US1613246A

US1613246A - Telephone-exchange system

Info

Publication number: US1613246A
Application number: US601016A
Authority: US
Inventors: Henry W O'neill
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1922-11-15
Filing date: 1922-11-15
Publication date: 1927-01-04
Anticipated expiration: 1944-01-04

Description

Jan. 4 1927. 1,613,246-

' H. W. ONEILL TELEPHONE EXCHANGE SYSTEM Filed Nov. 15, 1922' 3 Shqets-Sheet l five/70 Henry W OA/e M Jan. 4, 1927. H. w. ONElLL TELEPHONE EXCHANGE SYSTEM Filed Nov. 15. 1922 3 Sheets-Sheet 5 Henry W O/Ve/H ii. a e

HENRY W. ONEILL, OF BROOKLYN, NEW YGRK, ASSIGNOR TO WESTERN ELECTRIC CGMPANY, INC-OREORATED, OF NEW-YORK, N. Y., A COBlOEATION-UF NEW' YGRK.

TELEPHONE-EXCHANGE Application filed November 15, 1822. Serial No. 601,016.

This invention relates to a telephone exchange system, and more particularly to a system in which toll connections are established between exchanges by means of machine switching equipment controlled over toll lines.

{)ne of the objects of the invention is to improve the manner of establishing connections in systen'is of this nature.

A further object of the invention is to improve the control of automatic switches by impulses of alternating current over toll lines.

T o attain the objects of the invention the outgoing end of a toll line extending from a toll operators position to a machine switching office is provided with means for effecting current changes in the toll line to energize an electromagnetic devic associated with the incoming end of the toll line.

This device in operating; prepares switches at the automatic otlice for the reception of impulses. The operator may thereupon actuate her dial thereby a iplying' alternating current of a frequency preferably within the voice range to the toll line, which current is transmitted to the distant ofiice, Where a responsive device controls the setting of the switches at the automatic office in accordance with the digits dialed by the operator. The operators cord circuit is provided with a supervisory signal which is actuated when the called subscriber answers when he hangs up his receiver and when he flashes so as to provide full supervision for the operator.

These and other features of the invention will be more readily understood by reference to the accompanyingdrawings in which Figs. 1 to 4, inclusive, when taken together show partly in full and partly schematically the circuits involved in building up a con nection between a subscribers station through a toll operators position over a toll line to a subscribers station at a distanteirchange; Figs. 5 and 6 show a modified form of the toll line shown in Figs. 2 and 3; and F i g. 7 shows a cord circuit arranged for supflying direct currents as well as alternating currents for automatically establishing a connection over a toll line, and a toll line cquipn'ient suitable for use therewith.

In general. and referringmore particularlv to Figs. 1 to it, inclusive. the system functions in the following manner: A subscriber in the first. exchange desiring connection with the subscriber in the distant exchange which may be reachec directly from the first exchange over the toll line T, first obtains a. connection, through the position of the usual A or answering operator, with toll operator. After receiving instructions from the calling subscriber through the A opcrators position, the toll operator obtains a connection with the calling line over a toll switching trunk and extends the connection by means of her callinc" plug to an idle toll line such as toll line T extending to the desired distant exchange. In response to the seizure of the toll line alternating; cur rent of a frequency of approximately 700 cycles, inon'ientarily connected to the toll line to energize an electromagntic device normally bridged across the incoming end of the toll line to prepare automatic switching apparatus associated with the incoming end of the toil line for the reception of dialing impulses. The toll operator then proceeds to transmit dialing impulses over the toll line by the application of alternating current of a frequency of a n'iroxiii'iately 700 cycles to the toll line. These impulses actuate the electromagnetic devices at the incoming end of the selected toll. line and are translated into direct current impulses and repeated to the automatic switching apparatus accessible to the toll line. Through the operation of the electromagnetic device at the incoming; end of the toll line and the automatic switches, the connection is then extended to the desired. line in the distant exchange. Ringing; current is then applied automatically to the line of the called station in the usual manner by the automatic switching equipment. When the called subscriber answers. currents of two frequencies, preferably within the voice range, are momentarily applied to the incoming end of the toll line. At the outgoing end of the toll line these currents are translated to effect the control of a supervisory signaling device.

