US2248040A - Telephone system - Google Patents

Description

J y 8, 1941' w. M. BEAUMONT 2,248,040

TELEPHONE SYSTEM- Filed Feb. 20, 1940 4 Sheets-Sheet 1 F/GJ \ w INVENTOR g 9 WM. BEAUMONT k BV 4 Sheets-Sheet 2 QNN NNN TIDNN m W. M. BEAUMONT TELEPHONE SYSTEM Filed Feb. 20, 1940 mww #WTNNN Jul 8, 1941.

INVENTOR 7 WM. BEAUMONT 8V rron/w July 8, 1941.. w. M. BEAUMONT TELEPHONE SYSTEM iim k 4 Sheets-Sheet 3 INVENTOA" WM BEAUMONT y Filed Feb. 20, 1940 ATTORNEY y 3, 1941- w. M. BEAUMONT 2,248,040

TELEPHONE SYSTEM I Filed Feb. 20, 1940 4 Sheets-Sheet 4' SPEAKER CIRCUIT L OUD FIG- 4 IN VE N TOR ATTORNEY Patented July 8, 1941 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM William M. Beaumont, Summit, N. J assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application February 20, 1940, Serial No. 319,350

9 Claims.

This invention relates to telephone systems and more particularly to telephone systems in which keys are employed at an attendants position for use in handling calls extended to or originated at substations, central oflices, and the like.

It is the object of this invention to provide an improved type of key equipment and associated circuits which render it possible for an attendant to answer calls from, and originate calls to subscribers stations, central offices, and the like.

In accordance with a particular feature of the invention a subscribers station located on a key equipment line which is designed to provide conference facilities, is provided with a visual signal which functions, when an attendant at whose position the line terminates is busy handling a connection on another line, to indicate to the subscriber that the attendant is busy and not immediately available to receive a call originated at the subscribers station. More specifically, when an attendant actuates a key which functions to connect his telephone equipment with a particular line circuit, a relay in the key equipment conference line functions to effect the lighting of a busy lamp at the conference station, or stations, associated with the key equipment line or lines, to indicate to the subscribers thereat that the attendant is busy and not available to receive calls originating at the conference stations.

A related feature contemplates the provision of means whereby a subscriber on a key equipment line circuit of the conference type is not isolated from the attendants position when the attendant is busy in handling other calls as indicated by the lighted condition of the busy lamp signal at the subscribers station. This feature is particuarly desirable in that, in the event of an emergency, the subscriber may utilize the regular line circuit equipment and follow the same procedure in initiating a regular call to attract the attention of the attendant, though the latter is, at that time, engaged on another connection. This feature is made possible by the provision of means which functions, not only to light the busy lamp at the conference station, but also to prepare an auxiliary energizing circuit for the subscribers line relay so that, should the subscriber find it necessary to signal the busy attendant, he

may do so by removing his receiver from its switchhook to complete the auxiliary circuit and cause a line signal to be displayed at the attendants position.

These and other features of the invention will be readily understood from the following detailed description made with reference to the accompanying' drawings in which:

Fig. 1 illustrates diagrammatically two types of line circuits, a conference line L and a non-conference line L1, over which calls to and from the subscribers stations A and. B, respectively, may be originated and received at an attendants position;

Fig. 2 is a diagrammatic representation of the common signaling circuit which functions with the lines L and L1;

Fig. 3 is a diagrammatic representation of the attendants key equipment and associated circuits;

Fig. 4 illustratesan attendants and a supervisors telephone equipment, and a key for associating the latter with the attendants key equipments for monitoring and supervisory purposes;

and

Fig. 5 is a block diagram illustrating the manner in which Figs. 1', 2, 3 and 4" are to be associated in order to effect'a complete system.

The following description is directed to the operation of the system on a call originating at station A associated with the line L, which is arranged for conference service.

