US1488847A - Telephone system - Google Patents

Description

April 1, 1.924.

' n J. F. TooMEY TELEPHONE SYSTEM Filed Deb. 17 192e. ;S'fsvhets--sheet da/7 K700/W6] Patented Apr. l, 19254.,

maar? STATESy PATENT OFFIQE,

JOHN F. TOOMEY, GF NEW YORK, N. Y., vASSlIGrNOR TO AMERICAN TELEPHONE .AND

TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Application filed December 17, 1920.

To all iii/7mm t may conce-rn.'

Be it known that l, JOHN F. TooMnY, residing at New York, in the county of Nen7 York and State of New York, have invented certain improvements in Telephone Sysn tems, of which the `following is a specification.

This invention relates: to telephone systems, and more particularly, to systems in which trunk lines are employed for connecting different switchboards or operators positions. y

lt is the customary practice in telephone exchange systems to trunk connections for toll service from the originating switchboard or A operators position to a recording toll operators position over recording trunk lines. The recording operator answers the call incoming upon the toll trunk and records upon a ticket the details ot the call as given by the calling subscriber and notes if necessary the` class ot the calling subscribers line. Upon the completion ot the recording, the recording operator dis misses the calling subscriber and immediately releases the recording trunk. lVhen the trunk is released, the A operator receives a peremptory disconnect signal and disconnects regardless of the calling subscribers supervisory signal. The recording operator then secures the calling subscribers line over a toll switching trunk, enters the number of the trunk employed on the ticket and 'forwards the ticket to the toll operator at the toll line position. The recording operator then holds the trunk until the toll operator connects Witnthe trunk. The established connection then extends from the calling subscribers line over the toll switching trunk, through the toll operators cord circuit and thence over the toll line to the distant toll point, and the A operator and recording operator are free to perform other duties.

ln order that the operator at the recording; toll position may have complete data for' recording the toll vcall upon he'r ticket, it isv necessary to transmit to her information regarding the class ot service to which the calling subscriber is entitled. Heretofore in exchanges in which subscribers have access to recording toll trunks through an A op- Serial No. 431,424.

erators position, the A operator has identified the class of service to which the calling subscriber is entitled by means ot' a distinctive lamp cap on the calling lamp associated with the jack of the subscribers line and has advised the toll operator in case the call is from a coin box line or from a line to ivhiclrthe toll connection should be refused.v

To relieve the A operator ot the necessity ot advising` the toll operator of the class of servico to which the calling subscriber is entitled, it has been proposed to employ groups of recording trunks for each class of service, these trunks being equipped at the recording toll position With distinctive lamp-caps so that the A operator could select a recording trunk corresponding to the class of service indicated by the calling subscribers line lamp and thereby call the recording operator in upon the connection through the trunk signal `displayed at the incoming end of the toll trunk. The recording toll operator may thus readily determine from the lamp cap .associated with the trunk the class of service to which the calling subscriber is entitled. This arrangement obviously involves the employment ot a greater number of recording trunks than is necessary to adequately handle the maximum volume of trailic and since the toll po sition may be, and often is situated in a distant oilice of the exchange, the employment of several groupsv ot' trunks may prove to be an expensive item in the cost and mainte nance of the system. n

It is therefore the purpose of the invention to obviate this difficulty by the employ`v ment of a single group of trunks over which indications of the vclass of service may be selectively transmitted to the recording operators7 positions. This is accomplished. by terminating each trunk line in the A operators rpositions in separate multiples for each class of subscribers and providing mechanism associated With each trunk line for controlling the koperation ot class of service signals. at the recording toll position in accordance with the multiple. terminal ot the trunk line Which the A operator employed to establish the connection. ln the system illustrated each trunk line terminates in four sets of multiples, the lirst for lines which are not entitled t-o toll service, the second for lines which are entitled to originate toll calls and which are billed for this service in the regular way, the third for lines equipped with coin boxes, and the fourth for attended pay-station lines.

An object of the invention is therefore to reduce the number of trunk circuits required .between different switchboards or operators positions.

A further object is the provision of means for selectively operating one of a plurality of signaling devices over a trunk line in accordance with the particular terminal employed for connection with the trunk line.

A further object is the provision of a. selective signaling device at an operators position associated with and common to the cord circuits of the position which is selectively operated over a trunk circuit extending to a second operators position or switch-board.

ln accordance with one feature of the invention each recording trunk is terminated in the A operators positions in four sets of multiple terminals and in multiple jacks in the recording operators positions. At the incoming end of each trunk line a plurality of responsive devices corresponding in number to the sets of multiple terminals are provided which are selected and operated over the trunk line by synchronouslyv operating switching devices associated respectively with the opposite ends of the trunk line.

A further feature of the invention resides in the provision of a plurality of signaling devices associated with and common to the cord circuits of a recording operators position, which correspond innumber to said switching terminals and are selectively operated by the responsive devices upon connection of a recording operators cord circuit with the incoming end of a trunk line.

Further features of the invention will appear from the following description taken in connection with the accompanying drawings in which Figure 1 shows the out-going end of a toll trunk line together with associated signal transmitting apparatus, the cord circuit of an originating A operator and the line of a calling subscriber; Fig. 2 shows the incoming end of a toll line together with associated apparatus; and Fig. 3 shows the cord circuit at a recordingv toll operators position and signalinff apparatus associated therewith and common to the cord circuits of the position.

lt is believed that a clearer understanding of the invention may be had from the following description of the method of extending a connection from the line of subscriber A, Fig. 1 to the recording toll operators pcsiticn 0, Pig. 23. Subscriber A, upon initiating a call, removes his receiver from its switch hook thereby establishing a circuit through the windings of the line relay 100, which circuit may be traced from grounded battery through the left-hand winding of the relay, the outer left-hand armature and back contact of cut-olf relay 101, thence over the substation line loop and back through the inner armature and back contact of cutolf relay 101, to ground through the right hand Winding of line relay 100. Line relay 100 energizes in this circuit closing at its armature and front contact a circuit for the line lamp 102.

The operator at position O upon noting the illumination of the subscribers line lamp 102, picks up the plug P of an idle cord circuit at her position and inserts it' in the jack J of the line with which the lamp 102 is associated. A circuit is now established from grounded battery through the supervisory lamp 103, over the sleeve contacts of plug P and jack J and thence to ground through the winding of cut-oil relay 101. The cut-off relay 101 energizes in this circuit disconnecting the windings of line relay 100 from the conductors of the sub-v scribers line whereupon the circuit of line lamp 102 is opened and the lamp extinguished. The supervisory lamp 103 does not become illuminated in the circuit previously traced since upon the insertion of plug P in the jack J the answering supervisory relay 104 becomes energized over the calling subscribers line loop in the well-known manner closing at its armature and front contact a circuit in shunt of supervisory lamp 103.

