US1539866A - Telephone system - Google Patents

Description

. 1,5393 A. E. REINKE TELEPHOFE SYS TEN Filed Nov. 26, 1920 HrThzzrEHez'zzke I Patented June 2, 1925.

UNETED STATES PATENT, OFFICE.

ARTHUR E. REINKE, OF HAGUE, NETHERLANDS, ASSIGNOR TO KELLOGG SWITCH- IBGARD AND SUPPLY COIVLPANY, OF CHICAGO, ILLINOIS, A CORPQRATION OF ILLINOIS.

TELEPHONE SYSTEM.

Application filed November 26, 1920. Serial No. 426,366.

To (ZZZ 11:72am it may 00))067'71.

lie it known that I, ARTHUR E. REINKE, a citizen of the United States, and residing at The Hague, Netherlands, have inventedcertain new and useful Improvements in Telephone Systen'is, of which the "following is a description.

My invention relates to telephone systems and has to do more particularly with private branch exchange systems, such as are used for interconnecting local subscribers terminating at a branch exchange board, and for also connecting local subscribers and main exchange subscribers, and an object of my invention is the provision of an improved circuit arrangement which has desirable features of operation, all in a simple, eflicient' and economical manner In private branch exchange systems of the above type, it is desired to connect the branch exchange subscribers with main exchange subscribers, and in a board of this type it is often desirable to allow only certain ones of the substation lines terminating at the branch board to connect with the main exchange. One of the objects of restricting the service, of course, is to limit the use of the trunk lines strictly to business purposes, and so reduce the number of trunk lines require-d.

A feature of my invention is the provision of a plurality of jacks, which I term city service jacks, which are allotted to the lines at the branch exchange in addition to the usual local 1acks for local connect1ons. The

sleeve of the city servicejacks of the linesallowed city service are connected to one pole or a battery. To the sleeve contact of each of the city service jacks I connect a. conductor which leads to a sealed glass cabinet, which may preferably be placed where the person who has the authority tor allotting the city service pri-vile-ges to the subscribers can connect battery to the sleeves of any of the jacks that he desires. This feature of giving service to certain subscribers only may be called discriminating service.

Another feature of my invention is the provision of a trunk circuit, used in. connecting a private exchange subscriber allowed city service to a main exchange subscriber, provided with means, responsive when connection is made with a city service ack, to extend the trunk conductors to the mam exchange. WVhen a connect1on is made with a jack of a subscribers line not allowed city service in an attempt to extend a con nection to the main exchange, the said means remains unoperated or normal, and leaves the trunk conductors open to the main exchange so that a connection is not extended to the main exchange.

The features as above outlined, as well as others, will be more fully hereinafter described in the ensuing specification.

Referring now in general to my invention as illustrated in the accompanying drawing, at A I illustrate a substation terminating at the private branch exchange switchboard in a local cut-oil jack LJ and a line signal S. At 0 I illustrate one of a plurality of branch exchange cord circuits with-which the board is equipped for interconnecting the branch exchange subscribers, and which visory relay CS, the two relays controlling,

respectively, the answering supervisory and calling supervisory signals AL and CL. A

listening key LK is provided for connecting the operators Set Oto the cord conductors,

and a ringing key RK is also provided which when actuated connects ringing current to the called line. SK which when actuated connects the ringing key BK with a different source of ringing current. To the right of the drawing I show a substation B similar to A and tel-mi natin-g at the private branch exchange board in a local cut-off jack LJ and a. line: signal S.

The private branch exchange stations may be interconnected for conversational purposes by means of the cords C, and in addition certain of the local stations are allotted city service, whereby they may be extended to the main exchange and be connected to substations terminating thereat. For this purpose, I provide jacks which I will term city service jacks CJ, and the substations at the branch exchange that are allowed city service are connected to the acks CJ. Each I also show a key of the subscribers lines may be connected to a city service jack CJ. In addition, I provide a terminal or connection box provided with a plurality of pairs of screw terminals T; the. screw terminals 50 of each pair T. The COIIDGCHOII being connected to battery. box is provided with a suitable cover, which is sealed and can only be opened by an-aw thorized person. The other terminals 51 of the pairs T are connected to the sleeves of the-city service-jacks CJ Now, when a local substation is to be provided witha city service extension, a jackCJ is connectedto the said local substation (if not already provided. with a jack f CJ), in addition to is regularlocal jack 'LJ and a jumper wire- 52 used to connect the screw terminals 50 andf51, thus. extending the battery to the, sleeve of the city service jack CJ; The local jack'LJ of the substation is connectedgto groundand the jack CJ isconnected-to bat tery for purposes as will be more fully hereinafter described.

