US1815198A - Automatic telephone system - Google Patents

Description

July 21, 1931. T. o. GILCHRIST ET AL 1,815,198

AUTOMATIC TELEPHONE SYSTEM 4 Filed May 26, 1930 3 Sheets-Sheet 1 Thur-mas U. Gil: 'F'ET Eurward WIMP-E225 J ly 21, 1931. T. o. G|LCHRIST ET AL 1,315,198 AUTOMATIC TELEPHONE SYSTEM Filed May 26, 1930 3 Sheets-Sheet 2 NNN Durward July 21, 1931. T. o. GILCHRIST ET AL AUTOMATIC TELEPHONE SYSTEM 3 Sheets-Sheet 5 Filed May 26, 1930 Even-Tm Thmmas U. E'HEZ'W Durward mutfll' TIT Patented July 21,1931

UNETEE. STATEfi PATENT @FFHQE THOMAS 0. GILCHRIST AND DURW'ARD MURPHY, OF LORATN, OHIO, ASSIGNORS TO BE- SERVE HOLDING COIv'IPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF DELAVTARE AUTOIvTATIG TELEPHONE SYSTEM Application filed May 28, 1930. Serial No. 455,681.

This invention relates to automatic tele phone systems of the type commonly known as private branch exchange systems, particularly to systems in which incoming calls 5' from the public telephone system are normally intercepted and completed by an attendant. The invention is concerned primarily with circuits and apparatus for dealing with incomin calls in such systems when 1Q they are temporarily unattended.

The invention is particularly applicable to branch exchanges of the so called centralized type although its use is not limited to such systems. The centralized private branch exchange is characterized by having the switching apparatus located in an exchange of the public telephone system and only the subscribers telephone instruments and attendants switchboard located on the subscribers premises. A branch exchange system of this type is disclosed in United States Patent No. 1,804,575, granted May 12, 1931 to J. HfVoss et al., on which the instant invention may be considered as adirect improvement.

The utility of the private branch exchange, hereinafter referred to as the P. B. X., is well known. The particular advantages of the centralizec P. B. X. are fully discussed in the above-mentioned Voss patent and need not be considered in detail here. Exchanges of this type are used to a considerable extent in mercantile and manufacturing establishments and other institutions which require intercoimnunicating service. As a general rule the business of these organizations is carried on during the day with practically all activity suspended at night and on holidays. At these times the incoming telephone traffic will ordinarily not be sufficient to warrant the services of an attendant and, under these conditions, apparatus may be provided for automatically extending incoming calls to certain specified telephones where the calls can be answered by the night watchman or other person on duty. This type of service is commonly known as night service and will be referred to as such hereinafter.

It is the particular object of the invention to provide new and improved circuits and apparatus for supplying the so-called night service in a reliable and efficient manner. An incidental object is the simplification of the circuits and apparatus required for such service tending to increase their reliability and to reduce maintenance labor to a minimum.

Among the more important features of the invention is the complete controlof th night service set up by the P. B. X. attendant which frees the public exchange employees of all responsibility for this service. Another feature is the arrangement whereby the telephones assigned to night service are allowed normal local and outgoing service except, of course, when actually in use for incoming calls. The arrangement for establishing the night service condition without energizing any normally unoperated relays is also an important feature since it keeps the current consumption at a low figure. Another feature is the arrangement for utilizing the signalling andtalking equipment of the incoming connectors for night service without requiring these connectors to be directively operated. A further feature is the arrangement for busying all trunks not equipped for night service as soon as the equipped trunks are taken into use.

The foregoing features, together with oth ers not specifically mentioned, will be explained in detail hereinafter, with reference to the drawings comprising Figs. 1, 2, 3, and 4:. These drawings show, by means of the usual circuit diagrams, a sutlicient amount of the equipment in a telephone system embodying the invention to permit the invention to be readily explained and understood. The drawings should be arranged vertically in numerical order with Fig. 1 at the top and with corresponding lines in alignment. The apparatus shown in Fig. 1 and Fig. 2 is assumed to be located in a public automatic exchange and that in Fig. 8 located on the premises of a P. B. X. subscriber. Fig. 4 is a schematic diagram showing the trunk ing between a main exchange and a branch exchange embodyin the features of the invention. 1

