US1621503A - Automatic telephone system - Google Patents

Description

March 22,1927. 1,621,503

J. E. GARDNER AUTOMATIC TELEPHONE SYSTEM Original Filed Oct. 17, 1921 3 Sheets-Sheet -Imran a:

Jar hm Efiard'uar Mada 232 3 H2? (SA-RENE? AUTOMATIC TELEPEGXQE SYSTEM Original Filed Oct. 17. 1921 3 Sheets-Sheet 2 R lnuen n Jplm E'Eardnsr J. GARDNER AUTOMATIC TELEPHONE SYSTEM Original Filed Oct. 17, 1921 3 Sheets-Sheet 5 Juhn Efisrcfnar Patented Mar. 22, 1927. r v l i l it I Y siise STATES .QFEICE- (JOHN E; GARDNER, F CHICAGO, iLnIiiois, Assieiren BY MESNE"'Assiegiiiiii itrsf re AUTOMATIC ELECTRIC rim, OF CHICAGO, ILLINoIs, A conromurionfes DELA- I 7 AUTOMATIC TELEPHONE SYSTEM.

A pmne filed 'octbter 17, 1221, seriaI'NoLSOBQSEI. Renewed Jane 5, 1926;

The present invention relates in general tion by a nieste'r switch such as the; oneto'e'utomatic telephone systems, and is more shown at M. One of the local connectors particularly concerned withsuch systems 95S to which the line switch 0 ha 'snccess is are usually installed in mercantile estsbshownlin thefl'drawi ngs at H T; 1 1;;

5 lislnne'nts' and the like, and which are coin- V The master switch Mis of theusu'iil -solein-only known as privatei'eutomatic e inoid typefand mentioned before main-w changes. i b Y I V tains allthe line switch plungerses'sogcieted More specifically, the invention relates with an idle trunk line. r

to the provision of a new and improved The connector H is a switch ofthe usual 10 transfer or passing call sy' 'st end- Her'eto- St row ger verticaland rotary typeof mefore passi 311 sy tem have been design d chanical construction. The wipe-rs of this but all of these had to do \viththe passing or connector switch have access, to 100fb1ank transferring of the call from one subscriber contacts these being" divided intoten levels to another in the private automatic eX- With ten. sets ineach lev l-- On the first 15 change on an incoming call from the main nine levels thejconnector H has access to [to the branch exchange. The present inord nziry subscribers lines, which are s mi-" vention'provices means whereby in t-hecase arto the o e S w at A- On h tenth of an outgoing call from a subsrriber in the l v l h wev r, this connector has'a'ccess to' private automatic exchange to 2i subscriber trunk lines extending to thema ch ng i '20 in the ni-ein exchange, the calling party ma and is ap foper'ait ngi s a el b 7'5 transferthe call to another subscriber in the o Select and con-nectqwith an idle one of; branch exchange, Thi ty f s r i is these-trunk lines. One. of these trunk lines especially desirable in caseof an executive is show n the draw ngsr e i t gii t who has his secretnr 1 or ofiic'e boy set up bank. co tac -s 75- n sive 1 Assohis connection for hinn \Vhen such einciated with each one of the local connectors so, ployee has extended a connection to the deis a Small t P r y Wi C Y T sired called party, the call may then be rotary s it hesso ietegl withthe local conextended or transferred to the executive. nector H is shown at/VF, I

' There are other objects of the invention R tary Switch F is of h Same, ge l' not now specifically mentioned, which,to, echa cal co struction as h to hewl l-vss 'gether with the foregoing willbe described known rotary l v hQ E eisi fully hereinafter with reference to the accircuits a t g bi it 110W p fi "companyin drawings I as e finder switch, eswill be described lziter. Referring now to the drawings coinprisgr up of relays shown in h 1 .1 10

means of theusu-ul circuit diagrams-en outhector H Which h v 11 n Wh I going connection from calling subscriber Cluded in t e j i K to av id in the private automatic exchange to a sub-. too great complicationof the f circuits howscriber in theinnin exchange through the ever, it will be understood that inprnctice 40' line'switch C and connector H. v all these relays are mounted fon-the: con- Referring no v more .purticul-erlyto Fig. 'ne'ctor switch.- y i ,7 1, there is shown a subscribe-rs -substation Q Having briefly described the app u i A f th ual automatic type, the uss'oshown in the drawings," it's operetign will ciated line of which terminates at the ex now be described more in. detail. For this ing Figs. 1 2, and 3, there is shown by p t 0f1F g-3 are Certain relays on'th'e con- 90 45' change in the individual line switch C; purpose, it will be assumed l'l'fltvtlie 'fsub- The line switch C isof the usual Keith I scriberut substation desires to extend the or plunger type whose function is toextend connection to a subscriber i -the ma n exthe associated line when calling, over the change. In order to ClOtlllS, the subs'c'rlber trunk line which has been f are-selected .by ,will remove his receiver and op'er'tte his 50 the associated master switch; Line switch 'cnllingidevice for the digits oi the desired C in common with a plurality of other sinicalled number in the usual manner, except iler line switches has access to trunk lines that the digit 0 will be prefixed. extending to local connector switches. All When the receiveris removed at the al line switches of the group are adapted to be ing substation, a circuit is completed for the controlled "in their trunk selecting open linerelayQO of the line switch C, over the 1 0 line conductors 11 and 12 in series. Relay 20, upon energizing, at its armature 30, completes a circuit extending from ground, by

way of front contact and armature 30 through plunger arm 23 and the cut-off armature 24.