TWO-.Waytrunkcircuits TC are also pro-W vided in. additionto the local cords for connecting thesubstations provided with city service to the main exchange.

circuit as illustrated in the -.drawing termi' I nates at the private branclrexchange in" a trunk plug TR andiat the main exchange in a linecircuitL comprising the usual line. relay: LR,,cut-ofi relay-Co'andline signal The trunk circuit TC is provided with atrunkcord conductor control .relay TCR,I

which operates when the; plug TP 'is inserted intoa city service jack CJ to extend the trunk cordconductors throughto the main exchange, but remains ,at normal when the said. plug TP. is inserted into a local jack.

LJ Orintoa. jackCJunot connected to bat- CA to inform the branch exchange, operator thatpa call is awaiting her attention from the vmain exchange. A listeningv key. LK"

and .aringing heylRK'f are provided 'for connecting, respectively, the operators set i circuit through the calling supervisory lamp CL from battery at normal contact 13 of the calling. supervisory frelay CS,- through the O and ringing. current fromgenerator G;

Aiswitching key CK is. also. provided for: nightcservice, as will bemore fully herein after described.

The-private branch exchange board is A providedwith a plu'rality of local cords LC,

and localjacks LJinto which the local substations :at the branch exchange terminate.

In addition .theibranch exchange board is ceiver, thus closing a circuit through the provided with city. service jacks CJ which are. allotted to thelocal substations for city extension service. A plurality of trunk circuits TC are provided and are arranged in The trunk station-closes a cirouitthrough linesignal S, traced from battery through the lamp S, normal contact 2 of the -jack*LJ, normal contact 3 of the city service jack OJ, through the closed contacts at the substation switchhook, back through normal contact 4 of'jack CI to ground at normal contact -5 of the jack LJ. The lamp is lighted over-said'circuit, and the operator noting the lighted 'signal inserts the answering plug AP of one ofthe private branch exchange cords G into the jack 'LJ of the callingsub'stationyand this insertion opens the contactsQ and 5 ofthe jack L3 to eifaice the line-signal S; and establishes an energizing-circuitfor the answering supervisoryrelay'AS;',-traced from battery through the upper winding of relay AS; the tip contacts .0 the'connected plug AP and jack LJ, through"--the-substation,"

back through the ring contacts of the connected plug APand jack'fLJ to ground through the lower winding oi'relay AS.-

The-relay AS upon ,energization opens its normal contact 6 to prevent the lighting of the supervisorylamp ALat this-time. The" operator now actuates'her listening keyLK' V to connect her operators set 0 to'the cord conductors of cord. C, the said set 0 being connected thereto over conductors 7 and 8,

normal contacts 9 and 10,'of the listeningkeys LK" of the trunkcircuit'TG; and normal contacts.9 andlO' of a listening key of another trunk circuit, conductors 11 and 12,

the nowclosed contacts of the listening key LK'of the cord C- to the cord conductors.

The operator 'now inquires the wants of the callingsubstation, and assumingthat it is'the substation B' that is wanted,fthe operator inserts the calling LJ of the wanted su station'B, and 'actuates the ringing key RK to operate the call signal at the calletl station. The-insertion of the .plugCP into the jack Lil" closes a lamp CL, the sleeve-contact'ofthe plug GP The subscriber-at the substation B,-in'respouse .to his callsignal; removes his recalling-supervisory"relay CSat the now closed s'witchhook contacts at the substation B, and the relay CS, upon energization,

plug GP into thejack opens its normal contact 13, thus effacing the supervisory lamp CL, thus indicating to the operator that the subscriber at substation E has answered. The subscribers at the substations A and B are now in conversational circuit, which may be traced over the heavily marked conductors.

Upon termination of conversation, the subscriber at the calling substation A replaces his receiver upon the switchhook to open the energizing circuit of the relay AS, and the relay restoring again closes its normal contact (3 to close a circuit through the supervisory lamp AL to ground at the sleeve of the jack LJ. The replacing of the receiver at the substation B opens the energizing circuit of the supervisory relay CS and the relay restoring again closes it normal contact 13 to close a circuit through the supervisory lamp CL to ground at the sleeve of the jack LJ. The two lighted signals AL and CL indicate to the operator that conversation has terminated, and she now withdraws the plugs AP and CP from their respective jacks LJ and LJ, thus effacing the said lamps, and the apparatus used in establishing the above described connection is now at normal and available for establishing other connections.

