US1848196A - Semiautomatic rural telephone system - Google Patents

Description

SEMIAUTOMATIC RURAL TELEPHQNE SYSTEM Filed Feb. 6, 1950 e Sheets-Sheet 1 lazikwawsx ,dcccased, @Fdoaard E7072, Mitzi 0!;

@a-Jmw' A TTmA/EY March 8, 1932. L. PouNKowsKY ET AL 1,843,195

SEMIAUTOMATIC RURAL TELEPHONE SYSTEM Filed Feb. 6 1930 e Sheets-Sheet 2 1 "Mill-{l iiuzerd-orsz ,a uazwthzliv o. arrow,- r

' A Tram/Er MarCh 1932. L. POLINKOWSKY ET AL 1,848,196

I SEMIAUTOMATIC RURAL TELEPHONE SYSTEM Filed Feb 6, 1930 6 Sheets-Sheet 3 flu L Rlbzkowsg, de cgwsed, Q7 @aafalE'Ll/IL, Washfar;

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A T TUHNEY March 8, 1932. L POLINKOWSKY ET AL 1,848,196

SEMIAUTOMATIC RURAL TELEPHONE'SYSTEM Filed Feb. 6, 1950 6 Sheets-Sheet 4 i'izuerzfors: ll izdfowslr ,decaz z; B EclpuanlTncm, J and mafia/n,-

March 8, 1932.

1-.w POLINKOWSKY ET AL 1,848,196

. SEMIAUTOMATIC RURAL TELEPHONE SYSTEM Filed Feb. 6, 1930 6 Sheets-Sheet 5 iiuJeni-ors:

lZP fi'zzlrwsk deceased, I b Fdow-dRm,Mw-;

BY @q/W A TTUH/VE Y March 1.. POLINKOWSKY ET AL 1,843,195

SEMIAUTOMATIC RURAL TELEPHONE SYSTEM Filed Feb. 6, 1930 6 Sheets-Sheet 6 Patented Mar. 8', 1932 I nmren STATES PATENT OFF-ICE.

ZIPA POLINKOWSK Y, DECEASED, LATE OF ANTWERP, BELGIUM, BY EDO'UABD IBUH, .ADMIINISTRATOR, AND OWE N' C. FRO IL OF NEW YORK, N. Y., ASSIGNORS '10 WESTERN ELECTRIC COMPANY, INCORPORATEIW-"OF YORK, N. Y A. CORPORATION 03' new YORK snmaurorrh'rrc nuaar. 'rnrnrnonn srsrnn Application filed February e; an, swarm. 428,857, and at Great Britain February 14, 1929.

This invention relates to semi-automatic rural telephone systems of the'type in which connections may be established automatical- 1y by and under the control of'an operator located at some centralexchange, called in this description the main exchange,- between subscriberslocated in the same or dif ferent rural exchanges including the main exchange.

In sparsely populated districts, where the maximum number of subscribers in one rural ofiice is, say, 10 or 20, it would be uneconomical to provide each rural exchange with its own manual'or automatic switching facilities. This invention provides one semi automatic central switching exchange for a net work of rural'exchanges where switching to and from any subscriber in the area, as well as points beyond, is done from this exchange. The main exchange is connected to all the rural exchanges in the area either directly by a trunk line or through tandem offices which themselves serve as junction centers to a plurality of rural exchanges. .The num ber of trunks direct from the outlying rural exchanges or from their tandem junction centers is, of course, a function of the calling rate and the number of talking connections per unit of time between the various exchanges involved, but in rural areas when the exchange unit comprises but 10 subscribers, one trunk line would be sufiicient for all needs, including'its utilization for additional signaling service when not being used as a part of a talking connection. With the switching control mechanism at one point only, these trunks or junction lines are used to call the operator at the main central or,

-Jvice versa, for the operator to call subscribers directly (if a direct junction line connects the rural with the main exchange) or via the junction tandemcenter. The 0 erator at the main exchange is informed o the wanted number. With the aid of suitable dialing equipment the called subscriber is reached via the same trunk or junction, if

' theexchange in which he is located is connected to the'main exchange by the same trunk or junction center. nce the talking connection is established and its commencement 1 properly supervised by the operator, that part of the junction line not used as a part of the talking loop is liberated. It may then be used by other subscribers in the same junction center or exchange for initiating other. calls while the subscribers just connected talk over a local connecting circuit.

The object of the invention, then, is to provide an improved semi-automatic rural systerm in which the connections may be established between subscribers in small outlying one embodiment of which has been disclosed exchanges by an operator wat the main exchange. I f

In accordance with the present invention,

herein by way of example,- connections are established in such a manner that the trunk line or junction used by the operator forsetautomatically connected to the wanted party after the completion of the-dialing operation in such a way that the wanted party is rung from the manual exchange without any special operation necessary on the part of the operator supervising the settin up of the call. Means are provided where y the operator at the main exchange, after establishing the connection, is connected in a listening position to supervise the commencement of a conversation. Means are also providedffor the o erator to break down a local connection, old the desired line, and connect it to the junction for the establishment of a talkin connection with some distant toll point.

cans are also provided for charging the battery in a tandem exchange and the batteries in the rural exchanges connected thereto over the junction line connecting the tan dem and themain exchange; the chargingl current being disconnected when the junction is seized in either direction.

- -To enable the operator to set up connections the tandem ofiice and each rural ofiice is provided" with a set of five pairs of counting' relays andapair of addin relays. 1 These relays are so arranged that eac pair of count"- exchange who controls the arrangement of a connection to other subscribers located either inthe main exchange or in the said tandem exchange or m the said rural exchange or in another rural exchange having access to the same tandem exchange. After the connection has been established, the junction line extending between the main exchange and the tandem exchange is free for use to establish other calls, and the subscribers talk over a local connecting circuit in the said tandem exchange or in their respective rural exchanges. Necessarily, when the subscribers are located in two rural exchanges not connected by a common tandem junction and a call is to be established between them, the two junction lines connecting the calling and called rural exchanges with the main exchange form a part of the subscribers talking circuit. During such times, the junction lines so used cannot, of course, be used for establishing other connections.

Similarly, in the case of a call originating from a subscriber at a tandem exchange, a connection may be extended by the operator in the main exchange to another subscriber in the said tandem exchange, or to a subscriber located in the rural'exchange connected by a junction line to the tandem exchange, whereupon the junction line between the main and the tandem is freed as before.

The nature of the invention will be more completely understood from the following de tailed description which is given in connection with the accompanying drawings, in which Fig. 1 shows a diagrammatic illustration of the layout of the system.

Fig. 2 shows a cord circuit for either a rural or tandem exchange with a line circuit ending in the usual jack and supervisory equipment for a rural or tandem exchange.

Figs. 3 and 4 show a single junction tandem rural exchange circuit arrangement for use in an exchange such as (D) Fig. 1, wherein subscribers lines local to the said tandem exchange and junctions extending to outlyin rural exchanges terminate.

igs. 5 and 6 show the circuit arrangement for a single rural exchange terminating either in the main exchange, in which case the line wires (a) and (6) end in a jack of the character shown in Fig. 2, or at a tandem exchange such as Figs. 3 and 4 in which case the line wires (a) and (b) are are connected to the armature sprin s (a) grid (b) respectively of the relay J dr of Referring particularl to Fig. 1, the manual exchanges M and 2 are shown to the right of the drawing haying access to the main semi-automatic tandem exchange A. This semi-automatic tandem exchange has access to a small rural exchange such as F, a tandem rural exchange such as D, and a mechanical tandem exchange such as B. It will be seen that the tandem exchange D is connected directly to two small rural exchanges E and C, while the tandem exchange B is connected both to a rural exchange G and over another junction to an intermediate tandem exchange H which, in turn, has access to a plurality of rural exchanges such as I and J.