By the operation of the plunger arm 23,

the calling subscribers line conductors 11 and 12 areeXtended by way of springs 42 and 43, 40 andtl, trunk conductors 67 and 64, to the lower and upper windings of the line relay 101 of the connector H. r

Line relay 101 is immediately energized '7 over the calling line loop, and at its a11na ture l20 completes the circuit of the slowacting relay 102. The latter relay, upon energizing, at its armature 127, prepares the impulsing circuits of the connector H, and atits armature 126, places ground upon release trunk conductor 65, thereby. establishing a holding circuit for line switch C. This holding circuit may be traced from ground on release trunk conductor 65, springs 47 and 46, and thence through the holding winding 22 of the coil 21 to battery. It will be noted that the cutoff armature .24 upon being attracted, opens the circuit of the slow-acting line relay 20. However, it will be understood that the relay 20 maintains its armature attracted until the above traced holding circuit is completed. The branch of this holding circuit also extends by way of the private normal conductor 63 to multiple connected test contacts in the banks of the local connector switches, whereby the line of the calling substation is protected from intrusion in the usual manner. Another branch of this holding circuit extends by way of the springs 44 and 415 to the contact 79 in the master switch bank, whereby the master switch is caused to rotate the plunger arms of all idle line switches into association with an idle trunk line. This trunk selecting operation will now be described briefiy.

When ground is placed upon the master switch bank contact 79, a circuit is completed, if the master switch wiper is in engagement with this contact, extending from grounded bank contact 79, master switch wiper 77, common segment of the master switch bank, conductor 81, back contact and armature 8a, and thence through the upper winding of the starting relay 75 to battery. Relay 75, upon energizing, at its armature 85 closes a circuit for locking magnet 86. Magnet 86 operates to withdraw the locking arm from the fan shaped segment, whereby the line switch plunger arms of master switch wipers are moved under the influence of a spring (not shown) operated position.

into association with the next trunk lino. If this trunk line is busy, the starting relay will be maintained energized and consequently the locking magnet 'will be held magnet, thereby allowing a locking arm to engage the locking segment of the master switch, and thus stopping its rotation.

Should the master switch rotate until its wipers are in engagement with the last trunk line, the spring 93 will be operated into engagement with its working contact and the trip relay 90 will be energized. The latter relay, upon operating, closes the circuit of the solenoid S, and also a locking circuit for the starting relay 75. The solenoid operates to rotate the line switch plunger arms, master switch wipers opposite the first trunk line. During the time which the master switch is rotating from the last to the first trunk line, the armature of the trip relay 90 is held in an operated position by the spring 95, and consequently the master switch does not test for an idle trunk line. When opposite the first trunk line, the spring 95 is forced out of engagement with the armature of the trip relay 90, and the trunk selecting operation of the master switch takes place in the same manner as was before described.

Returning now to the operation of the connector H, it will be noted that the circuit of the line relay 101 includes a secondary winding of the-transformer of thetone machine T. This, of course, gives the calling subscriber a signal and notifies him that everything is in readiness for him to operate his calling device. By the operation of the calling device ten interruptions are produced in the line circuit of the line relay 101, which retracts its armature a corresponding number of times, each time send ing an impulse of current over the following path: ground by way of armature 120 and its back contact, armature 127 and its front contact, off-normal springs 119 and 117, through the winding of the slow-acting low resistance relay 103, and thence through the winding of the vertical magnet 113 to battery. The above is the circuit over which the first impulse through the vertical magnet is' sent. However, upon the first vertical step of the switch shaft, the off-normal springs are shifted and the remaining vertical magnet impulses traverse a new circuit which is the same as the one previously traced, except that it includes the off-normal springs 119 and 118, and armature 129 and its front contact, relay 103 being now in an raise the switch shaft carrying the wipers Magnet 113 operates to lector, the line relay will be energized and will operate to close the circuitof its associated slow-acting release relay. As this bridge across the two trunk conductors 199 and 200 includes springs on the line relay 101 of the connector H, the calling subscriber at substation A. by operating his calling device for various digits of the called number, controls the automatic switches in the main exchange in the usual manner, in order to extend the connection to the desired subscriber. When the calling device of the substation A is operated for the various digits, the slow-acting relay 108 is energized during each series of impulses, and operates to disconnect the impedance coil 104 from the bridge and closes the bridge direct across the trunk conductors through the springs on the line relay, in order to improve the impulse transmitting circuits.

