US1595132A

US1595132A - Telephone-exchange system

Info

Publication number: US1595132A
Application number: US726268A
Authority: US
Inventors: Samuel B Williams
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1924-07-16
Filing date: 1924-07-16
Publication date: 1926-08-10
Anticipated expiration: 1943-08-10

Description

Aug. 10 1926. LSQSJBZ 5. B. WLLAM'S TELEPHONE EXCHANGE SYSTEM Filed July 16. `1924 5 Sheets-Sheet l Erl@ 9 392.. 1,595,132

v n-E. WLLlAMs TELEPHONE EXCHANGE SYSTEM Filed July 16. 1924 5 sheets-sheet 2 Aug. 10 ,1926. 15953132 s B. WsLLIAMs TELEPHONE EXCHANGE SYSTEM Filed July 1,5. 1924 5 Sheets-Sheet 5 Aug., 1o- 1926u 1,595,132.

S. B. WlLLlAMS TELEPHONE EXCHANGE SYSTEM 5 She ts-Sheet 4 Filed July 16. 1924y 2 5 3 l m .J e m .m 5 .y L, t .m m 5 d m /W M Saw MB1 mm. LAM LH IICV. www am@ Smm EF L E T am 2 9 l 0 1 .6 M

Naw

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Fatented Aug. 1 0, 1925. i- Lggiig l 3 srarfss orties.

seiaunnn. wrLLraivis, or BROOKLYN, new ron-ir, nssienon ro wn's'rnRN nnnornio oorirANY, INCORPORATED, or Naw Yoan, N. .a oonronATioN OF New YORK.

TELEEEONE-EXCEAINTCTE SYSTEM.

' Application. filedJuIy 1G, 192e. Serial No. 726,268.

Vlhis invention relates to telephone "eX- shown in Fig. G disclose a telephone system change systeinsybut' more especially to that embodying the features ot the invention in 55 classot systems wherein automatic switches sulicient detail to give an understanding and apparatus are employed t'or the purpose thereof.

5 Ot controlling,l and completing conversational Fig. l in the Vupper portion illustrates connection. schematically apparatus tor extending a The invention is particularly applicable to local connection, including a line switch 50 systems adapted to handle toll vor long' disand a district selector switch. ln; the lower tance connections. rlhe arrangement in these part of this figure is shown schematically vsystems is oi' suoli a nature that the complea sender selector switch and one of a nuintion ot certain classes ot connections is `ogenber ot registering,` and controlling;` senders. erally under control of an operator. rllhe rllhe portion ot this ligure enclosed within 65 operator thus serving to complete connecthe dotted rectangle is diagrammatic repretions has allotted tor use certain portions ot sentation orn an operators position and the the exchange apparatus which function only coi' 1espoiidinnposition equipment. Entendin this class ot service, that .isv to say. the ingr through the central pastorl this ligure is ols the operation 'ot'V certain disclosed one of a number ot trunks in- 70 operator contr l A y switches, and the selection oi,` certain intercoming; from a distant oliice.

connecting` trunks, these switches and Vtrunks Fig. 2 in the upper portion shows Yone oiE being' used exclusively in handling particua. number of incoming' selector switches lar classes ot calls, such as long distance toll adapted to extend the usual local and interoalls. rl`his arrangement may also be emoliice connections. ln thelower part ot this ployed by so called verifying or checking; figure is shown an incoming selector switch operators when circumstances require that adapted to extend connections under con- 5 the condition ot a particular linefbe verified. trol of the operators equipment, shown in ln addition. the exchange is provided with l. other switches and interconnecting; trunks Fig. 3 illustrates a portion ot a final or S0 to take care Ot the usual interoice or local connector switch havingw access to called traliic. subscribers lines.

0 Jaccordingly, it is an object Ot the inven- Fig. l shows a portion ot one of a numtion to increase the efficiency of interconnectbei' of controlling,` markers, and also a coning' trunks by allowing certain of these necting device for associating' a selected B5 trunks to be usel indiscriminately in the sender with an idle marker. completion of local or interoiiice calls and Fig. 5 illustrates schematically trame and alsoiin the completion ot connections under trunk connectors for associating` the markcontrol ot an operator. ers with the incoming and iinal switches.

A feature Ot the invention is the manner The system disclosed herein is adapted to .it distributing trunks between different function in the handling ot both local calls ups oil switches, the switchesv ot each and calls originating in a distant oilice` as 40 group serving to comple-te ditlcrent classes oi' well as calls trom distant onices requiring connections. while certain ot the trunks are the intervention ot an operator.

l i; connections independrllhe local lines terminate in coordi- 95 capable oi' completin u entlv ot the class otl Vswitch taken :tor use. nate line switches lOl., which in their auto- Q-ther inherent ifeatures and advantages matic operation are adapted to entend calloLt this invention will become 'apparent after I ing lines to trunks, as 102, leadingv to district a consideration ot the following` detailed selectorswitchea as 103. The district se -scrip'tion andthe appended claims. lector switch is thereupon*selectively oper- 190 The drawingrshowing a preferred 'torinct ated under control of -ainarker to` entend 'carryingout theinvention consists-ot reprethe calling'line to an idle trunk.,- sucli' as 1350`'s"eii`tati'oiis,- "part'schematicallyand'v part lin trunk 115. which leads to an-inconiingse- `detailfot switching' and controlling apparalecto'i" switch, "as l Thesetrunk v ter- 't'usandpconiprises lto `5,`inclusive. ate. in vertical rows of 'contacts n` the 105 if" i coming selectorswitches. *l Forex-ample,

These'ngures when arranged' the-order trunk 115 appears in vertical row of contacts 213, while the remaining trunks would appear in still other ertical rows similar to rows 213 and 214-. The incoming` switches 200 are adapted to he selectively operated under control ot an incoming' marker, such as partly shown in Fig'. 4, to further est# tend 'the calling` line to an idle one of the

trunks

219, 220, etc. which lead to connector switches having' access to the desired line.

