US1429241A - Telephone system - Google Patents

Description

J. F. HAYDEN.

TELEPHONE SYSTEM.

APPLICATlON FILED FEB I2. I9I7.

1,329,241, I PatentedSept. 19,1922.

2 SHEETS-SHEET l.

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49} Jss Ffiayjsn J.F.HAYDEN.

' TELEPHONE SYSTEM.

APPLICATION FILED FEB-12, I917- PatentdSept, 19

2 SHEETS-SHEET 2.

I JfiZ/EZZZZY'ZT JE SE @5527.

Patented Sept; 19, 1922.

UNIT STATES Jessie F. HAYDEN, OF HIGH ,POINT, NORTH. CAROLINA, ASSIG-NOR TO KEL Loe-e SWITCHBOARID Ann SUPPLY COMPANY, on CHIGAG I QIS, 'AL coRPo-,

RATION OF ILLINOIS.

TELEPHONE SYSTEM.

Application filed February 12, 1917. I Serial No. 148,049.

T 0 all to ham it may concern Be it known that I, Jnssn FpHAYDEN, a

citizen of the United States of America, and

residing in High Point, county of Guilford, and State of North Carolina, have invented certain new and useful Improvements in Telephone Systems, of which the following is a specification.

My invention relates to telephone systems in which manual link or cord circuits are provided for interconnecting telephone lines, and has to do more particularly with systems of the class in-which instantaneous disconnect and recall, automa'tic ringing and set is in circuit with the link circuit and calling subscribers line she is aware that she has not as yet depressed the ringing key to signal the called for party.

Another feature is the provision of an automatic busy testin which a busy signal-is connected to the callingsubscribers line, should the called for subscriber at a called substation be busy when the operator connects the calling cord with a jack of the called line. No preliminary testingis necessary by the operator, and the mere plug ging into the jack of the wanted line operates means to connect the busy signal in cir uit with the calling line if the wanted line is busy; and it the said wanted line is idle, the said means remains ineffective. These and other objects of my invention will be more particularly pointed out in the ensuing specification and in the appended claims. 5 Referring now to the accompanying drawings, I illustrate in Fig, 1 one form to which my invention is adapted, and in:

Fig. 2 I show a, modificationot the circuit arrangements shown in Fig. l.

fiReferring' nowin general to Fig. 1, it

comprises a calling substation .A terminating at the exchange into a line circuit L comprising the usual cut-ofi relay CO, line relay LR, line signal S and the multiple jacks J.

The cord circuit C, for interconnecting callingand called subscribe'rslines, comprises an answering plug AP and a calling plug UP, the said plugs AP and GP being connected by the heavily marked conductors and having the condensers K and K interposed. The answering end of the cord circuit G includes. an answering sleeve super visory relay AS and. an aswering tip supen visory, relay AT, the said answering tip s'upervisory relay AT controlling the lighting of an answering supervisory lamp AL, while the answering sleeve supervisory relay AS,

upon: energization, connects the operators set'O to'the cord conductors. A link dis-' energized upon the restorationof the receiverupon the switch hook at thec'allin'g, .SHbSCTIbET substation and before the calling plug CP is disconnected fromrts connected jack to permit a recall by a calling subscriber, as will be more fully hereinafter described.

The calling end of the cor d'circuit'C insaid relay CS energizing upon the depression of a ringing key plunger of the ringing "key BK, while the relay CT is energized upon the response of the calledsubscriber. A ringing interrupter relay IR is provided which relay IR is intermittently energized and de-energized by the interrupter I. A

signal thereto. A calling supervisory lamp CL is provided for supervisory purposes and is not only under the control of the called subscriberbut is also'under the control of the calling subscriber. A meter reconnect relay LD is also provided which'is 'cludesa calling sleeve supervisory relay and a calling tip supervisory relay CT, the

lay MR and a meter magnetMM are also provided which are operated upon theac-' tuation of the ringing connections. V I 1 To the right of the drawing, I have shown a called substationB similar. to the substakeyRK to register the signals S tion A and connected to a line circuit L includin similar apparatus as that of L, the said apparatus bearing the same reference characters but with the suffix prime added.