It will be remembered that the above mentioned bridge includes the windings of the relay 104, and the lower winding of the electropolarized relay 251. energized in series with the line relays of the switches in the main exchange, but the electropolarized relay 251 is not operated at this time due to the current in both its windings being in opposition.

When the called subscriber in the main exchange removes his receiver from the switch hook, the battery is reversed over trunk conductors 199 and 200, and the electropolarized relay 251 operates. Relay 251, upon energizing, at its armature 258 prepares a circuit of the relay 252, at its armature 257 prepares a point in the circuit of relay 250, at its armature 259 places ground upon conductor 208 for a purpose which will be described later, at its armature 261 places an additional battery connection upon the conductor 211, and at its armature 260 opens a point in the circuit of release magnet 111.

Should the calling subscriber desire to transfer the connection to another subscriber in theprivate automatic exchange, he will operate his calling device in accordance with the digits of that subscribers number in the usual manner, except that the digit 1 islVhen the calling device at substation A is operated in accordance with the digit 1, a single interruption is producedin the circuit of the line relay 101 which retracts its armature in response thereto. lVhen the armature is retracted an impulse of current is sent over the circuit extending from ground by way of armature 120 and its back contact, armature 127 and its front contact, off-normal springs 119 and 118, armature 129 and-its back contact, conductor 209, front cont-act and armature 258, and thence through the winding of relay 252 to battery. Relay 252, upon energizing, establishes a Relay 10-1 is locking circuit for itself at its armature 262, at its armature 264 completes a circuit of the line relay 271 ofthe finder switch F, and at its armature 263 completes a circuit which extends over the following path: ground by way of armature 263 and its front contact, conductor 216, armature 15 1 and its front contact, wiper 172, bank contact 177 through the upper winding of relay 190, common conductor 193, back contact and armature 196 to battery. Relay190, upon energizing, establishes a locking circuit for itself at armature 191 which includes the winding of the common relay 195, and at its armature 192 removes the ground connection from the test contacts, such as 2941 in the banks of the tinder switches in order to enable the trunk line to be connected with. The common relay 195, upon energizing, at its armature 196 disconnects battery from the common conductor 193 so as to prevent any other subscriber operating a finder switch at this time, and thus causing interference as will appear later.

Returning now to the operation of the finder switch, it will be remembered that a circuit was completed for line relay 271. Relay 271, upon energizing, at its armature 275 completes a circuit which includes the winding of the switching relay 272 and the motor magnet 273 in series, and at its armature 276 connects the test wiper 293 to the above circuit at a point midway between the switching relay and the said motor magnet. If the wipers of the finder switch F are not associated with the trunk line in use, there will be a ground potential present upon the test contact engaged by the test wiper 293. Switching relay 272 is short circuited and the motor magnet being supplied with direct ground by way of the said test wiper, will operate as a buzzer, and advance the switch wipers step by step in search of the trunk line with which the wipers of the connector switch H are now in engagement, and which is the trunk line shown in the drawings terminating in bank contacts 293 295, inclusive. lVhen the switch wipers of the finder are rotated into engagement with this set of bank contacts, there will be no ground potential present upon the bank con tact 294, engaged by the test wiper 293, the rotation of the switch will cease, and the switching relay 272 being no longer short circuited will'be energized in series with the motor magnetv 273. Relay 272, upon operating, at its armature 27 9v completes the circuit of the release magnet 1,11, and at its armatures 277 and 291 establishes a new connection between the calling subscriber at substation A, and the trunkline comprising conductors 199 and200. The circuit of the release magnet 111 may be traced from ground by way of armature 27 4 and its front The relay 104 is immediately energized over restore the switch shaft to normal and at the spring 162 to open the circuit of the relay 107.

By operating the calling device at substation A for two digits of the called numher, the connector H may be re-operated into engagement with the called line in the same manner as was described before.

It will now be assumed that when the connector H is operated into engagement with the bank contacts 18et187, inclusive, that the associated line is idle. In this case there will be no ground potential upon the test contact 185 and relay 107 is not energized. Then, upon the deenergization of the slowacting relay 108, a circuit is completed for the switching relay 109. In orderto simplify the drawing as much as possible, the off-normals of the subscribers line associated with the bank contacts 18el187, inclusive, have not been shown. However, it will be understood that the normals of this line are connected in the same manner as that of the calling substation A, the normals of this substation terminating in the bank contacts 179l82, inclusive. In order to facilitate the explanation, it will be assumed that the substation A is the called substation. The circuit of the relay 109 may then be traced from ground on release trunk conductor spring 162 and its working contact, conductor 14:7, armature 140 and its back contact, through the lower winding of the switching relay 109, back contact and armature 145, normally closed springs controlled by armature 150, test wiper 171, test contact 180,'private normal conductor 63, and thence through the winding 22 of the relay 21 in-the line switch C to battery. The energization of the winding 22 serves to attract the cut-off armature 24, whereby the line of the called substation is disconnected from its normal battery and ground connections in the line switch associated with the called line.