Referring now to Fig. 1, CCis an incomion ing connector in which terminates two trunks, one accessible by way of the local and toll connectors of the public exchange, the other accessible by Way of selectors in either the public exchange or another private exchange. A simplex trunk from the connector extends to the attendants position, and by way of its bank wipers and banks, the connector has access to the various lines or" the P. B. X. Mechanically, connector CC is similar to the connector shown in the previously referred to Voss patent, modified however in accordance with the requirements of the present invention. Associated with the connector are the usual ringing tone generator G, ringing interrupter 1, and busy tone generator BT, which are common to all switches, such as connector CC of the P. B. X. In practice, separate auxiliary equipment would not be provided for each P. B. X. but similar equipment or the public exchange would be used in common.

Referring to Fig. 2, LS and LS1 represent lineswitches terminating, respectively, a P. B. X. line and a line from the attendants position. The switches shown are of the well known rotary type having no normal or home position although other types of lineswitches or finder switches may be used instead. Connector LC, shown in skeleton form, may be of the well known type commonly known as a P. A. X. connector such as that shown in U. S. Patent No. 1,582,226 to Ray. The connector is accessible to lineswitches of the P. B. X. and has access tothese lines and to trunks both to the public exchange and to one or more other private exchanges. The connector switches over and functions as a selector when one of the outgoing trunk levels is called. Xight relay group NR also shown in Fig. 2, is associated with connector CC and with certain of the P. B. X lines assigned for night service. A control trunk extends from the relay group to the P. B. X. attendants switchboard. Similar relay groups may be provided for each incoming connector if the volume of tratfic warrants, or only a few of the connectors may be so equipped. In the latter event, the relay groups are associated with the C011 nectors terminating the first choice trunks for reasons which will be discussed in later paragraphs.

In Fig. 8 is shown three ordinary automatic substations T, T1 and T2, terminating P. B. X. lines. Sub-station T is associated with lineswitch LS (Fig. 2) and substations T1 and T2 are associated with similar lineswitches which are not shown. The attendants telephone set AS includes the usual transmitter TR, receiver REC, calling device or dial SD, and is equipped with a key K for answering and extending calls over the extension line terminating in lineswitch LCl (Fig. 2). Relay group TRG terminates the simplex trunk extending from connector CC, (Fig. 1), and is equipped with two keys, key K1 for connecting the trunk with attendants telephone set and key K2 for controlling the night service apparatus. Calling and supervisory lamps L1 and L2 associated with the trunk relays are located at the attendants position. 7

Referring to Fig. l, TM is a main exchange substation associated with a line terminating in lineswitches LSM which has access to local selectors such as selector SM. Incoming selector ISM terminates a trunk from a switching level of a branch exchange connector such as connector LC. The banks of incoming selectors and local selectors are multiplied. These selectors have access to the various main exchange connector groups including a group of rotary connectors of which connector GM is one. The rotary connectors have access to the branch exchange line groups of which one trunk terminating in branch exchange connector CC is shown. Connectors CC and LC, night service relay group NR, lineswitches LS and LS1, operators set AS, trunk relay group TBG and substations T, T1 and T2 are shown in detail in Figs. 13. lit will be noted that a trunk from the banks of selector SM is shown extending to connector CC. This trunk may also be accessible to incoming selectors or switching connectors or" other branch exchanges as will be explained in later paragraphs.

Connector CG and the associated trunk circuits are adapted to operate when called from either a connector or a selector. A call from an outside subscriber is extended to the incoming connector which signals the attendant over the simplex control trunk ii. the P. B. X. is attended. The attendant determines the name of the party wanted and then dials back over the trunk to set the wipers or" the connector on the contacts of the proper P. B. X. line. The connector is arranged to give the usual answering supervision to the calling subscriber as soon as the attendant answers. After extending the call, the attendant disconnects the control trunk from the telephone set and the trunk relays operate to provide answering and disconnect supervision. Tn case the P. B. X. line called is busy, the attendant can release the connection and extend the call to another line while the calling subscriber waits. Both the connector and the attendants set are arranged so that the dialiing impulses cannot be heard.

lVhen the P. B. X is unattended key K2 will be operated and instead of the signal lamp L2 operating on incoming calls, relay group NR will operate to connect up the night service lines. All of these lines which are idle will be signalled simultaneously. When the call is answered from any of these the idle lines will be signalled in the usual way.