Referring now to Fig. 2, I illustrate another circuit arrangement embodying my invention, and in which the apparatus similar to that of Fig. 1 bears the same reference numerals but with exponents added. To the left of the drawing, 1 show a calling substation A terminating into a line circuit L having the usual cut-off relay CO line relay LE and the multiple acks J and line The line circuit L as shown, is known as a multiple line lamp type in which .a line lamp S is provided with each jack so that when a call is initiated a line signal as S appears before each of the calling line jacks, and anyone of a pluralityot operators may seize this call to the exclusion of the others.

A cord circuit C is provided having an answering plug AP and a calling plug 0P said plugs being connected by the heavily marked conductors and having the condensers K and K interposed. The answering end of the cord circuit C provided with a high resistance test relay TE, which is energized when connection is made with a calling line to connect the answering sleeve supervisory relay AS in circuit to connest the operators set 0 An answering tip supervisory relay AT is provided which ener gizes to prevent a premature lighting of the answering supervisory lamp AT). A link disconnect relay LD is also provided tor purposes to be hereinafter set forth A busy relay BB a ringing control relay RC a calling tip supervisory relay GT an interrupter relay 1R with its associated inter rupter 1 a calling sleeve supervisory relay CS a ringing key BER, and associated generators G G G and G", a meter relay MR a meter magnet MM and busy back apparatus BB are also shown and perform functions similar to the corresponding parts shown in Fig. 1.

To the right of the drawing, I show a called substation B terminating into a line circuit L similar to that of L Having described in a general way' my invention as illustrated in Figs. 1 and 2, I

will now describe more in detail the operation of the circuit arrangement of Fig. l

. in completing a connection between a calling subscriber A to a called subscriber B. Assuming now that the subscriber at the substation A initiates a call, the removal of the receiver thereat brings about the energization of the lino relay LR from battery through the winding oi" the relay LR nor- =mal contact 1. of relay CO, through the substation A baclt to ground at, normal Contact 2 of relay CO. The line relay LR, upon energiza-tion closes its alternate contact 3,

bringing about the lighting of the line signal S. The operator noting the lighted line signal S inserts the answering plug AP into the jack J of the calling line thus closing a series energizing circuit for the cut-oh relay CO and the sleeve supervisory relay AS from battery through the lower winding of the relay AS, normal contact 1 of relay LD, sleeve contacts of the connected plug AP and ack J through the winding 0 relay CO to ground. The relay CO upon energizing closes its alternate contacts 1 and 2 and opens normal contact 1 thereby interrupting the circuit of relay LR, thus er; facing'the line signal S. The answering tip supervisory relay AT is also energized upon the energization of relay CO, as is readily understood, thus preventing the lighting oi the answering supervisory lamp AL. The closing of alternate contacts 5 and 6 oi relay AS connects the operators set 0 to the cord conductors through the said. alternate contacts 5 and 6 of relay AS, and the normal contacts 7 and 8 of the calling sleeve supervisory relay CS. The calling supervisory lamp CL is lighted upon the energization of relay AT, the circuit being traced from battery through the lamp CL, normal contact 9 of relay RC, conductor 10, conductor 11 to the point 12 and from the point 12 through normal contact 13 of relay CT to the point 14, then over conductor 15 and normal contact 16 of the busy relay BR to ground at alternate contact 17 of relay AT, the said lamp remaining lighted until the operator depresses the ringing key BK. By arranging the circuit of the calling supervisory lamp in this manner, theoperator is always apprised of the next step required to complete the connection. The operator now in quires the wants of the calling subscriber at the substation A, and assuming that it is the subscriber at the substation B that is wanted, the operator inserts the calling plug GP into the multiple jack il of the called substation B without any preliminary testing, and should the line be busy the subscr ber receives a busy signal from the busy back apparatus BB, as will be more fully hereinafter described.

Called Zine idle.