Upon termination of the conversation and restoration of the receiver to the switchhook at the substation of the called subscriber in the distant exchange, currents of two frequencies are applied to the toll line at the incominnnend which currents are translated at the originating; eiid of the lineinto a supervisory signal to indicate that the COtlTleC- tied? truly is taken down l l bei'i the nrip} llt at u

'ClHiE 5c. The toll operator then seltats idle toll line extending to the dist-11st er: change, the busy toll lines of the group 0- tending to this c: ;change being; unt l-zed l busy potential upon the Sl'C-CYQH oi the jucx of these lines. it will be assumed that t line 'l disclosed in the drawing 's idle at hinting): toll operator withdraws the plug ol her cord circu t from the jacl: ot the toll line. an impulse 0t alternating current is etective to restore the apparatus at the automatic exchange to normal.

ll? the suhscriloer at the called station flashes in'ipnlses of alternating current will be returned to flash the supervisory signal in the ope 'at-ors cord circuit at the originat ng: exchange to indicate to the operator that the called station desires further attention.

The electromagnetic devices employed in this invention are such that when they are energized by alternating currents, preten ably within the voice oil fretpiencies they open taeir contacts. These contacts re main open until the current flow throng; t the device ceases. Such devices may he of he type employing an inertia ineiuher n'hic may be accelerated by alternating current shown in Patent No. 1507310, granted i veniher 223, 1926, to H. H. (l llcill, either it is to he understood that the invention not limited to the type ot the device disclosed in said patent.

Having now outlined in a general manner the system and described briefly the nature of the apparatus employed, it is believed that a clear understandin3;- ot the invention may he had from the following detailed description of the method of extending a connection from the st 'ion A at a change through a toll operators position, and over a toll line to a subscribers station 13 at a distant automatic otllcc in which the toll l ne terniiinates.

It will he assumed that the operator at the toll positioi has established a connection n'ith a suhscribefs station It over a toll switching trunk in any manner Well l-I11()Yr'll in the'art} and has ascertainml that the subscrih r at station A (l "res conncctio 'Y 1 l the subscriber at stat on at; the dis-an s theretoie the operator inserts a pl cord crcu t C into the pic 0? this lane,

1 thereupon completed ove a ran circuit is i ei-itendin u from ground, throt'rgh the \"ltt ing' of relay (3, sleeves o'l jacl; Z and plug the upper winding and lower contact of relay 32. and thence through the iarallel connsch ed local contacts o'l alternating' current rclays 2t) and ill) to grounsilcd hattrry. Relay is in operating closes its cont-acts l? betore contacts 16 open and energ zes relay over an obyiout circuit. Alternating current from the source 22 is thus momentarily c nected to the talking conductors 25 and 2o and to toll line 'll illlOlt -Ifill the contacts 40 and l. otrelay 4:8 and cont; cts and l?! of relay l'z), in order to encr -e the electromagnetic device 200 WlllCll is normally bridged across the incoming end of the t ill line T e in interval th distant exchange. the contacts 17 of relay 6 close. the coni relay 6 open thereby releasing aerated slorvto release relay 4' 8. releasingnow renders the tall:-

s of the Olltll'Ollll end of the :outnionn ant disconn the ternating current from the a an olwious p .i accessible to the inceinil gr end ot the l tor the reception oat impulses. t will he noted tiat relay 250 is normally operated. over a path extending from grounded hattery, through the vinding of relay 250, contacts 451 of relay thence through the contacts 201 oi device 200, and thence throi gh the contacts of relay to ground. l elay 250 is marginal and releases in series with high resistance relay which operates when the contacts 20L of the device lin l opened. Relay 250 in retract ng upper ar nature closes the loop across the conductors F0 and 261 extending from conductor s Winding 0t relay 262, rind i1 of relay 365, contacts of relay and uppermost contacts of relay .2 to the ring conductor 261.

