US1673036A - Monitoring supervision on party lines in automatically-operated telephone exchanges - Google Patents

Description

June 12, 1928. 1,673,036

A. S. BERTELS MONITORING SUPERVISION 0N PARTY LINES IN AUTOMATICALLY OPERATED TELEPHONE EXCHANGES Filed Nov. 27, 1925 5 Sheets-Sheet 1 June 12, 1928. 1,673,036

A. s. BERTELS MONITORING SUPERVISION ON PARTY LINES I-N AUTOMATICALLY OPERATED TELEPHONE EXCHANGES Filed Nov. 27, 1925 5 Sheets-Sheet 2 //7ve/7/0/".' Ame/d J". Ber/e/s.

June 12, 1928. 1,673,036

' A. S. BERTELS MONITORING SUPERVISION ON PARTY LINES IN AU'IOMATICALLY OPERATED TELEPHONE EXCHANGES Filed Nov. 27, 1925 5 Sheets-Sheet 4 //7 ve/yfor. Arm/d J1 fier/e/s.

June 12, 1928. 1,673,036

A. S. BERTELS MONITORING SUPERVISION ON PARTY LINES IN AUTOMATICALLY OPERATED TELEPHONE EXCHANGES Filed Nov.27, 1925 5 Sheets-Sheet 5 2y I Af/S/J Patented June 12, 1923.

UNITED STATES PATENT OFFICE.

ARNOLD S. BERTELS, OF TENAFLY, NEW JERSEY, ASSIGNOR '10 WESTERN ELECTRIC COMPANY, INCORPORATED; OF NEW YORK, Y., A CORPORATIONOF NEW'YORK.

MONITORING SUPERVISION ON PARTY LINEE IN AUTOMATICALLY-OPERATED TELE- PHONE EXCHANGES.

Application filed November This invention relates to a telephone exchange system and more particularly to a monitoring system for lines associated with a machine switching system.

Lines extending from a telephone ofiice become faulty from weather conditions, station set troubles or are removed from service for various reasons. In a telephone 'ofiice of the automatically operated type, calls for such lines must be received by an operator in order that the calling subscriber be advised of the condition of the called line. here the calling line has call charging apparatus associated therewith a difficulty arises in answering such calls in a manner to prevent the operation of the call charging apparatus. This difficulty is increased where the lines out of service are party lines, since the talking battery used for the operation of call. charging apparatus .is reversed, with relation to the line conductors, for the different parties. A further control difiiculty arises on account of the talking battery supply which may vary for different types of service.

It is an object of this invention to provide an improved method of monitoring on party lines extended through automatic switches.

A feature of this invention is the provision of means in an automatically operated telephone exchange for monitoring and supervising telephone calls from service charge lines to faulty party lines in a manner to prevent a charge for such calls.

\Vhile the invention has been disclosed as particularly adapted for monitoring 011 party lines associated with machine switching oihces, it is apparent from the following description that the invention has a, wider utility and by slight modification it could be adapted for purposes other than monitoring.

Referring to the drawings, Figs. 1, 2 and 3 inclusive illustrate diagrammatically machine switching apparatus necessary for establishing a telephone connection fromsubstation A shown in Fig. 1 to a party line having subscriber's stations B and C shown in Fig. 3. The right hand portion of Fig. 3 and Figs. 4 and 5 illustrate the circuits as-v sociated with such a party line for monitoring purposes.

Fig. 1 illustrates a subscribers station A 27, 1925. Serial .No. 71,651.

and call charging apparatus associated therewith. The line apparatus and line brushes 103, 104 and 105 illustratediagrammatically a line switch for selecting a district selector asshown' in the, main portion of Fig. 1.

The sender is diagrammatically shown onclosed by dotted lines in the lower portion of Fig. 1. i 4

, 1 1g. 2 illustrates an incoming selector circuit selectable by a district selector and controllable by a sender for selectinga final order to permit the association of plug 342 in a manner to connect the line terminals 303 and EMA-with the monitoring circuit separately from the connection of the line conductors and stations B andC with the monitoring circuit. The right hand portion of Fig. 3 illustrates a plugging up circuit arranged with apparatus responsive to various conditions associated with the line conductors orwith the conductors associated with the final frame. I I

F 4: and 5 illustrate a monitoring cord. circuit arranged to monitor and supervise faulty lines or telephone calls for such lines extended through the automatic switches of the telephone office.

Fig. 6 is a diagram-showin g the manner in which the several. sheets of the drawing should be organized.