When the handset I00 at station A is removed from its mounting, line relay IOI operates in a circuit extending from grounded battery, upper winding of relay IOI, conductor I02, backcontacts and lower armatures of relays I03 and I05, through the subscribers station loop, now closed at the handset mounting contacts, conductor. I04, upper armatures and back contacts of relays I05 and I03, conductors I06 and.- I0'I to ground through the lower winding of relay IOI. When the handset I00 is removed from its mounting the contact I08 is opened, thus opening the connection to the busy lamp I09 at station A.

Relay IOI in operating, establishes an obvious operating circuit for relay I I0. At its inner right armature, relay IIO connects ground to the lead III by way of the back contact and innermost upper armature of relay II2. At its outer left armature, relay IIO removes battery from the winding of relay I03 to prevent thisrelay from operating in case the attendant signals other conference line stations while connected to this line. At its inner left armature, relay I I0 connects battery to conductor I I3 which causes the supervisory lamp 3 I4 at the attendants position to be lighted. At its outer right armature, relay IIO completes a circuit from grounded Jbattery, armature and outer lower armature of relay IIZ, front contact and outer right armature I scribed more fully hereinafter:

of relay I I0, conductor II5, winding of flashing relay I I6, conductor 2I1 (Fig. 2), to ground by way of the back contact and armature of relay 2I8. At its outer left armature and front 'contact, relay I I connects battery to conductor I I9,

which extends to the right armature of flashing relay II6, for lighting the line and busy lamps for itself to the front contact of relay 2I8, and

and ground i armature, relay 22I prepares a locking circuit at its upper armature and front contact partially closes an auxiliary signal circuit.

Relay 222 operated, completes an obvious circuit for relay- 223,-w-hich' relay operates'an'd'in turn establishes an obvious operating circuit for relay 224. R'elay 224; which is slowtorelease,

operates relay 2H3. Relay 2'I8' opens thelead-2I1 1 and similar leadsto other line' circuits'and closes the'holdingcircuit for relay 22 I The opening of the lead" 2H and other similar 3 leads, releases relay II6 which had previously connected ground. to the-start lead2l'3.- Relay 220, accordingly releases and in'turn releases re- 1 lay-s. 222, 223, 224 and 2I8. When -relay2'I8re- 1 leases, ground is again connected to-tlie lead 2H 3 to the line circuit which will again causerelay II6 to operate and to again connect ground to thefstart lead 2I9. Relay 2'2I is-slow to release andholds operated duringthetime relay 2I8 're- 1 i leases until relay H6 and relay 220 reoperate. "Relays 220, 222, 223, 224' and 2l8-again reoper- I ate and release and continue to do so until'the call is answered by the attendant. As a result of l the repeated operations andreleasesof relay I I6, the line and busy lamp 320 at the key box at'the i attendants position is caused to flash 'to' indii cate an incoming callon the line associated with I the key K at the attendants position.

As the line on which station: A is located is a conference line, relay 225 will operate when ground'is'connected'to' the conductor III by the "operation of relay IIO as previously described. QRelay 225 operated, causes the buzzer 226 toopferate. steadily on current from the continuous ringing source connected. to the leads 228 and 229. If the call is on other. thana. conference line, the buzzer 226 will functionintermittently as-will be de-' when relays 2'22 and 224 operate When the attendant answers by operatingthe jline key K inthe key'box associated with the line upon which station A is 1ocated,.relay' I I2:oper.-

late's in a circuit extending from grounded batitery', winding or relay I-I2, conductor I20,- contacts: 32I of key K, conductor 322'; conductor 400, lclosedjack contacts'40I (it being understood that the attendants telephone set 402 will be plugged into the jacks 403' and 404 by means .of: the associated plugs), conductor 405ywindingof relay 323; conductor'324, outer upper armatureand back contact of relay 325, conductor 326 to ground: at the normally closed lower' contacts of relay321. I

Relay I I2 operated, removes battery at its outer lower armature from "the lead II5v which causes .relay H6 to release, and connects this battery to its 'front contact to cause. the line. and busy lamp 320 to operate steadily 'as a busy indication.

