US1658416A

US1658416A - Telephone system

Info

Publication number: US1658416A
Application number: US711751A
Authority: US
Inventors: Winfred T Powell
Original assignee: STROMBERG CARLSON TELEPHONE
Current assignee: STROMBERG CARLSON TELEPHONE; STROMBERGCARLSON TELEPHONE MANUFACTURING Co
Priority date: 1924-05-08
Filing date: 1924-05-08
Publication date: 1928-02-07
Anticipated expiration: 1945-02-07

Description

Feb. 7, 1928. 1,658,416

w. 'r. POWELL TELEPHONE SYSTEM Filed May 8. 1924 6 Sheets-Sheet J.

- INVENTOR E I 6 I I I H WINFREDT POW 1.1. :0 I l BY 3W. h-

ATTORNEY Feb. 7, 1928.

W. T. POWELL TELEPHONE SYSTEM 6 Sheets-Sheet 2 Filed May 8. 1924 mulin qz miko INVENTOR W\NFREDT. POWELL HOLIUMJUm KZDWEI \PM QZ Mu ATTORN EY Feb. 7, 1928. I 1,658,416

W. T. POWELL TELEPHONE SYSTEM Filed May 8. 1924 6 Sheets-Sheet 5 I FORTEST wrrn CALLING comp ONLY INVENTOR .WINFREP T. POWELL ATTORN EY TELEPHONE SYSTEM Filed May 8. .1924 6 Sheets-Sheet 4 FIG. 4

INVENTOR METER 0 WINFRED T. POWELL I Q ||H||| V l\ l A v I 4 3 v ATTORNEY SECONDARY TRUNK saLEm-oR Feb. 7, 1928.

' w. T. POWELL 16584l6 TELEPHONE SYSTEM Filed May 8. 1924 6 Sheets-Sheet 5 O i 4 l, 2 D

ID 9 [L L! at Q Q t 5 0 j U 2- g *2 a a U P [2 O x l! z I! ll INVENTOR WINFREV T. POWELL.-

Feb. 7, 1928.

Y W. T. POWELL TELEPHONE SYSTEM Filed May 8. 19 24 6 Sheets-Sheet 6 WINFREP T. POWELL BY ATTORNEY m obqmmmo Patented Feb. 7, 1928. i

WINFRED :r. POWELL, on EoonEsTEn, NEW YORK, AssIGNoETo THE's'rnoMBERG- CARLSON TELEPHONE MANUFACTURING COMPANY CORPORATION OF NEW YORK.

Application filed May a,

This inventionrelates to telephone systems and more particularly to telephone systems having one or more offices. In such -..tele phone'systems it has been customary to pro-p vide so-called order wires connecting the various otlices over which an operator at an originating oflice transmits the wanted number to a B operator at a. distant. office and this lastnamed operator in turn assigns a trunk over which the A operator may extend a call. Such order wire operation has proved to be especially 'inefiicient during busy periods and has resultedin numerous wrong connections.

It is the 'purposeof the present invention to provide an improved arrangementwhereby the order wires may be dispensed with to the end that the operation of the system may be greatly facilitated and the number of incorrect connections reduced to a minimum.

One of the features of the present invention resides in the provision of automatic trunking means, whereby an operator at. an originating otlice, by connecting the calling line to said trunking means operates mechanism to extend the calling line to a" B operators position at the distant office at which otiice each B operators position is provided with a plurality of manual link circuits with but oneconnnon ringing key for each of the sources of ringing current of the characteristic provided for selectively signaling the several stations on a party line.

Another feature of the invention consists in the arrangement for automatically extending a' calling line at an originating oilice by means of automatic switcl'iing de-- vices, to trunk circuits each of which terminates in multiple jacks provided with assoelated trunk lamps at several operators positions. 4

Another feature of the-invention includes the arrangement whereby a subscriber at an originating ofiice on initiating a recall. causes a. signal at the Byopera'tors position to be actuated in a distinctive manner and whereb ysaid B operatorcontrols means to actuate in a distinctive manner a corresponding signal at the A operato'rs position.

1n the-drawings Figures 1, 2 and 3 when arranged in the order named, diagrammati A TELEPHONE SYSTEM.

, 0E RQCH s'rER NEW' Y RK, A

1924. Serial No. 711,751.

cally represent one form of the invention.

Inthe upper left hand corner ofFig. 1 there is represented a calling lineand although it is indicated as provided with only one substation it may be provided with apl'urality of substations for party line ope-ration. 'lheremainder of Fig. 1 diagrammatically represents an A operators cord circuit together with certain portions of the equiplnent, which are common to a plurality of cord circuits at an A operators position.

At theleft of the there is represented a dottedline in Fig. 2 trunk selector switch which is located in the same office as the equipment of Fig. 1,

At the right of the dot-tedline in Fig. '2 there is represented a second trunkselector s n a distant ol'iice. Fi

witch which is located g. 3 diagrammatically representsagcord clrcult at a B operators position in the distant oflice, which is the same oflice as that represented at the rightof Fig. 2. At the upper right hand corner of Fig. 3 a party lineisrepresented.

Figures 4,- 5 and 6 when arranged in the order, named diagrammatically represent a modified form of the invention.-. In the upper left hand corner of Fig. 4 there is indicated a telephone line. and substation, but it will be understood that this line may beprovided with a plurality of substations for partygline operation, without departing from the present invention. A The remainder of Fig. 4: diagrammatically represents an A operators cord circuit and certain of the equipment which is common to a plurality of cord circuits at .th At the left hand side is operators position. of the dotted line of Fig. 5, there is. represented a trunkseleetor -ment of Fig. A. At

tor switch, which is located at a distant oflice. A two conduct-0r trunk connectsth'ese ofiices. In Fig. '6, there is indicated the equipment of a- B operators plug-ended link circuit and certain of the equipment at this position, which iscommon to a plurality of such link circuits, )In; cornerof Fig. 6, there station telephone line.

The selector switch the upper right hand is represented a. multies referred toin'this disclosure may be substantially similar to that disclosed in the patent to Clement No. 1,107,153 patented August 11, 192d, when modified by being provided with two sets of brushes for simultaneously engaging two sets of trunk terminals and for seizing an idle one of these sets of terminals.

It is believed that the invention will best be understood by describing the method of extending a telephone call from a subscribers substation indicated at A. It will "When the subscriber at A removes his receiverhorn its switchhook, the line relayt) is energized in the well known manner, over the two sides ofthe calling line in series and thereby lights the line. lamp The operator whose cord circuit is shown in Fig. 1 then inserts the answering plug 7 of this cord circuit into the jack 8 ot' the calling line. This operation is effective to energize the cut-off relay 9 and the operator's bar relay 10 in a circuit extending from grounded battery through the right hand high resistance winding of relay 10 through the sleeve contacts of the plug 7 and jack 8, winding of the cut otl' relay 9 to ground. As soon as the cut-off relay 9 is actuated it opens the energizing circuit oi the line relay 5, which relay deenergizes and opens the circuit of the lamp 6 to extinguish it. The opera-tors bar relay 10 when operated, closes a locking circuit for itsell through its low resistance left hand winding and through its left hand armature and front contact over the remainder otthe circuit previously described. As is w ll known, the high resistance and low resistance windings of therelay 10 are provided to prevent a second operators telephone set from being connected to a calling subscribers line at the same time, in the event that two operators should simultaneously connect the answering ends of their cord circuits to the same calling line.