The connector switches are divided into a number of groups, each group having access to a particular portion ol' the total number of suhscrihei lines. rllhe group of trunks appearing; in vertical row comprising trunks 217, 21S, etc. extend to, and have an appearance in connector switches ot a 'particular' group. The group of trunks appearing in vertical row 216 comprising`

trunks

219, 220, etc. extend and have an appearance in a second gro' ot connector switches, one switch opt' tlii. second group, switch 300, being shown. l' will he observed that the t'v nk i220, for example, appears in vertical row 301 in connector switch 300 and has access to link in each of the units sections ot this latter switch. Likewise, other groups ot' trunks leading,r from the incoming s vitch 200 have an appearance in still other connector groups, each of the trunks in a group being; multipled to appear in all of the incoming' switches composing a group.

In addition to the equipment provided for the completion of local connections the oii'ice is also provided with operators 'positions and equipment, as shown in Figi'. l. The trunks, such as trunk S, incoming' from distant oiiices may serve to extend toll or long' distance connections or for other similar purposes. These tw trunks it will he observed appear in vertical rows ot' contacts of a special group of incoming selector switches, which, switch 201, is shown. The trunk 1%. for example, which is partially shown, appears in vertical row of contacts 202 in switch Q01. inother trunk or similar nature 10? slwn appearing` in vertical row 203. "s oosition is provided a key set an assignment key 112 and a release ke?,7 113. The assignment and release keys :ire iii-ili'=,'itlunl to each ot the trunks 106, 107, etc.

The special incoming switches, as .201, have access to groups operators trunks extending` to the several groups conneo tor switches. For example, the vertical row of contacts 205 i'naj; include a numher of these operators trunks all leading; to the same group ot connector switches in which switch 300 is included. The trunks appearing in vertical row 206 in like manner lead to another group otfconnector switches.

lt will oe observed that trunk S220 appearing inl row 9.05 of Switch l201 is identical with the trunk which is multipled to appear in vertical row 216 of the local incorning switch G. The distribution of the trunks in switch 200 is such that trunk 220 is the last trunk to appear in vertical row 216. ln a similar manner the next operators trunk appearin' in row 205 will he inn tipled to appear as the last trunk in different rowo't' contacts in the same or a different local incoming svitch. rEhis arrangement holds true of the remaining trunks in row'QlOo, each trunk losing,l idene tical with the last trunk in a vertical row of contacts in a local incomingswitc i,

cludes a. switch 300. Thus, trunks 9,20, 2.22 223, and 22e are each, respectively, the last. trunk in different groups of trunks leading from incoming selector switches to the suine group o connector switches, which includes switch G. These several operators trunks all appear in the saine vertical row of contoets 205 in switch 201. ln a similar man-V ner the operators trunks appearing in ver` tical row of switch 2-(1 a'e identical with the last trunks in correspondins groups of trunks leading' coming' switches to a second connector' group. This same arrangement may hold true for as r any connector groups as there are provided.

Thus, it will he seen that each oi' the trunks 220, 218, etc. may serve to extend the usual local and interoilice connections or intero'dice connections where an operator required.

Each of the oerators trunks in :i1157 one group is arranged to appear hetore corre spending,` horizontal links in each ot the several connector switches ot a group. Each trunk, however, appears i a different vertical row otl contacts in these connector switches. For example. trunk Q20- appears before horizontal links 313, tical row 301 ol connector in a similar manner hetor ing links in other connector switches of this same connector group. The second trunk 222 is also accessible to

links

313, 314, etc. but onli,T 'oy means of vertical row ot' con-- tacts arrangement holds true with respect to the remaining trunks appearing in row of switch 201 and also 814i, etc. in verswitch 300 and the corresponda02. This 2415 with regard to the trunks in vertical row 206. In this latter case, however, the trunks appear in a different connector group fro'n that which includes switch 800.

