US1343489A - System for interconnecting manual and automatic telephone-exchanges - Google Patents

Description

7 a. a. WOLF. SYSTEM FOR IIH'ERCONNECTING MANUAL AND AUTDMATIC TLEPHON E EXCHANGiS.

APPLICAUON HLfD SE91 11. I9I4- mm June 15,- 1920.

2 SHEEIS-SIRET l.

G. D. WOLF.

SYSTEM FOR INIERCONNECTING MANUAL AND AUTOMATIC TELEPHONE EXCHAQGES.

APPuc/moa FILED SEPT- 14. m4.

1,343,4s9, Pamemne 15,1920.

2 snails-sun z.

' 5 EEUPQEZYZ/Z/EZZ FZZZPHE cnoncn n. wot-If, onjcmcaeo, ILLINOIS, ASSIGNOR 'ro KELLooe swrrcr'momn' SUPP]?! CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

,srs'rnn roa' VIVIANULL AND aurona'rrc TnLErnomi-nxcnancns.

I Specification of Letters Patent, Jun 15, 1920.

gm ileptembcr 1i, mi. Serial Re ssues.

To all wklomrit may comm:

Be it known the I, Gnomes D. WoLr, residing at Chicago, county of Cook, and State of Illinois, have invented new and useful Improvements 111 Systems for Interconnectand Automatic Telephone-Ely ing Manual which the following is a specichanges, of fication.

connecting main automatic and branch manual exchanges and is more particularly to such'systcmswherein the operator at the branch exchange actuated a calling device in extending connections from the 'manual to the automatic substations.

In connection with the installation of antomatic telephone systems, operator conexchanges for inter lines are employed. ,operators trolled private branch connecting the branch At the private branch eic'ha cord'circuits are provided for interconnectand trunk circuits are used for interconnec the manual and automa-tic exchanges. 7 en a branch ex change substation toibe connected to an automatic substation the operator connects ing the local lines,

' one end of a cord circuit tothe calling branch substation and then the callw ing pluge of the selected cord into a trunk 30 V nding to the automatic exchange 'after which she a calling device according to the number ofthe wanted antomatic substation, to operate the'automatic switches to extend the call. In systems of this character the operator upon answer ng a call from a branch substation throws-the listening 'key to converse with the calling subscriber and one of the features of my invention resides in a control circuit afi'ected by thethrown listening key when the calling'plug is inserted into a trunk jack, to operatively associate the operators calling device therewith. In" this way no extra manipulation of a key necessary to connect the calling device.

Another feature of my invention is directed to a control circuit whereby after the call has once been extended by the use of the calling device and either the listening key has been restored or the called SllbSCllbeI' has answered, the calling device cannot again be operativ ly associated with this particular trunk until the established connection has been taken down. In this way I eliminate the possibility of interference jack e V w w thereto. My invention relates to systems for inter e calling device.

qlilrent incidental or intentional actuation of t In the particular embodiment of my invention herein illustrated, I have chosen to use a two-way trunk circuit but it is to be understood that my invention is not limited For a better understandin of invention reference 15 to be had to the accompanymg drawings in which all parts are shown at normal and like parts are indicated by likereference characters and in which-- Figure 1, part 1, illustrates a cord circuit and two line circuits of a private branch exchange togetherwith a trunk circuit ex: tending to an individual switch capable of extending a connection to anautomatic switch in the automatic exchange as shown in Fig. 1, part 2, and

Fig. 2 lllustrates diagrammatically the line switches E and .1

Referring now in general to my invention as illustrated in Fig. 1, part 1, it comprises a local calling substation A of a well-known type which is connected by the line limbs 1 and 2 to a line circuit L whichcomprises a line relay LR, a signal S and a, jack J. The privatebranch cordcircuit C comprises an answering Elug P, and a calling plug P connected byt e heavil marked conductors T and S, and having t e condensers K and K interposed.- The answering endof the cord circuit comprises an answering supervisory relay AS which controls the supervisory signal SS and the calling end of the cord circuit C'comprises a callingsupervisory relay CS which controls supervisory relay S8. A' listening key LK is provided which when thrown connects the operators set 0 and a ringing key RK is also shown, which when thrown connects generator M to ring the called-for substation of a local line. To the right I haveshown a substation B similar to A connected by line limbs 1 and 2 tIL: a line circuit L similar to that shown at The two-way trunk circuit D comprises a trunk jack TJ, the terminals of which are connected by the heavily marked conductors. T and S to'a line switch E at the automatic exchange. A dial switching relay DS is also included, being energized when a plug of a branch exchange cord circuit is inserted into the jack TJ and the the rela nism.

listening key LK is thrown. Relay DS places the calling device. CB in operative relation with the trunk circuit D so that'its actuation will energize the dial connecting relay DR 11 on transmission of each set of im pulses. switching relay SW is associated with the trunk circuit D which disconnects the incoming call 'signal relay IC and laces the polarized supervisory re'lag P in bridge of the trunk talking con actors. A supervisory circuit control relay SCR is also associated with the trunk circuit D and con trols the supervisory circuit leading from normal contact 40 to thesignal SS of the cord circuit. Belay SCR' also controls the circuit of the dial switching relay.