Assuming now that the called line is idle,

' the insertion of the calling plug GP into the relay CS and the interrupter relay IR over a circuit traced from battery through the winding of the relay CS through the lower winding ol the relay IR, conductor 20, al-

ternate contact 19 of the end springs, conductor 21 to the point 12 and from the point 12 through the normal contact 13 of relay CT to the point 14, then over conductor 15, through normal contact 16 of relay BR to ground at alternate contact 17 of relay AT. The momentary closure of contact 18 establishes an energizing circuit for the meter relay MR traced from battery through the winding of the relay, MR, the closed contact 18 of the end springs, conductor 22, the normal contact 9 of relay RC, conductors 10 and 11 to thepoint 12, normal contact 13 of relay CT to the point 14, then over conductor 15, and through normal contact 16-of relay BR to ground at alternate contact 17 of relay AT, The closing of alternate contact 23 of meter relay MR establishes an energizing circuit for the meter magnet MM. traced from battery through the alternate- .contact 230i MR and through the winding of meter magnet MM to ground. The magnet MIMI upon energization operates the register mechanism to count a connection. The closing of alternate contact 8 of relay CS establishes a series energizing circuit for relay CS and cut-oft relay C of line circuit L over a circuit traced from battery through the winding of the relay CS, the alternate contact 8 of relay CS, sleeve contacts of the connected plug .CP and jack J and through the winding of relay CO to ground. vThe opening of normal contacts 7 and 8 of relay CS disconnects the operators set C from the cord conductors and connects the calling plug to the answering plug.

The closing of alternate contact 27 of relay IR bringsabout the energization of the ringing control relay RC over a' circuit traced from battery through thewinding of the relay RC, conductor 26, the alternate Contact 27 of'relay IR, conductors and 11 to the point 12, through normal contact 13 of relay CT to the point 14, thenover conductor 1.5 to ground at alternate contact 25 of relay CS. Relay RC, upon energizing, closes a-locking circuit for itself traced from battery through the winding of relay RC, its alternate contact 9, conductors 10 and 11, tothe point 12, normal contact 13 to the point'll, and conductor to ground at alternate contact of relay CS. The. closing of alternate contact 3001f the relay RC closes an interrupting circuit for the interrupter relay IR, from battery through the interrupter I, through the upper winding of relay IR, conductor 31, the alternate contact 36 of relay, BC to the point 12, through normal contact 13 of: relay CT'to the point. 14, then over conductor 15 to ground at alternate contact 25 of relay-CS. Upon the initial energizatioii of relay IR broughtabout by the momentary closure of the end springs, ringing current is connected to the called line immediately upon the depression of said ringing key plunger ol theringing key RK, thus producing an instantaneous prelimifirst ring. This instantaneous first ring is brought about by the. closing of alternate contact 32 ofrela-y IR, which 18 closedupon the momentary energizati'on' of relay 1R, due to the closing of end spring contact 19, and the lower winding being slowing-acting is slow to release so that the ringing current is connected for a short period. The interrupter I is then introduced into circuit with the upperfwinding of relay IR 'due to the closure of alternate contact 35 of the ringing key plunger, through conductor 36, alternate contact 32 of the relay IR, alternate contact 7 ofthe relay CS, the

sleeve contacts of the connected plug CPa-nd jack J through the call bell and condenser at the called substation B, I back through sleeve contacts of the connected jack J and through the alternate contact 37 of relay IR to battery and ground, the called. subscriber being thus intermittently signalled. 1 y

l pon the response of the said called subscriber at the substation B, an energizing eir-' cuit for the calling tip supervisory relay CT is established, traced from ground through the winding of relay CT, normal contact 32 .otrelay IR (when relay IR is'in its de-energized positions), thealternate contact 7 of relay CS, thetipcontacts of the connected plug CP and jack -J ,-.through the .now closed contacts of the substation switch hook, back through the sleeve contacts ofthe connected plug CB and jack J alternate contact 80f relay CS. and through the Winding of relay CS to ground The opening of normal contactl3 of relay CT brings, about the de-energization 'o'f the' relays RC and IR, which then restore tqnormal. The subscribers are now in conversational circuit, {said talking circuit being traced over the heavily marked conductors;