The operator upon establishing a connection with the line of the calling subscriber throws her listening key 105 to connect lier set (not shown) indicated by the letters Ofl. with the strands of the cord circuit and ascertains from the calling subscriber the nature of the connection which the calling subscriber desires. In the case assumed the calling subscriber requests a toll connection. It will be further assumed that the calling subscriber is entitled to regular toll service.

The operator having noted from the lamp cap of the line lamp 102 that the calling subscriber is entitled to regular toll service inserts the calling plug P of the cord circuit in the jack J 2.

Upon the insertion of plug P in the jack circuit for the i' llt:

1 ,4ssen switching apparatus or rotary time relay 11a which may be traced from grounded battery through the right hand armatures and back contacts of relays 115, 116, 117, and 118, conductor 119, 'the right hand armature and iront contact of relay 110, conductor 120, conductor 121 and thence to ground through the motor 122 of the rotary time relay 114. above traced extends from conductor 121 over conductor 123, brush 1211, collecting ring 125, the Winding of clutch magnet 126 and thence to ground, In response to the energization of the motor 122 and energizetion ol clutch magnet 126, the motor 122 drives the brush arm of the time relay 114 in a counter clockwise direction for advancing' the brushes 127 over the terminal bank 128. This switch may loe of the type disclosed in my co-pending application Serial No. 329,801 liled October 10, 1919 and therelore need not be described in detail herein.

Upon the energization ot relay 110 and the establishment of the circuit for starting rotary time relay 114;, a circuit is also established in parallel with a portion of the circuit previously traced extending' from conductor 120 to groundthrough the winding of relay 129. Relay 129 upon energizing connects grounded battery and ground respectively to the ring conductor 130 and tin conductor 131 of the recording toll trunk extending to the recording toll operators positions whereupon a circuit is established for the line relay 200 at the incoming end of the toll trunk. This circuit may be traced from grounded battery through the left hand armature and front contact of relay 129 the lower armature and baclr contact of relay 132, trunk conductor 130, the lower lett hand winding of repeating coil 250, both windings of relay 200, the upper left hand Winding of repeating coil 250, trunk conductor 131. the upper armature and back contact of relay 132 and thence to ground through the right hand armature and front contact ol relay 129. Relay 200 energizes in this circuit and at its armature and Jfront contact closes a circuit for relay 201. At its lett hand armature and -front contact relay 201 establishes a circuit extending in parallcl branches through the trunk lamp 202 and through the Winding oic tone relay 203. The circuit of lam-o 202 may be traced :from Igrounded battery through the left hand armature and trout Contact ot relay 201, conductor 204C, the outer lett hand armature and back Contact ol relay 205` conductor 206 and thence to ground through the lamp 202. The illumination of lamp 202 signals the toll operator that a call is awaiting attention on the toll 'trunk with which the lamp is associated. Relay 203. which .is enrgized in a branch or". the circuit just rtraced extending 'from conductor 206 to ground A branch 'of the circuitl through the winding of relay 203, connects a source of tone current 207 to the tip and ring conductors 208 and 209 of the incoming end of the toll trunk 'l'or inductively transmitting a tone signal to the calling sub scribers line through the windings of Arepeating coil 250` over the conductors 130 and 131 of the toll trunk, and through the A operator-s cord circuit which tone signal remains upon the toll, trunk until after the recording toll operator has answered the call incoming to her position over the trunk. This signal informs the calling subscriber that the recording operator is being signalled.

Relay 201 also closes at its right hand armature and front contact a circuit for starting the rotary time relay 210, This circuit may be traced from grounded battery through the inner right hand armatures and back contacts oli relays 211., 212, 213 and 214, conductor 215, inner right hand armatures and back contacts oi relays 216` 217, 218 and 219, conductor 220, right hand armature and front contact of relay 201, conductor 221 and thence in parallel circuits through the motor 222 and the clutch magnet 223 of the rotary time relay 210. The energization of the driving motor 222 and of the clutch `magnet 223 causes the movement of the brush arm ot the relay in a counter clockivise direction to advance the brushes 224, over the terminals ot the terminal bank 225.

From the preceding description it 'will be noted that the rotary time relays 114e and 210 at the opposite ends oin the toll trunk are started into operation at substantially the same time, and since these relays mn be so adjusted as to operate at the same speed and since the lag in the starting or time lay 210 at the incoming end of the toll trunk due to the time elapsing after the starting of time relay 114 because ot the necessary energization of relays 129, 200, and 201 can readily be compensated for, the tivo time relays therefore move their respective brushes 127 and 2211 over their corresponding terminal banks in syuchronism.

Rotary time relay 114. will continue to advance brushes 127 over the terminals of the terminal bank 128 until the brushes engage terminals 150| corresponding to the jack 2 Which has been employed for the establishment of the connection` when a circuit AWill be established tor relay 110 which may be traced .from grounded battery through the Winding of relay 110` the normally closed break contacts of the lett hand armature of this relay, conductor 133, brushes 127, conductor 134-` conductor 135 and 'thence to ground at the lett hand urinature and front contact of relay 110. Relay 110 cncrgizes in this circuit. at the malte contacts of its lett hand armature a l l a s holding circuit for itself independent oi the bank terminals 150 of the rotary time relay 114. This holding circuit may be traced troni grounded battery through the winding of relay 11G, the make contacts of its left hand armature, conductor 13G and thence to ground over the circuit previously traced at the left hand armature and front contact of relay 110. Relay 116 at its right hand armature and back contact also opens the circuit previously traced eatendinff through motor 122 and clutch magnet 126 or the rotary time relay 11e and the rotary time relay is thereby arrested in its forward rotary movement,y and, due to the deenergization ot the clutch magnet 126, the brush arm of the relay returns to its normal position as shown in Fig. 1.