An individualswitc h E is associated with each tru'nk'cirouit D and-comprises a line relay LR ha-cut-ofi relay CO and a motor magnet M which steps the wi are 3, 4', and 5 by the aid of the generator to select an idle connector F as shown in Fig. 1, part 2. A busy backBB is shown which sends a busy si nal .to the calling subscriber in the event t at .all the connectors with which the line switch Eis associated. are busy.

. The connector F which is of the Strowger type and illustrated in Fig. 1, part 2, com-.

w a called line'in the selected group. A busy relay BB is associated with the connector to connect the busy back BB in case the called line is busy. A rin ing relay RI is intermittently energized an deenergized by an interrupter I, to connect the ringing generator M to ring the called line and a ringing control relay RCR is energized when the called substation answers to disconnect the ringing'generator M A release relay RR and a release magnet REM areassociated with the connector, the magnet REM being ener ized upon the deenergization of 11 to release the switch mechan off-normal contact Olfl is asso ciated with the connector and assumes its off-normal posit-ion upon the first step of the wipers elf-normal. .Side switch arms 9, 10, 11 and 12 are provided and are stopped to their different positions u 'on each restoration of the re ay PV. n automatic substation H is shown to the right of Fig. 1, part 2, being similar to that of A and B, the only difference being that a calling device CD is associated with it; The substa tion H terminates in a line switch E similarto E.

Having described in general the apparatus associated with my invention, the operation will now be described.

Assuming now that two local substations such as'A and B are to" be connected, the subscriber at substation A removes his receiver energizing the rela LR by battery through the line relay L normal contact of the jack J, through the substation A to ground at thejaclr J. The operation of the line relay LR lightsthe signal S and the operator noting the signal inserts pl P into jack J and throws her listenin kei fiaK to ascertain the wants of the cal in subscriber. The insertion of the plug into pick J opens the circuit of the line relay R which denergizes and efiaces the line signaluS. The supervisory relay AS is ener ized from battery through its lower win ing, conductor S sleeve contacts of the plug P and jack J through the substation, tip contacts of the jack J and plug P, upper winding of rela ASto ground energizin the relay AS w ich prevents the signal SS from lighting. v

Assuming that it is the substation B which is wfliltilldj the operator inserts the plug P into 'ac thus lighting supervisory signal SS rom lground at the third contact of the ack J he operator then throws her ringmg key'RK to connect generator M to ring the called-for substation and when the sub scriber thereat answers the calling supervisory relay CS is energized efi'acing super visory si nalSS, The subscribers at substations and B upon finishing conversation replace their receivers upon their respective switch-hooks, the circuit for the relays AS and CS thus being opened effectin the li htin of the superv sory signals and S connect signals takes down the connection.

Assuming now that a subscriber at the local substation A at the branch exchange wishes to converse with a subscriber at an automatic substation as H, whose li'ne terminates in an automatic exchange, the subscriber at substation A removes his receiver from its switch-hook, and the operation of the circuit C in Fig. 1 part 1 is the same as before described up to the time the operator plugged into the jack J The 0 enter having t rown her listening ke L to ascertain the wants of the calling su scriber and noting that it is the automatic substation H which is wanted, she inserts the plug P into the trunk jack TJ with her listening key throwninto its alternate osition so as to place the calling device D in operative relation with the trunk circuit D. The listeningkey LK being thrown, the ground at its alternate contact2lclosesacircuit for the relay DS traced from ground at the alternate contact 24 of LK, the third contacts of the plug P and jack TJ, normal contact he operator noting the dis-,

m e est relay SW tracedfrom battery through its i 25, through the windinfiof relay us to batenergizing relay S. he closingof alternate coutact 50 of reab ishes an energizing circuit for windin closed contacts 29, 30, of the trunk jack T conductor 31, alternate contact 50, normal contact? 9, to ground at contact 34, energizing 'switchin relay SW which closes a locking circuit or itself from battery -:throu h its winding, closedcontacts 29, 30,