Each of the local trunks 102 and the incoming' trunks 106 may he associated with idle register senders, one of which, sender 107 is shown diagrammaticallf, by means of sender selector switches as 10e. In practice there Inav he two types oi' senders 10T one to he used for local connections and the other to be used for incoming calls. Ac;

Opxfv.. @t Y .lng access to the connector group, which 1ntroin the local in-` llfl les

cordingly the local'tr'unks 102 may be associated with one kind ot sender through one sender selector switch 104 whereas the 1ncon'iing'trunks 106 may be associated with the' other kind of sender through another' vsender selector 104. For convenience in the drawing, however, both local and'incoining trunks have been shown as appearing the single sender selector 'iraine104 and no attempt has been made to disclose the details of the diierent types ot senders. Each or" the several registerisenders, such as sender 107, may be associated with an idle one ot a number ot markers, part of one oit' these markers being shown-"in lligr.'V 4. For this purpose a.senderconnecting),` device 40,0 com- Vvprisinp` a number ot multi-contact relaysis providediior connecting' 'the' selected sender to the first 'idle inconiinpgniarker. n

' The called line numerical Vrecord as registered in the sender 107 is transferred to the f marker whichthereupon 'causes the selective line. After the Irecord has been yreceived operation of an incoming; and a linal switch to complete the connection tothe wanted i'l'e Lil marker is associated with the proper incoming switch by means oi"- the connector y500. The test relays 401 in the marker are thereby 'connected to the test conductors ot the hori' zontal links in the Kproper incoming switch. Incase the connection being' extended is one involving a local line and thereby entailing the use of a switch such as 200, the marker .is also associated with'the trunks outgoing;r

- from this switch to thevv 3ro 3er Oroun 'of ze l yconnector v switches by meansV ot the trunk connectorr 501.

liloreover, the marker is associated by means of the connecting' Idevice 502 with the particular connector switch in the connector group having;4 -access to the ,Qroup of lines whichincludes the wanted line. is a vresult of this vassociation the marker testing lto iechanism is connected to the horizontal links in a 'particular section oll tie selected connector switch, as determined by the units digit ot the called line designation. W ith the marker thus associated a three-point testis made to determine an idle link in switch 200, an idle trunk 'leading `trom switch 200, and an idle link in switch 300. Having; determined this available path the incoming and connector switchesv are operated to completethe extension ci the callingA lineJ to the called line. Y

Should the call be otsuch a natureas to require the use or"V a trunk as G and the consequent services of an operator the connection lis extended through a'switch, sin 'lar toswit'ch 201, tof-one of the operators trunks '220, 222, 'etc'. Since'the number-ot these latter trunks iis Ycoii'iparati'velysmall1 the truuk connector 1501 is replaced" by 'relays such as 503 and 504, etc. for the purpose-'ot 1fessociating=a liaiitec'lfnu-1nberf fniarker test .vidual to a connector group, and

'leading from switch 200 by causing these several portions of the exchange *relays in accordance with'the size ot the selected group of operators trunks.

Each ot the relays 503, 504, etc. is indiconsequently to a connecting' device asv 502. ample, relay 504 is individual to device while relay 503 would be individua to a ditlforent connectingdeviceassociated with a second connector group.

'The marker testingmechanism is so arranged that there is a set of test relays `for each of 'the trunks in a l.eroina leadingl 'from the local'incoming' switch 200 to the several connector switches. lnasmuch asthe nurnber of operators trunks in a group is considerably less 'than the trunks in a group leading' from the local incoming switches, relays 503, 504, etc. are provided 'tor con necting` the test conductors of these small trunk gro-ups to the corresponding,` marker test relays. lgroup oi connector switches including switch 300, the connecting' device 502 will have been operated to associatethe marker with the links in section :310 ot switch 300. rlhe vselective operation' of Ydevice `502 serves 'to identity to the vmarker the group ot trunks the operation ot a relay such as 504. Should the called line be accessible by the switches r ot another connector group then a dirlerent relay such as 503, would be operated to identity to the marker the proper `group of trunks leading from switch 201 to this connect r group.

rEhe selective swit drawing may Vbe of scribed in detail in the application ot Charles L. Goodrum and John N. leynolds, `Serial No. 486,442, liled July 21, 1921, Patent No. 1,515,785, granted November 18, 1024, and also further described in the application ot S. B. Williams Serial No. 596,179 tiled @ctw ber 23, 1922, Patent No. 1,517,331, pjrfu'ted December 2, 1924. lnasrnuch as a dei .ed description o1 the structure and operation or the senders 107, connecting' devices 400, the markers and the traine and trunk connectors shown in Fig. 5, is not necessary lor a complete understanding;` o'j the present invention,

. erraratus have been illustrated in a comparatively diagraminatic Ylorm. For a more com plete description ott the .operation ot these devices, reference may be had to the aA plication of S. B. llfilliams, Serial No, 707,705. iled April 21, 1,924.

Connections molt-ag m operator.

hes illustrated in the It will-be assumed orthe present that a connection originating -in--a distance Aoilice re- Vquires'ex'tei'islon tothe called line 30?. 'ln

"anyv well known mannen thel operatorie atitention is; called tothe Afact-f that the completienof" the .Call requires --her interne'nti-onu For ezithe type shown and de-y lt the called line occurs in thc f set 105.