At its innermost upper armature, relay II2 opens the circuit to relay 225 which, in restoring its armature silences the buzzer 226. At its outermost upper armature, relay II2 opens the circuit to relay I05 and at its middle upper and inner lower armatures closes the tip and ring leads of the calling line to the attendants telephone and key circuit.

When the keyK was operated, a circuit for relay II2 was completed as above described. This circuit includes the winding of relay 323 so that this relay also operates. The plug of the attendants telephone set 402 must be in the talk jacks 403 and 404 as hereinbefore mentioned, and all keys other than the conference keys must be normal, otherwise the circuit for operating relay 323 is open. Two or more conference keys may be operated at one time.

Relay 323 operated, causes relay 328 to operate in an obvious circuit which starts the voice recorder (not shown, but controlled over conductors 329 and; 330) to function; connects ground to lead 33! for lighting busy lamps'at the loud-speaker, not shown, and connects ground to the lead 332, 365 to provide-for the lighting of the busy lamps, such as lamp I00, atthe' conference stations, in a manner; to be more fully described hereinafter. At its inner lowerarmature relay 32B opens the circuit to relay 333 to prevent. this relay from operating'at this time, and at its outermost upper armature an obvious circuit forrelay 334.

Relay 334 operates and closes. the transmitter andreceiver circuits of the attendants handset 402. The transmitter of handset 402 is-connected across the winding 401 of repeating 0011408 in the following circuit; starting with the upper terminal of winding 401, thence through condenser 409, conductor 4I0, jack spring M I, plug contact 4I2, conductor 4I3, thetransmitter of handset 402, contacts of key 406 (closed for talking purposes) plug contact 4I4, jack spring 4I5, conductor 4H5 to the lower terminal ofrepeating coil winding 401. The remainder of the attendants speech transmitting path extends from the upper left-hand terminal of repeating coil 490, conductor 4I1, front contact and outermost upper armature of relay 334, conductor 335 conductor 336, upper normally closed contacts of Flash and Ring key 331, conductor 338, normally closed contacts 333 of theattendants key K, through corresponding contacts of other keys in the attendants key box, conductor 340, normal contacts 34I of key K, conductor 342, closed contacts 343 of key K, tip conductor 344, inner lower armature and front, contact of relay II2,

back contacts and lower armatures of relays I03 and I05, through the subscribers substation circuit, upper armatures and back contacts of relays I05 and I03, conductor I06, front contact and middle upper armature of relay I I2, ring conductor 345, closed fcontacts346 of key K, conductor 341, contacts 348 of key K, conductor 349,

The attendants handset receiver circuit is connected across the winding 42I of coil 408 in a circuit extending from the lower terminal of this winding, conductor 422, sleeve contacts of establishes jack 404 and the corresponding plug contact 424, through the receiver of the attendants handset 402, plug contact 425, sleeve spring of jack 403, contacts 426 of dial D, conductor 421, innermost lower armature and front contact of relay 334, conductor 355 to the upper terminal of winding 42I of repeating coil 4198. Talking current is supplied by the battery 428.

The subscriber at station A and the attendant may now carry on conversation,

On an outgoing call, that is, a call from the attendants position to the conference line subscriber at station A, the key K is actuated as in the previous case and the same circuit functions are performed. The attendant then actuates the flash and ring key 331, whereupon a circuit is established extending from ground, innermost upper armature and front contact of relay 32B, conductor 356, contacts 351 of key 33?, conductor 358, contacts 359 of key K, conductor 360, conductor I22, winding of relay I03, conductor I23 to grounded battery by way of the back contact and outer left armature of relay II 0. Relay I03 operates in this circuit, interrupts the continuity of the tip and ring conductors of the subscribers line and connects a continuous ringing supply to the station A by way of the conductors I24 and I25. Current from this source actuates the ringer I26 which is bridged across the line. In response to the operation of the ringer I25, the subscriber at station A removes the handset I80 from its cradle support which causes the operation of relays IQI and III! as described hereinbefore.

Besides the functions hereinbefore mentioned, relay III), at its back contact and outer left armature opens the circuit to relay I43 which causes this relay to restore its armatures. The tip and ring conductors of the subscribers line are thus again rendered continuous and the continuous ringing supply is disconnected from the called station.