In the connector H the relay 109, upon energizing, establishes a locking circuit for itself at armature 1 19, prepares the circuit for the relay 253 at armature 152, and at armatures 1 18 and 155. completes the ringing circuit. Ringing current is now intermittently projected out on the called line until the subscriber thereon responds.

When this occurs, the ring cut-off relay 106' is energized over the called line loop. Belay 106, upon operating, establishes a locking circuit for itself at armature 135, at armatures 134 and 136 opens the ringing circuit, and at the front contacts of these armatures finally completes the talking connection.

the called line. Talking battery is supplied to the calling substation from the windings of the line relay 101 and to the called substation from the windings of the relay 104.

upper winding and the relay armatures are attracted. The relay 10%, upon energizing, at its armature 1 17 closes the circuit of the slow-acting relay 110 and at its armature 131 opens a point in the circuit of relay 25'0'.

' The operation of relay 251 serves to prepare certain circuits, the functions of which will be described later.

The cell having been passed to the desired party in the private automatic exchange, a three party conference may now be held between the two subscribers in the private automatic exchange and the subscriber in the main exchange.

The original calling subscriber may by operating hiscalling device for the digit 1, release the second called party in the private automatic exchange from the connection. When the digit 1 is dialled, the relay 252 is energized as before described, and closes the circuit of the release magnet 111 of the connector H. The connector H is then released in the same manner as was described before, and may be re-operated.

Should the original calling subscriber desire to retire from the connection, he'ma'y do so merely by replacing his receiver upon the switch hook. This operation causes the deenergization of relay 101, and the latter operation opens the circuit of the slow-acting relay 102. Re'ay 102, upon deenergizing', prepares a point in the release magnet circuit, and at armature 126 removes ground from the release trunk conductor 65, thereby opening the holding circuit of the calling line switch C, and allowing it to assume its normal position. After the deenergization of the line relay 101, and before the deenergization of the slow-acting relay 102, an impulse of current is sent to the slow-acting relay 253. Shortly'after the deenergization of relay 102, relay 253 is deenergized. Ground is then replaced upon the release trunk conductor 6-5 and over the circuit extending from ground by way of front contact and armature 259, armature 268 and its back contact, backcontact and armature 126 to release trunk conductor 65. The ground on release trunk conductor 65' serves to maintain the connector switch H busy, so that it cannot be seized by another calling subscriber. The subscriber of the called substation in the private automatic exchange is still in communication with the called 'subscriber in the mainexchange. I

Should the called subscriber in'the private automatic exchange find it necessary to transfer the call he may do so by prefixing the digit 1 to the number of the desired called party. When the digit 1 is dialled a lOlretracts attracts its armature ,.,Re1'a 104 u on deener izin comv i w pletesa, circuit which extends from ground at a l matllre 124 by way of back contact and from the trunkcenduct-or 6.6 which extends to a bank contact in the auxiliary master switch bank associated with the trunk line connected to, the connectorH Still another .result'of the operationof relay 250 is-that a circuit for the release magnet 111 of the V cennector is prepared at armature 256', and at the front contactwof armature 255 a circuit is completed extending from ground their armature 255 and its front Contact;

conductor 216, armature 15A and its front contact, wiper 1T2,bank contact 181, normal conductor 62 t-hru the pull down winding of the-"coil 21 of the line switch associated with the called line, common conductor 50 and armature 72 and its back contact to =tive at this time as the relay '87 is energized as will subsequently appear. It will be recalled that the locking'circuit of the relay- 25,0jincluded the winding of the Common reat its lay 280. Relay I280, upon operating,

- Sa i-mature 284 disconnects battery from the common conductor 282 in order to preyent interference in passing the call and at armature 283 completes a circuit extending from ground by way of front contact and the said armature; conductor 204,conductor 10,;and through the winding ofthe relay Tote bat-V tery. Relay 76, upon ener-gizing,'at its armature 7 3 disconnects battery fromall the line relays in the line switches of the group, at 1 armature 84 disconnects the master switch wiper 77 from the starting relay and connects the auxiliary master switch wiper 78 thereto. As all the bank contacts of cept the trunk line associated with the connector- H, ground having been removed from the bankcontact of this trunk line by the operation of the relay 250, the masterswi-tch will then operate in the usual manner to select this trunk. Immediately upon so doing 'the-open-main relay 8'? which was energized during'the operation oft-he master switch deenergi'zjes 1 again "connects" ground through the pull downwinding of the line sw itches. 'As there is ground connected to the conductor ('32 the 'pull down winding of his calling device.