`She thereupon assigns an idle trunk such as trunk 106 and operates the assignment key 112, individual thereto. rl`he operation ot key 112 results in the association oit a key set such as 105 with an idle register sender such as 10T by ineens or' the automatic operation of sender selector' switch 104. operator the distant ottico upon receiving the assignment oit trunk 106 extends the connection thereover in the usual manner and 'also communicates to the local operator the designation of the Wanted line. @n learning this designation, the local operator then proceeds to setup a record thereoic on the key `When the designation has been t set up it is transferred by means oi 104 to the registers or" sender 107 (not VM" shown). For a detailed description oit the manner in which these latter operations are f7 3---p -a-v` l,- es eiiecteu, releieiice may be nad to the apolication ot S. Gibson, Serial No. 050,742, tiled August 10, 1023, Patent No. 1,550,244, granted Gctol-er 2'?, fitter the record has been thus transferred to the sender reg isters, sende-r connector 400 is operated. to assooiate the selected sender with an idle incoming marker. i-'issuininu' the marker shown in the drawing to be the first idle one, upon seizure thereof the numerical record is again transferred from the sender registers to the corresponding marker registers. The record as thus .received by the marker is therein translated, and the proper connecting device as 502, is actuated to associate the marker With the proper group of connector switches which includes switch 800. Assuming the device 502 shown is the one to be used, then rela 505 which is individual to the selected iarker is operated. In addition, relay 506 Which is individual to the section 310, in connector switch 300, as determined by the units digit ot the Wanted line is operated. rllhe translation of the called. line record in the marker at this time causes the operation of vertical magnet 300, individual to the row ot contacts 304 in which the called line 307 appears.

As soon as the marker has been associated with the sender, relay 402 is operated. The operation oi' relay 402 completes a circuit for relay 406. This circuit may be traced :trom battery through the Winding, ot relay 406, contact 451, contacts oi. connector 400, conductor 452, lettarniature and back contact oit relay 111, conductor 453, contacts ot connector 400 to ground at an armature ct' relay 402. At this time also, thel proper traine connector 500 is selected and operated to thereby associate the marker with the horizontal links or" switch 201. The actuation or connector 500 is initiated by the operation of relay 507 which energia/es in a circuit traceable from battery through its Winding, conductor .551, armature and contact oi relay 406, armature and back Contact of relay 405,

Lecciso to ground at an armature oil relay 402. Relay 50"7 is individual to the marker shown. lt some other marker had been selected then the corresponding start relay as for example relay 537 Would be Operated to bring about the operation of the corresponding multicontact relay 538. ln tire manner described in detail in the above mentioned application ot S. Gibson, Serial No. 656,742, tiled August 10` 1923, Patent No, 1,559,244, when the connection has been extended tol switch 201, Vertical magnet 206 is operated, to preparc the contacts in vertical row 202, rlhe operation of inagnetQO@ results in the actuation or" multi-contact relay 509 which is iiidividuai to the switch 201. lilith relays 509 and 510 operated, certain ot the test relays 401 are connected to the test conductors of the links in switch 201. Since the called line Z307 is reached by the group ot switches including switch 300, and since the switches in this group are accessible by the trunks leadinfr vertical magnet 20?- is operated.

A test is nov.7 niade to determine an availe able path through switches 2,01 and 300 to the called line 807. This path comprises an idle li ik in switch 201 giving` access to an idle trunk terminating before a link as 313 in switch 300. This pathalso includes an idle link in switch 300 before which the called line appears.

Betere the marker can make a test oic the available path-s to the called line, it is necessary to associate said marker with the se-V lectec group of operators trunks. it the time traine connector 500 is operated, and subse lnent to the association of register sender 1 109 is actuated to indicate that the connection requires the services et an operator. The circuit 'for relay 109 may be traced Jiroin battery through its Winding and normal contacts, conductor 456, contacts oit connector 400, conductor 457, contacts ot relays 510 and 509 returning thence to conductor 458, to ground at an armature ot relay 402. lle-y 109 locks through its Windin' rand lock- W. Le

ing' Contact to ground at the armature of holdingv relay 108 which has been previously energized. V lien relay 109 operated, a cire cuit Was completed :trom battery through the Winding` ot relay 404, conductor 454 cont-acts ot connector 400, conductor 455, lett armature and Contact of relay V109 to the ygrounded conductor 453. Relay 404 operates relay 504 in a circuit tr ceable from battery through the Winding of relay 504, Contact ot rela-y 505, conductor 552, to ground at the outer armature and contact of relay 404. The operation of relay 504 serves to connect certain ot the marker test relays to the .sleeve contacts or" the trunlts appearing in row 205.

The testing circuit fory the links. in

from vertical row 205, the correspond-v rio switches 201 and `300 and the inter-connectingv trunks-Will nor; be described. The circ-uitor testing horizontal link 228 lmay be traced 'from batteryl through the lett Wind ing of relay 411', contact oi relay 40?, conduct-or 553, contacts or connector 500, conductor 251to the test conductor oit linlr 228. In a similar manner, testu circuitsv may be traced from battery through the lett Windings of relay-s 410, 4091 and 408 to the test conductors of links 22'?, 225, and 226 respectively. The circuit 'for testing operator"s trunk 220 may be traced from Vbattery through the right winding of relay 411, con tacts of relay 407, rightinner armature and Contact of relay 419, conductor 459, armature and Contact of relay 504, to conductor 256. lt trunk 220 is busy, either relay 208 or 209 or both are operated thus placing ground on the sleeve conductor of trunk 220, and conductor 256. In like mann-er, test circuits for the operator-s

trunks

222, 223 and 224, may be traced through the right Windings ot relays 410, 409'and 408 respectively. The test relays 408, 409, etc. are so=adjusted that they Will be operated ifieither one Wind ing alone or both windings together are energized. Should either a trunk or a linlr to which a test relay is connected be busy, ground potential is found thereon to cause the actuation ot the corresponding test relay.