At the termination of a call on the subscribers line the key K is restored to normal and all perated relays restore to normal.

If it is desirable for a supervisor to listen in on line connections to the attendants position she may do so by plugging the listening set T into the listen jacks 43! When this is done, the receiver 43I is connected across the conductors 432 and 433 which are connected across the upper winding of coil 434, the lower winding of which is bridged across the left windings of induction coil 468. Thus the supervisor may listen in on an established connection.

S indicates a supervisors position from which the supervisor may listen in and talk on connections by using a telephone set T and plugging it into the talk or listen jacks 435. A key 435 individual to the attendants position shown in Fig. 3 is illustrated at the upper left of Fig. 4 and may be actuated to either a talk or listen position. When actuated to the talk position the upper contact springs are actuated while the lower set of springs is actuated when the key is actuated to the listen position.

Assuming the supervisors telephone set T has been associated with the jacks 435 and that the key 436 has been actuated to the listen position, the receiver of the set T' is effectively connected across the upper winding of coil 434, by way of the plug and jack receiver contacts, back contacts and inner upper and lower armatures of relay 431, normal contacts 452 and 453 of the upper portion of key 436 and. alternate contacts 454 and 455 of the lower portion of key 436. The lower winding of coil 434 is connected across the outer terminals of the repeating coil 438 which is effectively included in the established connection. In this manner, the supervisor may listen in.

In order to talk on the established connection the supervisor actuates the key 436 to the talk position so as to actuate the upper springs of the key. Relay 43'! is thus operated in a circuit extending from grounded battery, winding of relay 431, contacts 438 of key 433, conductor 439 to ground by way of the jack contacts 440. The transmitter of the telephone set T is now connected directly across the right winding of coil 444 whose left windings are now connected across the outer left terminals of repeating coil 498 by way of the front contacts and inner armatures of relay 437, contacts 446 and 441 of key 436 and conductors 448 and 449. In this manner the supervisor may talk on an established connection, the battery 453 supplying the necessary transmitter current.

It will be observed that when the key 436 is actuated to the talk position, the receiver of the supervisors telephone set T is connected across winding 444- of the coil 443 so that the supervisor may listen as well as talk on the connection whereas, when the key 436 is actuated to the listen position the supervisors transmitter circuit is on open circuit at the front contacts and inner upper and lower armatures of relay 431.

The foregoing description covers the operation of the disclosed system on a call originating on a line L arranged for conference service, and extended to the attendants position and on a call to a conference line, such as line L from the attendant. It also covers the lighting of the busy lamp I49 at the conference line station A when the attendant is busy handling a call on another line. The description also covers the operation of the supervisors equipment whereby a supervisor may listen in on a particular connection at a particular attendants position by plugging the receiver 43I into the jacks 43!] located at the particular attendants position and may talk and listen on any connection at any of the attendants positions by lugging the telephone set T into the jacks 435, it being understood that, at the supervisors positions there is provided a plurality of keys, such as key 436, one for each attendants position.

In the operation of relay 328 above described, it was indicated that a recorder was started operating when ground was connected to the conductor 323. This feature is provided because it has been found desirable, when review- 'ing the operations of a traffic control office after a period of heavy traffic or after an emergency, to have a complete record of all transactions which took place between the control office and other points concerned. A voice recorder is accordingly provided for each key equipment position in the control ofiice. Whenever an attendant is busy on any line associated with his position other than central ofiice or private branch exchange lines, his position circuit connects monitoring taps to the voice recorder (not shown) and by means of a relay such as relay 328, starts the voice recorder motor so that a phonograph record of all conversations involving the attendant and the other intercommunicating points is secured.

The following description is directed to the operation of the disclosed system on calls originated on and extended to lines other than those which are arranged for conference service. For this purpose there is shown on the lower portion of 'Fig. 1 an automatic line L1 on which is located the key equipment station B.