Immediately upon the energization of relay 116 and the opening ot the. driving circuit of rotary time relay 114, the circuit ot relay 129 is also opened and this relay being quick to release opens the circuit of' line relay 200 at the incoming end of the toll trunk before relay 132, which is slow to energize and for which a circuit is established upon the energization of relay 116, has time to energize. The circuit oi relay 132 may betraced from grounded battery through the right hand armature and back contact of relay 115, the right hand armature and front contact of relay 116, conductor 137 and thence to ground through the winding of relay 132. To diagramnmtically indicate on the drawing that relay 132 is slow to energize and that relay 143 is show to release arrows pointing in the direction in which armatures slowly move, are shown.

yThe momentary deenergization of line relay 200 following the deenergization of relay 129 opens the circuit ot relay 201 which, at its right hand armature and front contact, opens the driving circuit of the rotary time relay 210. Thus the forward movement of the brush arm of rotary relay 210 is arrested immediately following the energization of relay 116 upon the advance of the brush arm of the rotary time relay 114 to a position corresponding to the jack J2 which has been employed in the establishment of the connection. The brushes 224 of the time relay 210 will therefore be positioned upon the second set 227 of active terminals in its terminal bank 225. During the momentary deenergization of relay 200 and while the brush 224: is in engagement with terminal 227 a circuit is established for the relay 217, which, may be traced from grounded battery through the break contacts ot the lett hand armature or'- this relay, conductor 226, the second set of active terminals 22T ot the terminal bank 225, brushes 224, conductor 223 and thence to ground at the armature and back contact of linerelay 200. Relay 217 upon energizing establishes a locking circuit tor itself independent of the terminals 227 and brushes 224 of the time relay 210, and of the line relay 200, which may be traced from grounded battery through the winding and the make contacts otl the lett hand armature of relay 217, conductor 229 and thence to ground at the break contacts of the inner right hand armature of relay 205. At its inner right hand armature and back contact relay 217 opens the driving circuit previously traced tor the rotary time relay 210 to prevent a second operation of the rotary time relay upon a subsequent energization of relay 201. At its outer right hand armature and front contact relay 217 prepares a circuit for relay 212 which circuit becomes effective following the response of the recording toll operator. By the opening of the circuits of the driving motor 222 and of the clutch magnet 223 of the rotary time relay 210, the brush arm of the time relay returns to its normal position as illustrated in F ig. 2.

Following the energization of slow-toenergize relay 132, the circuit otl line relay 200 is reestablished and relay 200 again closes the circuit ot relay 201. Relay 200 is now energized over a circuit which may be traced trom grounded battery at the cord circuit ot position O, through the lower right hand winding of repeating coil 138, the winding of calling supervisory relay 139, the ring contacts ot plug P and jack J2, conductor 140, the lower armature and front contact of relay 132, conductor 130, the lower left hand winding of repeating coil 250, the windings of relay 200, the upper lett hand Winding of repeating coil 250, conductor 131, the upper armature and front contact of relay 132, trunk conductor 141, the winding of rela-y 1112, tip contacts of jack J2 and plug P and thence to ground through upper right hand winding ot repeating coil 138. The current flowing in this circuit while suflicient to energize the line relay 200 is not sutlicient to energize either relay 14-2 or supervisory relay 139.

The recording toll operator at position O in which the toll trunk line terminates, upon not-ing the illumination ot the trunk lamp 202 takes up the answering plug P5 of an idle cord circuit and inserts it in the `iack J5 of the toll trunk corresponding to the illuminated trunk lamp 202. A circuit is thereupon established which may be traced from grounded battery through the winding of marginal sleeve relay 300, conductor 301, the winding ot sleeve relay 302, sleeve conductor 303, sleeve contacts ot' plug P5 and jack J5, conductor 230, and thence to ground through the winding' ot the sleeve relay 231. Sleeve relay 300 being marginally wound does not receive sutlicient current when connection is nia-de with a toll trunk line for causing its energization, but relays 302 and 231 become energized in the circuit Cil traced. Relay 300 is provided with a niarginal action for a purpose which will be hereinafter set forth.

Relay 231 upon energizing establishes a shunt around the lett hand high resistance Winding of line relay 200, which shunt extends over conductor 232, the lett hand armature and :liront contact oi" relay 231, and conductor 233. Due to the shunting out of the high resistance Winding of relay 200, the current flowing over the circuit previously traced, extending through the winding of relay 142 and the Winding et supervisory relay 139 is nonT increased to such an extent that these relays become energized in series with relay 200. The energization ot' supervisory relay 139 establishes a shunt around the calling supervisory lamp 106 whereupon this lamp ceases to be illuminated. The energization of relay 142 establishes a circuit for relay 143 which may be traced 'from grounded battery through the Winding of relay 143, conductor 144 and thence to ground through the armature and front contact of relay 142. Relay 143 upon energization closes a circuit extending through the high resistance right hand Winding of relay 112 which circuit may be traced from grounded battery though the armature and front` contact ot supervisory relay 139 sleeve contact 107 of plug P', sleeve contact of jack J2, conductor 109, winding of relay 110, conductor 111, the lett hand armature and back contact oit' relay 112, the right hand winding of relay 112, conductor 145 and thence to ground at the armature and make contact ot relay 143. Relay 112 energizes in this circuit opening at its lett hand armature and back contact, the circuit ust traced though its high resistance right hand winding and removes a shunt existing up to this time around its lett hand low resistance Winding. Relay 112 is therefore maintained energized over the circuit previously traced extending from conductor 111 through the lett hand low resistance winding of relay 112, conductor 145 and thence to ground at the make contacts of the armature of vrelay 143. Relay 112 at its right hand armature and trent contact prepares a circuit for the perelnptory disconnect relay 146 Which circuit will be described hereinafter.