the coil-21 will immediately he actuated and l the line switch of the called subscriher will" be plungedfin on the trunk line leading to theconriector VWhen "this 'occu-rs a fcircuit is completed for the liner-slay 101 which nn'medlately'energizes and closes the circuit of the slow acting relay102. There is an I other clrcuit compl'e'ted'by the energizatlon of relayIlOLwhich extends from ground; by way of armature 120 and its front contact,

of relays 109 and 106 serve to restore certain 1 circuits in the connectorIH-to normal. Relay f104, upon deenergizing, opens the circuit of the "slow acting, relay llo'which deenergizes removing ground from the conductor 65/; The "deenergizati'on offirelays 250 and 251 restore varlou's circuits to norinaL Relay 28.0, upon deenergizing, again connects battery tothe common conductor- 28.2 whereby a second call may be passed and opens the circuit of the relay 76, in the master switch M. V Thedeenergization of battery. ,Howeventhis circuit is not efi'ecinlay 6 again n cts battery to the line conductor 210, armature 256 and-'itsfront relay of the line switches and disconnect-s 7 the-auxiliary masterswitch wiper and again connects the wiper 77. I

All the foregoing operations have; occurred in response to the dialling of the digit .1 by the called subscriber'in-Tthe prirate automatic exchange These operations take an exceedlngly short interval of time and the hunting operatlon of the-master switch under the 'control-- of i the auxiliary wiper 8 does not interfere With its regular 1 operatlon of preselect-ing trunks.

matic exchange is now connected to the contor in the same manncras before described to transfer the call'to another private automatic exchange party, Thecall may be again transferred by'that party in thelsame V inanner'as was that first described. trunk lines are grounded in this bank GXL it should be: noted that immediately upon the line switch of the; called: subscriber plunging in ont he tr-unk line leading to the, proper connector switch the circui-t'of the line relaytof that switch includes the secondary j windingof the transformer of the tone'machin'e. Consequentlythe called subscriber is notified when i Iclaim: 1 e. V '1. 'In a telephone system main and branch exchangestelephone lines in both exchanges, automatic switches in both exchanges, trunk" he :may operate lUl) hector H and may now operate thisconneov The called subscriber in the private auto-" lines'extendingtrom the branch to the main exchange, means controlled from a calling one of said telephone lines in said branch exchange for operating a series of said automaticswitches to set up aconnection with one of said telephone lines in said main exchange over one of said trunk lines, and automatic means controlled by said calling subscriber for then extending the connection by automatic switches in. the branch exchange to another called line in said branch exchange.

2. In a telephone system, telephone lines, main and branch exchanges, trunk lines connecting said exchanges, automatic switches in each exchange, means controlled from one ot'said telephone lines in said branch exchange for establishing a connection over one of said trunks by wayof a series of said automatic switches in said branch and main exchanges with one of said telephone lines in said main exchange, and means con trolled from said calling line for operating some of said automatic switches in said branch exchange in order to extend the said connection to a second one of said telephone lines in said branch exchange. i 3. In a telephone system, telephone lines, main and branch exchanges, trunk lines connecting said exchanges, automatic switches in each exchange, means controlled from one of said telephone lines in said branch exchange, for establishing a connection over one of said trunk lines by way of a series of said automatic switches in said branch and main exchanges with one of said telephone lines in said main exchange, means controlled from said calling line for oper ating some of said automatic switches in said branch exchange in order to extend the said connection to a second one of said tele phone lines in said branch exchange, and means controlled from the calling line for releasing the extended portion of the connection. V

4. In a telephone system, telephone lines, main and branch exchanges, trunk lines connecting said exchanges, automatic switches in each exchange, means controlled from one of said telephone lines in said branch exchange for establishing a connection over one of said trunk lines by way of some of said automatic switches in said branch and main exchanges with one of said telephone lines in said main exchange, means controlled over the calling line for then extending the connection solely through some of said branch exchange automatic switches to a second one of said telephone lines in said branch exchange.

5. In a telephone system, telephone lines, main and branch exchanges, trunk lines connecting said exchanges, automatic switches in each exchange, means controlled from one of said telephone lines in said branch exchange for establishing a connection over one of said trunk lines by way of some of said automatic switches in said branch and main exchanges with one of said telephone lines in said main exchange, means controlled over the calling line for then extending the connection solely through some of said branch exchange automatic switches to a second one of said telephone lines in said 7 'anch exchange, and means controlled from the calling line for disconnecting the said calling line from the connection.

6. In a telephone system, telephone lines, main and branch exchanges, trunk lines connecting said exchanges, automatic switches in each exchange, means controlled from one of said telephone lines in said branch exchange for establishing a connection over one of said trunk lines by way of said automatic switches in said branch and main exchanges with one of said telephone lines in said main exchange. means controlled over the calling line for then extending the'connection to another branch exchange line solely through some of said automatic switches in said branch exchange, and means controlled from the callingline for disconnecting the said calling line from the con nection while still maintaining a connection between the two called telephone lines.