lVhen therelay 10 is operated it closes a circuit from ground, its outer right hand armature and front contact,uppermost armature and back contact of relay 11, winding of the slow releasing relay 12, winding 01* the relay 13, left hand winding of the relay let, winding of the high resistance relay 15,

to grounded battery. The resistance of the relay 15 is such that it is operated in this circuit, but the other mentioned relays in series therewith are not operated at this time. vVith the relay15 operated, an energizing circuit is closed from grounded battery, right hand winding of the. relay let, front contact and armature of relay 15, to ground. When the relay 1% is thus energized, it extends a circuit from grounded battery, its front contact, armature and left hand winding, and thence through the windings of relays 13 and 12, over the remainder of the circuit previously described as 82-1- tending to ground at the right hand front contact and armature oi relay 10. Relays 12 and 13 are energized in this last circuit. Relay 13 closes a breakpoint in the operating circuit oi the. meter 16 and with the relay 12 energized the operators cutin relay 18 is energized from grounded battery, front contacts and armatures of relay 12, conductor 19, winding of relay. 17, to ground. The relay 18 is thereby energized and at its left hand arinatures and front contacts, extends the operators tele phone set through the conductors 20 and 21 over the answering end of the cord circuit in use, to the calling subscribers line. The relay 17 is energized in series with the relay 18 and closes the remaining breakpoint in the circuit of'the meter 16, causing the same to energize once and once only to record that this operator has answered a call.

The relays 13,1 1, 15 and the impedance coil 22, are common to an operators position and are provided to permit the operator to extend a second call through a second cord circuit while she is completing the connection on a first cord circuit such as that shown in Fig. 1. This arrangement permits the operator to plug up a second call while she is pressing the ringing key to apply ringing current over a lirst cord circuit. The arrangement 01 relays is such that only two calls may be in the process of completion by one operator at the same time. If the operator plugs up more than two calls before any one connection is completed, then all of the calls will fail. Such an arrangement has proved to be especially satisfactory in handling a large number of calls.

As soon as the operators telephone set is connected to the calling telephone line, the operator inquires for the number of the wanted telephone line and when she ascertains that the call is: a local call, that is, one terminating in the same oflice as the calling subscriber, she inserts the calling plug 23 into the multiple jacket the wanted line (not shown) and then depresses some one of the ringing keys, such as 24:, 25, 26 and 27.

Let it be assumed that the ringing key 26 is depressed to operate the relay 28, which in turn controls the selection of the proper ringing current to signal the wanted station.

Iii

As soon as the calling plug 23 is inserted in a multiple jack of the. calledline, the sleeve relay 29 is operated from grounded battery, winding of this relay, back contact and armature of relay 11, sleeve contacts of the plu 23 and thence to ground through the jaci; and the cut-off relay of the wanted line (not shown). \Vith the relays 28 and 29 actuated, an operating circuit is extended from ground, left hand front contact and armature of relay 28, lefthand armature and front contact of relay 29, Winding of the relay 30, to grounded battery. Relay 30 when thus operated, closes a ringing circuit, which will be described later, and closes a loclging circuit for itself through its left hand front contact and armature, left hand back contact and armature of relay 31, right hand front contact and armature of relay 29 .to ground. Also when the relay 28cis operated, a circuit for the ringing relay 32 is completed from grounded battery, resistance, winding of the relay 32, conductor 33, right hand back contact and armature of relay 34L, contact 35 and armature of relay grounded battery, its lower winding, lowermost armature and front contact and thence through the sleeve contacts of the plug 23, jack and cut-01f relay of the wanted line (not shown). It will be noted that the relay 11 opens the circuit of the slow releasing relay 29 and this relay when it deenergizes removes groundfrom the holding conductors of the cord circuit, but this ground immediately applied to theholding conductors through the inner lower armature and front contact of relay 11. The relay 29 on deenergization also restores the ringing keys to 27 inclusive, and the relays: individual thereto, for common use. At the inner upper armature and front contact of relay 11, a break-point is closed in the tip conductor of the calling end of the cord circuit. WVith the relay 30 and ringing relay 32 operated, G6 cycle ringing current is applied to the called line through the left.

hand back contact and armature of relay 37, right hand front contact and armature of relay 3(), winding of the trip relay 38, innermost, lower front contact and armature of relay 32, ring contacts of the plug 23 over the lower side of. the Wanted line and through the hell (not shown) at the wanted substation, over the upper side of the wanted line (not shown), tip contact 23 of the calling plug, inner-upper armature and front left hand armature and back contact opens the locking circuits of the frequency selecting relays such as 30 or 37, and the ringing relay 32, so that these operated relays now return to normal condition.

'lalking current is supplied to the calling party through the two windings in series of the answering supervisory relay 39, while talking battery isfisupplied to the called party through the windings of relays -10 and 31 in series.

, At the close of the conversation when the subscriber at A replaces his receiver on its switchhook, the energizing circuit of the answering supervisory, relayj 39 is opened so that the answering supervisory lamp 411 is lighted in a circuit traceable from grounded battery, lamp 4:1, conductor 42. middle armature and backcontact of relay 43, conductor 44, inner armature and back contact of relay 39, inner armature and front contactof relay 10, winding of the iinped ance coil45, to ground. Similarly, when the called party'terminates the connection relay 31 deenergizes and the calling supervisory lamp 46. is lighted in a circuit from grounded battery, lamp 46, middle back contact and armature of relay 32,'back contact and armature of relay 31, inner front contact and armature of'relay 11, to ground.

The operator on noting that one or both of these lamps are lighted, removes the answering plug 7 and the calling plug 23 from the acks with which they have been in engagement. i

Inter-077506 call.

Now let it be assumed thatthe subscriber' ation causes thelighting of the line lamp 6.

The operator on noting that this lamp is lighted, inserts the answering plug 7 of her cord circuit into the jack 8 of the'calling line. The relaysof the cord circuit function in themanner already described to connect the operators telephone set to the calling line, at which time the operator inquires III) till

plug the number of the wanted station and when she learns that the wanted line terminates at a distant office, inserts the calling plug 23 of her cord circuit into a jack 47 of a trunk through which the wanted office may be reached. The various operations in extending the call to the distant oflice up to this time, are the same as those described in the case previously assumed of extending a call to the local subscriber.

As a result of the insertion of the calling into the trunk jack 45. the sleeve relay 29, shown near the center of l is now operated. from grounded battery, winding of relay 29, livack contact and armature of relay ll, sleeve contacts of the plug 23 and the jack l7, winding of the relay -l8, back contact and continuity spring of relay 4-9, back contact and continuity spring of relay 50, to ground. The relays 2E) and l8 are thereby energized and the relay 14.8 when energized, closes an operatin circuit for the motor nu net 51 of tlr primary trunk selector switch whose brushes are designated 52 to 57 inclusive. The operating circuit of the magnet 51 is closed from groui'ided battery, resistance, winding of this magnet, its back contact and armature, left hand armature and front contact of relay l8 and thence to ground through the back contacts and continuity springs of relays l9 and 50. Under the control of this circuit the motor magnet 51 advances the brushes of the line switch, until the test brush 52 or the test brush encounter the test terminals of an idle trunk.