At the incoming end of the toll trunk upon the energization of relay 231 a circuit is established for relay 205 which may be traced from grounded battery through the right hand armature and front contact of relay 231, conductor 234v and thence to ground through the Winding of relay 205. Relay 205 at its outer lett hand armature and back contact opens the circuit previously traced extending in parallel branches through larnp 202 and through the Winding ci relay 203. The lamp 202 thereuponv loecornes extinguished and relay 203 deenergizes disconnecting the source ot tone current 207 from the conductors 20S and 209 of the toll trunk. u

Relay 205 at the break contacts et its inner right hand armature, opens the locking circuit }n:eviously traced extending through the Winding of relay 217, but relay 217 is held locked over a new holding circuit extending from conductm 220, through the outer right hand arniature and 'trent contact olf' relay 205, conductor and thence to gro-und through the outer left hand armatures and back contacts of relays 214, 213, 212, and 211, thus removing the control ot the locking circuit of relay 217 `troni the contacts of relay 205 to the contacts oiE relay 212, which relay is now energized over a circuit extending from grounded battery, Winding and break contacts of the inner lett hand armature of relay 212, conductor 236, the outer right hand armature and trent contact et rela-y 217, conductor 23'? and thence to ground at the inner right hand armature and front contact et relay`205. Relay 212 upon energizing establishes a locking circuit for itself extending through its Winding, the rnake contact of its inner left hand armature and thence to ground over conductor 237 and the inner right hand armature andtront contact of relay 205. Relay 212 at its outer left hand armature and back contact new opens the substitute locking circuit et' relay 217, and relay 217 becomes deenergized. Relay 212 at its inner right hand armature and back contact opens the circuit previously traced over conductor 215 to prevent` the reestablishinent of the driving circuit of time relay 210 when relay 217 become-s deenergized, and at its outer right hand armature and liront contact prepares a circuit for selectively operating class of service lamps associated with the recording toll operators cord circuit in a manner to be hereinafter described.

At the recording toll operators position relay 302 becomes energized in ythe circuit 'previously traced and at its outer right hand armature prepares a circuit for the super visory relay 304 for a purpose to be hereinafter described. At its inner hand armature, relay 302 establishes a circuit ttor relay 305 which circuit may be traced from grounded battery through the winding of relay 305, the right hand armature and back contact of relay 306, conductor 307, inner right hand aiunature and front contact ot relay 302, conductor 303 and thence to ground through the contacts 309 ot the operators talking key 310 provided the talking key 310 is in its norinal position in which the operators ytelephone set indica-ted at (l. T. is connected to the talking. strands 4ot the cord circuit. Relay 305 upon energizing establishesv a simplex operating-.circuit yfor controlling the selective operation of one of the class oic service lamps associated `with and common to the cord circuits of the open ators position 0.

It having been assumed that the respon sive device or relay 212 associated with the incoming end of the toll trunk has been selectively operated through the functioning of the rotary time relay 210, the control circuit for operating the class et' service signals may be traced as iollows: from the positive grounded pole ofabatteryr233 through resistance element 239, the outer right hand armature and iront contact of relay 212, conductor 24d), the mid point between the right hand windings ot repeating coil 250, ythence by parallel paths over trunk conductors 208 and 209, the armatures and back contacts of relay 241, trunk conductors and 243, the tip and ring contacts of jack J5 and plug P5, the tip and ring strands 311 and 312 of ythe toll operators cord circuit, normally closed contacts ot the talking key 310, conductors 313 and 314, the armatures and front contacts of relay 305, conductors 315 and 316, thence to the Inid point of coil 317, conductor 318 and to ground thro-ugh the windingv of marginal relay 319, the winding ot polarized relay 320 and the winding` ot' sensitive relay 321. Since the current flowing in this circuit impressed trom the positive pole of battery 233 and through only a portion 239 et the. resistance associated with the cir`` cuit battery 238, the marginal relay 319 at the operators position receives sutiicient current to energize in seriesA with relay 321. Polarized relay 320, however, does not energize since it attracts its armature only when current ot .negative polarity is impressed upon its winding'. lVith relays 319 and 321 energized, a circuit for class of service pilot lamp 322 is established, which may be traced trein grounded battery through lamp the outer right hand` armature and trent contact of relay 319, the armature and back contact oi relay 320 and to ground through the armature and front contact of relay 321.

Glass of service lamps 322, 323, 32st, and are. provided in the well-lniown manner with distinctive lamp caps corresponding to similar lamp caps which are placed upon the line lamps corresponding to lamp 102 ot sul)- scribers lines, and the toll operator upon noting the illumination oic a pilot lamp such is advised concerning the class olA service to `which theI calling subscriber is entitled.

It is to be noted in this connection that it responsive device 211 had been operated due to the seizure of jack J at the outgoingr end of the trunk, then resistance element 2114i would have been included in the circuit previously traced from battery 238 through the windings of relays 319, 320, 321 and in lhis'e'vent marginal relay 319 would not have essere@ sa-leien@ Current t0 energize and,

consequently a circuit tor lamp 323 would have been established "from, lgrounded battery through lamp 323, the outer armature and back contact of relay 319, the armature and back` contact of relay 320 and to ground at the armature and liront contact of relay 321. Had responsive device 213 been energized, then negative current 'from battery 2115 through resistance element 24:6 would have been impressed upon the control circuit and relays 319, 320 and 321 would all have been energized, since now the polarized relay 320 responds to the negative current. and lamp 325 would have been illuminated. In a similar manner had responsive device 2111- ifi' been energized, current from battery 2l?) `would have been impressed upon the control circuit through resista-nce elements 216 and 21T and relays 320 and 321 would have responded and the circuit ot lamp 321 would have been established.

The recording' toll operator upon notingr lhe illumination of class: of service lamp and upon receiving' instructions from the millingV subscriber as to the further exten sionoi the connection, proceeds to record the information on a ticket in the routine 'manh ner. Upon the completion of the recording, the recording* operator dismisses the callin subscriber.

1li iter having' obtained the necessary information from the calling subscriber, the ,recording toll operator may disconnect her set irom the `cord circuit which she has employed by throwing the key 31.0 to its hold ing` position. The contact 309 of the key is now opened and the circuit previously traced through the winding.;` of rclaj,v 305 is opened, thereby disestablishing' the signal control circuit previously traced tor controlling the operation of the class ot ser vice lamps. Relays 319 and 321 now become deenergized and lamp 322 is extinguished. lt at any time the operator desires to relight the lamp 322 to check up the class of service to which the calling subscriber is entitled, she may do so bv tluovving` the lrey 310 to the talking` position in which position contacts 309 are closed, and the control circuits previously traced are reestahlished. She may do this only when the pluie l)5 in the incl: J5. since the circuit f relay. not only depends upon the cl ircot contacts 309, but also upon the enerlnization sleeve relai' 302. i

Following the conipletimi ot recording. the recording' operator releases the recordinrT trunk by withdrawing plug- 135 from jack J5 and the circuitpreviously traced through the windings of relays 300, 302 and 231, is opened thereby opening the initial energ'izing circuit of relay 205 at the right hand armature and front contact of relay 231` Relay 205, however, does not deenergize at this time, Since relays 200 and are Still lill lill