When a call originates from a. subscriber S in the tandem exchan e D say, or in either of the rural exchanges and E, a connection is extended through the tandem exchange D over the junction line J to an operator in the semi-automatic tandem exchange A, who then dials the number of the wanted subscriber in the usual way. If the wanted subscriber is in the exchange D, after the connection is set up the junction line J is freed for use to establish other calls and the subscribers talk over a local connecting circuit in the exchange D. If the wanted subscriber is located in the exchange E, the junction line J is freed as before and the subscribers talk over the local connecting circuits in exchanges D and E over the interconnecting local junction line L. Similarly, if the call originates in exchange C and is to terminate in exchange E, the call will be established over the junction lines L L and J; junction line J being liberated as before, leaving the subscribers to talk over the local juncon lines L and L lhe calls to other exchanges such as F, H, I, J, and G will be dealt with in a like manner by the operator at the main tandem exchange A; the junction lines in all cases extending to those exchanges being released for other calls after the connection is once established.

Establishing a connection between local aubecrz'bers in a tandem rural exchange (Figs.

2?, 3 and 4) Referring now.to Figs. 2, 3 and 4, when the subscriber S located in an exchange such as D, Fig. 1, on initiating a call operates his magneto the line relay L1 operates. This relay upon operating locks in series with the Le-r relay which also operates at this time through its continuity contacts and through a back contact of the Cor relay. The L81 relay is common to all the subscriber line relays the junction to the-manualexchange; the circuit path being traced also through the back contacts oftheJorand Rm relays. The Br relay operates in series with'the Lr relay of' the tandem junctionline-circuit in the manual exchange, causing the L7 relay there also 5oz operate, lighting the junction line lamp 1?. The operator, on getting the line signal, inserts the answering cord shown in Fig. 2 into jack J of the junction thereby operating cut-off relay Cor. The ground through the transformer windings of the cord circuit is connected to the (a) wire of the junction causing the operation of the Ar relay in Fig. 3. The Ar relay operates relay Hr which, in turn, operates relay H67, thereby removing the ground connectedto the (1)) wire of the junction through the BI relay. It will be noted that the ground which operated the Hr relay extends in parallel through a back contact of the H61 relay and down in a preference circuit through the transfer contacts of the L2 relays of the subscribers lines (and the rural line relays Jlr as well) in such a fashion that the operation of any Lr relay cuts off this ground to all succeeding relays in the chain and transfers it to the Cor relay 1 winding of the subscriber initiating the call.

The object of this preference arrangement is to cut off the possible operation of other Cor relays of other subscribers initiating calls during the time that the junction is busy setting up one call. \Vhen the Ar relay operates, therefore, the ground which operates the Hr relay also extends down to the In relays and causes the operation of the C02 relay. The operated Gor relay is provided with a locking circuit from battery through its own winding through normal contacts of relays (Jr and Aer, a front contact of relay Cor to ground through the back contacts of the Bah relay and make-before-break contact of the operated Hbr relay. The Cor relay must be operated before the H61 relay operates and is, therefore, slow in releasing so as to hold up during the interval of time between the opening of the back contact on the HZ)? controlling the C07 operating circuit and the closing of the make-beforc-break contact combination controlling the locking ground. The Cm" relay, when operated, connects battery through a high resistance R from the back contact of the llbr relay to the winding of the Lr relay so as to prevent the release of the L2 before the HZW operates. This is to insure that the ground-series preference chain will not be disturbed by a false release of the L2 relay and transfer the ground to the next operated line relay,.thcreby causing the falseoperation' of: its associe ated Cor relay. WVhen the H61" has opcr ated, the L'r'relay releases' The operation oflthe Cor relay andthe re lease of the LT relay closes the subscribers loop through to the Bar relay and Aer retard coil; Relay L-r upon: releasing also re leases relay'Lsr- If." the subscriber should: have remained on the" line after, ringing u the Lr relay, the B81 relay operates over the subscribers loop to ground through. the. Asr retard coil. and operatesinturn, the Sr relay. The Sr relay closes the talking cir cuit through to. the junction. It also connects the Br relay to the (25) wire of the v junction through the operated contacts of the Hbr and. Sr relays and causes the o era tion of the Aer relay in the cord circuit; t iereby extinguishing the cord supervisory-lampand indicating tothe operator that the sub lcriber is still on the line. Since the talking, circuit between the subscriber and operator is closed through, the operator may ascertain the desired number by operating the listening key L. If, however, the subscriber is not on the line, the Bar relay and Aer retard COll will not operate and the supervisory lamp will remain lighted. This is a signal to the operator to ring the subscriber back.

In order to ring the party, the operator must prepare a ringing circuit before ringing by operating the dialing key D of the cord circuit and restoring it. The operation of the dialing key D causes the operation of the Par and Pr relays in the cord circuit.

This momentarily breaks the (a) wire to the junction, releasin the A1- relay. The release of the Ar rel ay causes the ground through its back contact to operate the Dis-r relay; this same ground, together with the ground on the armature of the operated relay Dkr at the same time holds the Dkr relay short-circuited. \Vhen the PST and Pr relays have operated, the (a) wire to the junction is reclosed, causing the operation of the A1 relay, the removal of'the shortcircuitingground around the Dior relay and the operation and locking of this relay in series with the D701 relay under the control of locking ground onthe Hb-r relay through the back contacts of the OZ? relay. The Far and Pr relays are suificiently slow in operating, not only to permit the aforementioned operation during the travel time of their armature contacts from the back to the front contacts respectively, but also for the additional operation of other relays mentioned later. lVhen the operator releases the dialing key, the Pr and Psr relays release, repeatingthe. operation of the A1" relay and causing the operation and-consequent locking of the R07" and Rcr relays in the same manner as the Dkr and D701; relays were previously operated and locked. The

operation of the Rcr 'relay transfers the (b) wire of the junction to one side of the subscribers line while the Bar closes the (a) wire ofthe junctionthrough a condenser to 5 the..otl1-er?side ofithesubscribers line thereby completing the ringing circuit from the subscribers line to the opc'rators. cord. The operator then throws the listening key L and the ringing key R, applyingringing current to thelb) .wire. of. the-junction, the current returningyover" the other side to ground throughthe As): retard and through the condenseritothe o)..wir e of the junction. The

condenser is for thepurpose of reducing the return. ringing current to the a wire so that the Ar relay will not follow the ringing current pulsations. v

. lYhen-t-hesubscriber answers, the operator restores both ringing and listening keys,

causing the (oi-wire, to the junction to be opened and closed in the manner already described The A? relay,,by following the break inthe (a) wire of the unction, causes the OZ?v and 0213 relays to operate and lock.

The .0113 relayreleases the DZJI' and D7071 relays and the release of the Dis-r3 causes the release ofthe R02 and R073 relays. With the releaseof the D701, rela the subscribers a, loop is connectedto the retard coil, causing the operation of the Bar and Sr relays, thereby closing once more the subscribers talking loop to the manual exchange-The condensers in the (a) and (b) wires andthe connection of the (5) wire of the junction through the-Br relay to ground through the operated Sr relay makes a balanced transmission circuit. This talking circuit operates the A8? relay of the cord which extinguishes the opera ors supervisory lamp. The operator then inquires for the wanted number. Y

On ascertaining. the number, the operator operates the.v dialing key D and dials the numberaof the wanted line. As explained previousl Y in connection with preparing the line for ringing, the operation of the dialing key breaks the (a) wire and causes the operation and locking of the D7112 and Dior, relays.