Assuming again that the subscriber at the substation A initiates a call, the said call is answered in the manner as above described, and the operator now inquires the wants of the calling subscriber, and having received a request from the said calling subscriber for a connection to the main exchange, she will remove the plug AP from the local jack LJ. The subscriber at the substation A, as before mentioned, is provided with city service and the substation A, in addition to its local jack LJ at the branch exchange board, is provided with a second jack, which I will term a city service jack CJ, the, sleeve of the said local jack LJ being connected to ground and the sleeve of the said city service jack CJ being connected to battery, and the purpose of the ground and battery connection for the respective jacks LJ and CU will be more fully hereinafter described. The operator, after removing the answering plug AP of the local cord C "from the jack LJ, now inserts the trunk plug TP of the trunk circuit TC into the city service jack CJ of the calling substation A. The insertion of the plug TP into the jack CJ closes an energizing circuit for the trunk control relay TCR, traced from battery at the sleeve 14 of the jack CJ, sleeve contact 15 of the trunk plug TP, con ductor 16, through the winding of the relay TCR, conductor 17 to ground at normal contact 18 of the control key CK. The insertion of the plug TP into the jack CJ also closes an energizing circuit for the super visory relay SR, traced from battery through the lower winding of the relay SR, normal contacts ofthe ringing key RK, ring contacts of the plug TP and jack CJ, through the substation, back through the tip contacts of the jack CJ and plug T]? to ground through the upper Winding of the relay SR. The relay SR upon energization closes its alternate contact 19, establishing an energizing circuit for the supervisory control relay CR, traced from battery at the sleeve 14 of the jack CJ, through sleeve 15 of the plug TP, normal contacts of the ringing key RK, over conductors 16 and 20, through the winding of relay CR, conductor 21, normal contact 22 of the key CK and conductor 28 to ground at alternate contact 19 of relay SR. The relay CR upon energization closes its alternate contact 24, establishing a locking circuit for itself traced from battery at the sleeve 14 of jack CJ, sleeve 15 of plug TP, conductors 16 and 20, through the winding of relay CR to ground at its alternate contact 24. The relay CR and supervisory relay SR control the lighting of the supervisory lamp SS. The relay T CR upon energization closes its alternate contacts 25 and 26, closing the continuity of the trunk circuit conductors and thus extending the line of the subscriber A to the main exchange. The said trunk TC terminates at the main exchange in the line circuit L The closure of alternate contact 25 of the relay TCR bridges the resistance 27 across the trunk conductors to establish an energizing circuit forthe line relay LR of the line circuit L at the main exchange, traced from battery through the winding of relay LR, normal contact 28 of relay CO, resistance 27, conductor 29, alternate contact 25 of the relay TCR, to ground at normal contact 30 of relay CO. The relay LR upon energization closes its alternate contact 30 to close a circuit through the line signal LS, which lamp LS is lighted to signal the main exchange operator. The main exchange operator noting the lighted signal LS inserts the answering plug of a cord pair into the jack J and inquires the wants of the calling branch exchange subscriber at substation A and extends the call to the called line in the usual manner. The resistance which is bridged across the trunk conductors upon the energization of relay TCR places the supervisory signal of the answering end of the main exchange cord under the control of the branch exchange operator. The called subscriber at the main exchange having answered in response to his call sigthe-usualdisconnect signal. :The replacing;

' of the receiver by the subscriberat the branch exchange substatiomA opens the energizing circuiti of the; supervisory relays SR at the: switchhook contacts, and' the; relay SR 5 upon restoration 1 closes its normal: -con i tact 19;"establishing .an energizing circuit for the supervisory lamp SS, tr-aced-fromw battery at alternate contactifill o't the relay. CR, through the lamp SS, conductor 32; to ground atwnormal 'contact- 19 of the supervisory relay SR The lighting of theisupervisory signal SS indicates tothe branch exchange -operator that the subscriber at substation A has replacedihis receiver upon the switchhook, and she now Withdraws the plug TP from theack CJ opening the energizing circuits-of the relays TOR and CR.- ThereIay-CR in restoring opens its alternate contact 31, el'l'acmg the supervisory signal SS, and therelay'lCR in restoring opens;

ing the main exchange operator a disconnect signaland she now Withdraws the plug frorn the andthe apparatus used in establishing the connectionis now at normal and available for establishing :other connections.