I, of jac TJ, alternate, contact 34 to ground,

" this relay remaining eneliglzed as long as the rela J. The switchingbeing brought about as follows: Upon the said energization of relay SW its alternate contact 37 is losedestablishing an energizing circuit for line relay LR of the line switch E, traced from battery through the winding of relay LE the wiper 4, conductor T; normalcontact 13, the normal contact 14, tip conductor T of the trunk D, conductor 36, alternate contact 37, conductor 38, the

winding of relay PSR, conductor S normal contacts 17, 18, conductor S to ground at wiper 5. Theenergization of relay LR closes an energizingv circuit for cut-oil relay CO from ground at alternate contact 19 of relay LE normal contact 20 of the ofl'norinal contact ON, through the winding of relay CO to batter Upon energization of relays CO and L an energizing circuit for the motor magnet MM is established at alternate contact 23 of relay LR? traced from the ungrounded pole of the generator M through the winding of the motor magnet MM, alternate-contact 22 to glfl li lld he motor magnet is energized and steps the wipers 3, 4, and 5 of the individual switch E to select contacts of an idle connector. Upon the first step of the wipers of the switch E ofl normal, the oil-normal contacts ON assume their alternate position and open the initial energizing circuit of the relay (0, but the relay CO remains energi'zed as long as the wiper 3 encounters grounded contacts 3 but as soon as the un grounded contact is encountered, the relay 0' deenergizes and disconnects the motor magnet MM to prevent further stepping of the wipers 3, 4 and 5. Relay LR being slow retains its armature attracted until a holding circuit is provided by the selected connectoras will be described.

An idle connector as F having been selected by the switch E, the interrupter relay IR which is bridged across the lineconductors of the connector '1' operates, its circuit bein traced from battery through'itsuppler win ing, normal contact 35, conductor contact-4, wiper 4, conductor T, normal contact 13, normal contact 14, conductor T conductor 36, alternate contact 37, conductor 38, through windings of the polarized supervisory relay PSR, conductor 8, normal contact 17, normal contact 1'8,-conducto'r S wiper 5, contact 5 conductor Sf, normal,

contact 39 andfthrough' lower winding of relay IR toIground; ,The battery flow vfor the polarizedrela PSR is in-such direction that said relay SR does not operate but relay SCR bein back because key LK and relay D8 are still operated ground at normal contact '40 does not affect the cord circuit.

The operation of relay, IR closes an energizautomatic substation is 45 the operator actuates the calling device Cl) to send four impulses over the line to operate the selected connector F. As the calling device leaves its normal position, contact 26 associated therewith assumes its alternate position energizing the dial connecting relay DR by current from battery through the winding of relay DR, alternate contact 27 of relay Db (which was energized when plug P was inserted into trunk jack TJ. and the listening key thrown) conductor 28, alternate contact 26 to ground. Relay DR remains energized during each operation of the calling device closing its alternate con Assuming that the number of the called tacts 83 and 84- to connect the calling derelay IR, alternate contact 42, winding of relay SR, conductor 43, winding of vertical magnet VM through the side switch arm 10 to battery. The relay SR being a slow acting relay maintains .its armature attracted during the ra fiid interruptions of its circuit by the relay 1 a but the vertical magnet VM being quick-acting is responsive to said impulses and steps the wipers 6, 7, and 8 of the Y armature of P attracted.

After thefirst set of impulses relay PV denergizes having its circuit opened at alternate contact 100 upon the deenergization of reiay SR, and mechanically steps the side switch arms 9,10, 11' and 12 to their second position to engage contacts 44, 45, 46 and 47. The side switch arm engagigig the contact 45 places the rotary magnet in series circuit with the relay SE to receive v impulses to cause the next set of impulses. The operator now alctuates the callin device CD to send five ve o erations of the interrupter. relay. IR. pon the first deenergizationf of reiayIR-ythe relay SR and the rotary magnet RM which are connected in series, are energized from ground at nor.-

mal contact 41., alternate contact 42, winding of SR alternate contact 101, the winding of relay ll-M, side switch'contact 45, wiper 10 to battery. The rotary magnet also being quick acting is responsive to the quick interruptions and steps the wipers 6, 7 and 8.

tothe fifthcontacts of the fourth level which are the contacts of the wanted line. The olf-normal contacts 0N assume their alternate position upon the first step of the switch movement.

After the last set of impulses the operator restores the listening key LK of the cord circuit Ciremoving the ground from the energizin circuit of the rela DS of'trunk circuit Upon the deenergization of the relay DS a circuit is closed for the signal control rela SCR traced from battery through the win 'ng'of the relay SCR, conductor 48, alternate contact 49, normal contact 50, conductor 31, alternate contact 34 to ground. The relay SOB upon energization, closes a lockin circuit for itself traced from battery throng its winding, alternate contact 51, conductor 31, alternate contact 34 of relay SW to ground. The closin of the alternate contact 25 of relay CR places a round upon the third contact of the jack J, this round closing an ene izing circuit for t esupervisory signal S traced from battery,-lamp SS normal contact 52,

normal contact 24, third contacts of the plug P and jack TJ, alternate contact 25, normal round, lighting the supervisory signal S which remains lighted until the subscriber at the called-for substation answers.