' When' the Dkr relay operate's,hut before the release of the Sr 1(which occurs as a consequence of o erating the Dkr relay), :1 ground is -passed'f i'orn the front contact of the Sr r-.--c rel ays through the bark contact of the Jar and Lbr relaysoperating the Tlo'v relay'which locks'to groundf'on" the H61 relay. The Tl? relay closes a ground from-the back contact of the Lbr relay to alead commonto a make contact of all the C01 relays of thetandem exchange. The Car relay of the calling subscriber using the junction, being operated,

extends this ground through to the connecting relays Car and Aer. The local connecting circuit, being free, has battery from the back contact of the Lbr relay connected to the operating windings of the Car relays so that s? relay and Ash the calling party will be connected to the calling side of the local connecting circuit. With the ground supplied from the operated TIP relay through the contacts of; theoperatedC-m" relayv andbattery from the back contact of the L117", the Car relay operates and transfersthe.calling subscribers line to the supervisory relay L0? and retard coil G07 of the local connecting circuit. The Lcr is now connected across the subscribers' line and op-, crates fromthe ground through the Gm" retard coilover the subscribers loop to battery through the relay Lcr. The Low relay connects ground from the back contact of the Brlrrelay to the locking contact of the relay Cor locking this relay and operating the relay Lbr which transfers the battery from the operating winding of the Cow relay to the answering side of the local connecting circuit Aer relay so that, when the called line is connected, the AC7 relay and associated supervisory relay La;- and retard coil Gar will be in an operative circuit; The Lbr relay also disconnects the ground for operating the local connecting relays so that the C01" relay is now'exclusively under the control of its looking winding. The C0? relay, in operating, also opens the locking circuit for the Correlay, but the Cor relay holds operated through a inake-beforebreak set of contacts on the Car relay to a ground on the back contact of the Lbr relay so that the Car relay will not release until the C02 relay is locked. The operation of the Lb? relay then removes this supplementary locking circuit of the Cm relay. The calling subscriber now waits on the local connecting circuit for the called party.

When the Dior relayoperated, it connected a ground to the B7 relay for dialing through a compensating resistance equivalent to 1500 ohms minus the resistance of the (1)) wire of the junction to the manual exchange. The Dim, relay disconnects the junction line from the Bar relay which releases the Sr relay and removes the subscribers talking circuit during dialing. The Dlcr relay also connects ground to the armature of the B7 relay for pulsing. and holding ground for the counting relays Sc) and To) described below. At the same time the Dar relay is placed in parallel with the dialing lead and is made slow to release so that it will not release during the cycle of pulses from the dial.

The set of five pairs of counting relays To) and SC? shown in Fig. 4 are connected to the C90 relays of the subscribers "lines, and the Cm relays of the rural exchange junction lines terminating at the tandem ekchange, through the contacts of the adding relays Aclr and Adm in such a manner that an operated pair of counting relays prepares a circuit for one of the Cor relays. The Car relays are preferably arranged in two groups of five each, if there are ten Cor relays in the exchange; the first five being connected to the back contacts of the Adr and Adr and the relays of the second group to the front contacts of these relays.

The dialing key D connects battery through the calling device C. D. to the (72) wire of the juuctionso that the dialing impulses pass over the (6) wire operating and releasing the Br relay in succession following the making and breaking of the circuit of the calling dc rice. The back contact of the Br relay operates the counting relays Sc-r and Tc'r in the usual manner; namely, the Sar relay operating from the back contact of the Br relay during the open period of the calling device, closing a holding circuit in series with the Tcr relay so that when the Scr relay operates, the Tar, relay is connected in series with the Scr but the Tar, will not operate during the open period of the impulse since it is short-circuited from ground on the back contact of relay Br over the right contact of relay Scr, inner right back contacts of relay L0r,' inner right back contacts of the J or relay to ground at the operated Dlcr relay. when the calling device reoperates the Br relay, the short-circuiting ground is removed and the Tor relay operates, locking in series with the Scr relay. The Tar, relay transfers the pulsing .lead to the Scr relay and Tcr relay so that the second impulse operates the second pair of relays. When the Tcr relay operates at the end of the second impulse, it opens the holding circuit for the Scr, and Tor, relays. The counting relays continue in this manner to the end of the digit except that when the Tor relay operates, it-closes the pulsing lead back to the first pair of counting relays S01 and Tar and also operates the Adr relay from the ground on the Dkr which also closes a holding cir' cuit through the Adr relay but holds it short- 4 circuited during the open period of the imulse. If the digit is above five, the Ter reay, operating a second time, releases the Scr and Tor relays and removes the shunt around the Adr relay, causing it to operate and lock in series with relay Adr, both of which are now locked as previously pointed out. The Adr and Adr relays transfer the counting relay switching contacts from the first'five Cor relays to the second five.

The slow releasing Dsr relay which holds up during the train of impulses, releases at the end of the digit and closes a ground from the front contact of the operated Scr relay through the back contact of the Bar and Dir relays through the operating winding of the Btr relay, back contacts of the relays J'cr and Dy'r, front contacts of the operated Tcr relay, contacts of either the Adr or Adr relays, back contacts of the local connecting relays Acr and Car of the called subscribers line to the winding of the Cor relay operating the Btr and Cor relays and locking be broken at the contacts of one of these relays and neither the Cor nor the Btr relay will operate. However, the'ground from the Scr relay, not only passed through the winding of the Btr relay but also through one of its back contacts so that ifthe subscriber is busy and the Btr does not operate, a path is closed for the operation of the slow operating relay Otr from battery through its winding, back contacts of the relay Jcr and Btr to ground on the operated Scr relay. The operation of the Otr relay connectsthe interrupter winding of the Tr relay to ground at the contact of relay Dlcr. These interruptions are induced in the secondary winding which, through the operated contacts of the Otr relay, is connected directly to the talking circuit connected with the main exchange. The tone thus induced is transmitted as a signal to the operator that the called line is busy. The Otr relay is made slow to operate so as to give sufficient time for the Btr relay to operate it the subscriber is idle and a path exists for it. Should the line be free and the operating path for Btr relay be closed, the Btr and Car relays will both operate; the Btr looking to its own operating ground, short-circuiting at the same time its operat ing winding, and the Cor relay locking to ground at the relay Hbr through a back contact of the Bdr relay.

When the operator restores the dialing key and causes the breakin the (a) wire of the junction in the manner already described, the Bar and Rcr relays are operated, closing a ringing circuit over contacts of the operated Cor relay to the called line as previously described for ringing back the calling party.

After restoring the dialing key, the operator operates the listening key L to ascertain if the line is busy, then holding the listening key operated, operates the ringing key 'intermittentl until the party answers. It will be note that the intermittent operation of the ringing key does not cause successive breaks in the (a) wire to the junction due to the fact that the operated listening key holds the Psr and Pr relays of the cord circuit locked. When the called subscriber answers,

the operator restores both the ringing and listening keys once more breaking the (a) wire of the junction and causing the Olr and OZr relays to operate. The operation of the Olr relay releases the Dlcr and D/ cr relays and the release of the Dkr relay releases the relays Bar and Rcr The operation of the Olr, relay connects ground through the front contact of the TZr relay to the lead common to the Car relays for operating the local connectin relays. Since the Lbr was operated when or relay was connected to the calling line only the A07 relays will have battery connected to their windings at this time from the contacts of relay Lbr.