Assuming that the subscriber A to whom city service is allottedreceiv'es a call from the main exchange the voperator at I the said main exchange lnserts the calllng plugof a cord pair in the jack J which is associated with the-trunk cord TC and'projects ringing current-to the branch exchange. The

current extendsfrom the tip of'the jack- J through alternate contact ofrelay 'CO,

condenser--3 l,-through the lower Winding r of relay RR,-over=conductor 36, normalcontact 26 of relay T CR, alternate contact 28.- of relay CO to the sleeve of the jack J. The

ringing current passing through thcuwindf ing 35 0f: relay RR causes theenergization ofthe relay RR, andthe closure of itsalter nate contact '87 establishes a lockinglcircuit for itself through its locking Winding, traced from batteryat normal contact 38' of relay TCR, through winding 39 of relay: HR to ground I at alternate contact 37 of relay RR." The closingof-alternate contact 37 of relay RR also-establishes-a circuitfor the call lamp CA, 't1'aced-:from battery through the said lamp CA and through alternate contact 37 to ground. The lamp CA is lighted and notifies the operator that a call from theniain exchange is awaiting: her attention. The private branch exchange I operatornoting the lighted signal actuates the listening key LK ot the trunk cord TC and receivesthe' number-or name of the subscriber wanted at the branch exchange. The

m-aining lighted until the subscriber A closing-of alternate contact of the listening key LK bridges the resistance 27 across 1 a the trunk-i cord conductors to" operate the supervisory signalat the main exchange so asto notify-the mam exchange operator that the call has been answered by the branch 'exchangeoperaton, Assuming that it is the subscriber A that is wanted, the branch ex- Clla-Dg8 OPEllltflIFlIlSBlliSitllG trunk plug Tl into the jack CJ of; the wanted line to close arr-energizing circuit..for the relay TCR," traced from battery at the sleeve 14 of the" .jack OJ, over sleeve lolofthe plugTP, conductorn 16 through the winding of relay 7 TCR conductor 17," to ground at normal contact 18 of key'CK. The .relay'TCR,

upon energization', closes itsialternate contact 41, establishing an energizing circuit. for the supervisory-{lamps SS, traced .rmm

battery at. alternate contact 41, over conductors 42 and .43, normalcontact 31'of relay -CR,itl1I'OllglLtll8 lamp ZSS and over conductor32 to ground at normal contact 19 of supervisory relay SE -the said lamp reanswers.

The relay {FOR upon energization opens itsn01mal'c0ntact38 to open the locking circuit of the winding 39 of the relayRR,

and the relay RR now restores and opens its alternate contact 37 to eflace "the signal CA. The. closingof alternate contacts 25 and 26 of relay TCR extends the trunk conductors through to-the substation Aland the closing of alternate contact 25 maiintains-the resistance 27. across thettrunk conductors for controllingitlie supervisory signal at. the main exchange, after tlietoperator of-the branch exchange; has restored her listening key- LK ator now actuatesthe: ringing key BK of tllButIllIllQ cord- TO to connect ringing cur-" rent over a path extending from one pole of the: generator Grover conductor 44, throughalternate contactwof'the ringing xkey BK, ringicontacts ofthe plug'iTPi and jack OJ, through the call bell andacondenser atthe' called station A,baok through the tip contacts ofthe connected jack CJ J and plug T'P, 1 thenother alternate contact ofthe ringing k'ey RKand conductor 45 to the other pole of the genera-tor. Thei subscriber-i in re sponseto hiscztllsignabremoves his receiver from the switchhook'i and closes an "energizingw circuit for ithel supervisory relay SR. The said relay. SR; .upon energization, closes its alternate contact 19 to close an energizing' circuit;- for the relay i CR. tracedi from ground-at alternate contact 19 of relay SR," over iconductor 23 normal cont act 22 of key CKwconductor 21,.the winding ct relayCR, conductors 20 and 16, sleeve 15 ot plug TP, to battery atsleeve-M of jack- CJ. The relay OR upon enengization closes" a locking circuit foritself, traced fronrbat- The privatebranch exchange oper- .1

tery at sleeve 14 of jack OJ, over conductors 16 and 20, through relay OR to ground at its alternate contact 24. The opening of normal contact 19 of the relay SR e'ffaces the supervisory signal SS, thus notifying the branch exchange operator that the sub scriber at A has answered. The subscribers are now connected in conversational circuit, and the talking circuit may be traced over the heavily marked conductors.