Ll l) maintained energized over the toll trunk. Relay 231 upon deenergizing also removes the shunt from around the high resistance Winding of relay 200, whereby the current firming over the trunk through the windings of relays 200, 1-12 and 139 is decreased to such an extent that` supervisory relay 139 in the mininating operators cord circuit and relay 1-'1-2 in the trunk circuit become deenergized. Relay 142 upon deencrgizing opens the circuit of sloW-to-rcle-ase relay 143, which a ter a predetermined interval releases and closes a circuit extending from grounded battery, through interruptor 14'?, the Winding ot' relay 146,V conductor lei-S, the ri ght hand armature and front contact ot relay 112 and thence to ground at the back contact of relay 143. iBela-y 112 is non' maintained energized over the sleeve conductor 109, through both of its windings and resistance element 113. Relay 146 is intermittently energized in the circuit traced and at its armature and front contact closes a shunt circuit intermittently around the high resistance Winding or relay 112, this circuit extending from` ground, through the resistance element 113, the right hand Winding of relay 112, conductor 145 and thence to ground'a-t the armature and front contact of relay 14:6.` -The resistance of relay 112 being thus intermittently decreased, the current iiowing over the sleeve conductor 109 is thus intermittently increased and since at this time relay 139 is deenergized and the shunt around supervisory lamp 106 is, therefore, removed, the lamp 106 flashes to give the originating operator ythe peremptory disconnect signal. The operator noting this pereniptory signal, takes down the connection regardless of Whether the answering supervisory lamp 103 signifies that the calling subscriber has hung up his receiver or not.

The' originating operator upon Withdarwing the plug P1 from the acl: J2, opens the circuit extending through the windings of relays 139, 141-2 and 200. Theserelays deenergize, the relay 200 opening the circuit of relay 201 which in turn opens the loching circuit or relay 205. Relay 205 upon deenergizing opens the locking circuit previously traced through the Winding of relay 212, whereby all of the apparatus at the incoming` end oi the toll trunlr is restored to normal condition. At the outgoing end oi the toll trunk. the Withdrawal ot plug` 1 from the jack J2 also opens the circuit previously traced through the windings of relays 110 and 112 and the apparatus at the outgoing' end of the trunlr is thereby restoredr to its normal position.

The recording toll operator'now proceeds lo secure a connection in the usual manner with the calling subscribers line over a toll switching trunk (not shown), and having on, holds it by inserta icing cord circuit not inc ng jack of the switchin and records the number ol Ithe ,j trunk employed on the ticket which she previously made out.y She then transmits the richt-t to the toll line operator, who has access to multiples ot the switching trunks and to toll lines. The toll operator after receiving the ticket proceeds to obtain the desired toll connection, and aiter obtaining the connection connects the calling subscriber to the toll line over a multiple of the toll switching trunk.r is soon as the connection is established, the recording operator receives a disconnect signal at her holding cord circuit and thereupon takes down the cord circuit. inasmuch as this invention does not involve vthe consideration of the establishment of the connection beyond the recording operators positiomthe other circuits employed to completely establish the toll connection have not been shown or described in detail herein.

Should the originating operator at position desire to reca-ll the operator at the recordingtoll position Wh ile the connection is established over the toll trunk with the recording operators cord circuit, she may do so by applying ringing current from her cord circuit to the conductors of the toll trunk. This ringing current flowing over the toll trunk i'iovrs through the lett hand Winding or supervisory reiay 304i-, opera Jing this relay as a ring-down relay. Relay 304; upon energizing locks up through the contacts 332 oit lrey 310 and through the auX- iliary lamp 333, and establishes a circuit for recall lamp 334. The toll recording operator noting the illumination of lamp 334i then throivs the lrey 310 to the talking position for connecting her h'cad setto the strands i the cord circuit, whereupon she may converse over the established connection with the originating operator.

rihe operator at position O may also recall the operator at position G by Withdrawing the plug l?" Jfrom the jack J2 and reinserting it therein, whereupon relays 142 and 200 become momentarily deenergized. llhe deenergization of relay ifi-.2 is Without eiect, since it does not open the circuit of sloW-to-release relay for a sufficient time to cause its deenergination. The deencrgization oiI relay 200 opens the circuit of relay 201. which at its lett hand armature and baclr contact closes a circuit for relay 241 extending from grounded battery through the left hand armature and baci; contact of relay 201, conductor 249, inner leit hand armature and front Contact oi relay 205 and thence to ground through the Winding oi relay 241. Relay 24-1 upon energizing momentarily establishes a circuit for relay 304, which may be traced from grounded battery,

through the lower armature and iront contact ot relay 241, trunk conductor 243, the ring contacts of jack J5 and plug P5, the innermost lower armature and back contact ot relay 300, the outer right hand armature and Jfront contact of relay 302, conductor 330, the lett hand winding ot relayBOl, conductor 331, thcinnerinost upper armature and front contact of relay 800, the tip contacts ci plug P5 and jack J5, conductor 242 and thenceto ground through the upper armature and iront contact ot relay 241, Relay 304 upon energizing locks up as previously described and establishes the previously traced circuit for lamp 334.

Should the recording toll operator O de sireto recall the originating operator at position O, she may do so by intermittently withdrawing the plug P5 from the `iack J5. Since at this time relay 200 is energized over the toll trunk, thereby maintaining re lay 201 energized, which relay in turn inaintains a locking circuit for relay 205, the withdrawal ot plug P5 and the consequent deenergization of relay 231 does not permit relay 205 to Ydeenergizc to restore the signaling apparatus including relay 212. The intermittent deenergizationV ot relay 231 however,opens and vcloses the shunt around the high resistance winding of relay 200 and thereby causes the intermittent operation ot relay 142 and supervisory relay 139.