The selector switch equipment and sender disclosed herein are the same, in operation as those disclosed in Patent 1,505,171 to F. A. Stearn. The district selector and line switch with associated call charging apparatus, are described in detail in Patent 1,491,323 toD. L. Temple. I Y

Gene ml cZescript2'0n.The operation of'a full mechanical telephone 'ofiice of therevertive impulse type illustrated in the drawings of Figs. 1 and 2 is well understood in the art. A description of the line conditions associated with apparatus of this type il be given.

The ringing apparatus of an incoming selector switch, Fig. 2, is the same for single party lines as it is for two-party .lines. However a change is made inthe group cross connections at the final frame when twoparty lines are associated with a telephone oflice of this type. The two party line stations such as B and C are connected to the same line conductors; but are not connected,

to the} sameterminals upon the final frame. A reversal of the conductors between the main frame arrestor, such as 3 10, is made in order that the ringing current from the inat stations B or G.

coining selector may be associated properly with the line conductors to, actuate the bell This reversal of the conductors between the final frame and the main frame further reverses the association of talking battery wit-h the line conductors for idifferent'parties on the same line.

WVhcn a faulty line is reported the heat coils are removed from thearrestor and a plug such as-342'is associated with the arrestor, and plugs 313and 314 are inserted into a set of monitoring jacks such as 319 that the conductors associated with these monitoring operator.

and 320 in order to actuate signals appearing before a monitoring operator responsive to calls for or from saidilineand permit supervision and tests of such lines.

When telephone calls from subscribers station's such as stationii-r are initiated for station B or C a finalselector such as 300 is directed to the final frame line terminals 303 and 304 01 344. and 3&5. It will be noted operation of this relay illuminates a lamp to signal the monitoring operator that a call has been received for a faulty subscribefsstation. In response to such a nail the monitoring operator inserts plug 00 into jack Apparatus in the monitoring cord circuit of Figs. 4 and 5' is now actuated to trip the ringing current apparatus in the incoming "selector. l/Vhenthe ringing current is tripped the sequence switch otthc incoming selector advances to talking position to associate talking battery with the talking conductors. l"

As described in detail in the patent to D. Ii. Temple, No. 1,491,323,1116 talking battery is used to actuatethe call charging apparatus and thereforethe monitoring circuit 1 and 5 mustbe associated with the incoming selector in such manner that the superi' isory relay 259- will not be operated.

I Detailed descriptions-Assuming that the line associated with stations B and C is faulty or that there is a fault in one of said stations, plug 342 is associated with arrestor 340 as shown in Fig.3. It will be noted that the. association of this plug with the arrestorseparates the stations and line from the conductors associated with the final frame. Plugs 313 and 31 are inserted in jacks 319 and 320 respectively; The stations B and C are now associated with jack 326. The final frame terminals303 and 304 3 14 and 345 are associated with jack 325. Insertion of plug 313 into jack 319 establishes a circuit to operate relay 329 over an obvious circuit. The operation of relay 329 establishes a circuit through the filament of the green lamp 328 to indicate to the monitoring operator that this apparatusis associated with afaulty line.

Let itnow be, assumed that a call is initiated at station A for station The line switch, selects the districtselector F ig. 1,

which associatesa sender therewith for positioning the district selector and other switches in the manner fully described in Patents 1,505,171 and1A91,323 hereinbefore mentioned. The incoming selector switch Fig. 2 is now positioned to select the final selector 300 and the final selector switch is controlled toassociate its brushes with terminals 303 and 30-1. Upon the selection of theseiterminals the sequence switch of the incoming selector Fig. 2, is rotated to a position for the association of ringing current with the ring conduetorjwhich is the normal function for actuating the bell at the subscribers station B. Since the conductors from the final frame are associated with the monitoring apparatus, Fig. 3, instead of with the subscribers station thisvringing current is associated with relay 324 instead of the ringer winding at" the subscribers station. This circuit may be traced from the alternating current source 254: through the interrupter 256. rightlower and upper contacts of cam 217, tripping relay 255, lower contacts of; cam 202, right contact of relay 221, which'is in an operated position, right lower contact of cam 214, brush 248, terminal 2419 and thence through the apparatus or the final selector switch to brush 302, terminal 304i, springs 303 and 312, conductor 313, sleeve of plug 31%. sleeve of jack 320, conductor 321, ring contact of jack 325, rightwinding of relay condenser tip contact of jack 325.couductor 335, sleeve of jack 319, sleeve of plug 313, conductor 316, springs 311 and 307, terminal 303, brush 301, thencethrough the apparatus of the finalselector switch to terminal 247, brush 2 16,' to ground through the right upper contact of cam 213. The energization of relay"32e'establishes a locking circuit for the relay from ground through the lower contact of jack 325, left winding and left inner contact of relay 324 to battery through the right inner contact of relay 329, A circuit is further established to illuminate white lamp 327 from ground, through its filament, left outer contact of relay 324 to battery through the right inner contact of relay 329.