It will be noted that after the operator has once restored her key LK after the transmission ofthe impulses, due to locking up of SCR any subsequent manipulation of the listening key does not operate relay DS and therefore it is impossible to operatively connect the calling device again. This prevents intentional or accidental interference with established connections.

Ualled line idle.

After the last set of impulses the private relay PV deiinergizes having had its circuit opened by the deenergization of SR, to step the side switch arms 9, 10, 11 and 12 to their third position to engage contacts 53, '54, 55

and 56. The arm 10, engaging the contact 54 closes an energizin circuit for the rin ing relay RI traced rombattery throng the side switch arm 10, conductor 57, normal contact 58 of relay RCR, conductor 59 through winding of relayRI, through inter. rupter I to ground. The relay RI isenergized and deiinergized to connect the ringing generator M to the alternate contacts 60 and 61 of relay RI to intermittently ring the call bell at the called-for substation H. \Vhen the subscriber at substation H removes his receiver from the switch-hook in reisponse to his call bell, the reversing relay R operates by current over the called line,

circuit being traced from battery through lower winding of reversing relay RV, normal contact 62, conductor S normal contact 61, wiper 8, contact8; line limb 1 through the substation, line limb 2", contact 7 wiper 7, normal contact 60, conductor T, I

of relay PSR, conductor 38, alternate contact 37, conductor 36, conductor T, normal contact 14, normal contact 13, conductor T, wiper 4, contact 4, conductor T alternate contact 35, lower winding of relay IRto ground. The contact 40 of relay PSR thus assumes its alternate position opening the circuit of the supervisory lamp SS of the cord circuit C- notifying the operator at the branch exchange that the called automatic substation has answered. 7

The operationof the reversin relay RV also closes an ener 'zing circuit or the ringing control rela CR traced from batter through the winding of the relay RCl alternate contact 64, conductor 65, the side switch arm 9 to ground at the contact 53 Release. 7

V p After conversation has been completed the subscriber at called substation H re- "places -his receiver upon its switch-hook circuit of the relay 7 opening the ener 10 RV, the relay Ra denergizing and again causing the reversal ofbattery through the windings'of relay PSR the ground upon the third contact 0 the jack TJ again lighting the supervisory lam SS of the cord circuit (1 and thus noti 'ng the operator' that the called; subscriber has hung up.

, lighting lamp release magnet RE The subscriber at'the substation having replaced his receiver opens'the circuit of the rela AS of the cord circuit C s and the operator noting the two lighted lamps withdraws the plugs P and P from-the jaclesJ'and J eifacing the lamps. The removal of plug P also oiae ns the circuit for the switchlng rela S through contacts 29 and 30. of the jach TJ and the denergization of relay SW causes deiinergization of relay SCR. The deia'nergization of relay SW also opens the energizing circuit of relay IR of the coin nector F at alternate contact 37, the said [relay IR deenergizing and opening the cir- RR which operates restoring the connector F. The removal of ground at alternate contact 69 of RR permits the restoration of LR of switch E whereupon its normal contact 19 is closed energizing rela CO. Relay CO energizing and relay 1R restoring, both retaining pawls are withdrawn allowing the wipers o restore to normal as will be clear from an inspection of Fig. 2.

From the above description it may be seen that the release of the automatic apparatus is underthe control of the operator at the local exchange and by the removal of the plug from the trunk jack the automatic apparatus is restored to normal.

Called line busy. 7 Assuming that the operator has operated cuit' for release rela the calling device to send the last set of impulses, which are five in number, to select the wanted line of the called substation. Now if the called substation 'is busy a round appears'at its private contact 6 irom the alternate contact 19 of the individual switch E. This ground will establish an ener ing circuit for the busy relay BR traced r dm battery through the upper winding of relay BR, the side switch contact 44, side switch arm 9 which is now in its second position, the conductor 68, private wiper 6, contact 6 to ground at alternate contact 19 of the line relay LR 'of the individual switch E The busy relay BR locks up from ground at alternate contact 69 of relay RB, conductor 70, alternate contact 71, lower windingof relay BR through the relay PV to battery. Due to the relay SR being a slow acting relay, it remains energized momentarily preventing the private I relay PV from releasing until another circuit is established for it in series with the lower winding of the relay BR. The-relay PV remainin energized does not step. the side switch wipers, they remaining in their second position. This connects the busy back BB through the alternate contact 72 of relay BR, side switch contact 47, the side switch arm 12, conductor S and upon restoration of key LK said signal continues back to the calling substation notifying the calling subscriber that the called line is busy.

he restoration of the operators listeningf key causes the operation of rela S and SCR-and lighting of SS as fore. The replacing of the calling receiver lights SS. Therefore the operatorwithdraws the plugs de'nergizing SW and SCR as before followed by the dener 'zation of IR effecting the restoration 0 the connector and line switch E as will be clear from the foregoing description.