Y Upon each deenergization of relay 142 the circuit ot relay 14S is openedbut as relay 143 is slow-to-release, this relay does not deenergize between the intermittent deenergizations oit relay 142. The intermittent operation ot supervisory relay 139 interinittently removes the shunt from around supervisory lanip 106 so that the lainp 106 flashes in unison with the withdrawal and insertion et plugrl at the toll position. The operator noting the flashing et the larnp throws her listening key 105 for connecting her head set with the strands or" her cord circuit. She inay now converse with the operator at the position G as soon as the operator lat the latter position restores the plug P5 to the ack .l5 and throws her key 310 to its talking position.

lt niay be desirable Vto permit the recording toll operator to have access directly to the calling suhscihers line, this trajliic teaturc VbeingVc-it special importance in financial districts where telephone lines troni brokers oiliccs are terminated directly before toll operators tor the. purpose oit' giving such lines VVcivici: toll service. To enable the toll operator to supervise such connectionV and to supply such calling lines with talking current, it then becomes necessary to equip the anering end of' the toll cord circuits with ap'iaratus especially designedY tor the purpose.` Y Y Vlillhen the toll operator answers a call initiated upon such a subscribers line she inthe plug' P5 in the jack oit the calling line whereupon a circuit is established through the cuteoff relay ot the calling line, the sleeve contacts ot the subscribcrs jack and plug P45, conductor 303, Winding ot sleeve relay S0 conductor 301 and Yto grounded hatt through the winding oil marginal relay 300. Sleeve relays 000 and now l'ioth cuerfi ,e since the winding of tlie'cut-eti' relay or the ibers line is otl such low resistance that marginal sleeve relay receives sufficient current to cause its cuergization. Relay S00 upon energizing disconnects at its innerinost armatures and backcontacts, thewinding ot hridgcd supervisory relay 3041. l' the strandsY ot the rroni circuit, and at these armatures and their front contacts bridges the windings otsupervisory relay 337 across thcrstrands 311 anc 312 or the cord circuit. At its uppermost armature and back contact relay 300 opens the circuittor lainp 33e entending to the contact ot relay 304;, and at its lowermcst armature and front contact es-v tablishes a circuit tor clay 30(1 Relay 306 upon energizing opens the circuit ot relay 305 to prevent a talee operation ofthe class of service signaling apparatusV whichjapparatus is not now needed, since the operator can obtain the class of service to which the calling suscriber is entitled directly troni the laiup cap of the calling subscribers line lamp. At its left hand armature and front contact, relay 806 establishes a circuit for lainp 331i which may be traced troni groundcd battery through the lamp, the lett hand armatureY and front contact of relay 306, conductor 338 and thence to ground at Vthe arniature and backV contact of supervisory relay 337. Lainp 381i-, however, is not illuminated at this time since supervisory relay 337 w iich was bridged across the strands of the cord circuit upon the energization ot sleeve relay 300 is energized at this time over the calling subscriberls lineV loop. e

The recording toll operator receives instruction froni the calling subscriber and proceeds in the manner previously described to make out a ticket and to transmit the ticket to the toll operator who attends to eoY l. lil

the establishment or the desired toll ccn-A nection. Y, Y Y 1 ierccording toll operator also has access to tie lines extending' to the information desk, the rate charging desk and othertratlic desks of the otlice and may, when requested by the calling subscriber, complete connections to such desksvby inserting the plug P .in the jack J6 of such a line. Upon the insertion ot the plug P6 in the pack J6, a circuit is established tor sleeve relay 323, which may be traced troni grounded battery, through the winding ot relay 323 and thence to ground through the sleeve contacts of lli incase? plug l and jack J. Relay 323 upon enern gizing establishes a circuit for relay 3242 eX- tending from grounded battery through the armature and front contact of relay 323 and thence to ground through the winding oi relay 324. Relay 321i upon energizing opens the circuit extending trom the tip ol plug P to the test lead 325 extending to the operators set and connects the tip ot the plug to the tip strand of the cord circuit, and at its lower armature and front contact closes a circuit for bridging the supervisory relay 326 across the strands of the cord circuit. rlhe supervisory relay 326 is controlled over the tie lines towhich the cord circuit is con nected and controls the circuit oic supervisory lainp 328 in the usual manner.

lf the calling subscriber abandons the call after becoming connected to the recording operators position O', the originating operator noting the illumination olii supervisory lamp 103 proceeds to take down the connection. Upon the withdrawal of plug l)I from jack J2, the circuit previously traced eX tending through the winding of: relay 139, the winding of relay 1112 and the winding of relay 200 is opened and these relays deencrgize. YThe deenei'gization of relay 200 opens a circuit of relay 201 which in turn opens the locking circuit of relay 205, which locking circuit extends from grounded battery through the lett hand armature and front contact of relay 201, over conductor 204C and the outer lett hand armature and liront contact and winding of relay 205. Relay 205, however, does not deenergize at this time as the recordingtoll operator still maintains the connection with the toll trunk over her cord circuit and the initial energizing circuit ot" relay 205 is still maintained at the armature contacts of relay 231.

Relay 201` at its left hand armature and back contact now establishes a circuit tor relay 24:1 which may be traced from grounded battery, through the lett hand armature and back contact oi relay 201, conductor 249, the inner left hand armature and iront contact or" relay 205 and thence to ground through the winding of relay 241. Relay 2li upon energizing establishes the .reviously traced circuit for relay 30er which upon energizing closes a locking circuit for itself extending from grounded battery through its right hand winding, its armature and front contact, contacts 332 of key 310, it being assumed that key 310 is in its holding position, since the operator throws it to the holding position following the establishment or" the connection, and thence to ground through the auxiliary signal 333. Relay 304 also establishes a circuit for the recall lamp signal 334. The circuit of lamp 334 may be traced from grounded battery, through the lamp, conductor 335, the uppermost armature and back contact ot relay 300, conductor 336 and thence to ground through the armature contacts of relay 304 and auxiliary signal lamp 333.

rlhe toll operator noting the illumination ot lamp 3311 proceeds to take down the connection by withdrawing the plug P5 from the jack J5, whereupon the circuit previously traced through the windings of relays 300, 302 and 231 is opened and these relays deenergize. The circuits at the toll operators cord lcircuit are now in normal position with thek exception of the circuit previously traced through the supervisory lamp 334i and through the auxiliary signal lamp 333. These circuits remain closed until the operator restores the key 310 to its normal position, in which position her head set is again connected with the strands or" the cord circuit.

Relay 231 upon deenergizing opens the circuit oi'` relay 205 and since at this time relay 201 is deenergized, relay 205 becomes deenergized opening the circuits of relays 241 and 212. The circuits at the incoming end ci the toll trunk are now in normal condition.

At the originating operators position upon the withdrawal of the calling plug P from the jack (l2, the circuit previously traced through the winding of relay 110 and the winding of relay 112 is opened and these relays become deenergized. The circuits at the originating or outgoing end of the toll trunk are now restored to their normal condition.