Lastly, a testis made to vascertain the condition of a linl; such as link 313 in the connector switch 300 having access to line 30?. Thev circuit for this purpose may be traced from battery through the Winding of relay 415 conductor 460, contacts of connector 502, conductor 557 to the test conductor ofb linlr 313. lt this link` is busy, ground potential exists on the test conductor and causes the operation of rela-y 415. lt will be assu-ined that liiilz 228, trunk 220 and link 313 are .simultaneously idle and links 225, and 227 and the corresponding

trunks

222, 223 and 224 areall busy. Consequently. test relays 408, 409 and 410 are operated and relays 411 and 415 are normal.

As soon as the above testing operations have been completed, a circuit is closed from ground through the right inner armature and front. Contact of relay 404, armature and back contact of relay 415, lett armatures and iront contacts of

relays

408, 409 and 410 in series, lett armature and back contactof relay 411, to `battery through the Windingv of relay 419. The operation oi relay- 419 completes a `circuit from battery through the Winding of magnet 305, conductor 351` right armature and contact of relay 504, conductor 554, right outer armature and Contact of relay V419 to ground at an armature of relay 402. Magnet 305 in operating` rotates rod 370 toprep'are the contacts of vertical row 301 in whichy theiidle trunk 220 terminates.

The operation ot relay 4119 also completes energizing circuits for magnets 229v and 318. The circuit for operating magnet 229 may be traced from battery through the right Winding thereof, conduct-or 252, contacts of connector 500, conductor 555, lett inner armature and contact of relay 419 to ground at an `armature of relay 402. Magnet 229 rotates the corresponding horizontal bar (not shown), and completes the connection of trunk 100With trunk 220.

he circuit for operating magnet 318inay be traced from battery through the right Winding thereof, conductor 352, contacts oft connector 502, conductor 555, to ground through the lett inner afri'nature and contact ot relay 4119. Magnet 318 rotates the associated horizontal bar (not shown) and ei:- tectsconnect-ion of trunk 220 by ineansot linlr `313 With the called line 30?.

When relay 419 operated, it also completed a circuit romground at the left inner armature and contact of relay 402', arinature and bach Contact ofrelay 4037 middle armature and Contact oi relay 419, conductor 402, lett outer Varmature "and contact of relay 504, conductor 556, to battery through the Winding of relay 210. Since connection through iie incoming switch-201' has been completed,r-ilay` 114 at the opera-V tors position is energizedin acirc'ui't traceable iironi battery throughitsWinding, slee-ve conductor ot' trunk 100,' contacts-'of switchv 201, conductor 251 contacts or" Connector 500, conductor 553-, innermost 'fr'oiitfcon'tact of relay 407, left outer contz'tct4 of relay 419, to lground'at an armature of r'elayf402. Relay 407 is 'operated at-this'tiine'fiii the' inanner described in detail in the a'pplicationot S. B. Vllilliains, Serial No. 707,795, filed Japril 21, 1924. Relay 114 immediately locks to ground atthe release lkey 113. rllhel operation oi" relay 114 also maintains this same ground as a busy condition ontlie'- sleeve conductor ot trunk 100 which serresv as a holding circuit for magnet 229 subsequent to the release otv the ma er.' same ground is extended through contacts in vertical row-205 to conductor 253 of trurli 220, through the'right Winding-and neri y contacts of relay 208 to' battery. Relay loclrs in a circuit traceable frein battery through the` Winding1 "of relayl 209, lett outer armature and front 'Contact ot relay 210, right inner armature andfrontc'ontact, and right Windingot relay'208 to the grounded conductor 253. Slow release relay 209=op erates in this last traced circuit. 14n obvious holding'circuittor relay 210 isno'w completed to ground at the armature oi' relay 209.

ln the manner described in detail inthe above-mentioned YapplicationI ot S. 13.' lf2/vih liains,-Serialfl\lo. 7.507.795,1Iiled April 21, 1924, since the called line has been'seized,

the marker is released. The release the marker also brings about the release or operated vertical magnets in switche and 300 and the subsequent release c various frame and trunk connectors.

Prior to the actuation oi" horizontal inag- 318 the test horizontal magnet 319 was operated to determine the idlA conflit-ion or" the called line. For a de' iled of the manner in which this test is made, and also of the various detailed operations hereinbe'lore referred to, but not fully described reference may be had to the L, mentioned application of l5, ld' Serial No. 707,795, filed April 21, 192e.