The subscribers having finished conversation, they replace their receivers upon their respective switchhooks, and the replacing 01: the receiver at the calling substation in the main exchange gives the main exchange operator the usual disconnect signal, as is well understood. The replacing of the receiver at the called station A at the private branch exchange opens the energizing circuit of the supervisory relay SR at the switchhook contacts, and the closing of normal contact 19 of relay SR closes a circuit through the supervisory lamp SS, traced from battery at alternate contact 31 of the relay. OR, through the lamp SS, and conductor 32 to ground at normal contact 19 of the supervisory relay SR. The lamp SS is light-ed over this circuit and indicates to the branch exchange operator that the subscriber A thereat has replaced his receiver and conversation has terminated. The operator then withdraws the trunk plug TP from the jack OJ of the called line A. The withdrawal of the plug T]? from the jack OJ opens the energizing circuit of the relays OR and TOR. The relay OR upon restoration opens the circuit of the signal SS, and the de-energization of relay TOR opens the bridge including the resistance 27 across the trunk conductors. The opening of this bridge brings about the lighting of the supervisory signal at the main exchange, and the operator noting the lighted signals withdraws the plug from the jack J. The apparatus used in establishing the above described connection is now at normal and available for establishing other connections.

Should the subscriber at the substation A, who is provided with a city service jack OJ, desire to remain in direct connection with the main exchange for the purpose of establishing several city connections, the operator 0 t the branch exchange after having inserted the plug TP into the jack OJ, actuates the control key OK, and this opens the initial energizing circuit of the relay TOR at the normal contact 18 of the key OK, but a substitute circuit is established for the relay TOR, traced from battery at the sleeve 14 of the jack OJ. through sleeve contact 15 of the plug TP, conductor 16, through the winding of relay TOR, conductor 17, alternate contact 18 of key OK, conductor 23 to ground at alternate contact 19 of the supervisory relay SR. The resistance 27 is opening and closing of contact 19 of relay I SR brings about the de-energizationand energization of relay TOR, which relay TOR opens and closes the bridge 27 across the trunk conductors and causes the flashing of the supervisory signal at the main exchange.

Should the private branch'exch-ange operator by chance, or intentionally, insert the plug TP of the trunk TO into a local jack LJ of the line, no energizing circuit for the relay TOR of the trunk circuit TO is established, as the sleeve of the jack of the local jack LJ is connected to ground and the other terminal of the relay TORis connected to ground. Should the branch exchange operator insert the plug TP into a local jack LJ, and then actuate the key OK, and should the subscriber at the substation that terminates in the jack LJ into whichthe plug TP has been inserted, have his receiver off the hook, no energizing circuit for relay TOR is established, as the circuit through relay TOR under these conditions extends from ground at the sleeve of the jack LJ to ground at alternate contact 19 of the relay SR, through the alternate contact 18 of the key OK, and the relay TOR failing to energize, the connection is not extended to the main ex- 100 change.

Should the operator of the branch exchange insert the plug TP into a local jack LJ from which the ground has been maliciously removed, and then place the sleeve of either plug AP or OP to the sleeve of the inserted trunk plug TP, no operative energizing circuit is established for the relay TOR, of the trunk circuit TO, as the said relay TOR is adjusted to operate from 24 volts direct, but will not operate in series with a supervisory lamp as AL or OL.

Should the operator at the branch ex change insert an answering plug AP of a local cord into the local jack of a line and actuate the listening key LK of the cord O and the listening keys LIC of two trunk circuits TO, no connection will be established as the circuit over conductors 11 and 12 leading from the alternate contacts of the listening key LK will be disconnected at the normal contacts 9 and 10 of the listening key LK and at normal contacts 9 and 10 of one of the listening keys of another trunk circuit TO, which was actuated. From-the above it may be seen that the blocking of an illegal connection is positive, and to receive city service the local substation, in addition to the local jack for local connections, must be provided with a city service jack at OJ connected to battery. *Shouldthe operator plug into a-i ack'CJ; not connected-togbattery,

, the relay-PCB cannot: be operated.