The operation of the apparatus on toll calls is the same as on local calls except that the attendant is not signalled until the toll operator rings. The called line is signalled automatically, however, as in a local connection.

he attendants position is also provided with a line over which local calls in the P. B. X. may be extended and received. The at tendant as well as the P. B. X. subscribers can call public exchange subscribers and other inter-connected private exchanges by way of the local switching connectors and outgoing trunks. Local calls in the P. B. X. are completed under control of a calling subscriber and do not involve any of the public exchange apparatus.

Having briefly described the operation and the apparatus involved, a detailed description will now be given. The progress of a call from a public exchange subscriber to the P. B. X. when the P. B. X. is attended will be considered first it being assumed that the subscriber at substation T1 is wanted. The calling subscriber extends the call over the public exchange apparatus in the usual way, local rotary connector such as connector CM (Fig. 4) connecting with a trunk to the P. B. X. for example, the trunk comprising conductors 2, 3 and 4 terminating in connector CC. Ground is extended over release trunk conductor 4 to relay 102 by way of contacts 196. Relay 102 operates, connects a bridge ineluding condenser 181 and the lower winding of relay 101 across the incoming trunk conductors at contacts 125 and 126, connects a busying ground to release trunk conductor 4 of the selector level trunk at contacts 123, connects ground to the local holding circuit at contacts 128, and closes a point in the simplex control circuit at contacts 129. This latter circuit is not effective at this time, however, since battery is connected to both ends of the simplex trunk. The connector in the public exchange now sends out ringing current in the usual way and relay 101 responds, completes locking circuit for its upper winding at contacts 121 and at contacts 119 closes a circuit for relay 103. flinging impulses from the connector will have no further effect on connector CC due to the opening of the bridge at contacts 120. Relay 103 operates, closes a circuit for relay 104 at contacts 130 and connects ground to the simplex trunk at contacts 133. Relay 104 operates and locks to the local holding circuit at contacts 135, opens the circuit of relay 103 at contacts 138, and at contacts 141 closes an additional point in the simplex control circuit. Relay 104 is made slowto-operate in order to allow sutficient time for relay 103 to become fully saturated. Relay 103 is a slow-releasing relay and maintains its armatures in actuated position for a short time after its circuit is opened by relay 104. Belay 103 then releases, disconnects ground from the simplex trunk and connects it through again to battery by way of contacts 134, contacts 129 and contacts 141 in parallel, contacts 1&7, lower winding of relay 103 to battery.

Returning now to the point at which relay 103 operated, ground from contacts 133 is extended by way of the right-hand windings of repeating coil R- and trunk conductors 6 and 'Z in parallel, left-hand windings of repeating coil R1, conductor 322, contacts 320, 319 and 343, lower windin of relay 309 to battery. Relay 309 operates and at contacts 340 closes a circuit for its own upper windings and lamp L2 in parallel. Relay 309 remains operated over its upper winding after relay 103 of the connector releases and disconnects ground from the trunk. Lamp L2 lights to inform the attendant that a call has come in over the trunk.

The call is answered by actuating key K1 to the right which closes a circuit for relay 307 at contacts 316, closes points in the talking circuit at contacts 315 and 317, and switches the control leg 322 of the simplex trunk from relay 309 of the trunk apparatus to the attendants set at contacts 319 and 318, respectively. Relay 307 operates and closes a circuit for relay 306. Relay 306 operates, opens the circuit for relay 309 and lamp L2 at contacts 341 and at contacts 342 prepares a circuit for relays 307 and 308. Lamp L2 is extinguished and relay 309 deenergizes. The simplex trunk now extends by way of conductor 322, contacts 320, 313, and 330, impulse contact 335 of calling device CD, and contacts 334 to ground through relay 304. Battery being now connected to the trunk at connector CC through relay 108 (relay 103 having deenergized) that relay and relay 304 of the attendants set energize in series. A circuit is completed for relay 109 at contacts 149 and that relay energizes, prepares the impulsing circuit at contacts 153, opens the release circuit at contacts 154, and connects a direct current bridge including resistance 182 across the incoming trunk conductors at contacts 152. A circuit is also closed for relay 105 at contact 194 but the operation of this relay has no utility in this particular connection. The bridge across the incoming trunk conductors causes the operation of the ring-cut-oft relay and back-bridge relay of the public exchange connector in the usual way and improves the transmission over the trunk by shunting condenser 178. The calling connector gives supervision in the usual way as when an ordinary call is answered. Returning to the attendants set, relay 30%. operates and completes a circuit for lamp L at contacts 337. Lamp L lights to indicate that the attendants set is connected to a trunk.