As soon as the marker is released and the

vertical magnets

206 and 20'.7 are deenergiaed the connection through switch 201 is maintained by magnet 229 which is now held in a circuit traceable from battery, through both its windings in series, contacts of switch 201 to the grounded sleeve conductor of trunk 106. ln a similar manner connector switch 300 is maintained operated after the release et magnets 305 and 306, by the continued energization of magnet om or@ which is held in a circuit traceable from battery, through both windings in series, lowermost conductor oi' link 313, contacts of row 301, conductor 353, right outer armature and front contact of relay 210 to ground at the armature of relay 209. This same ground is extended by means of conductor 321 through contacts of switch 300, to the sleeve conductor oi line 807 rendering trunk 220 and the line 307 busy. `When it is desired to release the connection the operator restores key 113 thus removing ground from the sleeve conductor of trunk 100. The removal of ground from trunlr 10G causes the release of magnet 229, thus releasing the incoming switch 201. The release or the incoming switch removes ground from conductor 253 thus opening the. holding circuit ot' relay 209 which releases it the called suhscriber has disconnected. Should the called subscriber still maintain the receiver oil the switchhoolr subsequent to the release oi relay 208, a substitute locking circuit for relay 209 is completed through the winding and locking contact oi said relay, mit dle armature and back contact of relay 208, over the ring conductor oit trunk 220, through the contacts of switch 300, through the called subscribers loop returning thence by means of switch 300 and the tip conductor of trunk 220, left inner armature and front contact of relay 209 to ground at the arinature of relay 208. rThe interruptor 212 is provided to limit the time the. called subscriber can thus maintain the connector switch in its operated condition, subsequent to the release of the incoming switch. YWhen interrupter 212 closes its lower contact, ground is connected through the. contacts oi relays 208, and 209 through the normal contacts and winding of relay 211 to battery. Relay 211 operates and loclrs to ground at the armature of relay 209. At the end of a predetermined interval when interrupter 212 closes its upper contact ground is connected through the lett arn ature and contact or relay 211, to battery through theleft winding ot relay 208 which operates.

'llhe operation of relay 208 at thistinie ooms the locking circuit for rela-y 209 which begins to release, YWhen relay 209 has conil Lely retracted its armatures, holding Found is removed from conductor 321, and rel ased thus bringing about ci magnet 318 and switch 300. Y ed with the lrey set 105 is a no 19 by means of which the operator foled to extend the connection to a fubscriberls line even though this line may be other vise busy at this time tor the purpose or informing the subscriber that a second call, such as a long distance or toll call, is awaiting. 1t the waiting call is or" suilicient importance, the called subscriber *l may wish to discontinue the prior conversation to taire care of the more important call. Should, however, the called subscriber deem li Vsecond call oit insuilicient importance to is necessary that the operator release the second extended connection. ln order to r lease the various trunks and switches ein ployed in this second connection, the op rtor restores release key 113. rlhe restoraion oi lrey 113 removes ground from the lceve conductor et trunlr 100, thus releas-r ing incoming switch 201 and nal switch 300. However, since trunir 106 has been exmeen:

tended to a busy line, the sleeve conductor l be entended to the called line regardless oi?V this busy condition. Accordingly to anticipate the busy condition of this called line, the operator upon receiving the called designation operates the no test key 119 wherebv ma" Ye; is subsequently operated. ln this insta Lce, however, since relay 4:03 is operated the operating circuit for line busy test relay L112 is opened at the leitcontact of relay 1103, and the connection through switches warrant discontinuance of vthe irst call, it

the no test relay located in the *t i f right winding,

lconductor of trunk 106.

301 and 300 proceeds in the manner already described when line 307 was assumed idle. llllhen the connection is later completed through

switches

201 and 300, relay 210 tails to operate previously.7 described, since the circuit tor energizing this relay is new open at the contact of relay 103.

n a manner already described.V relay 208 operates over a circuit traceable through its and immediately locks over a circuit traceable from battery at the lett outer armature and'back contact oit relay 210, locking contact and right winding ot relay 208, and thence to the grounded sleeve Since relay 210 remains normal, the previously traced circuit for relay 209 is opened and this latter relay also remains normal. Under this condition, switch 300 is now held by means ot a circuit completed from battery through both windings of magnet 318, lowermost conductor Contact of link 313, conductor 353, lett inner armature and back Contact ot relay 210 to ground at the lett inner armature and front contact ot relay 208. Relay 208 at this right outer armature and Contact also maintains ground on sleeve conductor 321 and thence by means of contacts in switch 300 to the sleeve conductor of the line, to render the same busy should this line be idle at the time. lt will be remembered in the preceding description, there was a substitute holding circuit' for relay- 209 which extended through the called subscribers loop. However, since relay 209 does not operate when key 119 is operated. this holding circuit is rendered ineffective; conseniently, the operator may release the connection immediately that release key 113 is restored without waiting for the interrupter 212 to function.

A description will now be given oit the sequence of operations in the establishment of a local connection necessitating the use of one olf the regular incoming selector switches 200. For this purpose it will be assumed that the subscriber ot line 100 desires to converse with the subscriber of line 80'?, both ot which lines are located in the saine exchange. rEhe removal of the receiver by the calling subscriber causes line 100 to be ei;-