Automatic to branch exchange. N ow assuming that the automatic subscriber at H wishes to call a local substation terminating at the private branch exchange, he removes his receiver which act energizes line relay-LR of the individual switch E.

The line relay LR operating closes an energizingcircuit for cut-ofl' relay G0 which in turn closes an energizing circuit for motor magnet MM which steps the wipers 3*, 45*, 5 to select an idle connector as F in a manner which will be apparent from the previous description.

Assuming now that the automatic substation is calling the number 43 which is the number of one of the trunk linestcrminating at the branch exchange, the calling device is operated to send four impulses to step the wipers of the selected connector vertically to the fourth row of contacts. He then operates the dial to send three impulses of current toestep the wipers to the third contact in the fourth row which are the contacts 73, 74, 75 associated with a trunk circuit such as D. When the connector wipers stop on the contacts BS80- ciated with the idle trunk, a ground is placed upon the private contacts 73 to opcrate the cut-off relay C0 of the line switch E to remove the trunk control thereof.

Assuming that the trunk circuit D is in an idle condition, ringing current is applied from the ringing generator, and operates relay IQ of the trunk circuit D over a circuit traced from ringing generator of the connector, the connector, normal contact 60,

' wiper 7, contact 74:, conductor 76, normal tact 75, wiper 8, alternate contact 61, back to the ringing generator. The relay 1C is energized and locks u over a circuit traced from batter throng the lower winding of the relay C, alternate contact 79 normal contact 34, to ground. This closes a circuit for the trunk call signal TS traced from battery through the lamp TS, alternate contact 7 9, normal contact 34 to ground.

The operator at the branch exchange observin the signal TS inserts an answering plug into the trunk jack TJ operating the switchin relay SW, the circuit being traced from Eattery through the winding of relay SW, closed contacts 29, 30, conductor 31, normal contacts 50, 49, 80, alternate contact 79, normal contact 34 to ground. The switching relay SW upon energization closes a locking circuit for itself traced from battery through the winding of relay SW, contacts 29 and 30 and alternate contact 34 to ground. The contact 34 of relay SW being a make before break contact gives the switching relay SW a chance to lock up through its own contact 34 to ground before the initial energizing circuit is broken. The relay SCR is energized upon energization of the relay SW, the circuit being traced from battery through the Winding of relay SCH, alternate contact 49, normal contact 50, conductor 31, alternate contact 34 to ground. The relay *S'CR closes a locking circuit for itself traced from battery through its winding, alternate contact 51, alternate contact 34 to ground.

Upon energization of relay SW the circuit of relay IC is interrupted to efface signal TS and the closing of alternate contact -37 of SW bridges the polarized supervisory relay PSR across the trunk. Current throu h relay RV now flows through relay P R in such direction as to attract the armature of PSR and interrupt normal contact 40, to prevent lighting supervisory lamp SS. Re-

. lay RV also energizes and operates relay RCR to prevent further application of ringing current in a manner as before described. he operator now throws the listening key LK of the cord circuit C and assuming that it is the local tele hone A that is wanted, she inserts plug 1 into the jack J lighting the supervisory signal SS then throws the rigging key RK to connect ringing generator to ring the called-for substation A.

The subscriber at A in answering, energizes the calling supervisory relay CS open- She.

ing the circuit for lamp SS The two substations are now connected in a conversational circuit. 1 7

Upon completing conversation the' subscribers restore their receivers upon their respective switch-hooks, the restoration at the called substation A effecting the deenergization of relay CS and lighting the signal 88, The replacing of the receiver at the calling substation H interrupts the circuit for the associated impulse relay IR which restores closing a circuit for the re lease magnet REM followed by the restoration 'of the connector F. Upon the release of the connector, ground is removed from its test conductor 102 b the restoration of release relay RR so t at the line switch E restores to normal in a manner which will be clear from the foregoing description.