While thek invention has been disclosed in connection with circuits operating upon a manual basis, it is obvious that the multiple terminals of the toll trunk at the originating operators position might terminate in the terminal banks of selector switches, as shown in applicants copending application Serial No.-4;31,2l25, liled December 17, 1921, and

be selected automatically by the functioning of the switches in accordance with digits dialed either by a calling subscriber or by a semi-mechanical operator. Further, it is obvious that the number of class of service lamps to be operated at the toll operators position need not be limited to four as herein disclosed, as the system may readily be eX- teiided to provide for the operation of any desired number of lamps.

llfhat is claimed is: i

1. A telephone exchange system comprising a trunk circuit terminating at its outgoing end in a plurality oi sets oiC switching terminals, a plurality of responsive devices associated with the incoming end of said trunk circuit corresponding in number to said switching terminals, a connecting circuit, switching apparatus associated with y the trunk circuit operating upon connection o'i' the connecting circuit with the trunk circuit or selecting and causing the operation of one of said responsive devices, means for connecting with the incoming end of said trunk circuit, and signaling means associated with said connecting means and adapted to he selectively operated by sai operated responsive device.

2. A telephone exchange system comprising a trunk circuit terminating at its outgoing end in a plurality of sets oi' switching terminals, a plurality of responsive devices associated with the incoming end of said trunk circuit corresponding in number to said switching' terminals, a connecting circuitswitching apparatus associated with the trunk circuit operating upon connection of the connecting circuit with the trunk circuit for selecting and causing the operation of one of said responsive devices, mea-ns for connecting with the incoming end of said trunk circuit, a plurality oi signaling devices associated with said connecting means corresponding in number tosaid responsive devices and means under the control of said operated responsive device tor causing the operation ot the corresponding signaling device.

3. A telephone exchange system comprising a trunk circuit terminating at its outgoing end in a plurality ot sets of switching terminals, a plurality of' responsive devices associated with the incoming end oi' said trunk circuit corresponding in number to said switching terminals, a connecting circuit, switching apparatus associated with the trunk circuit operating upon connection of the connecting circuit with the trunk circuit for selecting and causing the operation of one oit' said responsive devices, a cord circuit for connection with the incoming end of said trunk circuit, a plurality of signaling devices associated with said cord circuit corresponding in number to said responsive devices, and means under the control of said operated responsive device for causing the operation ot the corresponding signaling device.

4. A telephone exchange ystem comprising a trunk circuit terminating at its outgoing end in a plurality of sets of switching terminals, plurality of responsive devices associated with tlie incoming end et said trunk circuit corresponding in number to said switching terminals, a connecting circuit, switching apparatus associated with the trunk circuit operating upon connection ot the connecting circuit with the trunk circuit or selecting and causing the operation of one of said responsive devices, a cord circuit tor connection with the incoming end of said trunk circuit, a plurality of signaling devices associated with said cord circuit corresponding in number to said responsive devices and means operated over a simple-X circuit comprising a portion ott the tall-:ing conductors of said trunk circuit and of said insee-av cord circuit and under control of said operated responsive device for causing the operation of the corresponding signaling device.

5. A telephone exchange system comprising a. trunkcircuit, terminating at its outgoing end in a plurality ot sets of switching terminals, a plurality ot responsive devices associated with the incoming end of said trunl circuit corresponding in number to said switching terminals, a connecting circuit, switching apparatus associated with the trunk circuit operating upon connection ot' the connecting circuit with the trunk circuit for selecting and causing the operation of one oit said responsive devices, a cord circuit for connection with the incoming end oi said trunk circuit, a. plurality of signaling devices associated with said cord circuit corresponding in number to said responsive devices, and means comprising a sensitive relay, a marginal relay, and a polarized relay under the control ot'said operated responsive device ior causing the operation oir the corresponding signaling device.

6. A telephone exchange system comprising a trunk circuit terminating at its outgoing end in a plurality of sets of'switching terminals, a plurality of responsive d evices associated with the incoming end or said trunk circuit corresponding in number to said switching terminals, a connecting circuit, switching apparatus associated with the trunk circuit operating upon the connection of the connecting circuit with the trunk circuit for selecting and causing the operation of one of said responsive devices, a cord circuit for connection with the incoming end of said trunk circuit, a talking key for said cord circuit, a plurality of .signaling devices associated with said cord circuit corresponding in nunrher to said responsive devices, and means under the control of said key and of said operated responsive device for causing the operation of the corresponding signaling device.

7. A telephone exchange system comprising a trunk circuit terminating at its outgoing end in a plurality oi sets ot switching terminals, a. plurality of responsive devices associated with the incoming end ot said trunk circuit corresponding in number to said switching terminals, a connecting circuit, switching apparatus associated with the trunk circuit operating upon connection orn the connecting circuit with the trunk circuit for selecting and causing the operation ot one of said responsive devices, a plurality of cord circuits for connection with the incoming end of said trunk circuit, a plurality of signaling' devices coinmon to said cord circuits said signaling devices corresponding in number to said responsive devices and means under the meas-rr control of said operated responsive device for causing the operation oi' the corresponding signaling device.

8. A telephone exchange system comprising a trunk circuit terminating 'at its outgoing end in a plurality of jacks, a plurality of responsive devices associated with the incoming end of said trunk circuit corresponding in number to said jacks, a cord circuit, switching apparatus associated with the trunk circuit operating upon the con'- nection of the cord circuit with the trunk circuit for selecting and causing the opera-- tion of one ol said responsive devices, means for connecting with the incoming end otl" said trunk circuit and signaling means associated with said connecting means and adapted to be selectively operated by said operated responsive device.

9. A telephone exchange system comprising a trunlr` circuitterminating at its outgoing end in a plurality of jacks, a plurality of responsive devices associated with the incoming end of said trunk circuit corresponding in number to said jacks, a cord circuit, switching apparatus associated with the trunk circuit operating upon connection of the cord circuit with the trunk circuit fo selecting and causing the operation of one or said responsive devices, a plurality of cord circuits Jfor connection with the `incoming end of said trunk circuit, a plurality of signaling devices common to said cord circuits said signaling devices corresponding in number to said responsive devices, and means under the control of said operated responsive device for causing the opera-tion oi' bthe corresponding signaling device.

10.A telephone exchange system coinprising a trunk circuit terminating at its outgoing end in a plurality of sets ci switching terminals, a plurality of responsive devices associated with the incoming end of said trunk circuit corresponding in number to said switching terminals, a connecting circuit, a selective switch at the outgoing end of said trunk circuit opera-ting upon connection of the connecting circuit with the trunk circuit in accordance with the switching terminal employed, and a second selective switch at the incoming end ot said trunk circuit operating in accordance with the setting oll said first switch tor selecting and causing the operation ol one of the said responsive devices.