The closure ol the loop acro s the end of the line to which the aul'ounnic gwltche are accessible causes the energizaation oi the line relay 2T0 associated \Yllll the selector switch S and, ot the relay in the loop circuit. he line relay 3Y0 in o 'ieratiug causes the operation of relay \rhicu places a ground upon the third conductor, 271 which ground causes the euergization o l relay Relay 252 in operating closes the ilollowing substitute loop across the line; 't'roui tip conductor 26%, through the w nding of relay Winding: of relay 255, contacts $380 of relay the contacts 1,)" ol? device 200 contacts 281 of relay to the ri e; conduct;- or 261'. The closure ot' the contacts E35 o't' relay 272 operates relay 350 over an ()lJYlous circuit to apurpose to he described la ter. Relay 262 is energized in the circuit traced but relay is not energized since the latter relay is oil' the polarized type and the direction of tlow of current through its Winding}; at this time not such as to cause its operation. .Vhen relay 250 released, the passing contact associated with its lower armature causes a momentary response of relay 2%, which applied momentarily,"alter nating current from the

sources

291 and 292 through the

transformers

218 and 219 and the upperand lower alternate contacts of relay 290 to the talking conductors of the line and connected cord circuit.

The talking and dialing key 72 now-in its actuated position preparatory to the operation of the dial, such currents are manifested in the operators set as a dialingsig-- nal. That is, lamp 8 is extinguished and it should be understood that on the reoperation of relay 250, lamp 8 1S agaln lighted.

JV l 'lhus, tee dialing signal consists oi the momentary extinguishing of lamp 8- and it will become apparent as the descriptionproceeds how the operation of the relays in the cord circuit will efl'ect this result in response to the n'ioinentaryrelease of relay 250.

The operator thereupon *actuates the dial D to send a number of impulses corresponding to the digits in the number desired. As

thedial is rotated ofl normal, the primary-- winding of the lnduction cell in the -opera-" tors set is switchedfrom the transmitter to a source 77. Thls 1S accomplished by the opening-0t contacts St and the closure of contacts 87 of the dial. The opening of contacts also removes a shunt to permit the operation ofhighdmpedance relay 75 in the primary circuit of "the operators set) The operation of relay 7 5 disconnects the operators receiver and connects the normally closed pulsing contacts 73st the-dial in bridge of the secondary winding ofthe' induction coil of the operatorisset.

"Upon the return movement of the dial each separation of the pulsing contacts 73* permits an impulse ofalternatmg current from thesource 77 to traverse the cord-and line circuits and effect the response of the electromagnetic device 200.

In responding to these impulses the electromagnetic device 200 opens its contacts 201 in unison with the interruptions atthe' dial D causing thereby the interrupted opening of the loop across the conductors260 and- 261. y

The resistance of the Winding-of relay 254 bridged across the contacts 201 is 'sui'liciently high to permit'the release of pulsing relay-270 of the switch S. Relay 25 1 is adapted to continue energized during the reception of: a series of alternating-current impulses by device 200, thereby disconnecting ground to render responses of relay 262 to interruptions of the loop circuit iue'liectiveat this time with respect to rolav 220.

Under control-of device-200 the selector switch S advances to selze the connector 1 switch K following which the pulsing relay 270 and release relay 272 willbe disconnected, and a pulsing relay 294*andrelease-relay tut'ed therefor inthe usual manner.

ing of relay 32.

fer from its lower to its upper contacts.

-relay"32 to the sleeve conductor.

295 of the connector switch will be substi- Further operation of the dial will cause connector K to seize the terminals of the line leading to station E whereupon ringing current Will be automatically applied by the connector K to signal station E.

' When the called subscriber answers, the

line relay 299 will be operated over an obvious path thereby reversingthe How of current over the conductors 260' and 261, and causing the operation of the polarized relay'265. Relay 265 in operating opens its contacts 298 to disconnect the device 200 and closes its contacts 296-and 297 thereby electrically joiningthe toll line with be main I conductors through the automatic switches.