The attendant may now talk with the calling subscriber, the talking circuit including repeating coils R and R1 whichinductively connect the calling loop \VlLll the trunk and the trunk with the attendants set. The local talking circuit at the attendants position may be traced from condenser 321, right hand winding of repeating coil R1, contacts 315, 317 and 332, and the secondary winding of induction coil 10 across one winding of which the receiver REC is bridged. Talking battery is applied to the primary winding of the induction coil and transmitter TR, through impedance 305, the circuit being closed by the hook switch when the attendant takes the receiver REC into use.

It is assumed that the P. B. X. party wanted may be reached at substation T1 to which a local number assigned. lhe attendant now operates calling device CD in accordance with the digits of a local number and the previously traced operating circuit of relay 108 1) is interrupter at impulsing contacts When the calling device is turned oil-normal a circuit for relay 302 is closed at contacts 336. Relay 302 operates and connects direct ground to the simplex trunk at contacts 328 to improve the impulsing,and at contacts 329 opens the attendants receiver circuit so'that the dial impulses will not be audible to the attendant. Relay 108 responds to the interruptions of its oper ating circuit and transmits corresponding impulses to the vertical and rotary stepping magnets of the connector in a manner well known in the art. It may be pointed out, however, that relays 110 and 11 1 which operate during the vertical and rotary stepping operations, respectively, short-circuit a winding of repeating coil R at contacts 155 and 167 so that the calling subscriber does not hear the impulses from the calling device. WVipers 186-188 are set on the contacts of the called line in response to the dialling of two digits and the connector tests the line in the usual way. It the called line is busy relay 113 operates from ground on the test contact and locks up to ground at contacts 151. Busy tone is connected to the lower talking conductor contacts 106 and is audible both to the calling subscriber and to the attendant. The callin subscriber may hang up or may request the attendant to establish a connection with another extension line. The at tendant then momentarily operates key K1 to the left, opening the simplex trunk circuit, and relay 108 releases. The circuit of relay 109 is opened and that relay releases and closes the circuit of the release magnet. Relay 109 also opens the direct current bridge Release magnet 118 operates ringing urrent is sent over the calling line in the usual manner. The attendant will then restore key K1 to normal, thus making the telephone set available for other calls and reconnecting the simplex trunk to relay group It will be recalled that relay 307 operated over its upper winding when key K1 was operated to the right and that relay 306 was also operated. As key K1 is restored to normal, contacts 319 close before contacts 318 open and leg 322 of the simplex trunk is extended by way of contacts 3 12, lower winding of relay 30?, and relay 308 to ground. Relay 108 of the connector (Fig. 1) and re lay 307 remain energized over this circuit and relay 308 also operates. Lamp L1 lights l remains lighted until the called subriber answers. hen the called subscriber responds, the usual direct current bridge across the line is closed and ring-cut-ol'l' relay 112 operates in the usual manner to stop the ringing and extend the called line loop to battery teed relay 107. Relay 107 operates over the called subscribers loop and at contacts 147 and 148 disconnect-s the lower winding of relay 108 from the simplex trunk and connects the two windings of the relay in series thereto. The upper winding of relay 108 has a relatively high resistance and relay 308 of trunk relay group TRG is adjusted so that it will release under these conditions.