' Assuming that conversation has terminated, the subscribers replacetheir receivers upon their respective switch hooks, bringing about the de=energization or the supervisory plug CP, alternate contact 8,of'relayCS relays'AT and CT. The relay AT upon restoration, brings about the lighting of the answering supervisory lam AL from battery through the said lamp AL, the nor mal contact 17 of relay AT, normal contact 16 or relay BR and conductor 15 to ground at alternate contact 25 of relay OS. A further result due to the de-energization of relay AT is the energization of disconnect relay LD over a circuit traced from battery through the winding of said relay LD, contact 17 of relay AT, contact 16 of relay BR and alternate contact 25 of relay CS to ground. Relay LD, upon energizing, opens the link circuit strand at its contacts a and 40,-thus permitting the cut-off relay C0 of the calling .subscribers line to ole-energize and place line relay LR in position to be operated by the calling subscriber. The closing of normal contact13 of relay CT closes a circuit for the lamp CL traced from battery through the said lamp CL, normal contact 9 of relay BC, conductors 10 and 11 to the point 12, through the normal contact .13 of relay'CT to the point lt, and then over conductor 15 to ground at alternate contact 25 of relay CF The operator noting the two supervisory signals AL and CL knows that conversation has terminated, and therefore withdraws plugs AP and C]? from their respective jacks, bringing about the restoration of the relays AS and CS and the r'elaysCO and C0 The apparatus is now at normal and not available for establishing other connections.

'Assuming that the subscribers have finished conversation and have replaced their receivers upon their respective switch hooks, but that the operator has not restored the link circuit plugs to their plug seats and that the original calling subscriber now wishingto initiate a recall removes his receiver from'the switch hook. The removal of the receiver from the switch hook brings about the lighting of the line signal S due to the energization of the line relay LR, and the lighting of the said line signal S notifies the operator that a recall is desired. The same operator may now. seize the recall by removing the calling plug CP from its connected ack,'.'bringing about the de-energization of the relay US which opens the circuit of relay LD at alternate contact 25. Relay LD restoring now permits the relays AT and AS to again energize, and the closing of alternate contacts 5 and 6 of relay AS again connects the operator to the cord conductors so she may again inquire'the wants of the recalling subscriber.

Called lime busy.

Assuming now that'the called substation B isbusy, as either a calling or called subscriber, the operator plugs into the line in the usual manner and the line being busy,

the sleeve of the'jack has a battery potential upon it which. causes the busy relay BR to energize over circuit traced from the said battery on the sleeve of the busy Jack, through the sleeve contact of the plug GP,

over conductor 41, through the winding ot tion due to the fact that the operator has not depressed the ringing key RH). Should the operator depress the ringing key in case the line is busy, this connection does not connect ringing current to the wanted line, due to thejiact that normal contact 16 of relay ER is open, thus preventing relays lit and CS from energizing. The relay Bib, upon energizing, closes alternate contact 4-3 thereby associating the busy back apparatus BB with the calling line. local circuit for the busy back apparatus BB extends from ground through the interrupter l and through the primary winding 43 of an induction coil to battery and ground. The'interrupted current in this circuit induces a current inthe secondary winding 4A which travels from battery through said secondary winding 44 over conductor 45, through alternatev contact 413 and through the lower winding of the relay AT to ground. The current in this circuit induces a'current in the upper winding of the relay AT which is transmitted to the calling subscriber at the substation A, notifying the said subscriber thereat that the called line is busy. A iurther result due to the energization of relay is the closure of a circuit through the upper winding of relay AS over a circuit traced from battery through alternate contact 100 and the said upper winding of relay AS to ground. The current in the upper winding flowing in the opposite direction to that in the lower winding causes the relay AS to de-energize and disconnect the operators telephone set at its contacts 5 and 6. The calling subscriber receiving the busy signal replaces his receiver upon the switch hook thus causing relay AT to de-energize and close a circuit through link disconnect relay LD and supervisory signal AL over a path extending from ground at alternate contact 16 of relay BR through normal contact'l? of relay AT and then over multiple paths through lamp AL and disconnect relay Ll). The relay LD energizes and disconnects the calling subscribers line from the cord circuit thus placing the subscribers line apparatus in condition to make a recall. The operator then withdraws the answering and calling plugs from the connected spring jacks permitting the link circuit apparatus to restore to normal.