Let it be assumed that test brush 52 locates an idle trunk, such as that shown in Fig. 2, at which time a circuit extended from ground, back contact and armature of relay through its lower winding and through the sleeve contacts of the jack and plug to grounded battery, through the windings of the sleeve relay 29 of Fig. l.

lVith relay O operated as above described a circuit closed for operating relay 31 extending from grounded battery, winding of relay 31, inner back contactand armature of relay 32, ring contacts of the plug and jack, inner front contact and armature of relay 50, brush 54, back contact and armature of relay 5S), and winding of relay 58 to ground. As soon as relay 31 is operated it closes an operating circuit for relay 43 extending from the grounded battery, winding of relay 43, inner front contact and armature of relay 31 and lower inner back contact and armature of relay 11 to ground. Relay 4:8 is locked operated for a short interval to ground at the outer right hand armature and front contact of relay 29 and after the release of relay 29, relay 4,3 is locked operated to ground at the lower, inner front contact and armature of :relay 11. As soon as relay 43 is operated it closes an operating circuit for relay 1.1, from grounded battery, lower winding of this relay, left hand armature and front contact of relay 4-3, and thence to ground over -.the sleeve conductor and the sleeve contacts of the plug and jack. The operation of relay 11 opens the energizing circuit of the slow releasing relay 29, which shortly afterwards deenergizes and the relay 11 also closes a locking circuit for itself through its lower winding, lowermost front contact and armature and thence to ground through the sleeve conductor, which locking circuit is independent of the armature and contact of the relay 4}). l rom the foregoing'it will be seen that on a local connection when a ringing key is operated to cause the energization of the relay 11, relay 4-3 is not operated because relay 11 is operated before relay 31. On a local connection the relay 31 operates to give the regularsupervision and the relay 40 is energized, but this is ineffective because the circuit through its contacts is open at a front contact of relay \Vith the relay operated, the slow releasing relay 58 is actuated in a circuit closed from ground, winding of this relay, lower back contact and armature of relay 59, inner, upper front contact and armature of relay 50, ring contacts of the jack 4:7 and the plug 23, inner armature and back contact of relay 32, winding of relay 31, to grounded battery. As soon as the relay 5S attracts its armatures, the make-busy relay 59 energized. from ground through the lower winding of this relay, lower front contact and armature of relay 58 and the over the remainder of the circuit just described, through the winding of relay 31. Relay 59 when operated closes a locking circuit for itself from grounded battery, its upper winding, armature and continuity spring, brush 52, and thence through the lowermost front contact and armature of relay 50, resistance, to ground. Also as soon as relay 50 is operated, the relay 60 has a circuit completed from grounded battery through its high and low resistance windings in series, through the upper left hand winding of the repeating coil, line switch brush 53, uppermost front contact and armature of relay 50, tip contacts of the'jack 47 and plug 23, upper, inner armature and front contact of relay ll,

lilU

sistance, to grounded battery winding of relay 10, to ground. .The relay 6() is energized in this circuit, but the relay 40 will not operate in series with the high resistance winding of relay 60. The operation of relay extends a circuit from ground at its armature and front contact, winding of the relay 61, upper right hand winding of the repeating coil, over the upper side of the trunk 62 to the distant office, upper left hand winding of the repeating coil atthe distant oilice, through the high and low resistance windings in series of the relay 63, to grounded battery. Also when the relay 60 is operated, it closes a second circuit from ground through its armatureaiul front contact, conductor 64, back contact and continuity spring of relay 65, winding of the relay 66, lower right hand winding of the repeating coil, over the lower side 67 of the trunk to the'distant office, lower left hand winding of the repeating coil, winding of the relay 68 to grounded battery. The relays 63 and 68 are both actuated in these circuits and the relay 63 closes an energizing circuit for the slow releasing relay 69 from grounded battery, winding of this relay, inner back contacts and armatures 0f relays 70 and 71, back contact andarmat'ure of relay 72, front contactand armature of relay 63 to ground.

Thcenergization of relay 69 starts the secondary trunk selector switch in operation by the closure of a circuit from grounded battery, resistance, winding of the motor magnet 73,- its back contact and armature, right hand front contact and armature of relay 69, lower back contacts and armatures of relays 7 O and 71 to ground. Under the control of this circuit the motor magnet advances the

brushes

74, 75, 76, 77, 7S and 79 in a step-by-step movement over the terminals of the trunks leading to the B operators position. When an idle trunk is reached, a condition indicated by the presence of ground on its test terminal, the trunk selector switch is stopped by acircuit traceable from ground, back contact and continuity spring of relay 80, back contact and continuity spring of relay 81, test brush 7 1-, the low resistance winding of relay 71, inner armature and front contact of relay 69, re- This last described circuit is effective to shunt the motor magnet 73 and to operate the relay 71. \Vhen the relay 71 is operated, it closes a circuit from grounded battery, winding of the relay 80, inner armature and back contact of relay 81, brush 75, upper frontcontact and armature of relay 71, upper right hand winding of the repeating coil, through the low resistance winding of relay 82, armature and front contact of relay 68, front contact and armature of relay 63 to ground. This operates the relay 80 which in turn lights the incoming signal, lamp 83. The B operator shown in Fig. 3, into the multiple trunk jack 85.

There is one such jack and lamp 83 at.

each of several B operators positions. The

relay 81 is then actuated in series with the relay 86 of Fig. 3, over a circuit from grounded battery, through the high resistance winding of relay 86, conductor 87, through the sleeve contacts of the plug '84 and jack 85, winding of relay 81, to ground. The relay 86 abarring relay similar to relay 10 of Fig. 1 and when operated closes a lockingcircuit for itself through its low re sistance winding,- in order to bar another 0perators telephone set from the same connection. The operation of relay81eifects the deenergization of the relay 80 and also completes a holding circuit for the trunk selector switch from grounded battery, resistance, armature and continuity spring of relay 81,

test brush 74, high resistance winding of relay 71, lowermost front contact and armature of this relay, to ground. \Vith the relay 71 operated, a circuit .is closed for the answer: ing supervisory relay 88 of the B operators cord circuit from grounded battery, winding of this relay, tip contacts of the plug 84 and jack 85, brush 75, upper front contact and armature of relay 71, upper right hand winding of the repeatingcoil through the low resistance winding of relay 82, armature and front contact of relay 68, front contact and armature of relay 63, to ground. Relay 86 of Fig. 3, on operation completes a circuit from ground,its outer armature and front contact, upper armature and back contactof relay 89, winding of slow releasing relay 90, windings of

relays

91, 92 and 93 to grounded battery. Relay 93 is of especially high resistance so that the relays 90, 91 and 92 will not energize in series therewith. Relay 93 however, is energized and at its armature and front contact closes a circuit for the right hand winding of the relay 92, which causes this relay to energize and extend the previously described series circuit through the windings of relays 90, 91 and 92, to grounded battery, independently of the relay 93. The relays 90 and 91 operate in this circuit and relay 91 closes a break-point in the operating circuit of the meter magnet 94. The relay 90 completes an actuating circuit for the operators cut-in relay 95, which may be traced from groundedbattery, winding of this relay, front contacts and armatures of the relay 90, winding of the relay 96, to grouml. The relays 95 and 96 are energized in this circuit. Relay 96 completes the circuit of the meter magnet 94 and the relay 95 extends the conductors 97 connected to the operators telephone set to the answering end ofthe B operators cord circuit.