7. In a telephone system, telephone lines, main and branch exchanges, trunk lines connecting said exchanges, automatic switches in said branch exchange, means controlled from a calling one, of said telephone lines 1n said branch exchange for establishing a.

connection with one of'said telephone lines in said main exchange through a series of said automatic switches, and means controlled from the said calling line for releasing part of said series of switches while still maintaining a connection with said called telephone line.

8. 'In a telephone system, telephone lines, main and branch exchanges, trunk lines connecting said exchanges, automatic switches in said branch exchange, means controlled from a calling one of said telephone lines in said branch exchange for establishing a connection with one of said telephone lines in said main exchange through a series of said automatic switches, and means controlled from the said calling line for releasing part of said series of switches while still change over one on said: trunk lines, and totrunk linesconly and; controlled from said means'controlle'd' from thes'aid' calling telecalling line fort them extending the connecphone line for releasing; one of; saidautoe tion to, another called line in, said branch rnatic switches-- While maintaining a: COIHlGC'' exchange ,c 5 tioniWitlrsaidcalledtelephoneline.v 1'5. llnga telephone systenntelephone lines,

10.- In a telephone system, telephone lines, rnainiandibranchexchanges,trunk linescons mainand bnanchkexchangesr, tnunklines con:- necting said exchanges; automatic switches meeting said exchanges, automatic" switches in saiidiexchanges; means controlled from a in said branch exchange controlled from onecalling:- telephone line in said branch ex,- =-of said telephone lines. in: said branch; eXrchange{or-extendingcalliover one of; said v ch'a'nge fon establishing; a connection; with trunk lines by Way. of a: series of automaticv one of said telephone lines'in said main. ex;- switches in: sa'id'hranch. and maimexchange change over one of" said trunk lines, and to a; telephone linein said main er; hangs, meanscontrolled firoin the said calling te1e-. anda ineans controlled" from said callingline 15 phone line for; releasing one on said: auto-Q for'openating an automatic switchto. nai'nr IHZLtlG SWltCllG'S While inaintaininga connectain. said established connection While ne-i tionwith said called telephonelind whereby leasingpne; of; the switches. in. said series; in: saidswitch may he-reoperated. to extend; the Order: to extend the said connection to a established conncctiona to a: second: of said second one ofsaid telephone lines in said telephone lines. brancln exchange. g 1:1 In. a telephone system, telephone lines, 16. En. a telephone systenntelephon ines, automatic switches; means-1 controlled: from main and biian'ch exchanges,trunk lines con; a calling oneof said lines; fon operating a nectingsaid exchanges, automatic switches; series of said switches order to extend a, illusaid ex h nges, means controlled; iii-T0111 25 connection to: calledione of!- said: telephone calling telephone linein Said branch excalled line ..via: the remaining switches,; andxlne'ans controlledfromsaid calling,

lines, and means controlled from the-calling; changefon extending a call over one of said line for releasing part of said series, of tlfunk lines by Way of a series of automatic switches at the calling endi thereof While switchesin saidbranch: and rnain exchanges maintaining a connection; with the said 1 t lephon i e lisaid 1 M 1 lclge,

me whereby the connection may be extended to. Qpenating an:v allw fl s tc to ze. another of said; telephone lines. thetrunk; lineinvolwed in-saidcall in order 12. Ina telephone system, telephonelines; to; maintain said established connection automatic switches; means: controlled "from While re eas ng; o e of th Sw t n s a calling one of said; lines. for operating a Series in r XI IQ t c c i n 10 series ofsaid switches to extend connection; a second one of said telephone lines insaidto a called one of said! telephoneilines, and r nchceggcliange. V means controlled: from the; said calling line 8 17, I-n-Va telephone system, telephone; lines, for releasing andireoperating'the-first-switch o li ra Ql xc l g s, twill; lln'es conof said: series;whileirnaintain'inga connection nectrng; said exchanges, llfiom t c switches with; the said called line. by Way 055 the rein said exchanges, ineans, controlled fro-1n a maining switches: a calling te1eph0ne 11ne 111 said branch, s s 13. In a telephone system telephonelines, ha g'e fer ex n ng l over one oi; sa dautomatic switches; means controlled from trunk lines. byway of a series'o'f; automat c; a; callingone on said lines. 0 12 operating a W E hQS tu l i hi a d ma n" g S' 11 serieszofi said SWlllChGSitOi extend connection to: a epho e; n a mai exchange, to a called one of saidtelephone lines,- and: and means controlled froin' said calling l ne means controlled from the said calling line fol; openatlng: m; automatlc sw tch to se ne for releasing and: reoperating one switch at he mlpk line nyolved. 1n sa d call ln order the calling end of said series whil mailn+ toi ma nt n said establ shed connect on 115 taining' a connection; with; the said ca-liled wh ey l a lngone oii the-smtc es n sald line by Way of the" nemaining switches," ser es n rderto.=e xten cl 'Cl1e (101ineCll9 0a whereby the establish'educonnection may be{ second. one of sa d telephone 1 19 missile extended to include a second called: one of: ranch 2c ang a1 st ex e on e e said? telephone lines: a eemplishedi by r qperat g said ea ed 14'. In a telephone systern,- main and W'L Qh-r H v 7 1 L branch exchanges, subscribers l nes; trunk- Incatelephone systenntelepnonel nes, lines interconnec ng said: xchanges, n an ma e,h anch e eheeg s r nk oes ca including: an automatic switch: having a c-V nect1ng sa1d. e2gch anges,, antoma lc swi ches cess to subscribers? linesand -to' trin kf'lines: in Said Q Ql ll g5, means o t olled. item and controlled by} a calling subscriberin. oneof said t, elephone l1nes in sa d branch saidi branch: exchange for extending a call exchange, for establ slnngia connect on over to a subscribers line? in; said; main exchange? one of said trnnkll-liles by Way of automat c over one of said trunklines;; and means; inswitchesin sa d andma n e changes eluding an automatic switch haying aCQeSS: With one of sa d telephone l nes Hi said ma n 139 exchange means controlled over the calling line for then releasing one of said switches in said branch exchange while operating another automatic switch having access to trunk lines only into connection with the trunk line involved in the call to maintain the established connection.