Having described in detail the operation of the apparatus shown in Fig.1 of the accompanying drawings, I will now describe more or less in general the operation of the system shown in Fig. 2 ofthe drawings.

A subscriber at the substation A desiring to call removes his receiver to establish a circuit for the line relay LE whereby the line signals S before the different associ ated jacks are lighted. The first operator to seize the call by therinsertion of an an swering-plug AP into one of the-calling line jacks connects the high resistance test relay TE and cut-0ft relay CO in series, efiecting theenergization of the relayTE. The closing of alternate contact 50 of relay TE connects the comparatively low resistance answering sleeve supervisory relay A3 in series with the cut-off relay CO whereby the relay -AS energizes, closing its alternate contact 51 to connect its winding direct to the sleeve strand of the cord independent of the contacts of the test relay TE. Therefore, should the test relay TE restore due'to the shunting of its winding by the comparatively low reternate contacts and 5% are closed to conne'ct the operators set in bridgeof the talking conductors of the cord through normal contacts 55 and 56 of the relay BB and normal contacts 57 and 58 ofrelay CS Should the second operator insert .an answering plug AP into another jack of the calling line, subsequent to the insertion the first plug, the test relay TE of the se. -ond cord does not energize due to the shunting of its winding by the relay AS? of the first cord so that the second operator is unable to communicate with the calli'ng subscriber because her telephone set do-esnot connect with the calling line. Therefore, this second operator withdraws heranswering plug AP fromth e jack of the calling line. The first operator having ascertained that connection is desired with the'substation B inserts the calling plug C1 into a multiple jack J of the wanted line without any preliminary testing, and should the called line be busy as a calling or called line, thebusy relay BB is operated due tothe battery potential upon the sleeve of the busy jack, thus connecting a busy back apparatus BB? to notify thecalling subscriber of the busy condition of the line B as. previouslyrle Fig. 1.

The answering tip supervisory the 'closure' ofcontact 59 bringsaboutthe operation ofthe meter relay MR which" in turn operates the meter magnet MM? to register a connection as described in connection with The closure of contactc'o oi the end springs brings about'energ'izing circuits for the callingsleeve supervisory relay CS the interrupter relay lRfiand the ringing control relay RC as described, in connection with Fig. 1. i

The operation of the circuit in extending the call to the called substation IE is similarto that-ofFig. 1, asis also the operation when connection is made with they busy line. The operation of the recall apparatus is also similart'o that described in Fig-1, and I, therefore, do not deem a furtherdescription of the system of Fig. 2 necessary in' view of the extended description of Fig. l.

In working out my invention, I have shown two circuit arrangements to which my invention is adapted, but I contemplate using it in connection with other circuits than that shown. It will also" be apparent that changes and modifications will readily occur tothose skilled in the art after'becoming familiar with my invention, and I therefore do not desire to be limited to the exact structures as shown and described, but 7 aim to cover allthat which comes within the spirit and scope of the appended claims. v

What I claim, as new and desire to secure by United States Letters Patent is:

1. A telephone system includ ng a calling and a called subscribers line, a link circuit for connecting said lines, an operators telephone, a relay forconnecting said operators telephone to the link circuit, a relay for disconnecting said operators telephone from the link circuit, audible busy means for said link circuit, and a busy test relay operable only if the called line is. busy for rendering" said latter relay inoperative and to connect the audible busy means in circuit with the calling subscribersliine;

2. A telephone system including a calling subscribers line and a called subscribers line,.a link circuit for connecting saidlines in conversational circuit, an operatorls telephone set, automatic means'for connecting said operators telephone set to said link cir cuit, automatic means for disconnecting said operators telephone set from said link circuit, 'audiblebusy means for saidlink cir? cuit, a busy test relay for testing the called subscribers line, and for connecting 1 said audible busy means in circuit with the 'call-' ing subscribers line, and a circuit forsaid automatic disconnecting means controlled by said busy test relay for rendering said disconnect means inoperable only when the called line is busy. c

3,1.A telephone system including an operators link circuit, an answering and a calling supervisory signal for said link circuit, a subscriber-controlled answeringv supervisory relay, a subscriber-controlled calling supervisory relay, circuits for said answering and calling supervisory signals controlled by saidanswering supervisory relay, and a second circuit for said calling supervisory signal controlled by said calling supervisory relay in response to; a control exercised at the called substation.