When thereceiver at the station B is removed from the switchhook, relay I50 operates in a circuit which includes the right armatures and back contacts of relay I5I and the closed line loop at station B. At its outer right armature,

1 relay I50 completes a circuit for the flashing 'relay IIB which'may be traced from grounded battery, outer armature and front contact of 5 1 relay I80, winding of relay H6, conductor 2I1 to. ground by way of the back contact and armarelay I50, outer armature and back contact of ture of relay 2I8. At its inner armature and front contact relay I50 extends battery to the inner left armature of flashing relay I I6 by way of the inner armature and back contact of relay I30 and conductor I8I. The front contact of relay II 6, to which battery has been connected by the operation of relay I50, controls the operation of the line and busy lamp 380, being connected to the filament thereof by way of the 1 back contact and left armature of relay I5I, and a conductor I82.

At its outer left'armature relay IIG connects ground to the start lead 2I9 to cause the operation of start relay 220.

Relay 220 starts the'fiashing circuit to function in a manner previously described to cause the intermittent operation and release. of flashing relay II6 which j causes the lamp 380 at the attendants position to flash indicating the incoming call on line L1.

. It will be noted that relay 225, which is common j to conference lines only, does not operate on a call originating on the non-conference line L1 so that the buzzer 226 will operate intermittently 1 under control of relay 224 as a distinctive audible 1 signal.

When the attendant answers by operating the 1 line key K in the key box to the right, relay I5I operates in a circuit extending from grounded ;battery, winding of relay I5I, conductors I83 3 and 383, contac-ts 384 of key K, conductor 385,

contacts 386 of key K, conductor 381, winding i of relay 3 88, conductor 389, conductor 480, contacts 40I of jack 403, conductor 482, winding of jrelay 483, conductor 330 to ground at the lower normally closed contacts of relay 321. Relays 1 I5I, 388 and 483 operate in this circuit.

Relay I 5| operated, opens the energizing circuit for relay I which relay releases. At its left armature and front contact, relay I5I causes .the line and busy lamp 380 to be lighted steadily by connecting battery directly to conductor I82. QRelay I50 opens the circuit to flashing relay II6 which relay restores its armatures.

Relay 483 at its inner armature and front contact, establishes an obvious energizing cirqcuit, by way of conductor 490, for relay 325. At its lower armature, relay 325 establishes an energizing circuit for relay 392 by way of the closed make-before-break contacts of relay'334. :At its outer upper armature, relay 325 opens the circuit to relay 323 and at its inner upper armature, completes a circuit extending from ground, inner armature and front contact of relay 388, jconductors 393 and 394, front contact and inner upper armature of relay 325, back contact and outer lower armature of relay 328, conductor tact of relay I I2, conductor I35, winding of relay I05 to battery and ground. Relay I05 operating in this circuit opens the tip and ring conductors of the conference lines such as line L and causes the busy lamp I09 at the stations, such as station A to be lighted. Relay I05, as in the previous description prepares the line relay I 0! for operation in an emergency.

At its outer armature, relay 388 connects ground to conductor 329 to start the voice recorder operating as in the previous case. It also connects ground to lead 33I to light a busy lamp (not shown) at the loud-speaker (not shown) when two or more loud-speakers are located at one point to indicate which loud-speaker the conversation is being reproduced on. Relay 388 also establishes an obvious circuit for-relay 391.

With relays 392 and 331 operated, relay 334 operates in a circuit extending from grounded battery, winding of relay 334, conductor 398, inner armature and front contact of relay 392,

front contact and innermost lower armature of relay 391, to ground at the lower armature and front contact of relay 325. Relay 334 operated, locks to ground under control of relay 325.

Relay 334 closes the transmitter and receiver circuits of the attendants telephone set 402, releases relay 302 and connects the retard coil 399 and its associated battery across the conductors 353 and M1. Relay 3932 released, opens the operating circuit to relay 334 which is now looked under control of relay 325..

Relay 391 at its two outer lower armatures and front contacts connects the contacts of the flash and ring key 331 to a continuous ringing supply.

With the operation of relay 334 the circuit is placed in condition for talking.