Relays 108 and 307, however, remain operated. Relay 308 opens the circuit of lamp L1 at contacts 339 and lamp L1 is extinguished to inform the attendant that the call has been answered. When the called subscriber hangs up, relay 107 will restore and again connect the lower winding alone of re lay 108 in the previously described supervisory circuit. Relay 308 will again energize and close the circuit of lamp L1 which relights to inform the attendant that the call has terminated. Should the lamp continue to glow, the attendant will again reestablish a talking connection with the calling subscriber by operating key K1 to the right. The attendant may release the connection with the extension line and set up a new connection in exactly the same manner as described for the operation after a call to a busy line. In case both calling and called subscribers hang up, the connection is released without any action on the attendants part. The calling subscriber opens the circuit of relay 102 which deenergizes and opens the circuit of relay 104. Relay 104 releases, and opens a point in the simplex operating circuit to permit relay 108 to release. Relays 109, 112. and 115 tien release and release magnet 118 operates to restore the wipers of the connector to normal position in the usual manner. At the attendants end of the trunk relays 306, 307 and 308 release and the apparatus'is immediately in condition to receive another call.

The operation of the trunk apparatus on toll calls is exactly the same as the operation described for local calls except that the calling toll connector does not send out ringing current automatically when the called trunk is seized. Relay 101 consequently does not operate until such time as the toll operator causes the connector to ring. The incoming trunk from the selector level, however, is made busy immediately when the trunk is seized and the toll operator may hold up the connection without signalling the attendant as long as desired. When the connector sends out ringing current, relay 101 operates, signals the attendant in the previously described manner and the connection to the P. B. X. line is set up as previously described.

The previously described call was extended by connectors in the public exchange. A call from a selector or switching connector level of either the public exchange or another P. B. X. will now be considered. The calling selector or switching connector having been operated to the proper level automatically selects a trunk to the P. B. X., for example the trunk comprising conductors 24, terminating in connector CC. Ground is extended over a release trunk conductor 4 to slow-release relay 103 by way of contacts 198, 122 and 138. Relay 103 operates, closes the line conductors through to line relay 106 at contacts 131 and 132, closes a circuit for slow-to-operate relay 104 at contacts 130, and at contacts 133 connects ground to the simplex trunk as in the previous connection.

Relay 104 operates, closes its own locking circuit and also additional points in the loop circuit to relay 106, opens the circuit of relay 103, and connects a holding ground to con ductor 4' to maintain the preceding switches operated. Relay 106 operates, closes apoint in the holding circuit of relay 104 at contacts 146, disconnects release trunk conductor 4 from the relay 102 at contacts 196 and at contacts 195 connects a busying ground to that conductor. The attendant is signalled and answers the call as described in the previous connection. Relays 108 and 109 operate as previouslv described, as does relay 105. Relay 105 by means of the usual contact arrangement reverses the direction of current flow over the incoming trunk conductors for the purpose of supervising and metering the call. The attendant then operates the con nector and the call is completed in exactly the same manner as described for connector level calls.

The operation of the apparatus on an incoming call to the P. B. X. when the same is unattended will now be considered. The attendant, before leaving the switchboard will operate the night key K2 of which one is provided for each incoming trunk. This operation connects ground to conductor 286 at contacts 352, prepares the control circuit at contacts 353, disconnects lamp L2 from in parallel with the upper winding of relay 309 at contacts 354, and at contacts 355 connects the upper winding of relay 307 in place of the lamp. All of the relays remain in normal condition until a call arrives.

The public exchange subscriber will extend the call as before described and relays 103, 104 and 106 of connector CC will operate as in the previous connections. Relay 103 connects a ground to the simplex trunk as before to operate relay 309 of the trunk rela 7 group. Relay 309 on operating completes a circuit for its own upper winding in parallel with the upper winding of relay 30'? at contacts 340. Relay 307 operates and closes a circuit for relay 306 at contacts 338. Relay 306 is equipped with a copper slug which makes the relay slow to operate so as to permit the switching operations at connector CC to be completed. After a slight delay, relay 306 operates, opens the circuit for the upper windings of relays 309 and 307 at contacts 341 and extends the simplex trunk to the lower winding of relay 307. Relay 309 releases but relay 307 is now energized in series with relay 108 of connector CG after relay 103 of the connector restores. Relay 306 by closing contacts 351 extends ground over contacts 353 of key K2 and conductor 287 to relay group NB.