As was described in connection with the cord circuit of 1, the

relays

91, 92, 93 and impedance coil 98 permit the operator to Ill) connect the answering plug of a. second cord stead of at the outer right hand front concircuit and only one tothe jack of a calling line, in adition to the connection which she is extending on a first cord circuit. As soon as the operators telephone set is connected to the answering end of the B cord circuit. the B operator inquires the designation of the wanted connection.

Let it be assumed that this wanted line is that represented at B at the upper right hand corner of Fig. 3. The operator then inserts the calling plug 99 into the multiple jack 100 of this line. It is als ass1unecl that the wanted line is a party line and in order to ogerate the signal at substation B, it is'necessary to apply ringing current of the proper fretpiency. The operator then depresses someone of the ringing keys. 101. 102, 103, or 104:. Let it be assumed that the operator depresses key 103. which in turn actuates the slow releasing relay 104. As soon as the plug 99 is inserted into the jack 100, the sleeve relay 105 is actuated from grounded battery. its winding, back contact and armature of relay S9. sleeve contacts of the plug 99 and jack 100, through the resistance of the cut-off relay (not shown) of the called line to ground. lVith the relays 10a and 105 actuated. the ringing relay 106 is energized from grounded battery its winding, condnctor .107, back contact and armature of relay 10S, conductor 109, inner front contact and armature of relay 105 right hand front contact and armature of relay 1041-, to ground. As soon as the relay 101 is operated. a cir cuit is also closed from ground. its front con tact and left hand armature, outer armature and front contact of relay 1.05, winding of relay 110, to grounded battery. This last named relay on operation closes a locking circuit for itself through its contact and left hand. armature. conductor 111. baclr contact and armature of relay 112, front contact and i'u'niiature of relay 105, to ground.

The relay 89 is energized simultaneously with ringing relay 106 and its operating circuit is traceable from grounded battery. upper winding of relay 89, inner front Contact and armature of relay 105 right hand arn'n ature and front contact of relay 1.04. to ground. As soon as relay 89 is energized it closes a locking circuit for itself through its lower winding. lowermost armature and front contact. through the sleeve conductor and sleeve contacts of the plug 99 and jack 100. to ground through the winding of the cut-off relay (not shown) of the wanted line. The relay 89 on energization also opens the circuit of the slow releasing relay 105, which shortly afterwards deenergizes to restore tl e ringing keys to common use. The locking circuits for the ringing relay 106 and for the frequency selecting relays such as 110 and 118 are now completed through the inner lower armature and contactof relay 8% in tact and armature of relay 105, to ground.

lVith relays 106 and 110 actuated. 66 cycle ringing current is applied through the outer back contact and arnlature of relay 113. front contact-and armature of relay 110. winding of the trip relay 114, innermost front contact and armature of the ringing relay 106, ring contact of the jack 100 over the lower side of the called line and through the ringer at substation 13, over the upper side of the called line through the tip contacts of the jack 100 and plug 99, inner armature and front contact of the relay 89, armature and front conact of relay 106, to ground. Ringing current: is supplied over this circuit until the subscriber at substation B responds by moving its receiver from its switchhook. at which time the relay 114- is actuated and at its front contact and armature places a short circuit about the relay 106. Relay 106 thereupon deenergizes and at its armaturcs and back contacts closes a break-point in the talking connection. During the time that relay 106 is actuated a circuit is closed through the winding of the induction coil of the ringing tone devices. lowermost armature and front coni'iact of relay 106. right hand winding of relay 113, armature and back contact of relay 95, winding of the relay 115, ring contacts of the plug Set and jaelc S5. brush T6. inner front contact and armature of relay '71. lower right hand winding of the repeating coil. winding of re ay 116. to grounded battery. Relay 116 is operated and at its inner armature and front contact closes acircuit for actuating the relay 11.7. which in turn closes a locking circuit for itself through its front contact and armature. armature and front contact of relay 82, to ground. Relay 116 on operation also causes relay 72 to be actuated from grounded battery. its winding. right hand armature and front contact of relay 116. to ground. Relay 72 when energized closes a locking circuit for itself. its front contact and armature, front contact and armature of relay 63. to ground. The relay 72 is loci-zed energized as long as the A. operator has the calling plug 23 in the trunk jack 41-7.. so that when the secondary trunk selector at the right of Fig. 2. is released by the i5 operator disconnecting her cord circuit from the. jack 85. this last mentioned trunk selector will not seize a trunk. The operation of the relay 117 short-circuits the high resistance. winding, which may be 10.000 ohms. of the relay 63. to permit the relav 61 at the originating oifice to operate. This relay when operated closes a circuit from ground through. the winding of relay 118. lower left hand winding of the repeating coil. front contact and armature of relay 59, brush inner front contact and armature of relay ring contacts of the jack 4:? and the plug 23, innermost armature and back contact of relay 32, winding of relay l, to grounded battery. The relay 31 on operation extinguishes the calling supervisory lamp in the same manner as if this cord circuit had been used on a local call and the local subscriber had answered. The operation of the relay 118 closes a circuit to operate the relay 65 and this relay at itscontinuity spring and armature completes a substitute circuit from ground at the front contact; and armature of tact and armature of relay 89,"to ground.

The deenergization of the relay 112 removes ground at its outer right hand armature and front contact fronrthe ring sideof the answering cord circuit to[ allow the relay 116'to deenergize'. The relays 117 and 72, however, are locked at this time so that the release of the relay 116 is ineffective.

, lVhen the subscriber at A replaces his receiver on its switchhook the relay 39 deenergizes, but the; answering: supervisory f ll lamp 41 notlighted. The deenergization of relay 39 establishes a circuit from grohnd, armature and front contact of relay l0,'armature and front contact of relay 48, conductor 120, armature and back contact of relay 89, over the ring conductor of the calling cord of Fig. 1, winding of relay 31, to grounded battery; This last described circuit maintains relay 31 energized, but shortcircuits and thereby releases relay 118 of Fig. 2. The release of relay 118- removes ground throughthe relay 66and the con-' du"tor 7 of the trunk leading to the distantoiiice which causes the relay 68 to deenergize. This connects the 10,000 ohm winding of the relay 82 in series with the tip side of the trunk conductor leading to the I jack The high resistance causes the relay 88 of Fig. 3 to deene-rgize and thereby light the answering supervisory lamp-121. Relay 82 does not deenerf rize at this time, so that the relay 117 is maintained operated to shortcircuitthe high resistance winding'ot relay 83. The B operator on noting that the lamp 121 is lighted, disconnects the plug 84 from the jack 85 and removes the plug 99 from the jack100, which causes the relays 82 and ll'ito deenergize. The release of the relay 117 connects the 10,000 ohm winding of relay 68 in series with the trunkconductors 62, which causes the relay 6]. to release.