4. A link circuit including a subscribercontrolled answering supervisory relay and a siibscriber conti-olled calling supervisory relay, a pair of supervisory signals for said link circuit, circuits for said signals con trolled by said answeringsupervisory relay, and ,a second circuit for one of said supervisory signals controlled by said calling supervisory relay in response to a control exercised at the called substation.

5. A telephone system including a calling subscribers line and a called subscribers line, a link circuit for establishing connection betwe en said lines, automatic ringing apparatus, associated with said link circuit for signaling the called substation, an ope'rators telephone set, an answering sleeve relay responsive to the-connection of said linkcircuit to said. calling line for connect ing said operators set with said link cirouit, a calling sleeve relay for disconn-ecting said operators set from said link circuit, a ringing key for connecting said ringing apparatus to the called line and for operatively energizing said calling sleeverelay, and a locking circuit for said calling sleeve relay including a contact 01"- said calling sleeve relay.

6. A telephone systemincluding a calling subscribers line and av called subscribers line, a link circuit for connecting said lines conversational circuit, a callingusupervisory signal for said link circuit, relay controlled by the calling subscriber for closing an operating circuit for said SLlPQIVlSOTY signahmeans for opening said circuit, and a relay controlledby the called subscriber for closing a second circuit for said supervisory signah I 7. A telephone system including a callino' subscribers line and a called subscriber's line, a linkcircuit for connecting said lines in telephonic circuit, a supervisory signal for said link circuit, means controlled by the calling subscriber for closing an operating circuit for saidsupervisory signal, signaling means for signaling the called substation, means for actuating said signaling means and for efl'acing said supervisorysignal, and

weasel means controlled by the called subscriber for again closing anoperating circuit for said supervisory signal.

8. 'A telephone system including a calling subscribers telephone line and a called subscribers telephone line, a link circuit for connecting said lines in a conversational cir cuit, a supervisory signal for said link circuit, a relay under the control ofthe calling subscriber for closing an operating circuit for said supervisory circuit, ringing apparatus for signaling the called, substation, means for initiating operation of said ringing apparatus and for etfacing said supervisory signal, and a relay under the control of the called subscriber for again closing an operating circuit of said supervisory signal.

9. A telephone system including a calling subscribers telephone line and a called subscribers telephone line, a link circuit for connecting said lines in a conversational circ'uit, a supervisory signal tor said link circuit, a relay under the control of the calling subscriber for closing an operating circuit for said supervisory circuit,,r1nging apparatus for signaling the called substation, means for initiating operation of said ringing apparatus and for effacing said supervisory signal, a relay under the control of the called subscriber for againclosing an operating' circuit of said supervisory signal, and operator controlled means for again etfacing said supervisory signal;

10. A telephone system including a called telephone line, a two-conductor link circuit having a calling end for connecting thereto, a calling sleeve relay for said link circuit, ringing apparatus for said link circuit for signaling the called substation, means for initiating operation of said ringing apparatus, a circuit for said calling sleeve relay controlled by said means, and means for preventing said calling sleeve relay from operating when the called line is busy and connection is made thereto,

11. A telephone system including a called telephone line, a two-conductor link circuit having a calling end for connecting thereto a calling sleeve relay for said link circuit normally disconnected from the calling plug,

manually controlled lllQSllSlllClUflillQ'zll'illllk ing key for energizing said calling sleeve relay and for connecting it to the said calling plug, and ringing means including a pair of relays and energizing circuits for said pair of relays, said energizing circuits including a contact of said calling sleeve relay when said calling sleeve relay is connected to said calling plug.