If the call is to be held, the holding key 310 is operated which connects battery to the hold lead 3'II which causes the lighting of hold lamp 312 in the key box at the attendants position. The circuit for this lamp includes. the uppermost normally closed contacts of key K1, corresponding contacts of intermediate keys (not shown) and contacts. 313 of key K. Relay 321 also operates, when the hold key 310 is actuated, and locks over lead 31I and remains locked until the line key K is released. Relay 321., operated, releases relays 483, 388 and I5I.

When relay I5I releases its armatures, relay I50 is again connected across the line L1, and reoperated over the substation loop. Relay I80 which operated in parallel with the hold lamp 502 when key 310 was actuated, is now held operated to battery at the outer armature and front contact of relay I50. Relay I80, operated, prevents relay IIB from operating and. the line and busy lamp 380from lighting.

In the above description of theoperation of the system on a call originating on line L1, the operation of relay 328, is indicated and reference made to the fact that, under this condition, relay. I 05 in the line circuit L operates in the circuit hereinbefore traced. It is to'be understood that the conductor 355 is common to all conference lines such as lineL so that relay I 05 and all similar relays individual to other conference lines will be operated. Relay I05 operated, establishes a circuit for busy lamp I03 which circuit includes the normal switchhook 365, outermost upper armature and back concontacts I08 and the upper armature and front contact of relay I05. The lamp-|09 at station A, and all similar lamps at the other conference stations are thus lighted to indicate to the subscribers thereat that the attendant is busy handling another call and is not available toanswer calls initiated at the station at which the lamp I09 or similar lamp signals are actuated.

At their lower armatures, all relays such as relay I05 connect the tip conductors of their respective lines extending from the attendants position, to the ring leads at the substations. This is done for a purpose which will be indicated presently. 7

Though the subscriber at a conference station, such as station A, upon noting the lighted condition of the lamp I09 would not, under ordinary circumstances attempt to initiate a call to the attendant, conditions of emergency may arise when it becomes necessary for a call to be put through to the attendant even when it is known that the latter is busy handling another call. In such an event the subscriber at a station, such as station A, would remove the handset I from its cradle support as in the case of a regular call, that is, during the time when the lamp I09 is not lighted. Upon such action by the subscriber at station A, line relay IOI operates in a circuit extending from grounded battery, front contact and upper armature of relay I05, through the subscribers station circuit, lower armature and front contact of relay I05, conductor I37, upper armature and back contact of relay I03, tip lead I06, conductor I01 to ground by way of the lower winding of relay IOI. It will be noted that the circuit to the upper winding of relay IOI is, at this time, open at the lower armature of relay I05. Relay IIiI causes relay IIO to operate in an obvious circuit and to perform the same functions it did in the case of a regular call from station A, as previously described. One of these functions is to cause the lamp 3M at the attendants position to be lighted as an emergency signal. Upon receipt of such a lamp signal when occupied in handling another call, the attendant would give preference to the emergency call and proceed to answer it by actuating key K to the left position.

It is to be understood that the emergency feature just described is provided also when the attendant is busy handling a call on a conference line as well as on a non-conference line such as line L1. It was pointed out in the description having to do with a call originated at station A, that relay 328 operated and connected ground to conductor 365, which conductor is common to all the conference lines. This ground causes the operation of all other conference line relays I05 which, as indicated above, causes the station lamps, such as I09 to be lighted and an auxiliary operating circuit for their corresponding line relays, such as IN, to be prepared. This auxiliary operating circuit for the line relays of the conference lines renders it possible for subscribers at the conference stations to signal the attendant in an emergency even though they are advised by the lighted lamps I09, etc., that the attendant is busy.

The telephone system described above is particularly suitable for use in airways traffic control ofiices located in control centers of large airports. It is obvious, however, that it is not limited in its usefulness to this particular application.

What is claimed is:

1. In a telephone system, a plurality of switching keys located at an attendants position, a line circuit terminating in the contacts of one of said keys and having a station thereon, a visual signal at said'station, a second line circuit terminating in the contacts of another of said keys, and means responsive to the actuation of the key associated with said second line circuit for energizing the visual signal at the station of said first line circuit.