hen the current is reversed over the

conductors

260 and 261, relay 262 releares mo-- mentarily and closes its passing cmitacts again causing the ener lzation of relay .390

and the application of the'alternating currents from Oll1'C-

6S

291 and 292 to the line. The'tlppllCtttlOll Of the alternating current at this tinie energizes the electron agnetic devices 20 and 30 bridged across thecord circuit, to extinguish supervisory lamp 8. At the time the plug 4 was inserted in pick 5 current "from grounded battery,as previousl traced throu 'h the u oer winding and u D a,

lower contact of relay 82, serves to shunt relay 18. Therefore, battery flowing through the normal contacts o't' the latter relay, the winding of relay 10 and the low r winding of relay 32 to thesleeve conductor, energizes 'relay 10 to cause the illuminationot super v1sory lamp 8 and also to'disconnect relay 18. The'operation 01 devices 20 andSi') in response to" the impulse of current transteam upon the answer of station- B,

disconnects battery from the upper wind- This permits the current flowing through the lower winding of relay 32 over the path already traced to-move the a ri'nature of this relay to trans- On Cessation otthe incoming alternating currentsand the resultantrestoration of devices 20 and 30, grounded battery applied to the upper contact of relay 32 through its armature shunts relay'lO to effect its release to extinguish lamp 8. The normal position of relay Relay 262 again closes its passing pal contacts and energizes the relay 290 to again apply alternating current from the

sources

291 and 292 to the trunk circuit to energize the devices and bridged across the cord circuit. The resulting cessation of current flow through the lower winding of r lay permits the current present already "traced through the upper winding of this 1 plug 4- :Erom the jack whereupon relay 6 releases operating relay 48 and releasing re the toll line.

lay 49. The quick operating characteristic of relay 4L8 comhineo with the slow releae characteristic of relay ll) permits an impulse of current to flow from source 22 over the line. The final release of relay 49 disconnects the source 22.

When relay 265 released, following; the restoration of the receiver station B, in addition to the disconnection oi the line from the main conductors of the automatic switches, the device 200 was reconnected to The impulse of alternating current changes the resistance of the loop circuit so as to permit the restoration of release relay 295 of Connector K. The resulting removal of groundirom conductor 271 permits the restoration of relay 252, thereby switching the circuit of relay 250 by way of contacts 201 of device 200 to ground at the normal contacts of relay The slow release of relay 250 permits it to hold during this operation and prevents ro-selzure of the loop circuit and prevents any e'tl'cct at this time with respect to relay 290.

It, during an. cstaolished connection, the called. subscriber flashes, relay 2% will alternately dccnergl'imi and cnci ze thereby causing the intermittent actuation oi the devices 20 and 30 oi": the cord circuit and the consequcnt [lashing of the lamp 5- Lamp 5% will be lighted and estinguishcd in the manner pre viously described and the operattunot this flash may actuate her listening key to inquire what the called station desires.

Figs. 5 and 6 show a modification ot' the toll line whereby an originating operator n'iay release the distant automatic suitches irrespective of whether the receiver has been returned to its switchhooh at a called station. In this arrangement. upon the insertion of plug 4 of cord circuit- C in jack 5 ct Fig. 5, the response of relays correspondingly numbered with respect to relays of Fig. 2, will take place to apply to the line an impulse formed of alternating currents from sources and ll At the distant equipment shown in Fig. 7 the device 200' responds to the current of TOO-cycle frequency flowiin from source 4C5, the current of lfiOO-cycle i'requency being without material c'il'ect at this time. It will be noted that device 2 0 tuned for response to current or" lfitlO-cyclc frequency is normally shunted through contacts 298 of relay 265. The response of device 200 causes a series of operations to take place similar to that described in connection with Figs. 1 to l, inclusive, whereby a connection is established between the toll line and the called station Qu response oi? the called station and the consequent operation of relay 265, the

hunt around device 240 is removed to bring 'uch device in series with device 200 across he main conductors of the line. Closure of contacts 2 -2 of relay 265 establishes the contacts 2-ll of device 240 in parallel with the contacts 201 of device 200. This condition obtains during an established connection in order to insure that tuned

devices

200 and 240 may not jointly respond to voice currents. In the case of a separate response of either device the other device will be inert and thereby maintain the connection. Further protection against premature release of the connection is also provided through the slow release characterist-ics of the regular holding relay of the automatic switches such as relay 272 or relay 295. Supervisory effects take place in a manner similar to'that described in connection with Figs. 1 to 4.