Relay 63 does not deenergize at this time,

.so that the relay 72' is locked operated to prevent the operation of the'secondary trunk selector. The de energization of the relay 1 opensthe circuit of relay 1.18 and relay 31 also connects the 10,000 ohm winding of the relay 60, in the tipv sideof the calling cord,

which e'auses the relay 40 to cleenergize. Since the relay 31 is deencrgized at this time, and sincethe calling party has replaced his receiver on its switchhook, the supervisory lamp 4:1 is now lighted ina circuit completed from grounded battery, lamp l1, conductor 42, middle armature and back contact of relay 43, conductor 14:, inner, lower armature andback' contact of relay 39, inner armature and front contact of relay '10, impedance coil 45, toground The A'operator on noting thelighting of this lamp removes,thezanswering-plug7 and the calling plug '23 from[ the jacks with whic'hthey werein engagement. This operation permits the relays 50, 59and 60'to release and the release of relay 60"removes ground from the tip side of 62 of the trunl; to permit the relays and/72 to dee nergize. The circuits of the systemi are now in normal condition. I I" I Recall operation 7 In theevent thatthc calling subs(:riher initiates a recall before the B operator rfei'novestliel answerindplugSt from the trunk j ack 85, relays .88 and 10801? the cord circuit o'tFig. 3, are operated to-fiash thesnpervisory lamp 121, under the control of the interrupter devices 122. This is effected as follows: The temporary deenergization of relay 88 is eflected by replacing the calling receiver on its switchhook and subsequently removing it again. Relay 118 is short circuit-ed and released when relay 39 is deen'ergized by the callin subscriber replacing his sn itchhook. hen the calling subscriber again removes the receiver "from its switchhoolethe relay 118 again operates and connects groui'id to the ring conductor :67 of the .inter-oflice trunk, which agai'noperates relay (i8.

to be energized again. Relay 108 is operated, during the interval when the relay 88 deenergizes, in a circuit closed "from grounded battery, resistance, winding of relay 108,

Relay 681short-circuits the high resistanceof relay 82, which allows relay 88 liU lowermost back contact and armature oi circuit just (lee ribechbut'independentlyof the back conta 'ctfand armature of relay 88.

With the relays 88fand108 now operated'the.

answering supervisory lamp 121 of Fig. 3, is

interi-nittently flashed in a circuit from grounded battery, lamp 121, armature and front contact of relay 8S, outer armature and front cont-act of relay 108, winding of relay 123, interrupter 122, to ground. Relay 123 also intermittently lights the pilot lamp 121%.

i If the callingsubscriber desires another subscriber at the distant oifice, the B operator release of relay 117 includes the 10,000 ohm winding of the relay 63 in the trunk conductors 62, which causes the relay 61 to deenergize and this in turn opens the circuit of the relays 118 and 31. With relay 31 in its "normal, condition and with the relay 39 energized, since the recall relay 31 is now operated owing to the temporary releaseof relay 39, the supervisory lamp a1 is intermittently flashed in a circuit completed from grounded battery, lamp 41, conductor 42, middle armature and back contact of relay 43, conductor 1 1, lower armature and front contact of relay 39,, left hand armature and front contact of relay 3 1, winding of relay 124:, interrupter 125, to ground.

Relay 12 1' is also intermittently operated in this circuit and in turn intermittently lights the pilot lamp 126. The intermittent lighting of the supervisory lamp 611, is a signal to the A operator that the calling subscriber desires to initiate a recall.

Local call.

In the modified form of the invention shown in Figures 4, 5 and 6, when the subscriber at C desires to originate a. call to another subscriber whose line terminates at the same exchange. The subscriber at C removes his receiver from its switchhook. This completes a circuit for the line relay 128, over the two sides ofthe calling line in series and through the calling substation network. l/Vhen theline relay is thus energized, it closes a circuit to light the line lamp 129, which is a signal to the operator that a call. is waiting attention.

The operator then inserts the answering plug 130 of one of the cord circuits at her position into a jack 131 of the calling line. As the result of this operation the operator's barring relay 132, which functions for the same purpose as the corresponding relay in Fig. l, is energized from grounded battery through its high resistance winding, through the sleeve contacts of the plug 130 and the jack 131, winding of the cut-off relay 133 to ground. The relay 132 and cut-01f relay 133 are both actuated in this circuit and the cut-off relay at its armatures and back contacts opens the circuit of line relay 128,

which deenergizes to "extinguish the line lamp 129. The relay 132 when operated closes a locking circuit through its low resistance left hand winding, left hand arrna ture and front contact and thence to ground in series with the cut-off relay 133, as pre viously described. Also when the operator inserts the plug 130 into the jack 131, the answering supervisory relay 13a is energized in the well known manner, but the answering supervisory lamp 135 is not lighted at this time, since its circuit is open at the arn'iature and front contact of relay 136. With the relay 132 operated, a circuit is closed from ground at its right hand armature and front contact, upper armature and back contact of relay 137, winding of relay 136, winding of relay 139, left hand winding of relay 1&0 and winding of the high resistance relay 111, to grounded battery. The

resistance of winding 1 11 is so great that the other relays in series therewith arenot operated. The relay 141 is, however, oper ated in this circuit and at its armature and front contact, closes a circuit from ground through the right hand winding of relay 140, to grounded battery. This last circuit energizes the relay 1 10 and thereby extends a circuit from grounded battery, front contact and armature of relay 140 and thence through the windings of relays 1 10, 139 and 136, to ground as previously described, but the circuit no longer includes the high resistance winding of 14:1.

The arrangement of the relays as ust described together with impedance coil 1412, permits the operator to connect the answering end of a second cord circuit to a calling line for extending a second connection before all the operations in connection with a pre vious call have. been completed. But this arrangement is such that if more than two calls are sinniltaneously inthe process of connection, all of the calls will fail. The operator is therefore instructed not to attempt the completion of more than two calls at the same time. Since thehigh resistance winding has been eliminated from the series.

circuit in the manner just described, relays 139 and 136 are operated. Relay 139 serves to close a break-point in the operating circult of the meter magnet 1 13, while the operation of the relay 136 closes a circuit for the operators cutin relay 141 1. This circuit is closed from grounded battery, winding of relay 1 1%, right hand front contact and armature of relay 136, left hand armature and front contact of this relay, conductor 145, winding of relay 146, to ground. lhe relays 1&6 and 14A are thus actuated and the relay 146 completes the circuit of the meter magnet 143, which operates to record the number of calls answered by this operator.

The relay 1e 1- connects the operators telephone set (not shown) over the conducvtors 117xand the answering .end of the cord circuit, to 'the calling subscribeflsline. flt

should be pointed out atthis ,timethatthe answeringsupervisorylamp 135 is dimly lighted to indicateto the operator to which cord circuit hertele'phone set is connected.