The Acr relay of the called line is then operated from ground at the front contact of the Cor relay of that line, transferring the called subscribers line to the supervisory relay Lar and retard coil Gar. The Lar relay operates over the subscribers line loop to ground through the Gar retard coil and locks the Aer relay to ground on the back contact of the Bdr relay through the operated contacts of the calling line connecting relay Car. The Aer breaks the holding circuit of the called subscribers Cor rela but holds it oper ated through a make-befbre-break contact until the Tlr relay is released so as to insure that the Aer relay is locked before the Car relay is released. The calling and called parties are then connected together in a talkmg circuit over the local connecting circuit having condensers interposed therein.

When the Olr relay operated it connected the (a) and (6) wires of the junction through a condenser in each wire over back contacts of rela Otr to the listening connection on the loca connecting circuit so that the operator can observe the beginning of the conversation. The Tlr relay was locked to ground on the front contact of the H61 relay and also looked the relays Ol'r and Olr to the same ground through the operated contacts of the relay Tlr. After the operator observes the beginning of the conversation on the local connecting circuit she Withdraws the plug from the unction line releasing the A1- relay, in turn releasing the Hr relay which also releases the Hbr relay. When the Hbr rela releases, all relays except those held by the local connectin circuit are then released.

' At the end oft e conversation on the local .oeiver first, the

connecting circuit either subscriber, in restoring the receiver, releases the corresponding supervisory relay Lcr or Lar, in turn releasin the corresponding local connecting relay. Tf the callin subscriber restores his re.- flr rela releases and removesthe lockin circuit rom both local connecting relays or and Car. But if the called subscriber should restore his receiver first, the release of the Lar rela releases the Aer relay only, and the Lor re ay holds the Lbr relay operated thereby keeping the local connecting circuit as to any other calling subscriber until the rst calling subscriber bein described restores his receiver.

I a connection exists on the local connecting circuit when a call is received, the Lbr re ay is locked with the Car relay of the busy subscriber and prevents the Tl'r relay from ggfirating when the dialing key is operated.

's operates the Lor relay through the back contacts of the Tlr relay and front contacts of the Lbr rela to ground over the front contacts of the r relay; this operation taking place before the release of the Sr relay (which occurs as a result of the operation of the Dior relay) and prevents the calling party from being connected to the local connectlng circuit when the Dim" relay operates. The release of the Sr relay disconnects the subscriber from the junction line while the operator is dialing.

The operation of the Lor relay operates the Otr relay and opens the pulsing lead to the counting relays preventing them from being operated when dialing takes place. The locking contact of the Lor relay or the front contact of the Otr relay causes the Tr relay to buzz and produce a busy tone which is transmitted to the o )erator in the manner already described. en the dialing key is restored, operating the. Bar and R-cr relays by the break in the (a) wire of the junction line, the operator throws the listening key before ringing and hears the tone.

The ringing circuit from the (b) wire to the subscriber s line is opened by the Otr relay so that the operator cannot ring on the subscribers line. The operator then operates the ringing key and restores both rmg- 'ing and listening keys causing the release of the Olr, Oln, Dkr, Dim, Rcr and Rcr relays as before described. The release of the Dkr,

relay reconnects the subscribers line to the Bar relay and the Aer retard coil, operating' the Bar and Sr relays and reconnecting the subscribers line through the condensers to the junction line so that the operator may inform the calling subscriber that the local connecting circuitis busy. The release of the Dkr relay releases the r relay, in turn releasing the Oh" and Tr relays and stopping the busy tone. The operation of the Lor relay also transfers the locking circuit forthe Ohand 0Z1 relays to the ground on the front contact of the Dkr relay so that the Olr and Olr relays release when the Dkr relay releases, thereby preventing the operator from being connected to the listening connection on the local connecting circuit.

In case the local connecting circuit is free when the dialing key is operated, the calling subscriber will be connected to the calling.

side of the local connecting circuit as previously described. If the called party does .not answer, the operator restores both the ringing and listening keys, causing the operation of the Olr and Olr relays as before. The Th relay, being operated when the calling party was connected to the local connecting circuit, holds the Olr and 021, relays operated, connecting the operator to the listening connection on the local connecting circuit so as to inform the calling subscriber that the called party does not answer. When the plug is withdrawn from the junction line,

all relays are released except the localv connecting relays and the relays they control.

Establishing a connection between a calling subscriber in a tandem rural exchange (Figs. 3 and 4) and a called subscriber in one of the satellites (Figs. 5 and 6) S in 'Figs. 5 and 6. The operation of the C09 relay closes the (a) and (6) wires of the junction to the satellite, causing the Ar relay in the satellite to operate in series with the Aer retard coil of the tandem exchange. The

, operated A1- 0 erates the Hr relay, in turn operating the br relay. When the Car relay is operated by ground from the Sm relay as previously described, the pilot relay JIM, which is common to all the junction Cor relays, operates in series with it. The Jkr tolay, in operating, operates the Jar relay which then closes through the locking ground of the Car relay through to the Jar relay operating it and looking it to ground on the front contacts of the Dkr, relay.

The operating ground for the Jar relay is also closed through by this relay to the'Jp-r and Pr relays. The J01- relay is slow to operate in order to give suili cient time tooperate the Jpr and Pr relays, while the Jpn relay is made slow to release so that, when operating ground is removed, sufiicient time will be allowed for prolonging the operation of the Pr relay. It willhe noted that the operating ground of the Jpr relay is controlled through the operated contacts of the counting relays and these relays, in turn, are locked by 's ground on the back contact of a malre-before-break set of contacts on the Jar relay.

When the J01 relay operates, therefore, the counting relays release and the .ground for operating the Jpn relay is lost. To insure that the Jpr relay operates, a supplementary ground is closed through the make and break contacts of the Joy-relay to a ground on the front contact of the Ditr relay.' The operation of the PT relay produces" a break in the (a) wire otthe junction to the till satellite and the Ar relay of the satellite releases, causing the operation of the Dkr relay. When the Jor relay is fully operated, the circuit for the J pr relay is opened, eventual ly releasing the Pr relay, reclosing the (a) wire to the satellite, reoperating the Ar relay and operating the Diary which looks in series with the D727 relay. The grounded Br relay of the satellite is now con nected through the proper compensating resistance to the (1)) wire through the operated contacts of relay Car in the tandem exchange, operated contacts of the Dim" relay, operated contacts of relay J or, back contacts of relay Rcr relay to the (7)) wire of the junction to the main exchange. The circuit at the satellite is now ready to receive dial impulses.