Assuming that the operator desires to release the connection betore the receiver has been restored to its switchhook at station B, the removal of the plug t from jack 5 results in the response of relays in Fig. 5 to apply an impulse of current from sources 45 and 46 to the toll line. The joint response of correspondingly tuned devices 200 and 24 0 serves to change the resistance in the direct current loop circuit, thereby oilecting the release of the autonuitic switches in a manner similar to that previously described for similar switches of Fig.3. In case the receiver has been restored at the called sta lion and relay 265 thereby returned to its normal condition, separation ol its contacts 242 disconnects contacts 2-H, of device 21!) which will. then stand shunted through the normal contacts 298' ct relay 265'. There fore. the impulsev of current resulti g from the removal of plug 4 from jack 5 will coutrol device 200. Response of such device will release the connection as described in connection with the arrangement shown in Fig. 3.

The cord circuit shown in Fig. 1 is also adapted to control switches over a direct current loop as in extending a connection by lit) way of a toll switching trunk to the line of a calling station, such as station A. In the dialing position, the talking key actuated and the dial D moved from its normal position, the pulsing contacts 73 will be connect ed by way of the forward contacts of relay 75 in bridge of the main conductors of the cord circuit. At each interruption of contacts 73 during the return of the dial the direct current loop which may be assumed as extending froin'the automatic switching apparatus leading to the station A, will be opened due to the presence of condenser 90 inserted in series with the secondary winding of the operators induction coil, since relay 7 5 is operated. These impulses control the switches in a well known manner. During periods intermediate successive operations of the dial while the dial is in its normal condition, the released condition of relay 75 in addition to reconnecting the operators receiver also shunts condenser 30 to provide a direct current path through the secondary winding of the operatofls ind netion coil to hold the automatic switches.

Atter the dialing is completed and the talking key 72 is restored, the automatic switches involved in the connection to station A will be retained by a direct current bridge which includes the serially connected devices 20 and 30 and relay 99 and the normalcontacfs oi? key 72. Relay 99 controls the supervisory lamp 100 under reversals of current in the direct current loop efiected by the supervisory efiects controlled by the substation A.

Combined dialing and splitting' keys 95 and 96., respectively serve to separate the cord circuit. During periods the key 9? may be in its actuated position, its outer contacts will establish the supervisory relay 99, across the end of the cord circuit connected with station A for holding and supervisory purposes. In such a case the operators telephone set will be available'by way of the key T2 for talking or dialing over the toll line. In an inverse manner key 96 in an actuated position applies devices 20 and 30 across the toll line while the operators set may in a similar manner be connccted for dialing or conversing with. respect to station A.

A description oi the operation of Fig. will now be given. This combination presents a modification of the arrangement shown in Figs. 1 to 4, inclusive, the modification consisting of preparingthe switches for reception of impulses and controlling the supervision over the trunk line by direct current instead of alternating current. It will be assumed that the operator at the toll position has answered and established a connection through the jack 300 and the plug 301 with the substation A in any manner well known in the art and ascertained "from the subscriber at substation A that a connection with substation B is desired.

In establishing'the connection with'call ing station-A the plug 301 of cord circuit C is inserted in jack 300 01": a toll switching trunk associated with automatic switches not shown. A splitting key 320 is actuated to disconnect the equipment associated with plug 305. Talking key 321 is actuated and dial D operated. When the dial moves oil normal, relay 3&3 operates over an obvious circuit to disconnect the operators telephone set and to connect the pulsing contacts 01 the dial in series with slowto-release relay 322 in bridge of the cord circuit. The latter relay responds to the direct current supplied to the trunk circuit by the automatic switches to disconnect the alternating current source 351. ct contacts 341 as the dial D returns to norand, controls the setting of the automatic switches upon the terminals of the line lead ing to station A in a well known manner; \Vhen key 320 is restored the switches are held by a bridge including repeating .coil 302 and relay 303. Relay 303 controls lamp from station A.