*Fornightservice so that a'private branch exchange "subscriber can make outgoingcalls, the plug "PP is placed-in a jack CJ and keys and CK operated. The operation of prevents thelfighting of lamp -SSWh8n the receiver "at "the calling substation is on the sWitchhookJ'No current is usedrbyany of the relays at the'branch'exchange when the trunk circuit is -*e'om1e'ct'ed to a subscribers' {line jfor' nightservice, i the keys GKI and CK" operated, and the receiver at the subst a- VhiIe l hayevdesorrbed a specific form of {ny' nvention, I do not,'hon ever,-wish to he imitedto the exact circuitarrangement as tion on'fits' switchhooli.

I illustrated and described, as changes and modifications -will' readily suggest theinselves iby" those skil=ld lnith6= w31t,:.fllld I, =therefore,"aim to'coverall such changes and modifications as come Within the spirit and scgge jof the appended claims. 3 hat'I'c'lahnas -new and desire-to secure oyUnited states Letters Patent, is

1 .lL g A manually operated telephone system including a number of telephone 1 lines of difiiefeht cl'a'sses; 'exten'ding fromsubstations to terminals at an-"exchange switchboard; a ;comrn'on battery terminal 5 block for supplying potentiaitothe terminals ofonesof said "classes, a"- eonnecting;ieircuitfon usc.in=extelephone lines extending from substations to an exchange switchboard, terminals for saiditelephone lines, conductors extending fromthe' terminalsto a terminalablock, oonnectingi circuits"' 1 for extending connections from said telephoneglines to a distant: ex-- change, means iotapplyingzpotential to certain of th'e conductorsextendingito said terminal block, and means in said connecting circuit 'operati've when: the sai d: connecting circuit-is connected toone ofsaid lines:to

,v hijch a potential is connected to .extenddihe said line; through tothe distant exchange, said last} means being iITOPBI zttIVBfWlIQD said connecting c rcu t is conneot-edto one of said lines to which "n05 potential hasubeen. connecte 3: Aetelephone "system iliclliding 'i sub- .sqribei's linesextending from A substations and-terminating in' connection terminals-at an exchange switchboard, said connection ttl'llllllfllflbeillg provided with test contact some i of, which havebattery. potential cor.- nected thereto, while others have ground-potential connected thereto, aconneoting circuit for extending connections from said lines toa distant exchange, via certaiirot said connection terminals, discrin ii-nating means ;in said connecting (ZlIECIlitOPQIZIlJlYG when connected to oneofisaid lines through one set said termina'ls having a-battery :potentialconnected to thei-test contact for connecting the K line through to the distant .exchange, said -.disorimi-nating means not. beingioperable When-the 'connecting'circuit is connected to oneof-saidili-nes through asterminal having a gmnndipotentialconnected to the itest I contact; thereby. preventing the connection :ofisa-idulast .line. to the distant ,"ex-

change,andinieans foripilacingsaiddiscriminating meansmnder the control. of the con nected -si ibscriber' when the ieonnecting-cir- .cuit is'connectedto a terminallha'ving-bat tery potential on i its test contact.

1 4. A1 manually ii'operatedrtelephone exchange system iha'vingi lines of different chraraetersextending dimm S stations. to an exchange switchboard, adink' circuit -t'ior use in extendi-ng connections .--inom.-.said lines to a distant exchange, normally .open con ct in the conductors -ot said dink circuit, abattery, abridged across said ilinkncirrouit rat .the

distant exchange; signaling means .included in said bridge, discriminating-means inisaid dink: circuit.- wherebyi ywhenaaaidglink circuit is connected to a li-neof; one character. said discrimmating :means operates: to .place: a bridge across thevlink circuit toiopeizate said signaling means :at the distant exchange and to close saith-normally opencontacts, .Wllllll when i said link. circuit is connected it o. a line of adifllerent character saiddiscriminating means does-not operate to iclose, a bridge across the link circuit cooperate the sign-a ling means atithe. distant exchange andineans for placing said discriminating, means. .nnder the control zof-ithe connected-1 subscriber when said link eireuitzisconnectedto a line of =saidlone character.