The said restoration of the connector also removes ground from the private or test contact 73 of the trunk individual switch E whereb its cut-oil relay GO restores. This establis es an energizing circuit for the line relay LR which brings about the operation of the trunk switch D to select an idle con* nector F whereupon the polarized relay PSR is rendered inert and establishes a circuit for the supervisory signal SS. The forego' ingyoperation is brought about as follows:

p on said restoration of relay G0 a' circuit is established traced from battery through the winding of LB, wiper 4 and its normal contact, conductor T normal contact 13, conductors T 36, alternate contact 37 the winding of PSR, normal contact 17, normal contact 18, conductor S and wiper 5 to ground. The direction of current flow through relays LR and PSR- is such as to restore relay PSR andthe energization of LR is followed by the energization of CO as before described. Therefore normal contacts 13, 18 of C0 are interrupted opening the circuit for PSR and relays CO and LR being ener ized switch E advances its wipers until an id upon relay CO immediately restores connecting the impulse rela IR of the selected connector in circuit wit the polarized relay PSR, the current flow beingin such di rection as to maintain relay PSR inert. Normal contact 40 of the polarized relay is thus maintained closed establishing a circuit for superviso signal-SS and therefore the operator withdraws plugs P and P from the jacks. The withdrawal of the le connector is reached. There-,

, tening ke calling device is operatively disassociatedfrom the trunk should the called subscriber respond prior to the restoration of the lis- It will be remembered that after a ca 1 has been extended by the use of the calling device, the operator restores her listening key which restores the dial switching-rela DS and causes the energization of,

relay S R so that any furthermanipulation of the calling device during an established connection is without effect. It may sometimeshap n that a called subscriber will reof the 'polarized nelay which occurs when the subscriber answers efl'ects the closure of its alternate contact 10 causing the energizetion of relay SCR so that the interruption of its normal contact 25 restores relay DS. Re lay SCR also locks up through its alternate contact 51 in a manner as already set forth. A subsequent restoration of the operators listening key will therefore have no effect upon the trunk circuit relays. The circuit of relay DS having been interrupted at norcmal contact 25, it will be apparent that it is impossible to again associate the calling device with the cord circuit by the manipulation of the listening key until the connection has been taken down.

Having described my invention, what I claim as new and desire to secure by United States Letters Patent, is:

1. A telephone system comprising a main automatic exchange, a branch operator controlled excha ge, an operators cord circuit for interconnecting the branch substations, a trunk circuit extending from the branch to the main exchange, a calling device incapable of normal operative association with the trunk circuit, a relay for operatively associating said calling de vice with said trunk circuit, a listening key for the cord circuit, and means responsive to the connection of the call plug of the cord with the trunk circuit an the operation of the listening key for rendering said relay capable of being operated to operatively associate said calling device with the trunk circuit.

2. A telephone system comprising an operators position having a cord circuit for interconnecting telephone lines, a trunk circuit extending from the operators position to an automatic exchange, a calling device for the trunk circuit incapable of normal operative association therewith, a relay for associating said calling device with said trunk circuit, an operators key for the cord circuit,

and the operation of said key for rendering said relay capable of being operated to operatively associate said calling device with the trunk circuit. 3. A telephone system comprising an operators position having a cord circuit for interconnecting telephone lines, a trunk circuit extending from the operators position to an automatic exchange, a calling device for the trunk circuit incapable of normal operative association therewith, an operators key for the cord circuit, means responsive to the connection of a' terminal of the cord with the trunk circuit and the operation of said key for rendering said calling device capable ofcperative association with the trunk circuit, and means responsive to each operation of the calling device for operatively connecting it with the trunk circuit.

4. A telephone system comprising a cord circuit, a trunk circuit for connecting said trunk circuit and said key is operated for effecting one step in operatively connecting said calling device-with the trunk, and means responsive to the operation of the calling device for operating the other one of said relays for operatively connecting the calling device with the trunk.

A telephone system comprising a cord circuit, a trunk circuit for connecting said cord with an automatic exchange, a calling device for the trunk circuit, means controlled by the operator for operatively associating said calling device with the trunk circuit, automatic switches responsive to said calling device for extending the trunk circuit to a called line, and means operated u on response from the called substationor 0peratively disassociating said calling device and trunk circuit.

6. A telephone system comprising a cord circuit, a trunk circuit for connecting" said cord with an automaticexchange, a calling device, an operators key for the cord circuit, means responsive to the actuation of said key and the connection of said cord with the trunk for operatively associating said calling device with the trunk circuit, and means responsive to subsequent restoration of the key to operatively disassociate said calling device and the trunk circuit and prevent their operative association while said cord and trunk remain connected.

7. A telephone system comprising an operaters cord circuit provided with an operators key, a plurality. of trunk circuits trunk circui 1-,

accessible to said cord circuit and extending to automatic switches in an automatic exchange, a calling device common to said trunk circuits, a relay for each of said trunk circuits for operatively associatin said calling device with its respective trun circuit, means for connecting said cord circuit with one of said trunk circuits, a circuit for the relay of the connected trunk circuit including contacts of said operators key, and means for operatin said relay to operatively associate the calling device with said trunk circuit.