Insertion oi the plug 305 into the jack 303 of the toll line B completes a circuit through lamp 307 over a path extending from grounded battery, through lamp 307, resistance 303, sleeve ot plug 305 and Jack" 300 and resistance 309 to ground; The inseriion of the plug 305 into jack 306"also completes thefollowing circuit: grounded battery, winding of relay-310, lower righthand winding of repeating coil 302, rings of plug 305 and jack 306, in'lpedance coil 41-01,

left-hand high resistance winding of relay 4.00, tips of jack 306 and plug 305 and upper right-hand winding-0t repeating coil- Relay 310 is of marginal across the conductors 410-and 4-11 causes the energization of the line relay (not shown) of the selector swltchin the manner well known 1n the art.

The operator may then proceed to dial; Theactua-tion of the key 350 disconnects the trunk side of the connection, the switches of winch are held by the brldge including relay 323. Lamp 325 under control of relay O l to give supervisory signals transmitted Relay 400 energizes, however, in this Successive interruptions 1 323 prevents isolation of calling station A.

Theoperator then actuates the talking key 321.

The operator may thereupon actuate lil ill

dial D a number of times corresponding to the digits in the number desired. Relay 822 does not operate at this time since no direct current is now present in the dialing loop. Upon the return movement of the dial to normal position the contacts 341 are interrupted a number of times corresponding to the digit dialed. The short circuit through the condenser 327 of the alternating current source is opened each time the contacts 341 of dial 1) are opened, thereby interruptedly applying current from the source 351 to the cord circuit. This current is induced into the secondary winding of repeating coil 302 and passes over the upper and lower talking conductors of the cireuit'E through the normal contacts of relay 4-12 and the winding of the electromagnetic device 420. The device 420 is ener ized by the alternating current applied to its windings, a number 01 times corresponding to the digits of the number dialed. During energization of the device 420 its contacts are opened thereby interrupting the loop across the talking conductors 4.10 and ill. The setting of switches by interruptions in a loop circuit is an arrangement which is old and well known in the art and therefore a description of the manner in which the selector switch S and connector K are set will be omitted. A 'ter the connector K has been set, the called station 13 will be signalled in the manner well known in the art.

X Then the subscriber of the called station answers, relay 44:0 will be operated over an obvious circuit thereby reversing the iiow of current over the talking conductors 410 and 411. Polarized relay 412 will then be operated thereby opening its normal and closing its alternate contacts. The opening of the normal contacts removes the device 420 from bridged relationship with the toll line and the closure of the alternate contacts of relay L12 connects the low resistance right-hand winding of relay 400 across the circuit in parallel with the high resistance winding of relay 00. Relay 310 of the cord circuit now operates in series with the parallel connected windings of the relay L00. Relay 310 in operating connects the resistance 360 in series with the resistance 308 and lamp 307 is thereupon shunted. The extinguishment oi lamp 307 indicates to the operator that the called party has answered.

Vl hen the called party restores his receiver to the switchhook, relay 440 will deenergize and again cause a reversal of current over the conductors 410 and 411 thereby releasing the polarized relay 412. Relay 412 in releasing disconnects the low resistance winding of relay 4:00 fromthe circuit. Marsupervisory relay 310 releases its armature due to the high resistance of the letthand winding of relay 400. Relay 310 in retracting its armature removes the shunt from lamp 307 whereupon said lamp again lights to indicate to the operator that the called party has restored the receiver to the switchhook.

The operator may'thereupon remove the plug 305 from the jack 308, whereupon relay 400 will release thereby interrupting the loop across conductors 410 and 411. The opening of the loop circuit causes the release ot the switches in the manner well known in the art.

In the cord circuits shown in Figs. 1 and 7, it is evident that although the operators set will be disconnected during the actuated periods of the dial, it will, however,

be reconnected, when the dial is at rest. Therefore, any signals such as dialing, busy back and out oi order tones may become effective in the receiver of such set.

ll hat is claimed is:

1. In a telephone exchange system, :1 called station, a source of alternating current of a single frequency, means for transmitting impulses from said source, electromagnetic means energized by said alternating current impulses means controlled thereby and responsive when only a single frequency is transmitted for establishing a connection with said called station, and means for giving supervision back from the called station.