The lighting circuit for-lamp 135 is trace-- able from grounded battery, through this lamp 185, inner armature and front contact of relay 184, left hand armature and back contactof relay 118, left hand. armature and from contact of relay 136, conductor 115,

the sleeve relay 150, ishactuated from.

grounded battery, its winding, back contact and continu ty spring of relay 137, conductor 151, through the sleeve contacts of the plug 149, to ground through the ,winding of: the cut-oil relayot the called line (not shown). "It is assumed'that the wanted line is a party line, and it is necessary for the. operator to depress some one of the common ringing keys 152, 158, 15,51 or 155 to select ringing current of the proper frequency to signal the wanted station. It is assumed that the operator depresses ringing key 154,, to actuate slow releasing relay 156, this is ellective to extend a circuit from ground, left hand front contact and armature of relay 156, outer left hand armature and front contact of relay 150, winding of relay 157, to grounded battery. At this same time the ringing relay 158 and the relay 187, are operated in multiple. A circuit for the relay 158 ,is traceable from grounded battery, resistance, winding of the relay 158, conductor 159, right hand armatureand iback contact of relay 1 18, conductor 160, contact 161 and inner rightfhand armature oi relay 150, conductor162, r ght hand armature and front contact of relay "156 to round. The circuit :for rela Y 87 closed 1 10111 grounded battery, upper winding of thisi'elay, inner, right hand lront contact andarniature or relay 150, to ground over conduct-or 162. The relay-181 when thus operated closes a locking circuit :tor itself through its lower winding, its

lowermost armature and continuity spring,

conductor 151 and thence toground through the sleeve contacts of the plugand jack and winding of the cutoff relay of the called line, (iiotshown). The ringing relay 158 is locked operated at this time from grounded battery, resistance, ts winding,

conductor 159, back contact and armature of relay 148, conductor 160, middle front contact and armature of relay 158,T back contact and arinat ure of relay 168, and to ground either at the outer from contact and armature of relay 150 or through the inner,

lower armature and front contact of rela-y 187. It should'be noted that-theactuation of relay 18-? opens the circuit of the sleeve relay 150, but the holding circuits controlled by this last named relay are-maintained by the relay 137.

\Viththe ringing relay 158 and the relays 137 and 1.57 operated, 66 cycle frequency ringing current is applied to the called line through the outer armature and back contact relay164t, armature and front contact of relay 157,-winding of the trip relay 165,

innermost front contact and armature of relay 158," through the ringcontactsot the -plug1l9, over'the lower side of the called line and the ringer the wanted substation, over the upper side of the called line (not shown), tip contact Oil the. plug 149, inneryupper armature front contact of relay 187,upper armature and front contact of relay 1-58, to ground. ll-ingingcurrent is supplied over this circuit until the calledparty. responds, atwhich time the trip relay 165 isenergized and at its front contact and armature short-circuits the ringing relay 158 which immediately deen'ergizes. The response ofthe called party also f ctuates the relays 168 and 166 through which talking battery is supplied to the called party. W hen therelay163 attracts its armatures, it o ens the holding circuit for the relay 157, w ich deenergizes. I

'At' the close of the conversation when the subscriber at C replaceshis receiver on'its switcl hook, the answering :supervisory relay 184 .deenergizes and lights the: ttIISWQ-llllg supervisory -relay 135 in a circuitqclosed from grounded battery, lamp 135, lower arn'iature and back contact of relay-13 1,

inner armature and front contact of relay 1:82, winding of impedance coil 167, to ground. Also when the called party replaces his receiver on its switcl hook, relays 163 and 166 deenergize' and the calling supervisory' lamp 168 is lighted in a circuit completed from grounded battery, lamp 168, middle back contact and armature of relay 158, back contact and armature of ref lay 1 63, inner, lower armature and front contact of relay 187, to ground. The lighting of lamps 135 and 168 is a disconnect signal for theoperator, who thereuponremoves the

plugs

130 and 1 19 from the jacks with whichthey were in engagement.

Recall operation on". local call.

In the event that the calling subscriber desires to initiate a recall, the relays and 170f11110t1011 nthe same manner asqiireviously described in the case of corresponding relays of Fig. l.

later-o fice call.

Let it be assume that the calling subscriber at C desires to call a subscriber such as D,

I whose line terminates at the distant oiiice.

The subscriber at G initiates a call by removing his receiver to light the line lamp 129 in the manner already described. The operator then inserts plug 130 into the answering jack 131, as a result of which the circuits function in the same manner as in the case of a local call to connect the operators telephone set over the conductors 147, to the calling line. The operator then inquires the number of the wanted line and inserts the calling plug 149 into a trunk jack such as 171 through which the distant oil-ice is reached. In this system the subscriber may be instructed to pause between giving the office designation and the remainder of the wanted number, so that the operator at the originating oiiiee can connect the cord circuit to the trunk leading to the distant oflice and an idle B operators position selected, before theealling subscriber gives the line designation to the operator of the distant oflice. In this way it will not be necessary for the A operator to repeat the number and it will likewise be unnecessary for the subscriber to give the line designation more than once. In the case of an inter-oflice call, it is unnecessary for the operator to depress any of the ringing keys such as 152 to 155 inclusive, but when the plug 149 is inserted in the trunk jack 171, a circuit is closed from grounded battery, winding of the slow releasing relay 150, back contact and continuity spring of relay 137 conductor' 151, sleeve contacts of the plug 149 and jack 171, winding of relay 172, back contact and continuity springs of

relays

173 and 174, to ground. The relay 172 is energized in this circuit and closes an operating circuit for the motor magnet 175, which circuit extends from grounded battery, resist ance, winding of the magnet 175, its back contact and armature, inner armature and front contact of relay 172, back contacts and continuity springs of relays 17 3, and 174, to ground. Under the control of this circuit the motor magnet 175 advances the

brushes

176, 177, 178, 179, and 181 over the vari ous pairs of trunks until a test brush such as 178 encounters the test terminal of an idle trunk leading to the distant office. This idle condition is indicated by the presence of ground potential on this test terminal. lVhen the idle trunk is reached, the motor magnet 17 5 is shunted and the relay 174 is actuated in a circuit completed from ground, upper back contactand armature of relay 182, back contact and continuity spring of relay 183, test brush 178, low resistance winding of relay 174, left hand front contact and armature of relay 172, resistance, to grounded battery. This circuit is effective to stop the operation of motor magnet 175 and causes the actuation of relay 174, which closes a locking circuit for itself from ground, continuity spring and inner armature, its lower winding and thence to ground through the sleeve contacts of the jack 171 and the plug 149, and the winding of relay 150. With the relay 174 operated, the calling supervisory relay 163 is actuated, from grounded battery, its inding over the lower side of the cord circuit, inner back contact and armature of ringing relay 158, ring contacts of plug 149 and the jack 171, inner, upper armature and front contact of relay 174, brush 177, lower armature and back contact of relay 183, winding of the slow releasing relay 182, to ground. Relay 182 attracts its armatures, whereupon the relay 183 is, operated from ground, its lower windings, lower armature and front contact of relay 182 and thence to grounded battery through the winding of relay 163 of Fig. 4, as previously described. Relay 183 on operation closes a iocking circuit for itself from grounded battery, its upper winding, upper armature and. continuity spring, test brush 178, lowermost front contact and armature of relay 174, resistance, to ground. As soon as the relay 163 of Fig. 4 actuated the relay 137 is energized from grounded battery, its lower winding, inner armature and front contact of relay 163, conductor 15], sleeve contacts of plug 149 and the jack 171, lower winding of relay 174, to ground through its armature and continuity spring. Relay 137 on operation closes a locking circuit for itself, through its armature and continuity spring, over conductor 151, which locking circuit is independent of the control of relay 163. At the upper, inner front contact and armature of relay 137, a breakpoint closed in the calling 0nd of the operators cord circuit.