12. A telephone system including a called telephone line, a two-conductor link circuit having a calling endi 'or connecting to said called line, ringing apparatus'itor said link circuit, means for initiating an operation of said ringing apparatus, a calling sleeve relay, and a circuit for said last relay closed responsive to an operation of said means for connecting said last relay to said calling end. e

13. A telephone system includng a subscribers line, a link circuit provided with a terminal for connection to said line, a relay associated with said link circuit and adapted to be connected to said terminal through one of its own contacts, a ringing key, and means controlled by an operation of said key for connecting said relay to said terminal.

14. A telephone system including subscribers lines, a link circuit for interconnecting said lines, a busy test relay for said link circuit for applying a busy signal to thecalling line when connection is..made with a busy called line and for applying signaling current to the called line when connection is made with an idle called line, and a disconnect relay under substation control adapted upon energization to operatively disconnect a subscribers line "from said link circuit.

15. A telephone system including subscribers telephone lines, a link circuit for interconnecting said lines, a busy signaling device, a ringing current device, a busy test relay for said link circuit operative to connect current from said busy signaling device to a calling lineor for permitting current from said current generating device to be applied to a called line, and disconnectmeans under substation control operative upon actuation to disconnect a subscribers line from the link circuit.

16. A telephone system including a calling subscribers line and a called subscribers line, a link circuit for connecting said lines in conversational circuit, ringing apparatus for said link circuit, a key for actuating said ringing apparatus, busy signaling apappara-tus, an operators telephone set, automatic means for connecting said operators telephone to said link circuit, automatic means for disconnecting said operators telephone from said link circuit when said key is actuated to operate said ringing apparatus, and a busy test relay for said link circuit forcausing either ringing current to be applied to said called line or busy current to said calling line dependent upon the idle or busy condition of the called line connected with.

17. A telephone system including sul scribers telephone lines, a link circuit for interconnecting said lines, a ringing current device, a busy signaling device, a ringing key, an operators telephone'set, automatic means for connecting said operators set to said link circuit, means controlled by said ringing key for disconnecting said operators set from said link circuit, and a busy test relay for either applying current fronr said.

busy device to a calling line or for permitting current from said ringing current device to be connected to a called line. Y

18. A telephone system including an operators link circuit, an operators telephone set, a relay forconnecting saidoperators telephone set to said link circuit, a second relay for disconnecting said operators telephone set from said link circuit, a calling and a called subscribers line, means responsive to the connection of said link circuit to said calling subscribers line to actuate said first relay, and means actuated upon connection of said link circuit to said called subscribers line to either actuate said second relay or to de-energize said firstrelay.

19. A telephone system including an operators link circuit, automatic means for connecting said operators telephone to said linkcircuit, other automatic means for disconnec'tin said operators telephone from said link circuit, means for actuating said first automatic means, and othermeans for either restoring said first automatic means or for operating said second automaticmeans to disconnect said operators telephone set from said link circuit, said last means being dependent upon the busy or'idlc condition of the called line. r

20. A telephone system including a calling subscribers line and a called subscribers line, a link circuit for connecting said lines in conversational circuit, an operators telephone set, a relay for connecting said operators telephone set to said link circuit and a second relay for disconnecting said operators telephone set from said link circuit, means for energizing said first relay responsive to the connection of said link circuit to said calling subscribers line, andmeans responsive to the connection of said link circuit to said. called subscribers line to either energize said secondrelay or to de-energize said first relay, depending upon the idle or busy condition of said calledline;

QL'A telephone system including a calling subscribers line and a .called subscribers line, an operators link circuit, an answering plug for sald link circu t normally connected with the talking strands ct said link circuit, busy test apparatus for said link circuit adapted when said link circuit is connected to said called subscribers line to either furnish the calling subscribers line with a busy signal or to signalthe called subscriber, and automatic means controlled by the calling subscriber and said busy test ators' cord circuit provided with an answering plug normally connected with said link ciriuit, busy test means operative responsive to the connection of said cord circuit to said called subscribers line to either permit the signaling of the called substation or to send back a busy signal to the calling subscribers substation, and means controlled over the calling subscribers line and by said busy test means for automatically disconnecting said calling subscribers line from said cord circuit prior. to the disconnection of said answering plug from said calling subscribers line.