The slow operating J 391' relay and the slow releasing Pr relay are designed to give a break in the (a) wire of the junction to the satellite exchange of the proper duration under extreme voltage limits. The J or relay also releases the pair of counting relays in the tandem exchange last operated in response to the first digit dialled and transfers the (b) wire of the junction from the manual exchange direct to the (b) wire of the junction to the satellite exchange as already explained. The operator now dials the second digit, causing the Br relay at the satellite to respond to the dial impulses. The consequent dialing operations are the same as already described. At the end of the second digit -f the Car relay of the called line in the satellite is operated by the path established by the counting relays S02 and Tcr in Figs. 6 and 7 in the same manner as previously described in connection with the tandem exchange. When the dialing key is restored and a break in the (a) wire of the junction to the manual exchange takes place, relaysRcr and R073 in the tandem exchange are operated as before. When relay Rcr operates, it closes a ground through the back contact of the Rcr relay to the frontcontact of the J or relay causing the J pr and Pr relays to operate, breaking the (a) wire of the junction to the satellite and causing a corresponding operation of the R01 relay in the satellite. When the Ron relay is operated at the tendem exchange due to the reclosure of the (a) wire between the tandem exchange and the manual exchange, the circuit for the relays Jpr and Pr is broken, causing a reclosure of the (a) wire to the satellite and thereby allowing the operation of the R023 relay in the satellite. f Y I Itwill herecalled that mention was made in the earlier part of the description that the exchange occurring during the traveling period of the arinatures of the Par and Pr relays in the cord circuit was not only sufiicient to operate the Rcr relays but other relays as well. The additional relays are relays Jpr,

Pr in the tandem exchange and Dior in the satellite. The operation of the Bar and R01 relays in the satellite establishes the ringing circuit frointhe' (Z2) wire of the tandem exchange direptly to the (3)) wire of the satellite to one" side of the subscribers line through the operated contacts of the Rc-r relay at the tandem exchange, through the operated tan dein exchange relay Cor to one side of the subscribers line at the satellite exchange and to the other side of the subscribers loop to ground through the A81 retard in the satellite and through a condenser in the satellite exchange to the (a) wire of the tandem exchange and thence to the manual exchange, but also through a condenser at the tandem exchange. The operator now rings the called subscriber at the satellite in the same manner as in ringing a called subscriber at the tandem exchange. When the subscriber answers, the operator restores both the ringing and listening keys as before producing a break in the (a) wire at the tandem exchange and car I ng the operation of the Oh and Olr relays at the tandem exchange. This operates the Aer relay of the satellite at the junction. As before, the operation of the OM relay at the tandem exchange closes a circuit through the operated contacts of the J or relay to operate the Jpr and P1 relays producing a break in the (a) wire to the satellite and thereby causes the operation of the Olr relay at the satellite. The operation of the OZ? relay at the tandem exchange opens this circuit, causes the release of the J pr and Pr relays, recloscs the (a) wire to the satellite and likewise causes the operation and locking of the ()l'r at the satellite. The operation of the Olr at the satellite releases the DIM and D/tr relays. The B87 relay and As? retard coil at the satellite are now across the subscribers loop, 0 crating the Bsr relay and connecting the su )scribers line to the junction over a condenser and impedance talking circuit. The operation of the Sr relay releases the OZ?" and Olr relays in the satellite and connects ground through the Br relay to the (7)) wire of the junction in series with the 1387* relay of the unction, establishing a balanced transmission circuit and switching supervision to the tandem exchange as more fully described below. The Oh and OZ? relays in the tandem exchange, however, remain operated due to the holding circuit established by the T1?" relay which, it will be remembered, became operated when the calling subscriber was connected to the local connecting circuit and connects the junction to the satellite on the answering side of the local connecting circuit in the tandem exchange for the operator to observe the commencement of conversation as has already been described for a local connection. The talking circuit for the subscribers extends over the subscribers loop, since the Cor relay of the satellite does not release during talking being held from relay Hbr, in the satellite through the (a) and (b) wires to the junction with the Gar retard coil on the (a) wire holding the A?" relay of the satellite and the battery of relay Lar holding the Bar relay. As already explained, this not only forms abalanced trans mission circuit, but also brings supervisory control to the supervisory relays of the local connecting relays at the junction.

It will be noted that in this type of connection the Aer relay of the called subscribers local connecting circuit is not 0 erated since the local talking circuit is not to used. The circuit for this relay depends on the operated condition of the Lbr relay at the satellite whose operation, in turn, is controlled by the operation of the Cor relay of the calling subscriber. Since the calling subscriber is at the junction exchange, no Cor relay at the satellite is distributed and therefore the Acr relay docs not operate.

The operator also listens in on a local connection through this circuit to observe the beginning of the conversation as previously described. lVhen the operator removes the plug from the jack of the junction, all the relays are released at the tandem exchange except those held by the local connecting circuit. The junction from the tandem exchange to the manual exchange is now free for other service. The removal of the plug at the manual exchange, however, does not cause the release of the relays at the satellite due to the fact. that the Ar relay is held up during talking by the Gar retard coil of the tandem oflice. The operated A1- relay holds the relays depending upon it.

At the end of the conversation the local connecting circuit is released as proviously described, except that if the called subscriber in the satellite restores his receiver first, it will release the B87 relay in the satellite which releases relay Sr, opens the (6) wire of the junction to the tandem exchange, in turn releasing the supervisory relay Lav in the local connecting circuit of the tandem office which then causes the release of the local connecting relay Aer. If the calling subscribed restores his receiver first, the Lcr relay will release, in turn releasing both the local Car, and Aer relays. The Ac'r relay will close the (6) wire of the junction from the satellite to the J11 relay, thus creating a call momentarily until the subscriber restores his receiver.

If the local connecting circuit in the tandem exchange is busy, the operator receives the busy tone by the operation of the Otr relay at the tandem oflicc as already described and informs the calling subscriber that the line is busy. But if the local connectin circuit in the tandem exchange is free and t e called subscriber is busy within the satellite itself, the calling subscriber will be'connected to the calling side of the local connecting circuit and the o erator receives the busy tone from the sate lite exchange. This tone is likewise received by the calling subscriber.

If the called subscriber is free but does not answer, the operator restores both the ringing local connecting circuit to inform the calling subscriber that the called subscriber does not answer. At the same time the junction to the satellite exchange was connected to the answering side of the local connecting circuit, but since there is no party on the line in the satellite, the subscribers loop at the satellite is not closed and, no operating ground for the La?" relay isavailable on the (b) wire from the satellite and therefore the junction to the satellite releases.

Establishing a connection between a calling subscriber at the satellite (F igs. 5 and 6) and a called subscriber at the tandem ewchange (F igs. 2, 3 and 4) When the calling subscriber'is located at the satellite he rings up the Lr relay which from battery supplied from the back contact of the Hbr relay, the J lr relay also operating at this time and closing through the chain wire from the contact of the Ar relay to the winding of the satellite'junction Cor relay. The Jlr relay also closes a ground from a back contact on relay Hbr through the winding of relay Br to the (b) wire of the junction, connecting this relay in series with the L1" relay of the junction line circuit at the manual exchange. Both the LT and Br relays operate, giving the operator the usual signal from a calling subscriber. When she inserts the plu of her cord, the operation of the Ar and H-r relays follows in the usual way, operating the satellite junction Cor relay which now locks in series with the J k? relay to ground on the Hbr relay. The Jkr relay operates at this time, causing the operation of the J or relay and which, in the proper sequence of operation, controls the operation and release of the J pr and Pr relays for reproducing breaks in the (a) wire to the satellite when necessary as already described.

The calling subscriber is connected to the operator through the talking circuit controlled by the 138? relay in the satellite. The talking circuit to the operator, however, is extended by the operation of the Bar relay of the tandem exchange over the (b) wire in series with the grounded Br relay of the satellite; the Asr retard coil holding the Ar relay of the satellite operated over the (a) wire.

If the subscriber restores his receiver and has to be called bacl:i the operator performs the operations alrea y described, operating the D707, Dkr Bar and Ron relays of the tandem exchange while the reproduction of the break in the (a) wire to the satellite causes the corresponding operation of the same relays atthe satellite. When the subscriber answers, both sets of Olr and 0123 relays operate, releasing the Dkr, Dkr Bar. and Ber relays, reclosing both talking loops and the operator inquires the number.