It will first be assumed that the night service telephones T, T1 and T2 are idle at this time, and consequently that relays 252, 254 and 256, which are associated with the lines of these telephones, are normal. Relay 251 operates from the ground on conductor 287, connects battery to conductor 284 at contacts 261, completes a circuit for relay 258 at contacts 259 and extends conductor 286 through to relays 253, 255 and 257 by closing contacts 260. Relay 258 operates and by closing contacts 281-283 completes circuits for the relays corresponding to relay 102 of all incoming connectors not equipped for night service. These circuits extend over conductors corresponding to conductor 285 and the ground thereon serves to mark the trunks busy in the banks of the connectors. The re lays corresponding to relay 102 operate and mark the respective trunks busy in the banks of the selectors by closing contacts corresponding to contacts 123. This arrangement prevents an incoming call from seizing a conn-ector not equipped for night service and, of course, is not required when all connectors are so equipped.

Returning now to the relay group, relays 253, 255 and 257 on operating will connect the associated P. B. X. lines to the common trunk comprising conductors 288 and 289 which are connected to the talking conductors of connector CC.

It will be recalled that relays 307 and 308 of trunk relay group TRG were automatically connected to the simplex trunk by certain switching operations, and that the usual switching operations have taken place in connector CC. Relay 108 is, therefore, energized over the simplex trunk and relays 104 and 109 are also operated. Relay 108 by closing contacts 100 prepared the circuit for relay 111 and that relay operates when battery is connected to conductor 284 as previously described. Relay 111 on operating connects ground directly to release trunk conductor 4 at contacts 197 and at contacts 199 completes a circuit extending through resistance 100, contacts 168, upper winding of relay 115, contacts 163 and 151 to ground. Relay 115 operates, completes a holding circuit for its lower winding at contacts 175, and connects the talking conductors through to the ringing circuit at contacts 172 and 177. Kinging current is now transmitted over the com mon trunk to each of the P. B. X. lines connected up. When the call is answered from any one of the lines, a direct current loop is closed for operating ring cut-off relay 112 01 the connector. This relay functions as in ordinary connections and connects up the battery teed relay 107. The two subscribers may now converse over the talking circuit which is exactly the same as for the previously described connections except that the wipers of the connector are not included therein.

When the called P. B. X. subscriber hangs up battery feed relay 107 restores. This relay controls the supervision as in ordinary calls, which has no utility in the present connection. The calling subscriber on hanging up opens the loop circuit over which relay 106 is energized and that relay restores. Relay 106 opens the circuit of relay 104 which restores and opens the simplex control trunk at contacts 141. Relays 108 and 307 now restore, the latter opening the circuit of relay 306 which also restores. In the connector, relays 109, 111 and 115 restore following the release of relay 108. Relay 306 on restoring removes ground from conductor 287 which permits relay 251 to restore. Relay 251 opens the circuits of relays 258, 253, 255 and 257 and these relays release, which places the apparatus in normal condition.

An originating call from one of the night service telephones, for instance the telephone T, will operate the associated lineswitch, in this case lineswitch LS, to select an idle local connector. The lineswitch and connector will mark the line busy by connecting ground to release trunk conductor 193. A branch of this conductor extends via contacts 273 to relay 256 of the night relay group. This relay operates, closes points in the chain busy circuit at contacts 270 and 271 and opens the operating circuit of relay 257 at contacts 272. An incoming call at this time will operate the night relay group as before, except that relay 257 will not energize and only the lines associated with substations T1 and T2 will be connected to the common talking circuit.

In. the event that substation T1 is also busy, relay 254 of the night relay group will be energized and the circuit of relay 255 will be open. An incoming call will, therefore, signal only the substation T2.

In case all night service lines are busy, relays 252, 254 and 256 will be energized and grounded, conductor 286 will be extended via the chain circuit including contacts 262, 266 and 270 to relay 251. Relay 251 operates and closes the circuit of relay 258 which also operates. Relay 258 marks the other incoming trunks busy by closing contacts 281- 283. A branch or the above described chain circuit extends through contacts 271 and conductor 285 to relay 102 of connector CC. Relay 102 operates to mark the connector busy in the banks of the selectors. The connector is like wise marked busy in the public exchange connector banks by ground through contacts 196. Under these conditions, a calling public exchange subscriber will receive a busy tone, either from the selector which fails to find an idle trunk or from a connector which engages a busy trunk. When any of the night service lines become free the associated relay in the night relay group will restore and open the chain circuit, thereby removing the busy condition from the incoming trunks.