The illumination of the white lamp 327 is an indication to the monitoring ope 'ator that a call has been received through the automatic switches for the faulty line associated with the plugging up apparatus indicated by said lamp. To answer such a call. plug 400 is inserted in jack 325 which establishes a circuit for relays 405 and 407 and opens the energizing and locking circuits for relay 324 to extinguish the white lamp 327 and associate the ringing current with the apparatus of the monitoring circuit Figs. 4 and 5. The circuit for energiz ing relays 405 and 407 may be traced from ground through the sleeve of jack 325, sleeve of plug 400 to battery through the windings of relays 405 and 407 in multiple with the resistance 421. The operation of relay 405 establishes a circuit to energize the winding of relay 507 which may be traced from ground through the Contact of relay 405 to'battery through the winding-of relay 507. The operation of relay 507 establishes an energizing circuit for relay 404 from battery through the winding of relay 404 to ground through the right outer contact of relay 507. The operation of relay 507 further establishes ground circuits to be used for the progressive establishment of cir cuits for relays 500 to 502 and 504 to 500, inelusive. The operation of relay 407 establishes a circuit to energize the winding of relay 403 from ground through the contact of relay 407, left outer normal contact of relay 400, winding of relay 403 to battery. The operation of relay 403 establishes an energizing circuit through the winding of relay 400 from battery through its winding to ground through the right outer contact of relay 403. Relay 40G establishes a locking circuit for itself through its inner contact to ground through the right inner contact of relay 507 and remains operated to prevent the operation of relay 401. Should relay 401 be permitted to operate apparatus of the circuit could energize relay 259.

The monitoring operator actuates the talking key 414 to associate the n'lonitoring set 423 with the calling subscribers line. The ringing current must be tripped and he party called determined before the set 423 is associated with the calling lines.

With key 414 operated relay 508 is bridged. across the tip and ring conductors to associ ate the ringing current therewith. The ringing current source and ringing ground has already been traced to the tip and ring springs of jac 325 and thus associated with the tip and ring conductors connected to plug 400. Assuming that brush 302 is asscribed the ringing current may be traced through the left normal contact of relay 401, right inner normal contact of relay 402,

left contact of relay 403, right normal contact of relay 500, tip contact of talking key 414, left normal contactof relay 504, Wind ing of relay 508, right inner contact of relay 403, left normal contact of relay 402, right v normal contact of relay 401 to ground at the incoming selector the tip conductor of plug 400. Relay 508 is operated by the ringing current conducted through its winding and establishes an energizing circuit through the winding of relay 509 which may be traced from battery through the winding of relay 509, contact of relay 508, right normal contact of relay 501 to ground through the left outer contact of relay 507. Relay 509 in operating establishes .a locking circuit for itself through its left contact to ground through the left outer contact of relay 507. The operation of relay 509 establishes an energizing circuit through the winding of relay 504 from battery through its Winding, left inner normal contact of relay 500, right outer contact of relay 509, contacts of interrupter 5:20, left normal contact of relay 502, left normal contact of relay 503 to ground through the left inn-er contact of relay 507. Interrupter 520 is continuously operated at intervals of proper duration for the establishment of the circuits traced. The operation of relay 504 establishes a locking circuit for itself and an operating circuit for relay 500 which is effective when interrupter 520 opens its-contact. This circuit may be traced from battery through the windings of relays 504 and 500, right contact of relay 504, left normalcontact of relay 503 to ground to the left inner contact of relay 507. A. ground shunt is maintained around the winding of relay 500 during the'closed period of the interrupter contacts since ground is associatedwith one end of the winding through interrupter 520 and associated with the other end of the winding through the right contact of relay 504, left normal contact of relay 503 and left inner contact of relay 507. When the contact of interrupter 520 is opened the shunt is removed to allow the encrgization of the winding of relay 500. i

The operation of relay 504 disestablishes the circuit through the Winding of relay 508 and the operation of relay 500 bridges the resistance 521. across the tip and ring conductors in order to energize the tripping relay to disconnect ringing current from th monitoring circuit. The tripping circuit may be traced from the ring conductor of plug 400 through the left normal contact of relay 401, right inner normal contact of relay 402, left contact of relay 403, right contact ill) Err

of relay 500, resistance 521, left normal contact of relay 505, right inner contact of relay 103, left normal contact of relay 102, right normal contact of relay 401, to the tip conductor of plug 400.