The secondary trunk selector at the right of Fig. 5, is now started in operation as the result of the operation of the relay 184, which is energized over the

trunk conductors

185 and 186, in series to grounded battery, through the winding of relay 163 of Fig. 4, and to ground through the winding of relay 166. lVhen the relay 184 is thus energized it effects the operation of the slow releasing relay 187 and this last named relay closes an operating circuit for the motor magnet 188 from grounded battery, resistance, winding of the motor magnet 188, its back contact and armature, inner front contact and arma ture of relay 187, back contacts and armatures of

relays

189 and 190, to ground. Un der the control of this circuit the motor magnet 188 advances the

brushes

191, 192, 193, 194, and 196 of the secondary trunk selector until an idle trunk is located by one of its test brushes such as 192. At this time the motor magnet 188 is shunted and the relay 189 is operated in a circuit traceable from grounded battery, resistance, middle front contact and armature of relay 187, through the low resistance winding of relay 189, test brush 192, conductor 197, continuity spring and back contact of relay 198, lowermost back contact and armature of relay 199, toground. Therelay 189 is thus energized and the circuit previously described, as including the windings of relays 163 and 166 of Fig. 1, and the

trunk conductors

185 and 186, are now extended through the armaturgs and front contacts of relay 189, selector brushes 191 and 193, the left hand windings of the repeating coil of Fig. 6, through the high and low resistance windings in series of relay 200; This last named relay is energized and atits armatures and front contact causes the actuation of the slow releasing relay 198. 'A locking circuit is thereupon completed for the relay 189 of Fig. 5, traceable irom ground, lower armature and back.

contact of relay 190, upper high resistance winding of this relay, test brush 192, conductor 197, continuity spring and armature of relay 198, resistance, to grounded battery.

The incoming and disconnect lamp 201, is now lighted from grounded battery (not shown) lamp 201, conductor 202, middle armature and back contact of relay 199, inner.- most front contact and armature of relay 198, back contact and armature of relay 203,

to ground. On noting that the lamp 201 is lighted the operator depresses the answering key 204, of the telephone set (not shown), to the incoming trunk circuit over which the designation of the wanted line is received. On learning which line is wanted the B operator-inserts the plug 205 into the jack 206 of the wanted line and depresses some one of the

common'ringing keys

207, 208, 209 and 210. The insertion of thewplug into the jack 206, of the called line, extends a circuit for slow releasing sleeve relay 207, from grounded battery, winding of this relay, innermost back contact and armature of relay 199, sleeve contacts of the plug 205 and the jack 206, through the resistance of the cut-off relay (not shown), to ground. Let it beeassumed that ringing key'207 is'the proper key to select the'desired ringing cur- 7 rent to signal the wanted substation B.

This key operates the slow releasing relay 208 which effects the operation of the frequency selecting relay 249 from grounded battery, winding of this relay, inner front contact and armature. of relay 207, outer. front contact and armature of relay 208,to ground. The relay199 and ringing relay 210 are now energized in multiple. The circuit of the ringing relay 210 is traceable from grounded battery, resistance, its winding, right hand front contact and armature of relay 207, conductor211, inner 'front Congrounded battery, upper winding of this re lay, right hand front contact and armature of relay 207 conductor 211, winding of relay 212, to ground. The relay 212 is energized in this circuit and actuates the meter magnet 213, to record the completion of the call. The relays 2 19 and 210 when actuated in the manner described are locked operated in multiple. is completed from grounded battery, winding of this relay, its front contact and armature, lowermost armature and back contact of relay 203, lowermost front'contac't and armature of relay 199, to ground. The locking circuit for relay 210 extends from grounded battery, resistance winding of this relay, its middle front contact and armature, conductor 213, andthence in multiple with the circuit just described for the relay 2 19. The relay 199 on operation closes a locking circuit for itself from grounded battery, its lower winding, innermost front contact and armature, throughthe sleeve, contacts of the plug 205 and the jack 206, and the winding of the cut-off relay (not shown), to ground.

Ringing current is now applied to the ,wanted station from the 50 cycle source of ringing current contact 21 1 of the interrupter, lamp 215, front contact and armature of relay 249, back contact and armature of relay216, upper front contact and armature of relay 198, Winding of the trip relay 217, innermost front contact and armature of relay 210, through the ring contacts of the plug 205 and the jack 206, over the lower side of the called line and through the ringer at substation D, which responds to 50 cycle ringing current, over the upper side of the called. line through the tip contacts of the jack 206, plug 205, upper armature and front contact of relay 210, to ground. Under the control of this circuit, ringing current is supplied to the station D, until the subscriber thereat responds, at which time the trip relay 217 is energized. armature and contact of the trip relay shortcircuits the ringing relay 210, which deenergizes to disconnect the ringing currentand up his receiver, the relay 203 through, which talking battery is fed to the called line de- The locking. circuit of relay 2419a The closure of the lift) energizes and again'includes the 10,000 ohm winding of the relay 200 .in series with the

trunk conductors

185 and 186 and the relays 102-3 and 106, causing them to deenergize. The (leenergization of relay 162-) causes the supervisory lamp 168 to'be lighted but the supervisory lamp 201 of Fig. 6, does not light at this time. hen the subscriber at substation C hangs up his receiyer, the answering supervisory lamp 135 isfllighted, but no change is etlected in connection with the 15 trunlt circuit. The A operator now removesthe plugs 130 and 1&9 from the jQ-CkSWitl] which they have been in engagement, which causes. the disconnect lamp 201 to be lighted, since the remoyal. ot plug 145) causes the relays 17%, 183, 189 and 200 to deenergize. The relay 200 in turn causes the release of relay 198. The circuit for lighting the lamp 201 is thereby completed from grounded battery (not shown), lamp 201, conductor 202, middle armature and front Contact of relay 199, inner back con tact and armature otrelay lQS, inner baclt contact and a mature of relay 203, to ground. On noting that the lamp 201 is lighted, the operator removes the plug 203 from the jack 200, since the trunk is held busy until relay 10$) deenergizes.

Recall operation.

It the callingsubscriber should give the wrong oiiice designation the B operator at the distant oiiice can cause the answering supervisory relay 135, at the originating oflice to flash in order that the A operator thereat may connect the telephone set to the calling telephone line and then extend the call to the proper oliice. Neither the relay 163 nor 106, in the A cord circuit will be operated when the B operator at the distant oliice answers but by depressing ash back key 219, an energizing circuit is closed from grounded battery through the contacts of the listening key and thence over the tip side of the connection through conductor 185, to the winding of relay 16G. Relay 163 is shunted by the closure of the contacts of the key 215). and. since relay 106 is operated and relay 163 is inert, the relay 1-18 is actuated from grounded battery, resistance, its winding conductor 220, outer arn'iature and back -contact of relay 163, front contact and armature of relay 166, uppermost front contact and armature of relay 137, right hand contact and armature of relay 132, to ground. Relay 148 when operated closes a locking circuit for itself through its inner left hand front contact and armature, conductor 221, uppermost front contact and armature 01" relay 137, to ground at the outer front contact and armature of relay 132. The answering supervisory lamp is them intermittently flashed in a circuit extended from grounded battery, lamp 185, inner armature and front contact of relay 13 1, outer armature and front contact 0t relay 1&8, winding of relay 170, interrupter 222, to ground.

lVhile the answering supervisory lamp 135 is being flashed, the pilot lamp 223 is also intermittently lighted. The A operator at the originating ollice then removes the calling plug 1 19 from the jack with which it has been in engagement, which is effective to connect the telephone set to this cord circuit. The circuits are now in condition to initiate another trunk connection by plugging into the proper trunk jack.