It will be noted that in dialing, the impulses are not reproduced at the satellite for the reason that when the operator operatesthe dialing key, and both sets of Dior and Dkr relays are operated, the operation of the Dim at the tandem exchange opens the circuit of the Jar, J pr and Pr relays. The release of the Jor relay closes the pulsing lead through to the counting relays. of the tandem exchange. The dialing of the called subscriber then proceeds in the manner already described.

It is also to be noted that the calling sub scriber is not connected to the calling side of the local connecting circuit until after dialing, as contrasted with the previous type of call where, as a result of the operator depressing the dialing key, the Car relay of the calling subscriber operated. In this case the Tlr relay does not operate in the usual way, as the operating path is held open by the operated J or relay. When relay Dsr releases after the digit has been dialled, closing a ground to relay Btr, this ground passes over a back contact of relay Btr to the Jar relay which, being operated, closes the circuit through the back contact of the Lbr relay to relay Tlr instead of the Otr relay. The J or relay also holds the circuit open for the operating winding of the Btr relay, thus preventing the operation of the Cor relay of the called subscriber until the calling junction has been connected to the local connecting circuit and the Car relay of the junction releases. The operation of relay Tl?- closes a circuit to the satellite junction relay Cer which operates from battery on the back contact of relay Lbr, breaking the locking circuit of the satellite junction relay Car and presenting battery to the calling side of the local connecting circuit. The release of the satellite junction relay Cor releases relay Jim", in turn releasing relay J or and closing the circuit through to the C07 relay of the called line. It will be noted also that the C01 relay of the calling line at the satellite remains locked to ground, since none of the above operations are repeated at the satellite, closing through the subscribers loop over to the junction in the way already described.

Establishing a call between two suba'cn'bers in one of the satellites (Figs. 5 and 6 but cownccted to a and 4) When a subscriber in one of the satellites asks for a connection to a subscriber in the same satellite, the calling part rings up the L1 relay in the usual way an is rung back junction point (Figs. 8

by the o rator in the same manner as previously escribed. The operator in this case must dial two digits, as is the case of dialing any subscriber in a satellite, the first to operate a pair of countin relays in the tandem exchange to select the or relay of the junc tion extendin to the satellite in which the called subscri r terminates and the second to operate a pair of counting relays in the satellite to operate the Cor relay of the called a subscriber. It will be remembered, however,

that when a calling subscriber is in the satellite, the Cor relay of the satellite was operat ed when the junction was connected to the operator and held locked until the calling subscriber was connected to the local connecting circuit. The Cor relay was then reoperated from the operated pair of counting rclays. Since, in this case, the originating and terminating Cor rela is the same at the tandem exchange, the or relay is not released after the first digit is dialed. When the Dar relay releases after the first digit, the ground from its back contact is closed through the front contact of relay Djr and front contact of relay J or, operating the Jc'r nelay. The operating ground for the Jar relay passes over a back contact, operating the Jpr and Pr relays, giving a break in the wire of the junction operating the Dior and Dlzr relays 1n the satellite exchange. The operation of relay Dkr causes the operation of relay Tlr and results in the calling party being connected to the local connecting circuit in the manner already described. The operation of the J or relay releases the counting relays in the tandem exchange and transfers the (6) wire of the junction from the manual exchange direct through to the a wire of the junction of the satellite. The (6) Wire is the impulse wire so that when the second digit is dialed, the Brrelay of the satellite follows the impulses and operates the proper pair of counting relays at the satellite.

The called subscriber is connected to the local connecting circuit after ringing in the same manner as previously described. .The Olr and Olr relays in the satellite are held f s mme- 0 rated by the Tlr relay, thus connecting t o satellate to the listening position on the local connecting circuit, it being remembered thatthe Olr and Olr relays of the tandem are released at this time.

A ground from a front contact of the ()lr relay in the satellite is connected through a winding of the Br relay to'the (6) wire of the junction to the tandem exchange, operating the Bar relay in the tandem exchange. The operation of the B81 relay in the tandem r exchan e o crates the Sr relay releasing the 0a and 015,

relays, thus preventing the operator from being connected to the istcning connection of the tandem local connecting circuit and connects the junction from the manual exchange to the satellite exchange over the normal condenser and impedance talking circuit.

The operator can now listen to the beginning of conversation and then remove the plug from the jack of the junction releasing the A5, Hr and HM relays in the tandem exchange. 7 This releases the satellite Cor relay at the tandem exchange, opens the (a) and (6) wires to the satellite and causes the release of the Ar, H1, and Hbr relays at the satelite. Thejunction from the manual exchange to the tandem junction and the junction from the tandem exchange to the satcllite are now free.

Should the called party not answer, or if the local connecting circuit is busy, the o rator receives the busy tone from the sate lite exchange and so informs the calling party as previously described.

Establishing a connection between a subscriber in one satellite (Figs. 5 and 6) and a subsom'ber in another satellite (homing equipment similar to that shown in Figs. 5 and 6') and connected by a common rural tow dam exchange (Figs. 3 and 4) The method of operation for a calling subscriber in a satellite to signal the operator is the same as already described and the manner of connection to the called subscriber in another satellite is the same. In this type of call there will be two satellite Cor relays involved at the tandem exchange. In this case the operation of ringing the calling subscriber in the satellite is the same as previously described and the connection to the called subscriber in another satellite is established in the same manner as was the case for the called subscriber in Figs. 5 and 6, the calling subscriber being connected to the calling side of the local connecting circuit in the tandem exchange over the junction of the calling satellite after the first digit has been dialed, and the called subscriber being connected to the answering side of the local connecting circuit in the tandem exchange over the junction from the called satellite in the manner as previously described.

When the operator withdraws the plug after observing the beginning of the conrersation, the junction from the manual exchange to the tandem exchange is liberated in the usual manner and leaves the junctions of the respective satellites connected to the local connecting circuit in the tandem exchange. Either subscriber restoring his receiver removes the ground from the (b) wire of the junction from its respective satellite to the tandem exchange which releases itself from the local connecting circuit in the usual manner.

Establishing acon'nectz'onfrom a subscriber in the manual creche age (as for ewample, subscriber S in ew chcmg'e A, Fig. 1 to a subscriber in a tandem rural exchange (Figs. 3 and 4) 01' a statellz'te emchange,

Figs. 5 and 6' "When a subscriber in the manual exchange calls a subscriber in a rural exchange, the opera-tor dials the number of the Wanted suberated.

scriber. However, due to the fact that the Sr relay is not operated when the dialing key is operated, the Tlr relay will not operate. When the operator produces a break in the (a) wire after ringing, causing the 017* and Olr relays to operate, the called subscriber is not connected to the local connecting circuit but operates the 1381 relay which in turn operates the S1 relay, releasing the Oh and 0Z2 relays and connecting the sub scribers line through a condenser and impcdance talking circuit to the junction.

If the called subscriber is busy on the local connecting circuit, the operator receives the busy tone after dialin in the same manner as previously describe Toll connections When the operator receives a toll call for some subscriber in the area controlled by the main exchange, she dials the Wanted number. If the called subscriber and the local conneeting circuit are idle, the connection is established in the usual way. If, on the other hand, the subscriber is busy, the operation of the dialing key and the consequent operation of the Dkr and Dior, relays causes the ()t-r relay only to operate, since the T17 relay cannot operate because the Lbr relay is op- Also the L01 relay cannot operate because, as there is no. calling subscriber signaling the operator, the Sr relay is not ,operated. The operator then operates the listening key to ascertain it the line is busy and gets the tone induced in the secondary winding of the Tr relay which is placed across the trunk. Provision is now made whereby the operator is connected to the busy extend the toll call to the wanted subscriber. This is accomplished as follows.