tended, by means of the automatic operation of line switch 101, through the district trunk 102 to the district switch 103. At this time also sender selector 10e is actuated to associate an idle register sender with thev calling line. rlfhe association ot a sender with the calling line causes the actuation oi' a connector similar to connector 100, resulting in the association of an outing marker with the calling line. Alfter the marker has thus been associated the cistrict selector switch 103 is selectively operated under control oiC the othce code as recorded in the marker resulting in the selection ot an idle trunk-as- 115 leading to a local incoming switch as 200. T.Vhen' such a trunk `has been selected the outO'oing n arkcr and sender connector release and a second sender connector l00 is actuated to` associate the eender with an idle incoming marker such as is partly shown in Fig. e. rEhe numerical portion ot' the called line designation is now transferred from the sender registers to the registers ot the incoming` marker wherein it is translated to cause the selective operation oi2 the connecting device 502. A record of the incoming trame to which trunk 115 leads haying been recorded in the sender-the-marker is no-w caused to select and actuate the proper incoming trame connector 500, resulting in the operation olf vertical magnet 237. The translation of the marker also brings about the actuation ot the vertical magnet 300 controlling the vertical row of contacts in which the called line appears, and since t-he called line 307 is located in section 310 of the connector switch, relay 506 is operated. Since the group ot trunks required to complete eXtension to the called line has been deiinitely locatedgas leading from incoming switch 200 to connector switch 800 the trunk connecting ldevice 501 is selectively operated to associate this group oit' trunks with the marker testing mechanism.

lt will be assumed that the trunks appearing in vertical row 216 compose the group leading to the connector group having access to the called line. Only three ot these trunks have been shown, but it will be understood that the number will be in proportion to the requirements ot the-trahie conditions.

As hereinbeiore mentioned trunk the last trunk in the group appearing in vertical row 216. rlihe marker now performs a test of the horizontal links in switch 200, of the

trunks

219, 220, etc. and also ot the horizontal links in section 310 of connector switch 300 in substantially the same. manner to that previously described in connection with an interot'rice call. ln this case, however, since the trunk groups are relatively large and trunk connector 501 is operated in place of relays suoli as 503, 504i-, etc., the maximum number of test relays corresponding to a maximum number ot trun rs in a group is required. From an inspection orp the figures it will be seen that the test circuits ior the trunks in this instance, however, are substantially similar to those described in connect-ion with the operation or" switch 201, except that these circuits are now completed through contacts of device 501, instead of through contacts or a relay such as 503, 504, etc. lt will be 'further observed that none oi" the relays 503, 501i, etc. operated in this case because ot the tact that relay L10st inthe marker is not energized. The reason relay 4011 is not energized at this time is because the relay 109 in the sender has not been previously operated. lr" the test reveals the fact that link 235, trunk 220 and link 313 are simultaneously idle relay 419 is operated in a circuit traceable from ground tlifoug.L the right inner armature and Contact ot relay lO2, right inner arinature and hack contact ot relay LlO-l', lett armature and front contact ot relays 4508, ZlOQ, e110 in series, left armature and hack contact ot relay L111 to battery through the winding 1" relay Relay L19 operates in the manner hereinbeiore descr'hed and causes the operation ot horizontal magnets 236 and 318 whereby the connection is ei;- tended through switches 20() and 300 to the called s hscribers line 307.

The release oi a connection alter the termination ot conversation substantially similar to that d scribed in connection with interoilice call.

From the foregoing' description it will he seen that in certain classes of connection wherein incoming switches oi th type ot switch 200 are employed a simultaneous test is made ot a selected trunk group determine the first idle one thereolrl thel purpose of completing a connection ther-cover. This selected idle trunk obviously may he located at any point in the group. ln the class of connection requiring the use ot an incoming` switch similar to switch 201 a particular trunk in each of these trunk groups must he selected, namely, the last one thereof, thus allowing one trunk in each of the trunk groups outgoing from the regular incoming switches to be used for both local connections and interolice connections requiring,` the service oit an operator.

Certain other features of invent-ion disclosed in the drawino' lout not claimed in this application are beingl claimed in a cepending application or' E. S. Gibson, Serial lilo. 726,241, tiled July 16, 1924:.

1. ln a telephone exchange system, a callin@` line., an operators position, a first selec- Ji Y rre cli 'for extending said callingv line, a second selective switch, a group of trunks intereonnecting` saiLL lirst and said Second selective s 'it-ches, means under control of said calling' line for selectively operating said lirst selective switch to seize aA y trunk in group oit trunks and means -under control ol said operators position for seizing a particular trunk in said group ol' t"unks.

2. ln a telephone exchange system, a calling line, an operators position, a first selective switch Jfor extendingt said calling line,

a second selective switch, a group of trunks intercoi'inectino said lirst and said second selective switches, means under control ot" said calling line for selectively operating said tirst selective switch to seize an idle trunk in sait group of trunks and means unoer control oi said operators position for a telephone eiicvliange system, a calloperatons position, a first selecli :tor el* 1 Y,ctiie swi cli, a :group of trunks fino said i'irst and said second se lies, means under control sa line tor selectiyely operatiii.,` sal I switch to seize any trunk in means under of trunks and erator/s position for seizt trrnk in said group o'i l.or s position, a first selec- `.1'on 1 or a particui un ci trunks without opnentioned selective switch.

4Aeesystein, a calli d tors position, a lirst selecv i@ calling,` line.` p second selective switches, groups of trunks inter-connecting said first selective switch and said plurality or second selective switches, means under control of said n.wllina' line, t i marking a particular one c ,1d groupsot trunks, means :tor selectively operating' said 'first selective switch to seize any trunk in said marked group, and ineaunder control ot said operators position for seizing` particular trunk in any' et said plurality oi groups of trunks.