' 19. Ina telephone system, telephone lines, main and branch exchanges, trunk lines con necting said exchanges, automatic switches in said exchanges, means controlled from one of said telephone lines in said branch exchange for establishing a connection over one of said trunk lines by way of automatic switches in said branch and main exchanges with one of said telephone lines in said main exchange, means controlled over the calling line for then releasing one of said switches in said branch exchange while operating another automatic switch having access to trunk lines only into connection with the trunk line involved in the call to maintain the established connection, and means for reoperating said released automatic switch in order to extend the call to a second one of said telephone lines in said branch exchange.

20. In a telephone system, telephone lines, main and branch exchanges, trunk lines interconnecting said exchanges, automatic switches, means including an automatic switch having access to telephone lines and to trunk lines and controlled from a calling telephone line in said branch exchange for establishing a connection over one of said trunk lines with one of said telephone lines in said main exchange, means controlled over the calling line and including an automatic switch having access to trunk lines only for then extending the connection solely through some of said branch exchange automatic switches to a second one of said telephone lines in said branch exchange, and means controlled from the calling line for disconnecting the said calling line from the connection.

21. In a telephone system, telephone lines, main and branch.- exchanges, trunk lines interconnecting said exchanges, automatic switches, means including an automatic switch having access to telephone lines and to trunk lines and controlled from a calling telephone line in said branch exchange for establishing a connection over one of said.

trunk lines with one of said telephone lines in said main exchange, means controlled over the calling line and including an automatic switch having access to trunk lines only for then extending theconnection solely through some of said branch exchange automatic switches to a second one of said'telephon'e lines in said branch exchange, and means controlled from the calling line for discon necting the said calling line from the connection while still maintaining a connection between the two calledtelephone lines.

23. In a telephone system, telephone lines, 7

main and branch exchanges, automatic switches in said branch exchange, means controlled from a calling one of said telephone lines in said branch exchange for establishing a connection with one of said telephone lines in said main exchange, said means including an automatic switch colnprising two elements, one of said elements having access to telephone lines and to trunk lines, the other element having access to trunk lines only, and means controlled from said calling line for releasing part of said connection while still maintaining a connection with said called telephone line.

24. In a telephone system, telephone lines, main and branch exchanges, automatic switches in said branch exchange, means controlled from a calling one of said telephone lines in said branch exchange for establishing a connection with one of said telephone lines in said main exchange, said means including an automatic switch comprising two elements, one of said elements having access to telephone lines and to trunk lines, the other element having access to trunk lines only, and means controlled from said calling line for releasing part of said connection while still maintaining a connection with said called telephone line by way of said element having access to trunk lines only.

25. In a telephone system, telephone lines, main and branch exchanges, automatic switches in said branch exchange, means controlled from a calling one of said telephone lines in said branch exchange for establishing a connection with one of said telephone lines in said main exchange, said means ineluding an automatic switch comprising two comprising; two: independently operable: elements-, means controlledfrom a calling one of. said lines for operating a series of said switches to extend connection. to a called one of said telephone linesvia one element. of. said dual switch, and means controlled from said calling line for releasing. and re-' operating said: element while maintaining a.

connection with said called. line by way of said second element.

27. In a telephonesystem,telephone lines, automatic switches including. a dual switch comprising two independently operable elements, means controlledfrom a callingone of said lines for operating a series of said switches toextend connectionto a called one of said telephone lines viaone element of said dual. switch, and means controlled: from said callingi line for releasingand. reoperatingsaid: element while. maintaining a. con-- ing access to telephone lines and to trunk lines, the second element having access to trunk linesonly, means controlled from a calling one of said telephone lines for operating said first element to extend a con-' nection to a called one of said telephonelines via one of said inter-oflice trunks, and means controlled from the calling line for releasing said first element and operating said second element into connection With said inter-oifi'ce trunk to maintain the connection.