What I claim is:

1. In a telephone system, an originating oflice, a distant oflice, a plurality of operators positions at said distant oflice, telephone lines terminating at each of said ofiices, means including automatic switching devices and trunks for extending a calling telephone lineat the originating oflice to a plurality of said 13 operators positions, certain of said automatic switching devices operating to test trunks in pairs and to interconnect an idle trunk of a pair to-a trunk connected to the calling telephone line, and means at each of said positions for connecting the calling telephone line thus extended to a. wanted telephone line. i

2. In a telephone systennan originatinq oliice, a distant oliice, a plurality of operators positions at said distant oiiice, party telephone lines terminating at said oi'lices, trunk jacks at said operators positions, a signal associated with each trunk jack, a plurality of trunks arranged in pairs, each trunk terminating in a trunk ack at each operators position, means including automatic switching devices for testing said trunks in pairs and connecting a calling telephone line at the originating office to an idle trunk ofo'ne of said tested pairs, means responsive to the selection of a trunk for actuating its associated signals at the operators positions, and means at each of said operators positions for connecting the selected trunk U) a wanted telephone line. s

I 3. In atelephone system, an originating otiice, a distant oflice, a plurality of opera tors positions at said distant ollice, party telephone lines terminating at said ollices, trunk jacks, at said operators positions. a signal associated with each ack, a plurality of trunks each terminating in a trunk jack at each 'operators position. means including automatic switching devices for connecting acalling telephone line at the originating oflice to an idle trunk, means responsive to the selection of a trunk for actuating its associated signals at the operators positions, a plurality of link circuits at each of said operators positions for connecting the selected trunk to a wanted telephone line, a plurality of sources of ringing current of several diflierent characteristics associated lit) ing said party telephone lines, and a single ringing key for each source or current, common to the link circuits'at an operators position.

at. The method or handling telephone calls in an interotl ice telephone system-which consists in testing trunking channels in pairs, extending a telephone connection from one office to points at; a distant otiice accessible to a plurality o'toperators through a se lected idle trunking channel of" tl'letestcd pairs, and manually completing the call to a wanted telephone line at any one of said points.

5. In a telephone system, an originating oltice. a distant otlice, a plurality or party telephone lines terminating at each of said ofiices, means including trunks and automatic switches for extending'a calling telephone line at the originatingoflice to said distant office, a plurality of links at said distant oiiice for connecting aselected trunk to a wanted telephone line, ax: plurality of sources of ringing current of several ditfercnt characteristics associated with said link circuits for selectively signaling said party telephone lines, and a single ringing key for each source of current, common to said link circuits. 7

6. In a telephone system, an originating oiiice, a distant ofiice, telephone lines terminating at each of said oflices, means including automatic switches and trunk circuits for interconnecting calling and called telephone lines, means for releasing from a called telephone line one of said trunks of a connection and means for preventing the subsequent seizure of a trunk by the extended calling telephone line if the calling subscriber thereon has not terminated the connection at this time. i

7. In a telephone system. an originating oliice, a distantoflicc, telephone lines terminating at each of said oitices, means ineludin trunks and automatic switches for interconnecting a calling telephone line at the originating oilice with a wanted telephone line at the distant office, means for releasing a trunk and a switch of the connection, means for preventing one of the automatic switches that extended the calling line from seizing a second idle trunk, until the calling telephone line originates a second call and means controlled from the originating oiiice for disabling said means. i i I 8. In a telephone system, an originating ofiicc, a distant oflice, telephone lines terminating at each of saidoflices, means including automatic switches and trunks for interconnecting said ofiices, means including operators equipment at each of said oflices for connecting theca-lling and called tele phone lines through said trunks and automatic switches, a signal at the distant cities arranged to be automatically intermittently operated under the control of the calling tt-llQPl'lOllQdlflQ, asignal a1-1ahgerlto he interinittently and autoniatically operated at said originating oiiice, and means including an operators equipment at the distant ollice for causing the operation ofthe signal at the originating ofiice. 9(In an automatic telephone systenn a'n originating o'llicc, a distant oiiice, telephone lines terminating at each of said oiiices,

meansincludingtrunks for interconnecting said ollices, operator-s equipment at each of said. oiliccs, for interconnecting a calling and a called telephone line through said trunking means,a recall device each of said oliices,

means controlled over the calling telephone line for actuating the recall device at the distaut oliice, and means including the operator's equipment at the distant otlice for disabling the recall device, thereat, and for actuating the recall device at the originatingoifice.

v 10. In a telephone, system, an originating oilice, a terminating oliice, party telephone lines terminating at each of said oliices,

trunks and automatic switches for interconnecting said originating office' and said distant oiiice, cord circuits at said originating oliice for extending a calling telephone line to any wanted telephone line terminating at said oflice and for extending any calling telephone line to a wanted trunk, cord circuits at said distant ofiice for interconnecting telephone lines terminating thereat and for extending a trunk connected to a calling line at the'originating olfice to a wanted telephone line at said distant oiiice, sources of ringing current of difierent character at each of said offices, and a single ringing key at each office for each source of ringing current common to the cord circuits at said otlices.

11. In an automatic telephone system, an originating office, a distant oilice, operators positions at each of said oflices, party tele phone lines terminating at each of said oh iices, a plurality of trunks terminating at each of said ollices, a plurality of cord circuits at each operators position at each of said offices for interconnecting telephone lines terminating at said oflices and for interconnecting a telephone line and a. trunk, sources of ringing current of different character at each of said oflices for signaling party lines terminating thereat, a single ringing key common to all the cord circuits of an operators positionfor selecting each source of ringing current, and means including at a cord circuit to a calling telephone line at the originating ofiice.

1-2. In anautomat c telephone system, an

originating olliee, a distant ottice, telephone lines terminating at each of said ofiices, means including trunks for interconnecting said oiiices, operators equipment at each of said oflices for interconnecting a calling and a called telephone line through said trunking means, a recall device associated with the operators equipment at each of said oiiices, means controlled over the calling telephone line for actuating the recall device at the distant oll'ice, and means including the operators equipment at the distant oi'hce for actuating the recall signal at the originat ing oflice While said trunking connection is maintained between said offices.

13. In an automatic telephone system, an originating oliice, a distant oiiice, telephone lines terminating at each of said. oilices, trunks terminating at each of said ofiices, means including an automatic switch functioning to test simultaneously pairs of trunks and to interconnect an idle trunk of one of said pairs to an idle trunk of a second pair of trunks for extending connections between calling telephone lines at the originatingofiice and called telephone lines at the distant ofiice, operators equipment at each of said oilices for interconnecting calling and called telephone lines through said trunks, a recall device at each of said offices, means controlled over the calling telephone line for actuating the recall device at the distant station, and means including operators equipment at the distanto'liice for actuating the recall device at the originating oiiice.

1 In a telephone system, an originating office, a distant oliice,a plurality of operators positions at said distant oifice, telephone lines terminating at each of said oflices, an automatic switch at each of said oliices, trunks arranged in pairs terminating at each of said automatic switches, said automatic switches functioning in tandem to test said pairs of trunks simultaneously and to extend a telephone line through certain of said tested trunks to said operators positions and means at each of said positions for extending the calling telephone lines to Wanted telephone lines.

in Witness whereof, I hereunto subscribe my name this 3rd day of May A. 1)., 192%.

VVINFRED T. POWELL.