23. A telephone system including an operators link circuit, automatic means for connecting said operators telephone to said link circuit, other automatic means for disconnecting said operators telephone from said link circuit, means for actuating said first automatic means, and other means for either restoring said first automatic means or for operating said second automatic means.

Qt. A. telephone system including subscribers telephone lines, a link circuit for connecting said lines in conversational circuit, an operators telephone set, a differential relay, means responsive to the connection of said link circuit to the calling one of said subscribers lines to close a circuit through one of the windings of said difierential relay, thereby energizing the same to connect said operators telephone set to the link circuit, and means responsive to the,

connection of said link circuit to the called one oi said subscribers lines to close a circuit through the other Winding of said difierential relay, thereby causing the same to tie-energize and disconnect the operators set from the link circuit, said last means being operable only When said link circuit is connected to a busy called line.

25. A telephone system including a calling and a called subscribers line, a link circuit, a relay provided with a pair of differential windings for said link circuit, an operators telephone set, means for closing a circuit through one of the Windingsot' said differential relay to cause the same to connect said operators telephone set to said link circuit, and means for closing a circuit through the other winding of said differential relay to cause the same to disconnect said operators telephone set from said link circuit, said last means being operable only When said link circuit is connected to a busy called line.

26. A telephone system including a pair of subscribers telephone lines, a two-conductor link circuit for connecting said telephone lines, subscriber-controlled means for disconnecting one of said telephone lines from said link circuit, an operators set, automatic means including a differential relay for connecting and disconnecting said operators set to said link circuit, said differential relay assa-a1 only operable to disconnect said operators set from said link circuit When the link circuit is connected to a busy line, another relay operable to disconnect said operators set When thelink circuit is connected to an idle line, and automatic busy test means for the said link circuit only operable upon con nection of said link circuit to the called one of said subscribers lines to either transmit an audible busy signal to the calling one of said lines or to permit the application or" ringing current to the called one of said lines' 27. A telephone system including a pair of subscribers telephone lines, a link circuit for connecting said lines, an operators telephone set, automatic means including a dit- -l'erential relay for connecting and disconnecting said operators telephone set and said link circuit, and automatic busy test means for said link circuit operable upon connection of said link circuit to the called one of said subscribers lines to either transmit an audible busy signal to the calling one of said lines or to permit the application oi ringing current to the called one of said lines.

28. A telephone system including a calling subscribers line and a called subscribers line, a link circuit for connecting said lines, an operators telephone set, a relay for connecting said operators telephone set to said link circuit, a second relay, automatic busy test means for said link circuit operative to tie-energize said first relay to disconnect the operators telephone set from said link circuit if said called line tests busy or for op erating said second relay to disconnect said opera-tor s set from said link circuit if the called line tests idle.

29. A telephone system including a calling subscribers line and a called subscribers line, a cord circuit for connecting said subscribers lines in telephonic circuit, an operators telephone set, means responsive to the connection of the cord circuit to the calling subscribers line to connect said operators telephone set to the strands of the cord circuit, means responsive to the connection of said cord circuit to the called one of said subscribers lines, providing the said called subscribers line is busy, to disconnect said operators set from said cord circuit, and other means operable When said cord circuit is connected to said called subscribers line, providing said called subscribers line is idle, to disconnect said operators set from said cord circuit.

30. A telephone system including a pair of subscribers telephone lines, a link circuit for interconnectingsaid lines,'an operators telephone set, automatic means for connecting said operators telephone set to said link circuit, and tWo different automatic means for disconnecting said operators telephone set from said link circuit, one of said automatic means operable only if the called line is busy, and the other of said automatic means operable only if the line is idle.

31. A telephone system including a link circuit, an operators telephone set, automatic means for connecting said telephone set to said link circuit,automatic means for disconnecting said telephone set from said link circuit and only operable When the called line is busy, and other automatic Signed by me at High Point, in the county 15 of Guiliford and State of North Carolina, in the presence of two Witnesses.

JESSE F. HAYDEN.

WVitnesses:

V. L. HUNT, D. N. VVILBOUR.

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