WVhat is claimed is:

1. In a telephone system, a branch exchange, an incoming trunk, an attendants circuit for intercepting incoming calls over the trunk, a switch including means adapted to be directively controlled by the attendant to further extend an incoming call to a subscribers line, and means controlled by the attendant for causing said switch to extend an incoming call to said subscribers line independent of all directive control.

2. In a telephone system, a branch exchange, an incoming trunk terminating in a switching device equipped with wipers adapted to engage contacts terminating subscribers lines, an attendants circuit for in tercepting incoming calls over the trunk and for operating said device to further extend such calls to a subscribers line via said wipers, and means controlled by the attendant for adapting said switchto automatically extend an incoming call to said subscribers line independent of said wipers.

3. In a telephone system comprising a main exchange and a branch exchange in which the switching apparatus for completing calls between branch exchange subscribers is lo cated in the main exchange, attendants switchboard for intercepting incoming calls from the main exchange and for further extending such calls to subscribers lines, and means effective when said switchboard is un attended for automatically extending incoming calls from the main exchange to a branch exchange subscribers line.

4-. In a telephone system comprising a main exchange and a branch exchange in which automatic switches for completing local and incoming callsin the branch exchange are located in the main exchange, a branch exchange attendants switchboard located at a point remote from the main exchange, a trunk extending from the main exchange to one of said switches and having a branch extending to said switchboard, means responsive to an incoming call over the trunk for signalling the attendant over said branch, means controlled by the attendant over said branch for operating said one switch to further extend the call to a subscribers line, and means controlled over the trunk and said branch for automatically operating said one switch to extend a call to said subscribers line when said switchboard is unattended.

5. In a telephone system comprising a main exchange and a branch exchange in which automatic switches for completing local and incoming calls in the branch exchange are located in the main exchange, a branch exchange attendants switchboard located at a point remote from the main exchange, a trunk extending from the main exchange to one of said switches and having a branch extending to said switchboard, means responsive to an incoming call over the trunk for signalling the attendant over said branch, means at the switchboard for operating said one switch over said branch to further extend the call to asu'bscribefls line, a night s rvice switching device for automatically operating said switch to extend an incoming call to said subscribe-rs line, and means for rendering said device controllable over said branch when the switchboard is unattended.

6. In a telephone system connprising a main exchange and a branch exchange in which the switching apparatus of the branch exchange is located in the main exchange, a branch exchange attendants switchboard located at a point remote from the mainexchange, a key at said switchboard, a trunk extending from the main exchange to branch exchange switch ing apparatus and having a branch extending'to said switchboard, and means responsive to a call over said trunk for signalling the attendant over said branch provided said key is for extending connections to certain of said lines independent of said wipers S. In an automatic switch equipped with wipers, means for directively operating said wipers to extend a connection to a line, and means for causing said switch to extend a connection to said line independent of said wip ers.

9. In a switching device equipped with wipers, stepping magnets for moving said wipers from normal position to extend a connection to called line, and means for extending a connection to said line while said wipers remain in normal position.

10. In a switching device equipped with wipers, stepping magnets for lifting and rotating said wipers to extend a connection to a called line, and means for extending a connection to said line without operating said magnets.

11. In an automatic switch, vertical and rotary stepping magnets for operating the switch to extend a connection to a called line, and means for extending a connection to said line without operating said magnets.

12. In a switching device equipped with a set of wipers, means for extending a connection to a called line either through or independent of said wipers, and common signalling means effective to signal the line in either type of connection.

13. In an automatic switch equipped with wipers, a switching relay adapted to operate responsive to the wipers engaging an idle line for connecting certain of the wipers tothe talking conductors of the switch, and means for operating said relay while the wipers remain in normal, unengaged position,

lt. In a connector switch equipped with line wipers and a double wound test wiper, a switching relay for connecting said line wip ers to the talking conductors of the switch, an operating circuit for said relay including one winding of the relay and said test wiper, and'a second operating circuit f 5 said relay including said one winding of the relay but excluding said test wiper.