29. In a telephone system, telephone lines, inter-oflice trunks, an automatic switch comprising two elements, the first element having access to telephone lines and to trunk lines, the second element having access to trunk lines only, means controlled from a calling oneof said telephone lines for operating said first element to extend a connection'to a called one of said telephone lines via one of said inter-otfice trunks, and means controlled from the calling line for releasing said first element and operating said second element into connection with said inter-ofiice trunk to maintain the connection, said released element being then available for further extensions.

30. In a telephone system, telephone lines, inter oifice trunks, an automatic switch comprising two elements, the first element having access to telephone lines and to trunk lines, the second element having access to trunk lines only, means controlled from a calling one of said telephone lines for operating said first element to extend a connection to a called one of said telephone lines via one of said inter-office trunks, and means controlled fironr the calling line for releasing. said: first-element and. operating said; second element intoconnection with. said inter-ofiice trunk to maintain theconnection, said released element being then available for furtherextensionsund'er control of. said calling telephone line.

Ina telephone system, telephone lines, main and branch exchanges, trunk linesconnecting said. exchanges,.'a first. automatic switch insaidbranch exchange havingidi-rect. accessto trunk lines an'd to telephone lines,.

a second automatic switch.- auxiliary thereto I and. having access to trunk lines only, and, means to; prevent said second. automatic switch from seizing a trunk line unless-said trunk line has-already been taken into use in. theextension of acall.

32. In a telephone system, telephone lines, main: and branch. exchanges, trunk lines connestingv said exchanges, a first automatic switch. in said branchexchange having direct access to trunk lines and to telephone lines, a second automatic switch auxiliary thereto and having access to trunk lines only, and means to prevent said second automatic. switch from. seizing a trunk line unless said trunk line has already beenv taken; into use by said first automatic switch in the extension of a-. call.

33; Ina telephone}system,.telephone lines, main and branch exchanges, trunk lines connecting said exchanges, a first automatic switch in said branch exchangehaving direct access to trunk lines and to telephone lines, a second automatic switch auxiliary thereto and having access to trunk lines only, and

means to prevent said second automatic switch from seizing a trunk line unless said trunk line has already been taken into use from said branch to said main exchange.

34. In a telephone system, main and branch exchanges, subscribers lines in said IUU exchanges, trunk lines interconnecting said exchanges, a connector switch in said branch exchange comprising two elements, one element having access to said subscribers lines and to said trunk lines, the other element having access to said trunk lines only, means for seizing said switch from a calling line and for causing said first element to automatically select an idle one of a group of trunks, thereby forming a link in a call from said branch to said main exchange, and means controlled by said second element controlled from said calling line for releasing said first element and for capacitating said first element to be thereafter operated by directive control of said calling line to extend said connection to another called line in said branch exchange.

35. In a telephone system, main and branch exchanges, subscribers lines in said exchanges, trunk lines-interconnecting said exchanges, a connector switch in said branch exchange comprising two elements, one element having access to said subscribers lines and to said trunk lines, the other element having access to said trunk lines only, means for seizing said switch from a calling line and for causing said first element to automatically select an idle one of a group of trunks, thereby forming a link in a call from said branch to said main exchange, and

means controlled by said second element controlled from said calling line for releasing said first element and for capacitating said first element to be thereafter operated by directive control of said calling line to extend said connection to another called line in said branch exchange, said second element maintaining the continuity of said first established connection to said main exchange.

86. In 'a telephone system, subscribers telephone lines, main and branch exchanges, trunk lines connecting said exchanges, a first automatic switch in said branch exchange having access to subscribers telephone lines and to said trunk lines, an auxil iary automatic switch associated with said first automatic switch and having access to said trunk lines only, means controlled from a calling one of said subscribers lines in said branch exchange for operating a series of automatic switches including said first switch to extend a connection to a subscribers line in saidmain exchange over one of said trunk lines, and means in said switches controlled by said calling subscriber for then releasing said first switch while maintaining the connection over said second switch, and for operating said first switch into connection with another called line in said branch exchange.

37. In a telephone system, telephone lines, main and private automatic exchanges. trunk lines connecting said exchanges, an automatic switch in said branch exchange comprising two independently operable elements, one element having direct access to said telephone lines and to said trunk lines, the other element having access to said trunk lines only, subscriber controlled means for seizing said switch to extend a call via said first element over a trunk line to a called line in said main exchange, and means controlled by said second element controlled from the calling line for releasing said first element and for capacitating said first element to be thereafter operated to extend the connection to another called line.

In witness whereof, I hereunto subscribe my name this 15th day of October, A. D, 1921.

JOHN E. GARDNER.

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