When the operator receives the busy tone after dialing, she operates the ringing key and then restores both the ringing and listening keys, whereupon the breaks in the (a) wire cause the operation of the Dior, Dlcr Ber, R013, OZ?" and 01m relays. The operation of the Oh, relay causes the release of relays Die? and Dice, and which, in turn, causes the release of the R01 and Rm relays. Since the line is busy, the Lbr relay is operated and prevents the TM relay from being operated. As soon as the Olr and Gir relays are operated, a circuit is closed to operate relay L01 from ground through the front contacts of relays Olr and Ol r front contacts of the Lbr relay, front contact of relay Dkr, back contacts of relay Jar, front contacts of the transfer set on relay Lbr, back contacts of relay Tbr to battery through the L07 relay. This relay, in operating, locks itself to aground on the Dkr relay and also transfers the holding circuit of relays OZ? and OZ? to the same ground so that, when the Dkr and Dkr relays release, the 021' and OZ?" relays release also. Relay Lor is slow in releasing to make sure that the Olr and OZI' relays are unlocked before the Lor relay releases; otherwise these relays would remain looked through a back contact of relay L01 to ground on the back contact of relay Sr. The operator then operates the dialing key and restores. it, producing two breaks in the (a) wire of the junction, causing the operation of the DkiyDkr R01, and Rcr groups of relays and then operates the listening and ringing keys, producing another break in the (a) Wire and causing the opera; tion of the Olr and Olr relays. The opera tion ofthe 031', relay again releases the Disc and For groups of relays as-before, but relay Lor, being released at this time, leaves the normal holding circuit for the 011 and Ol-r relays closed, causing these relays to remain energized and connect the operator to the listening position on the local connecting circuit.

The operator now informs the subscriber on the local connecting circuitthat a toll call is waiting and proceeds thereafter to break down the local connection in order to set up the toll call. The operator operates the dialing key and dials the number of the wanted party. The operation of the dialing key again operates the Dior and Dim relays to prepare the circuit for dialing. When the Dlcr relay 0 )erates, it connects the ground through the 1' relay to the (b) wire of the junction, operating the Br relay and when the D727, relay operates, a path is closed for the Bdr relay from battery through its winding, front contact of relay 011', front contact of relay Br, back contact of relay R01, to ground on the front contact of the Dim" relay.

Relay Bdr operates and locks to holding ground.

Relay 13(1) closes a circu t to operate the Sr relay through a front contact of relay Olr and since relays OZ) and (ll/* are hot 1 locked to ground through a back contact of relay S), the operation of relay Sr will release the Oh pair of relays and the release of relay Olr opens the circuit for the Sr relay. The Bdr relay locks to the holding ground of relay Dkr but opens the holding path of these relays--tl1ey now holding from a back contact of relay R013. Therefore, when the Rcr relay operates, the Dior and Dlar relays will release. The operation of relay Bdr also breaks the holding ground for the local connecting circuit as well as for the Cor relay. The operator then-proceeds to dial the wanted number. \Vhen the Dsr relay releases after the digit is dialed, the ground from the operated pair of counting relays is closed through relay Btr and the Car relay of the wanted line.

\Vhen the operator restores the dialing key, causing the operation of the Rcr and Rcr relays, the Dkr and Dkr 'relays release as already explained. The operation of relay Rcr also unlocks relay Bclr-whieh releases at this time. The release of relay Bdr also releases relays R01- and R02 which were held by relay Ball. The Bdr relay is also in releasing in order to hold relay R01, operated long enough to insure the release of the D702 and D/rr relays. The release of relay Bdrrecloses the locking ground for the Cor relay before the operating path is broken by the release of the counting relays.

The operated Cor relay puts the B37 relay and Aer retard coil across the subscribers loop, causing the operation of the Bsr and Sr relays, closing the line to the junction for talking.

Faulty junction If the (1)) wire of the junction from the manual exchange to the tandem exchange becomes grounded, it operates the junction line relay giving the operator a permanent junction line lamp. If the (a) wire becomes grounded, it operates the Ar relay, in turn operating the Hr and HM relays, closing a ground through the back contact of the Sr relay, back contact of the D/cr relay, back contact of the Dlm' relay, back contact of the 01-7 relay to the thermal heat relay T720". If this circuit is not broken within a period of approximately one minute, the thermal heat relay Th7 closes a circuit for the Pg? relay which locks to the front contact of the Ar relay and breaks the circuit to the Hr relay, thus releasing the H1, H6? and Tim relays. The Pgr relay connects a ground to the (7)) wire of the junction to the manual exchange, operating the junction line relay, giving a permanent line lamp. If the fault becomes cleared, releasing the Ar relay, the Pgr relay is released and the circuit 15 restored to normal.

[Nmbliag a faulty satellite exchange from a junction If a junction from a satellite exchange (Figs. 5 and 6) to the tandem exchange (I igs.

3 and 4) becomes faultyon either the (a) or (1)) wire, the ground on the (6) wire op-' eratcs the Jlr relay in the tandem exchange, connecting ground through the Br relay on to the ((1) Wire of the manual exchange, thus causing a permanent line lamp in the manual exchange. The operator will ascertain whether a subscriber is on the line and on getting no response will recognize it to be a faulty line by successfully ringing on it, there being a ground return on the (b) wire, and will know that it is a junction to a satellite since the line relays of the local subscribers lines are connected to ground and do not become operated from a faulty line.

In order to ascertain which junction is faulty, the operator makes a test call on each junction until the faulty junction is found.

The operator then disables the unction by dialing zero, followed by the junction numher and then remo es the plug from the jack.

lVhen the digit 0 is dialed, the Or relay is operated from the front contact of the Adm relay and the frontcontact of the Tar, relay. The Or relay, in operating, closes a circuit from the Jr relay to the back contact of the Tar, relay so that when the second digit is dialed, releasin the Com relay, the Jr relay will operate. The operation of the Jr relay transfers the Cor relay operating leads from the Tor relays to the respective Jdr relays, so that when the Dar relay releases after the second digit, the ground is eonnectedto the Jdr relay of the junction which was dialed. The J Jr relay in operating opens the (a) and (5) wires of the junction and locks itself to the (15) wire. When the fault becomes clear, the J03? relay is released and the junction is restored to service.

F use alarm The circuit is fused with the Ar, Otr, Lor and Tr relays on a separate fuse back of the main fuse so as to ive a tone to the operator when any fuse is blown except this one.

A blown fuse connects battery to the fuse panel alarm bar, operating the Far relay which connects ground through the Br relay to the (6) wire of the junction operating the junction line relay, giving a permanent junction line lamp. When the operator plugs into the jack of the junction operating the Ar relay, it connects ground through the make contact of the Far relay, operating the Lor, Otr and Tr relays, connecting the busy tone to the unction. This tone makes a distinction between the permanent line lamp for a blown fuse and a ermanent line lamp fora faulty junction. en the operator removes the plug from the jack of the junction, the Ar relay is released, thus releasing the Lor, Otr and Tr-relays, so that the busy relays are operated only while the operator is on the junction.