8. AL telephone system comprising an op-l.

erators COIdeClIT-Jlllt rovided with an operators key, a plum ty of-trunk'cucuits ac essible to said cord circuit and extending to automatic switches in an antomatic' e1:-

change, a calling device common to said trunk circuits, a relay for each of said trunk circuits for operatively associating said call ing device with its respective trunk circuit,

means for connecting said cord circuit with one of said. trunk circuits, azc'ircuit for the relay of the connected trunk cii'cuit including contacts ofusaid operators key, and

, means ior operatfing'i- 'said relay to opera-v tively associate the calling device with Said.

trun circuit,-an d a subscriber controlled relay'for said ltrjmk circuit for operatively dis'associati calling device and said 9. A telephciiesysufi com rising an operators cord=cirfli1tprovided with an operators key,a plur i accessible to said cord circuit ,and extending to equipment inan automatic exchange, a calling device common to saidftrunk circuits, electromagnetic means for each of said trunk circults for operatively associating said calling device with said trunk circuits, means for operatively disassociating said callingdevlce from a connected tion of the subscriber from the trunk circuit. V. i

11. A telephone system inciuding a two way trunk circuit extending from a manual exchange toanautoniatic exchange, a calling device, means for operatively associating said calling device with said trunk circuit when said circuit is used to extend a said trunk circuit;

tyof trunk circuits call in one direction, and means for preventing an operative association of said calling device and said trunk circuit when saidtrunk circuit is used toextend a call in the opposite direction.

12. A telephone system comprising an operators cord circuit provided with an operators listening kc a trunk circuit, a calling device associate with said trunk circuit but normally disconnected therefrom, means for connecting said ,cord circuit with said trunk circuit, electromagnetic means for op-. eratively associatingsaid calling device with said trunk circuit, a circuit for said electro-v magnetic means including contacts of said operatbrs listening-key, and means for operating saidelectroma etic means to operatively associate 'saicf 13. A tele hone system comprising an operators cor circuit; erators listening lie trunk-circuit, a calling device associatediwitlia -said trunk circuitbut normally disconnected therefrom, means for connecting'fsaid cord circult with said trunk circuit,electrom etic means for operatively associating sai callmg device with said trunk circu t, a circuit for said electromagnetic means inciudin contacts of sa'idoperators listening key, an means for operating said electromagnetic calling device and videdflwith an opmeans tooperativelflassociate said calling 7 device and said circuit, and means responsive to an operation of said operators key to disassociate said calling device and said trunk circuit and prevent a reassociation of said calling device and said trunk circuit while said cord circuit is operatively connected to said trunk circuit.

14. A telephone system comprising a trunk circuit extending to an automatic-exchange, a rotary manually operable calling device for said trunk circuit, and a relay individual to the said trunk circuit energized responsive to each operation of said calling device when dialing a number for directl connecting said calling device to said trun circuit.

15. A telephonesystem including an operators position, a plurality of trunk circuits extending from said operators position to automatic equipment in an automatic exchange, a calling device common to said trunk circuits, electromagnetic means individual to each of said trunk circuits for operatively associating said calling device with said trunk circuits, and means responsive to an operation of said calling device for operating the electromagnetic means of a trunk circuit to operatively associate saidcalling device with said trunk circuit prior to an operation of said automatic equipment.

16. A telephone system including an operators cord circuit, a plurality of trunk circuits accessible to said cord circuit and extending to equipment in an automatic exchange, a calhng device common to said trunk circuits, and means res nsive to the a connecting of said cord circuit with one of called line, 'andmeans operated upon re spouse from the called substation to .operatively disassociate saidcalling device and said trunk circuit and for preventing a reassociation of said calling device and said calling circuit while said link circuit is connected to said trunk circuit. I

18. A telephone system including a trunk circuit extending from a manual exchange to an automatic exchange, a calling device, electromagnetic means individual to said trunk circuit for operatively associating said callin device with said trunk circuit, and subscriber-controlled means for operatively disassociating said calling device from said trunk circuit.

19. Atelephone system including a trunk circuit extending to an automatic exchange,

\ a calling device, an operators cord circuit provided with a listening key, and electromagnetic means responsive to an actuation of said listenin key and an operation of said calling demos for operatively associating said calling device. and said trunk circuit.

20. A telephone system including an operators link circuit, a trunk circuit, a calling device, manual means for connecting said trunk circuit directly tosaid link circuit, and means responsive to a'contr'ol exerted at said link circuit and an operation ofsaid calling device for operatively connecting said calling device with said trunk circuit.