1l. il.. telephone exchange system cornprising a trunk circuit. terminating at its outgoing end in a plurality ot sets of switching terminals, a pluralityot responsive devices associated with the incoming end oi said trunk circuit corresponding innuinher to said switching terminals, a con-- necting circuit, a selective switch at the outgoing end 0i* said trunk circuit operating upon connection of the connecting circuit with the trunk circuit yin accordance with the switching terminal employed, and a second selective switch associated with the incoming end of said trunk circuit operating synchronously with said first switch for selecting and causing the. operation of one of said responsive devices.

A telephone exchange-system comprising a trunk circuit terminating at its outgoing cnd in a plurality of sets of switching terminals, a plurality or responsive devices associated `with the incoming end of said trunk circuit corresponding in number to said .witching terminals, a connecting circuit, a rotary time relay at the outgoing end of said trunk circuit operating upon connection or the connecting circuit 'with the trunk circuit in accordance with the switching terminal employed, and a second rotary time relay associated with the incoming end or said trunk circuit operating synchronously with. said first relay for selecting and causing the operation of one of said responsive devices.

i3. A telephone exchange system comprising trunk circuit terminating at its outgoing end in a plurality of sets of switching terminals, a plurality of responsive devices associated with the incoming end of said trunlr circuit corresponding in number to said switching terminals, a connecting circuit, a selective switch at the outgoing end of said trunk circuit operating upon connection of the connecting circuit withv the trunk circuit in accordance with the switching terminal employed, a second selective switch at the incoming end of said trunk circuit operating in accordance with the setting of said lirst switch for selecting and causing the operation of one oic said responsive devices, means for connecting with the incoming end of said trunk circuit, a plurality oic signaling devices associated with said `connecting means corresponding in number to said responsive devices, and means under the control of said operated responsive device for causing the operation of the corresponding signaling device.

14. A telephone exchange system comprising a trunk circuit terminating at its outgoing end in a plurality or sets of switching terminals, a plurality of responsive devices associated with the incoming end of said trunlr circuit corresponding in number to said switching terminals, a connecting circuit, a selective switch at the outgoing end of said trunk circuit operating upon the connection of the connecting circuit with the trunlr circuit in accorda-neef with the switching terminal employed, a second selective switch associated with the incoming end of said trunk circuit operating synchronously with said first switch for selecting and causing the operation of one of said responlll() sive devices, means for connecting with the incoming end of said trunk circuit, a plurality of signaling devices associated with said connecting means corresponding in number to said responsive devices, and means under the control of said operated responsive device for causing the operation of the corresponding signaling device.

15. A telephone exchange system comprising a trunk circuit terminating at its outgoing end in a plurality of sets of switching terminals, a plurality of responsive des vices associated with the incoming end of said trunk circuit corresponding in number to said switching terminals, a connecting circuit, a rotary time relay at the outgoing end of said trunk circuit operating upon connection of the connecting circuit with the trunk circuit in accordance 'with the switching terminal employed, a second rotary time relay associated with the incoming end of said trunk circuit operating synchronously with iid first relay for selecting and causing the operation oit one or" said responsive devices, means for connecting with the,incoming end ot said trunk circuit, a plurality of signaling devices associated with said connecting means corresponding in number to said responsive devices, and means under the control of said operated responsive device for causing the operation of the corresponding signaling device.

16. A telephone system comprising a trunk circuit terminating at its outgoing end in a plurality oit' sets of switching terminals, a plurality of electromagnetic devices associated with the incoming end of said trunk circuit corresponding in number to said switching terminals, a connecting circuit, switching apparatus associated with the trunk circuit operating in response to the connection ot the connecting circuit with 4the trunk circuit tor selecting and causing the operation of one ot' said electromagnetic devices, and signaling means selectively operated by said operated electromagnetic device.

17. A telephone exchange system comprising a trunk circuit terminating at its outgoing end in a plurality of sets of switching terminals, a plurality of electromagnetic devices associated with the incoming end of said trunk circuit corresponding in number to said switching terminals, a connecting circuit, a selective switch at the outgoing end of said trunk circuit operating upon connection of the connecting circuit with the trunk Y circuit in accordance with the switching terminal employed, and a second selective switch at the incoming end of said trunk circuit operating in accordance with the setting of said first switch for selecting and causing the operation of one of the said electromagnetic devices.

18. A telephone exchange system comprising a trunk circuit terminating at its outgoing end in a plurality of sets of switching terminals, a plurality of signals associated with the incoming end of said trunk circuit corresponding in number to said switching terminals, a connecting circuit, a selective switch at the outgoing end of said trunk circuit operating upon connection of the connccting circuit with the trunk circuit in accordance with the switching terminal employed, and means including a second selecting switch at the incoming end of said trunk circuit operating in accordance with the setting of said iirst switch for selecting and causing the operation of one of the said signals.

19. A plurality of classes of telephone lines, means for similarly supplying said lines with operating current, a trunk circuit therefor, means for connecting any one of said lines to said trunk circuit, visual signaling means for each of said classes of lines, and means responsive to the seizure of the incoming end of said trunk forop'erating said signaling means to indicate the class oiE telephone line associated therewith.

20. In a telephone exchange system, a plurality of classes of telephone lines, a trunk circuit having a terminal corresponding to each of said classes of lines, an electromagnetic device individual to each of said classes of lines, and synchronously operable means common to all of said lines for selectively actuating one of said electromagnetic devices in response to the seizure of said trunk by way of a corresponding terminal.

21. In a telephone system, a plurality of classes of lines, a trunk circuit terminating at one end in a switching terminal for each of said lines, a cord circuit for interconnecting said lines and said trunk circuit by way of said switching terminals, a second cord circuit adapted to be associated with said trunk in the establishment of a connection, a rotary switch at the outgoing end of said trunk, a rotary switch at the incoming end of said trunk, a signaling device for each ot said classes of lines, means responsive to the connection of said first cord circuit with one of the terminals of said trunk for effecting the synchronous operation of said rotary switches, and means responsive to the operation of said switches subsequent to the association of said second cord circuit with said trunk for selectively actuating a signal corresponding to the switching terminal employed in completing the connection.

In testimony whereof, I have signed my name to this specification this 15th day of December, 1920. V

JOHN F. TOOMEY.

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