2. In a telephone system, a plurality of switching keys located at an attendants position, a line circuit terminating in the. contacts of one of said keys and having a station thereon equipped with a telephone handset and a visual signal device, a second line circuit terminating in the contacts of another of said keys, means responsive to the actuation of the key associated with said second circuit for energizing the visual signal at the station of said first line, and means controlled by the handset thereat for deenergizing said signal device.

3. In a telephone system, a plurality of switching keys located at an attendants position, a line circuit terminating in the contacts of one of said keys at said attendants position and having a station thereon, a visual signal at said station, a second line circuit terminating in the contacts of another of said keys, a relay in said first line circuit responsive to the operation of the key associated with said second line circuit, and means controlled thereby for completing an energizing circuit for said visual signal.

4. In a telephone system a plurality of switching keys located at an attendants position, a line circuit terminating in the contacts of one of the keys at said attendants position and having a subscribers station thereon, a visual signal at said station, a second line circuit terminating in the contacts of another of said keys, a relay in said first line circuit responsive to the operation of the key associated with said second line circuit, means controlled by said relay for completing an energizing circuit for said visual signal, and means responsive to the removal of the receiver at said subscribers station for interrupting the energizing circuit for said visual signal.

5. In a telephone system, a line circuit extending from a subscribers station to an attendants position, a signal device at the attendants position, a switching device at the attendants position, a line relay controlling the operation of said signal device, means responsive to the removal of the receiver from its support at said station for energizing said line relay by way of the tip and ring conductors of said line circuit, and means controlled by said switching means and rendered efiective by the removal of the receiver from its support subsequently to the actuation of said switching means for energizing said relay by way of the tip conductor only of said line circuit.

6. In a telephone system, a subscribers station, an attendants position, a telephone associated with the substation circuit at said subscribers station, a line circuit extending from the substation circuit to said attendants position and comprising tip and ring conductors, a line relay, means responsive to the removal of said telephone from its support at said subscribers station for completing an energizing circuit for said relay including the tip and ring conductors of said line circuit, a switching device at said attendants position, and means controlled thereby for preparing an energizing circuit for said relay which includes but one of said line circuit conductors.

'7. In a telephone system, a subscribers station, an attendants position, a telephone associated with the substation circuit at said subscribers station, a line circuit extending from the subist ation cir cuit attendants position and comprising tip and ringfcor'iductors, a two-winding line rel'ay,-means-respo nsive to the removal ants key switchingposition, a two-winding line relay for said line circuit, a normal energizing cincuit for said relay which includes both oi its windings and is completed when the subscriber at said station' removes the receiver thereat from: its 'switchhook, an auxiliary energizing circuit for said line relay which includes but one of its windings; switching means atthe attendants position, and means controlled-thereby for rendering the auxiliaryenergizing circuit effective in operating said'relay when the'subscriber'at said station removes the receiver from its switchhook.

9. In a telephone system, a subs'oribers station, an attendants position, a telephone associated with the substation cincuit at said subscriber's station, a line circuit extending from the substation circuit to said attendants position and comprising tip and ring conductors, a two winding line relay having one winding connected between ground and the tip conductors of said line circuit and the other winding connected between battery and the ring conductor of said line circuit,whereby said relay operates by way of both its windings and the tip and ring conductors of said'li'ne circuit when the telephone at said subscribers Station is removed from its support to; close the substation circuit, switching means at said attendants position, and means controlled thereby for opening the ring conductor of said line circuit,

connecting the tip lead of said line circuit to the ring lead of the substation circuit and connecting a battery source toth e tip lead of the sucstation lcincuit whereby said relay is energized over-a circuit including only the tip conductor of said line circuit and the winding of said relay connected between ground and the tip conductor 'of tlie line circuit, when the telephone at said substation is removed from its support sub- 25 j.

sequently to the operation of said switching means. 7

WILLIAM M. BEAUMONT.

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