the supervisory lamp 442, that is, the superviSory lamp may be lighted when response is had at a called point or station while the lamp may be extinguished when disconnect has taken place et suclu point. 'In case any irregularity et operation may occur and the lamp 442 should be improperly affected relative :to its energization or .deenergization, a momentary operation of just described, lead 533 Wlll be disconnected from lead 538 at the upper inner normal contacts of relay 520 while the upper inner alternate contacts of this relay Will apply battery to tl1elead 533 for establishing a busy condition at the outward equipment 500. A:tter a connection has been established and during the talking period when,

and 518 to insure that subsequent operation of relays 501 to 504 will not affect relays 520, 530, 540 and 545, ortl1c equipment ot Fig. 6. In case a busw condition of :1 station under call may be encountercdthe automatic equipment Will become effective to establish reversals of current intrrupted. at a predctcrmined rate in the trunk Circuit L vas well understood in the art, tooperate polarized relay 565. Sucl1 respoxises of relay 505 will cause supervisory lamp 442 to bu alternatel extinguished and lighted to indicate snch busy condition to the operator who ma thereupon disconnect by and release the automatic switches by removing the plng 401 from the ack 402 as already described.

In the opcration of tl1is system., a few seconds only sufiice for permitting all the selective impulses required for cstablishing a connection. Therefore, it Will be clearthat the pilot lamp 120 Will, in eflect, be fiashed as the lead 242 is successively advanced 'through the associated counting relays.

Therefore, in the event that pilot lamp 120 should be steadily displayed, it Will serve t0 indicate to the outward operator that irregularity is present.

From the foregoing description it will be clear that the inward eqnipment oi the present s vstem, shownin Figs. 5 and 6,may in general, be considered as a substitute for un instrument and calling clevice or dial of a subscriber station which may be connectcd for service through an automatic exchange over a circuit similar to the trunk L It is generally thecase tl1at pressent day types of toll lines are opaque todir6ct currents, and, there=fore, it Will be clear that in this System, where the automatic equipment rcquirs a direct current Path such as trunk line L, this trunk line must be open when disconnection is desired; Tothis end the release of relay 515, which is due as previously described to the removal of the plug 401 from the toll line jack 402. Will resultin opening the direct current path of the trunk L t0 permitthe automatic equipment assumed as connected thereto to release and 1estore to normal in the usual manner. Therefore, the circuits of the present system enable the originatihg toll operator t0 completely control the distant automatic equipment. Linesas employed in this sys- 1301H, aft'ord a patlr for direct curreut from a circuit such as the t1unk L and may thercforeliave suclr means as c0ndnsers 547 and 548interposed in the condnctors of the toll lino L as shown, to prevent flow et direct cnrrent over the toll line proper.

Relativeto control otthe supervisory signal 442, the purpose of the four alternating current relayg405408 is to insure that voice or other currents may not become effective t0 result in translation of Signals. A total of four definite requencies beingrequired before the signal 442 may be afi'ected.

- VVhatis claimecl is: 4

,1. In a =telephone exchange system, a toll l e, automatic switching means associated with the incoming end thereol, a called sub sciibefsline terminating insaid switching menus, sources of alternating current sondingmeansior transmitting pulses over said tollli'ne to set said switcl1ing means to conneet said snbscribers line With said toll line, 051ch et saidpulses comprising currents from various combinations of said sources and 1neans responsive to the first of said pulses to condition said switching means for receiving said pulses.

In a telephone exchange system, a toll ]i1ie,:automatic switching means associated With the incoming end thereof, a'called sub- Scribers line terminatrig in said switching means;sourcesof alternating current, sending means for transmitting over said toll line a single pulse for each cligit of the called subscriberscodeto set saicl switch ing means, each of said pulses comprising currents from a certain combination of said sources, and *means responsive to the first impulse of said code for conditioning said switching means for receiving said pulses.

3. In a telephone exchange system, 3. toll line, automatic switching means associated with the incoming and thereof, a called subscribers line terminating in said switching means, sources of alternating current, sending means for transmitting over said toll line a single pulse of said current for each digit of. the :called subscribel"s code to set said switchihg means, means responsive to the first pulse of said code for conditioning said switchin, means for receiving said pulses. and.other menus responsive to the conditiouing of said; switching means for translating said first pulse into direct currentpulses to set said switching means.

, 4. In atelephone excl1ange system, a calling exchange, a called exchange, a toll line extendiiig tlieiebetv een, automatic jsWitching means at said called exchange, asubscribers line terminating therein, sources of alternating current, means at said clling ex han,ge for transmitting over said toll line successive pulses of said altcrnating current corresponding; to the code ofthc called sub scribers line to cause said switching means to connect said toll line with said subscribers line, and means, responsive to the setting of said sivitching meai1s in response to animpuls ofsaid code, for transmitting an impulse of alternating cuirent oVer the toll line to said calling exchange t0 release the hext code impulse.