G. ln a telephone exchange system, a. callline. an operators position1 a lir'st selece witch for etending` said calling line, plurality or second selectiveV switches of trunks inter-connecting said selective switch and said plurality second .se entive switches, neans uriner control oi calling line for niarkenteric ng said calling' line, a

selectiveV said' particular one ot said` groups of a particular trunk in said 0*rou* ot Y means under control ot said calling line Jfor seizing any trunk in any ot said groups ot trunks, and ineens under control ot said operators position .tor a particular trunk in any ot said groups ot trunks.

8. ln a telepl'ione exchange systenn av calling line, an operatoria position, a iirst selective switch tor extending said calling line, second selective switch c ntrollahle troni said calling line and t n said operators position, groups ot trunks inter-connecting said first and said second selective switches, means under control ot said calling line tor seizing j trunk in any of said `groups of trunks, and nierns under control of said operators position for seizing); the last trunk in any ot said ot trunks,

9. In a telephone exchange system, a calling line, an operators position, a first selective switch for extending; calls originating on said calling line, a second selective switch, tor extending calls originating at said op'- erators position, a third selective switch accessible in common to said tirst and said second selective switches, a group ot trunks inter-connecting' said lirst selective switch and said third selective switch, particular trunk in said group also interconnecting said second selective switch and said third selective switch, means under control ot one ot said calling lines for selectively operatingI said rst seective switch to seize the 'first idle trunk in said group of trunks, and means under control ot said operators position of seizing' said particular trunk in said group ot trunks.

l0. ln a telephone exchange system, calline' lines, an operators position, a first selective switch tor extendingr calls origrinatinp,` yon said callingr lines, a second selective switch tor extendingcalls originating at said operators position, a third selective switch accessible in common to said lirst and said second selective switches, a sgroup ot trunks interconnecting said lirst and said third selective switches the last trunk in said group also interconnecting` said second and said third selective switches, means under control ot ono ot said calling lines tor selectivelyT operating said iirst selective switch to seize the tirs-t idle trunk in said group of trunks. and means under control ot said operators position for seizing; only the last trunk in said ejroup ot trunks.

ll. In a telephone exchange system, calling lines, an operators position, a tirst selective switch tor extending calls originating' on said calling` lines, a second selective switch for extending calls oricjinating.;` at said operators position, a third selective switch accessible in common to said iirst and said second selective switches, a Agroup of trunks leading to said third selective switch, a particular trunk in said lgroup bein?,` accessilole in common to said first and said second selective switches, means under con..- trol ofonefof saidV calling; lines. for select-ively operating'said first selective switch to seize the first idle'trunk in said group ot trunks, and means under control of said operators position tor seizing only'salid c oninion trunk in said group ot trunks.

12. In a telephone exchange system, a calling;` line, a called line, an operators position, a first selective switch tor extending` said callingl line, a second selective switch, a K@group ot trunks interconnecting said first and said second selective switches, means under control ot the calling' line for seizing,v any one ot said trunks, means under control ot said operators position tor seizing; particular trunk in said group tr means tor aaintaining a busy condition on said called line, and means eii'ectiif'e when said particular trunk ha heen seized tor operating' said second selective switch under cor.- trol ot said operators position to complete the extension of said calling line to said called line while said calledline is being maintained busy.

13. ln a telephone exchange system, a calling' line, a called line, an operators position, a first selectiveswitch for extending said calling` line, a second selective switch controllable from said calling); line and from said operators position, groups of trunks extending between said lirst and said sec-- ond selective switches, means tor maintaining' a busy condition on said called line, means under control ot said calling line for seizino,` an idle trunk in any of said groups ot trunks, means under control of said operators position tor seizing' a particular trunk in any oit said groups ot trunks and for selectively operating said second selective switch to seize said called line while it is being maintained busy.

14. In a telephone exchange system, a suliscribers line, an operators position, a first selective switch tor xtending connections troni said line, a second selective switch for extending connections to said. line, groups ot trunks leading to said second selective switch, means under control ot said first selective switch for maintaining said line busy, a third selective switch, means under control ot said operators position tor operating,` said third selective switch to seize a particular trunk in said group ot trunks and for oiieratino said second selective switch to complete a conversational connect-ion to said line while it is being maintained busy by said first selective switch.

l5. ln a telephone exchange system, a subscribers line. an operators position, a first selective switch tor extending),l connections from said line, a second selective switch for extending connections to said line, grou s ot trunks leading to said second selective switch, means under control..

l0 Leraars.;d

said lirst selective switch for maintaining said line busy, a third selective switch, means under Control of said operators position for operatingT said third selective switch to seize a particular trunk in said group of trunks and for operating said see ond selective switch to complete a conversational Connection to said line regardless of the busy or idle condition of said line.

16. In a telephone system, a. telephone line, aw selective switch, a group of trunks, means for operating said switch to extend tor for governing' said marker to cause the f extension of a. connection over a particular one oi said trunks to said line regardless of the condition of said line.

In Witness whereof, I hereunto subscribe my naine this 14th day of July, Au D. 1924.

SAMUEL B. VILLIA MS.