5. A telepli.(me .-exchange. system; having lines of diflierent characters extending .ti'ion'i substations l to i :a n exchange switchboard, a1

cuit, anbattery bridged across. saidqlink ,cir

c-uit atji the distant .--excl1ange, signaling means ,included in. saidbridgca discriininatingineansiin saidlink cimuit whereby when saidilink circuit is'conn ed to a lineof one character saith-discriminating means opcrates to. place. a, bridge acrossthe link circuit to operate-nsaid signaling, means at the .dis-

,tant; exchange and: to close said normally open con acts, while when said link circuit means is connected to a line of a different character said discriminating means does not operate to close a bridge across the link circuit to operate the signaling means at the distant exchange, said discriminating means being operable when a call is extended from the distant exchange to a subscriber at the exchange switchboard ot the first of said classes for connecting the said subscriber with the distant exchange and being inoperative when extending a call to a subscriber of the other of said classes for connecting the said subscriber to the distant exchange, a supervisory signal at the distant exchange controlled by said discriminating means, and for placing said discriminating means under the control of the connected subscriber when said link circuit is connected to a line of said one character whereby the operator at the distant exchange may be signalled from the connected subscribers substation.

6. A telephone system including subscribers telephone lines extending from substa tions to an exchange switchboard, a link circuit for extending connections from said substations to a distant exchange, a normally open contacts in the conductors of said link circuit, a supervisory signal for said link circuit operable by a subscriber when the link circuit is connected to one of said subscribers lines, responsive to the opening and closing of the bridge across the subscribers lines, a signal for said link circuit at the distant exchange and means in said link circuit for closing said normally open contacts and also for rendering the signal in the link circuit at the exchange switchboard inoperative responsive to the opening and closing of the said bridge across the subscribefls line and for rendering said signal at the distant exchange operable by the opening and closing of the bridge across the subscribers line.

7. A telephone system including subscribers lines extending from substations to an exchange switchboard, a connecting circuit having its talking strands normally in open circuit, means for closing said talking strands to extend calls from said subscribers lines to a distant exchange, a signal for said connecting circuit at the exchange switchboard and a second signal at the disant exchange, means controlled over a connected subscribers line for operating the signal at the exchange switchboard but not the signal at the distant exchange, and means for preventing the operation of the signal at the exchange switchboard and for rendering operative the signal at the distant exchange.

8. A telephone system including subscribers lines of different characters extending from substations to an exchange switchboard, a connecting circuit having its talking conductors normally in open circuit for ext-ending calls from said subscribers lines of one character to a distant exchange, discriminating means for said connecting circuit for preventing the subscribers lines of another character from being extended to a distant exchange, a signal for said connecting circuit at the exchange switchboard, a second signal at the distant exchange under the control of said discriminating means, means controlled over a connected subscribers line for operating the signal at the exchange switchboard but not the signal at the distant exchange, means for said link circuit including a switchboard operators manually operated key for placing said discriminating means under the control of the connected subscriber for rendering the signal at the distant exchange responsive to the substation control and the said first signal at the exchange non-responsive to the substation control, and a third signal for said connecting circuit at the exchange switchboard controlled from said distant exchange for indicating a call from said distant exchange.

9. A telephone system including subscribers lines extending from substations to an exchange switchboard, a connecting circuit for extending calls from said subscribers lines to a distant exchange, normally open contacts in the talking conductors of said connecting circuit, automatic means for closing said normally open contacts, a signal for said connecting circuit at the exchange switchboard and a second signal at the distant exchange, means controlled over a connected subscribers line for operating the signal at the exchange switchboard but not the signal at the distant exchange, and means for rendering the signal at the exchange switchboard non-responsive to the substation control and for rendering the signal at the distant exchange responsive to the subscriber control.

10. A telephone system including subscribers telephone lines extending from substations to an exchange switchboard, a link circuit for use in extending connections from said substations toa distant exchange, means in said link circuit for opening and closing the talking strands of said link circuit, means responsive to the connection of said link circuit to one of said subscribers lines for operating said means to close the conductors of said link circuit, and locking means for preventing the connected sub: scriber from opening the conductors of said link circuit.

11. A telephone system including subscribers telephone lines extending from substations to an exchange switchboard, a link circuit for use in extending connections from said substations to a distant exchange, means in said link circuit for opening and closing the talking strands of said link circuit,

means responsive to the connection of said 7 link circuit to one of said subscribers" lines for operating sa'id means to close the conductors of said link circuitylocking means for preventing the -connected subscriber from opening the conductors of said link circuit, and means in saidllink 'circuit' for rendering signaling means atthe distant'exehange.

Signed by me at The Hagueg the Netherlands, this 5th day of November, 1920.

ARTHUR E: REINKE.

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