15. In a telephone system, a connector switch equipped with wipers adapted to engage bank contacts terminating subscribers lines, means normally effective for directively operating said switch to extend a connection to a subscribers line via said wipers and the associated bank contacts, and means for adapting saidswitch to'extend a connection to said line independent of said wipers and bank contacts.

16. In a telephone system, a connector switch normally adapted to connect with and signal any one of a plurality of subscribers lines, and means for adapting said switch to simultaneously connect with and signal a plurality of said lines.

17. In a telephone system, a connector switch having access to a plurality of subscribers lines, means for operating the switch to connect with and signal said lines individually, and means for operating said connector to connect with and signal certain of said lines simultaneously.

18. In a telephone system, a connector switch adapted to connect with and signal a group of lines simultaneously, means for seizing the switch when one or more of said lines are idle, and means for preventing the seizure of the switch when all of said lines are busy.

19. In a telephone system, trunk lines, subscribers lines, connectors terminating said trunk lines and having access to said subscribers lines, circuit arrangements in one of said connectors adapting the same to signal certain of said subscribers lines responsive to the seizure of the associated trunk, and means for marking the other of said trunk lines busy responsive to said one connector being taken into use.

20. In a telephone system, trunk lines, subscribers lines, connector switches terminating said trunk lines and having access to said subscribers lines, other automatic switches adapted to select and connect with said connectors, and means responsive to one of said ing a connection to a subscribers line and for rendering the other of said connectors unselectable to said other switches.

21. In a telephone system, an automatic switch including a set of wipers, a called line, means for operating said switch to extend a connection to said line and to apply signalling current thereto either through or independent of said wipers, and means in the switch for supplying talking current to the called line in either type of connection.

22. In a telephone system, an automatic switch equipped with wipers adapted to be set by directive operation upon a set of bank contacts terminating a subscribers line, means for adapting said switch to extend a connection to said line independent of any directive operation of the wipers, and manually controlled means for rendering said last means operative.

23. In a telephone system, a connector switch having access to a group of subscribers lines, means in the switch for sig nalling called lines and for supplying talking current thereto, means including a preceding switch for seizing said connector switch to extend a connection to a called line,

connectors being connected with for extendand means operated responsive to said subscribers lines becoming engaged in other connections for preventing the seizure of said connector switch.

24. In a telephone system, a connector switch having access to a group of subscribers lines, means in the switch for signalling called lines and for supplying talking current thereto, selective switches having access to said connector switch, means responsive to the extension of a connection to said connector switch by one of said selective switches for marking the connector switch busy to the remaining selective switches and means operated responsive to all of said subscribers lines becoming engaged in connections excluding said connector switch for marking the switch busy to all of said selective switches.

25. In a telephone system, a pair of trunk lines terminating in an automatic switch, other similar pairs of trunk lines terminating in other automatic switches, means operated to mark both trunk lines of a pair busy responsive to either trunk line being taken into use, means for marking all of said other trunk pairs busy when the same are not in use, and means for rendering said last means operative responsive to a trunk line of said first pair being taken into use.

26. In a telephone system, a plurality of trunk lines associated in pairs, means operated responsive to the seizure of any trunk line to mark that trunk line and its associated paired trunk line busy, a device common to said trunk lines for marking all but one pair of trunk lines busy, and means for operating said device responsive to the seizure of either of the trunk lines constituting said one pair.

27. In a telephone system, a trunk line, other similar trunk lines, means individual to each trunk line for marking the same busy when the trunk lines are in use, means for marking said other trunk lines busy when not in use, said means being associated with said first trunk line, and means for operating said last means responsive to said first trunk line being taken into use.

28. In a telephone system, a group of trunk lines, automatic switches for selecting idle ones of said trunk lines and for connecting therewith, means for designating certain of said trunk lines for night service, means for operating certain of said switches to connect with said designated trunk lines, and means responsive to all of said designated trunk lines being connected with for rendering the remaining trunk lines unselectable to the remaining ones of said switches.

29. In a telephone system, trunk selecting switches, a group of trunk lines normally accessible to said switches, means individual to each trunk line operated responsive to the extension of a connection thereto by one of said switches to mark the trunk line unselectable to the remaining switches, and means temporarily associated with the first trunk line of the group and operated responsive to the extension of a connection thereto by one of said switches to mark all of the remaining trunk lines of the group unselectable to i

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