5. Ina switching system, a line circuit, a pluiality ol alternating current' sources, menus for applying single impulses from said sources to said line, sWitching means for translathig said single impulses into a plurality of impulses, and means responsive to a single impulseof alternating current for conditioning said switching means l'or the translation of impulses.

6. In a switching system, a first and a second point, a line intermediate said first and second points, switches for joining said second point to said line, means et the first point :fo1 applying successive impulses of alternating current to said line to control said switches, and means a-esponsive in the control of said switches for efecting the release of said impulses of alternating cur rent.

7. In a system -for automaticaliy joining remote telephone stations, automatic means for translating a single impulse into a plurality of impulses, switches controlled by saidplurality of impulses, and means eiective on a first response of said switches for rendering said plurality of impulses effective therewith.

8. In a system for transmitting impulses of alternating current, a line, a plurality of electroresponsive frequency selecting devices available to said line, switching means to'render said devices effective t0 energize said line, when said line is associatedwith said devices, and electroresponsive means associated with the opposite end of said line for limiting the duration of the energization of the line.

9. In a system for automaticaliy transmitting a succession of impulses of alternating currents, a line, a plurality et circuit control devices available to said line,*means for rendering said devices effective to select alternating currents of various f1equencies for energizing said line when said line is associated with said devices, electroresponsive means available to said line for succes sively rendering such selected currents ef fective with said line and other electroresponsive means associated with said line for -(zontrlling said lirst mentioned electroreelectroresponsive relays for Selectingcertaint of said currents, electroresponsiveineans for sucressivcly applyii1g said solected currents to the toll line, and otl1er electroresponsive 1iieans associated ithsaid toll. line and responsive to'alter*nating currents transmitted back oter said toll line for controlling said ,first inentioed electioresponsive relays.-

11. In a telephone eitchange system, a toll l1ne, a.cilled station, a plui*ality of different "lrequeiicy alternating current sources, sond- 1ng means for transmitting over said toll line combined :li 'equcncy pulses from said,

sources, tuned electromagnetic devices directly actuated by said pulses, and ineans controlled by said electromagnetic devices for establishing a conncction between said toll line and said called station. 1

12. In a telephone exchange system, a call ing exchange, a called exchange, a toll line extending between said exchanges, automatic switching meai1si at said called exchange, a plurality of difi'erent trequency alternating (aiment sources, means at said calling exchange for transmitting impulses :trom said sources over said line, and tuned electromagnetic devices aotuated by said impulses for setting said switching menus 13. A telephone exchange system com prising au originating operators position, 21 toll line extending therefrom to and terminating in rcceiving equipment, a trunk circuit extending lrom said receiving eq1iipment to automatic switches, a ealled subscribers station, a plurality 01 sources et alternating current oi difEerent frequency, sonder means at said originating operators position for sequentially transmitting over said toll line a single chnracteristic composite pulse of said alternating cu1rent for each digit of the called subscribers number, and means associated with said receiving equipment comprising a plurality of tuned relays for translating each of said composite pulses into direct current impulses and for transmitting the1ninto said trunk circuit to set said switches.

14. In a telephone exchange system comprising an originating operators position, a toll line extending therefrom to and terminating in receivingequipment, a trunkcircuit extending from saicl receiving equipment t0 automatic switches, a called subscribers line, a plurality of sources of different frequeney alternating ouvrent, sender means at said originatingoperators position for sequentially transmitting over said toll line a single characteristic composite pulseof said alternating current foreach dlgit of the called subscr1bers nmnber, and means associated with sa1d recewmgeqmpnient comprising a pluraliiby Of tuned relays each' having a vibratory element and a loose contact member carried tl1ereby foi translating each of said composite pulses into di- 1'ect current-impnlses of the proper decimal chgracteiistic and for transxnitting said di rect current impulses into said trunk circuit foi" setting said switches into connection withsaid called subscribers line{ 15. A telephone exchange system compris- 1ng an originating exchange and a called excliangeia tell lime extnding therebetween, an automatic s witch et said called exchange, sources of alternating cnrrenfl of di'fleient frequency, means :115 said origin&ting exchange for simultaneously applying a plu rality of said currmits to the toll line in difigrent combinations, and meens at said called exchange comprising {L plurality of tnned electromagnetic devises directly responsive to each of said diffrent frequency currents and u plurality of counting relays contr0lled thereby foi setting said switch.

16/ In a telephone exchangc system, a first exchzmge, en opemtors position thereat in clnding 'a cord circuit and a. supervisor .snid opemtors position inclndingtnned cloctromagnetic devices directly rsponsive to said alternating cuments to actnate suidsn pervisory signal. j

In witness whereoi, I herennto s'ubscribe my name this 27 dW of October A. D., 1923.

HENRY W. ONEILL.

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