C'bm'gz'ng battery The battery charging equipment consists of the 07, Cj'r relays, D resistance and Y wiring. When the battery-- is charged via the junction, fromthe manual exchange, the polarized relay Chr is connected between the Xv wire' of the junction and the Ar relay.

negative battery of 48 volts or higher potential is connected throu h the back contact of the junction line re ay and the junction cut-ofi' relay in the manual exchange to the (a) wire of the junction, which flows through: the operating winding of the C724? melay through the Ar relay to the battery of the rural exchange by way of the Y wire. When the battery 1s fully charged, the potentialis reversed and the polarized relay Chr operates on the reversed flow of, current, disconnectin the ground from thearmature spring of t e Ar relay, so as to prevent the Hr and Hbr relays from operating. When the operator plugs into the jack of the junction ap lying a ground to the (a) wire, the flow 0? current is reversed throu h the olarized relay which operates in t e opposite direction, restoring the ground to the armature 5 ring of the A? relay so that the circuit will unction in the normal manner. The holdin winding of the Oh? relay is energized w enever the circuit is in operation, so as to aid the operatim winding in maintaining a firm contact for the ground to the armature spring of the A1- relay.

When the junction is seized by a callincoming to the manual exchange, the opera tion of the junction line relay removes the charging current and likewise when the junction is seized by the operator plugging into the jack of the junction, the operation of the junction cut-ofi' relay removes the charging current from the line. I

The batteries in the satellite exchange are charged in the same manner by connecting the charging battery to the (a) wire of the junction to the satellite in parallel and in parallel with the battery of the tandem exchange through the (D) resistance.

The operation of the Oh? relay in the tandem exchange operates the Cy'r relay connecting the charging battery through the D resistance in parallel with the C resistance. The value of these resistances depends upon the resistance of the. junction from the man.- ual exchange to the tandem exchange and the resistance of the junction to the various satellites in the charging current required for each of them, Y

What is claimed is: a

1. In a telephone exchange system compris ing a main exchange, a plurality of tandem rural exchanges each connected by a trunk line to said main exchange, a plurality of rural exchanges each connected by a trunk line to either said tandem rural exchanges or to said main exchange, a local connection and at each of said rural exchanges, a register sender at each of said tandem rural ex-' changes means at said main exchange for controlling said sender at each of said tandem rural exchanges to interconnect lines at said tandem rural exchanges over said local connection trunk in each of said tandem rural exchanges or to connect lines at said tandem rural exchanges with any of said rural exchanges connected thereto, a register sendnecting lines of an of said rural exchanges over the local trun thereof.

.75 trunk ateach of said tandem rural exchanges 2. Ina telephone exchange system, a main exchange, a tandem rural exchan e, a rural exchange, a plurality of suhscri ers lines and a trunk outgoing to said rural exchange terminating in said tandem rural exchange, a trunk line extending from said tandem rural exchange to said main exchan e, a register sender at said tandem rural exc ange, a local connection trunk at said tandem rural exchange, means at said main exchange for controlling said sender to interconnect lines at said tandem exchange over said local trunk or to connect lines at said tandem rural exchange with said rural exchange over said outgoing trunk, a register sender at said rural exchange, lines terminating in said rural exchange, a local connection trunk at said rural exchange and means at said main exchange and at said tandem rural exchange for controlling the sender at said rural exchange for further extending a connection from a line in said tandem rural exchange over the local connection trunk of said tandem rural exchange to a line in said rural exchange or for interconnecting lines of said rural exchange over the local connection trunk thereof.

3. In a telephone exchange system, a main exchange, a tandem rural exchange, a rural exchange, a plurality of subscribers lines and connection trunk at said tandem rural exchange means at said main exchange for controlling said sender to interconnect linesatsaid tandem rural exchange over said local trunk or to interconnect lines at said tandem rural exchange with said rural exchange over said outgoing trunk, a register sender at said rural exchange, lines terminating in said rural exchange, a local connection trunk at said rural exchange, means at said main exchange and at said tandem rural exchange for controlling the sender at said rural exchange for further extending a connection from a line in said tandem rural exchange over the local connection trunk of said tandem rural exchange to a line in said rural exchange or for interconnecting lines of said rural exchange over the local trunk thereof, and means for releasing the trunk line from said main exchange to said tandem rural exchange and the trunk outgoing from said tandem rural exchange to said rural exchange for establishing other calls when such trunk lines are not used as part of an established talking connection.

4. In a telephone exchange s stem, a main exchange, a tandem rural exchan a plurality of subscribers lines, a trun line extending from said tandem rural exchange to said main exchan a register sender at said tandem rural exc ange, a local connection trunk at said tandem rural exchange, means at said main exchange for controlling said sender to interconnect lines at said tandem rural exchange over said local connection trunk, and means for thereafter releasing the said trunk line from said main exchange to said trndem rural exchange for establishing othet calls at said tandem rural exchange.

5. In a telephone exchange system, a main exchange, a tandem rural exchange, a rural exchange, a plurality of subscribers lines and a trunk outgoing to said rural exchange terminating in said tandem rural exchange, a trunk line extending from said tandemrural exchange to said main exchan e, a register sender at said tandem rural exc ange, means at said main exchange for controlling said sender to interconnect said tandem rural exchange with said rural exchange over said outgoing trunk, a register sender at said rural exchange, lines terminating in said rural exchange, a local connection trunk at said rural exchange, and means at said main exchange and at said tandem rural exchange for controlling the sender at the said rural exchange for interconnecting lines at said rural exchange over the local connection trunk thereof, and means for thereafter releasing the trunk line from the said main exchange to said tandem rural exchange and the trunk outgoing from said tandem rural exchange to said rural exchange for estab lishing other calls at said rural exchange.

6. In a telephone exchange system, a main exchange, a tandem rural exchange, a rural exchange, a plurality of subscribers lines and a trunk outgoing to said rural exchange terminating in said tandem rural exchange, a trunk line extending from said tandem rural exchange to said main exchange, a register sender at said tandem rural exchange, a local connection trunk at said tandem rural exchan means at said main exchange for control ing said sender to interconnect lines at said tandem rural exchange over said local connection trunk thereof or to interconnect lines at said tandem rural exchange with said rural exchange over said outgoing trunk, a register sender at said rural exchange, lines terminating in said rural exchange, a local connection trunk at said rural exchange and means at said main exchange and at said tandem rural exchange for controlling the sender at said rural exchange for further extending a connection from a line in said tandem rural exchange over the local connection trunk of said tandem rural exchange to a line in said rural exchange or for interconnecting lines of said rural exchange over the local connection trunk thereof, and means at said main exchange, at said tandem rural exchange and at said rural exchange for enabling the operator at said main exchange to listen to the commencement of conversation on the estab lished connection at said tandem rural exchange or on the established connection at said rural exchange or on the established connection between said, tandem rural exchange and said rural exchange.

7. In a telephone exchange stem, a main exchange, a tandem rural exc iange, a plurality of subscribers lines terminating in said tandem rural exchange, a trunk line extending from said tandem rural exchange to said main exchange, a register sender at said tandem rural exchange, a local connection trunk at said tandem rural exchange, means at said main exchange for controlling said sender to interconnect lines at said tandem rural exchange over said local connection trunk, and means at said main exchange and at said tandem rural exchange for enabling the operator at said main exchange to listen to the 001m mencement of conversation on the established connection at said tandem rural exchange.

8. In a telephone exchange system, a main exchange,a tandem rural exchange, a rural exchange, a plurality of subscribers lines and a trunk outgoing to said rural exchange terminating in said tandem rural exchange. a trunk line extending from said tandem rural exchange to said main exchange, a register sender at said tandem rural exchange, means at the said main exchange for controlling said sender to interconnect said tandem rural ex change with said rural exchange over said outgoing trunk, a register sender at said rural

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