In a telephone exchange system, a first oiiice, a second ofiice, a line extending between said oilices, a calling station at the first ofiice, a called station at the second otiice, a source of alternating current of a single frequency, means for transmitting impulses from said source, electromagnetic means energized by said alternating current impulse for establishing a connection over the line between the calling and called stations, and means for giving supervision back over the line.

In a telephone exchange system. a first oliice, a second otlice, an operators position at the first otlice, a called station at the second ollice, means including automatic switching mechanism for connecting the called station with the operators position, a source of alternating current, means for transmitting impulses from said source, elee tromagnetic means energized by said alternating current impulses for actuating said automatic switching mechanism, means for giving supervisory signals back over the line to the operator, and means responsive thereto at the operators position.

4. In a telephone exchange system, a first ofiice, a second oflic-e, a line extending between the otfices, an operators cord circuit at the first otlice adapted for connection with said line, an automatic switching means at the Second oflice, a source of alternating current, means for transmitting an impulse from said source over the line when it is connected with the cord circuit. electromagnetic means responsive to said. impulse for pre paring the automatic switching means for the reception of directive impulses ctrom said source, and means for transmitting directive impulses from said source over said cord circuit and connected line for actuating said electromagn-i-itic means to control the setting of said autoi'nat-ic switching means.

in a telephone exchange system, subscribers stations, a source of alternating current of a single frequency, switching means. for transmitting series of current impulses from said source, a tuned relay including an inertia element and responsive to said im pulses, and means controlled by said inertia element for establishing connection with a subscribers station corresponding; to the combination of impulses transmitted.

6. In a switching system, sources of directand alternating currents, a first circuit provided with means for controlling said currents, a second circuit including); automatic switching means and adapted to be manually connected to said first circuit, and means at said second circuit responsive to said direct and alternating currents to ettectresponse o't said switching means for extending the second circuit.

7. In a telephone exchange system, a switching system including a, line circuit, calling and called stations, alternating current receiving means, means for applying; alternating currents to said line, switching means controlled by said receiving means in response to said alternating currents to join said stations, a direct current source associated with the line during the joining of the stations. means tor reversing the current from said source on the line when the stations are joined, and means actuated thereby to disable the receiving means.

8. In a telephone system, a toll line, a cord circuit adapted to be connected to one end of the toll line, automatic switching means associated with the opposite end of the toll line, means ope 'ated to supply an impulse of alternating current to said toll line when the cord circuit is connected thereto, means responsive to said impulse to prepare said automatic switching means for actuation to extend the toll line, and means for transmitting directive impulses 0t alternating current over said cord circuit and the toll line to operate said switches.

9. In a telephone system, a toll line, automatic switching means, means including devices for transmitting one impulse from an alternating current source to prepare. said switching means for directive operation, and means for transmitting directive impulses from said alternating current source to actuate said automatic switching means to extend the toll line accordingly.

10. In a telephone system, a toll line, a cord circuit adapted to be connected thereto, automatic switching means associated with said toll line, means including devices for transmitting one impulse from an alternating current source to prepare said switching means for directive operation, and means for transmitting an impulse consisting of current from plurality oi alternating current sources to the cord circuit. means associated with said cord circuit for indicating the reception of said impulse, and means for transmittingdirective impulses from said first mentioned alternating current source to actuate said automatic switching meansto ere tend the toll line accordingly.

ll. in a. telephone system, a toll line, a cord circuit, automatic switching means, means Olwl'tii'lllg to supply a current impulse to said toll line when the cord circuit is connected to the toll line, and means responsive to said current impulse to prepare the automatic switching means for the reception of directive impulses, and means for transmitting directive impulses to said switching means to actuate the same to extend the toll. line accordingly.

12. In a telephone system, a line, auto matic switching means, an alternating current source, means for transmitting impulses therefrom, means responsive to a preliminary impulse to prepare the automatic switching means for the reception of directivc impulses, means responsive to subsequent impulses to control the. automatic switching means to extend the line accordingly, and means for disabling the last mentioned means when the line is extended.

In witness whereof, I hereunto subscribe my name this 8th day of November A. D.,

HENRY W. ONEILL.

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