21. A telephone system including an 0perators link circuit provided with a key, a trunk circuit, a calling device, a simple relay adapted upon encr "zation to operativel associate .said calling evicc with said trun circuit, and means de endent upon an actuation of said ke an an operation of said calling device or actuating. said relay to operatively associate said calling device with said trunk circuit.

22. A telephone system including a trunk circuit, a caling device, a rotary manually operable settintg member for said calling device, a pair 0 ontacts adapted to .be actuated each time said settin member is operated, 'a key, a relay in ividual to sald trunk circuit for connecting said calling device with said trunk circuit, and a circuit for said relay controllable by said key and said contacts.

23. A telephone system including a trunk circuit, an oiperators rotary impulse-sending "device, 0 -normal springs ada ted to be closed upon each actuation of saidimpulsesending device, and a relay individual to said trunk circuit provided with a circuit including said contacts adapted to be energized' upon each operation of-said device for associating said device with said trunk circuit.

24. A telephone system including a trunk circuit, an operators impulse-sending device, a relay responsive to an o eration of said device for associating said evice with said trunk circuit, and subscriber-controlled means for disassociatingsaid sending de vice and said trunk circuit.

25. A telephone system including an operators link circuit provided with a key, a calling device, a rotary manually operable setting member for said calling device, oil'- normal springs adapted to be actuated upon each operation of said setting member, and

a relay individual to said trunk circuit controllable by said key and the off-normal contacts of said calling device for operativel associating said calling device with said lin circuit.

26. A telephone system including an op erators link circuit provided with a key, a trunk circuit connected to said link circuit, a calling device, means controlled by said key and said calling device for connecting said calling device with said trunk circuit, a numerical switch, and a non-numerical switch for connecting said trunk circuit to said numerical switch.

27. A telephone system including operators cord circuits provided with listening keys, trunk circuits, a calling device commen to said trunk circuits, manual means a for connecting one of said cord circuits to said trunk circuit, means for said trunk circuit operable in re sponse to an operation of the listenin key of said cord circuit for associating sai call-V ing device with said trunk clrcuit.

and electromagnetic:

device for connecting said device to said a trunk circuit.

29. A telephone system including an 0 erators link circuit, a trunk circuit exten ing from a manual exchange to an automatic exchange, a calling device, means responsive to an operation of said calling device to connect said calling device with said trunk circuit said-means including a rela provided with a circuit the closure of whic is contingent u on an operation of said calling device an the connection of said link circuit to said trunk circuit.

30. A telephone system including a trunk circuit ternimating in a manual connection terminal and in an automatic switch, an 0 crators callin device, and a rela adapte when 0 crates to connect the sai calling device wit said trunk circuit and to operate said automatic switch.

31. telephone system including a trunk circuit terminating in a manual connection terminal and in an automatic switch, acalling device, a relay individual to said trunk circuit for connecting said calling device'to said trunk circuit, and means responsive to the connection of said calling device to said trunk circuit for operating said automatic switch. 7 r

32. A telephone exchange system including-a trunk circuit terminating in a manual connection terminal and in an automatic switch, a key, a calling device, a relay, means for o crating said relay to connect said calli'ng evice to said trunk circuit responsive toan operation of said calling device and said key, said automatic switch being operable responsive to the connection ofsaid calling device with said trunk circuit.

3. A telephone system includingan operators cord circuit provided with a key, a trunk circuit, a calling device, a pairof relays for said trunk circuit, means for operatin one of said relays responsive to an actuat on of said key, thereby reparing a circuit for the other of said re a s, and means responsive to an actuation 0 said calling device to operate said other relay to operaators cord circuit trunk 01!C\11i38, a cal ing device common to said trunk circuits, and electroma 61310 and tivel associate said calling device with said trun cllclfit.

84. A telephone system includin an 0 errovided Willi a Eey,

means individual to each of said trun circuits and responsive to an actuation of said calling device to connect said calling device with a trunk circuit...

35 A telephone system including an open ators cord circuit, trunk circuits, a calling device common to said trunk circuits, means for connecting said operators cord circuit many of said trunk circuits, and means individual to a trunk circuit 0 erated respon sive to an actuation of said calling device for connecting said calling device to the trunk circuit to which said cord circuit has been connected.

36. A telephone system including an operators cord circuit, trunk circuits, a calling device common to said trunk circuits, means for connecting said operators cord circuit to any of sand trunk circuits, means individual to a trunk circuit operated responsive to an actuation of said calling device for connecting said calling device vto the trunk circuit to which said cord circuit has been connected, and means for preventing a subsequent actuation of said calling device from again connecting said calling device to said trunk circuit,

Si ed by me at Chicago, county of Cook, tate of Illinois, in the presence of two witnewes.

GEORGE D. WOLF.

Witnesses Gnonon E. MUELLER, B. OBnmN.

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