The operation of tripping relay 255 in the Well known manner, opens the holding circuit for relay 221 and the release of relay 221 establishes an energizing circuit for sequence switch magnet 200 W iich rotates the sequence switch into a position WHGIG the talking battery is associated With the tip and ring conductors through theright windings of the repeating coil 258.

The brushes of the final selector may be associated with the terminals of either party line indicated by terminals 303, 30 1, are and 345. If brushes 301 and 302 areassociated with. terminals 303 and 301, the ungrounded pole of talking battery is associated With the a-rrestor spring 308 and talking ground With spring 307. If brushes 301 and 302 are as-.

sociated with terminals 3 14iand 3&5, the ungrounded pole of talking battery is associated' with arrestor spring 307 and talking ground vith arrestor spring 308. Since the operation and release of supervisory relay 259 establishes a circuit to actuate the call charging apparatus of the calling line, means must be provided in a monitoring circuitto prevent the operation of the supervisory relay in order not to charge thesub? scriber for a call to a faulty line.

Apparatus in the monitoring circuit is new operated to determine the conductor to which talking battery is connected in order to further operate the apparatus of this monitoring circuit in amanner to prevent the operation of the supervisory relay. It will be'ren'iembered that the initial closure of interrupter 520 operated relay 50a and'its opening removed a shunt path from relay 500 to allow it to operate for the establishment of the tripping bridge through resistance 521. A subsequent closure of interrupter 520 establishes a circuit for the operation'of relay 505 from grounded battery through its Winding, left normal contact of relay 501, left inner contact of relay 500, right outer contact of relay 509, contact of interrupter 520, left normal contact of relay 502. left normal contact of relay 503, to

ground through the left inner contact of recuit for relay 501 which is effective upon the opening of the interrupter contacts. The

shunt around the Winding of relay 501 is maintained by closure of interrupter contacts in the same manner as described for relay 500. Upon a subsequent opening of the interrupter contact the operation of relay 501 takes place. v

The operation of relay 501 opens the lock,

ing circuit for relay 509 traced tln'ough its right contactand establishes a circuit for the operation of relay 506 upon a subsequent closure of interrupter 520.' The operating circuit for relay 506 maybe traced from battery through its Winding, left contact of relay 501, left inner and outer contacts of relay 500, interrupter 520, left normal contact of relay 502, left normal contact of relay 503 to ground through the left inner contact of relay 507. The operation of relay 506 establishes a locking circuit for itself and an operating circuit for relay 502 in the manner previously described for relays 505 and 501. The operation of relay 506 further establishes a ground for holding the relay 509 if it should operate and associate a ground through its left contact With one end of the Winding ofrelay 508.

The ground vis associated With the Winding of relay 503 in order to test the tip conductor for talking battery. If talking battery is connected to the tip conductor an operating circuit for relay 503 isestablished from this -round, through its Winding, ri-ght inner contact of relay 403 leftnormal contact of relay 402 right normal contact of relay 101, tip conductor of plug 100, tip spring of jack sleeve of plug 319, sleeve of plug 313, conductor 316, spring 311 of plug 342, spring 307 of arrestor 34:0, terminal 3 15 to talking battery over the ring conductor of the incoming selector. To receive talking battery in thisjmanner it Would of course be necessary that the final selector brushes 301 and 302 be associated with the final multiple terminals 344; and 3 15 representing one party of a party'line; If the talkingbattery is received at the monitoring circuit over the ring conductor, the relay 508 is not associated With a talking battery and therefore its Winding is not energized and since relay 508 is not energized a circuit forrelay 509 is not established. Theholding circuit for relay'509 is thus not established. The noncompletion of a circuit for relay 50S indicates that the talking battery is connected to the ring conductor of the monitoring circuit and'that the final selector brushes are connected to terminals 303 and 304.

Upon a subsequent opening of the contact of the interrupter 520 relay. operates from battery through the windings of relay 506 and 502, right inner contact of relay 500 to ground tl'irough the left outer contact of relay 507. The operation of relay 502 re moves the ground circuit from interrupter 520 at its left contact and prepares an operating circuit for relay 510 through its right inner contact. It further establishes an operating circuit for relay 4.09 from battery through its Winding, right outer contact of relay 502 to ground through the left outer Contact of relay 507. The energizing circuit for relay tee is opened through the left outer contact of relay 409 to cause its release.

Let it be assumed that the final selector switch brushes are connected to terminals 344 and 345 and that talking battery is thus associated with the tip conductor of the monitoring circuit to energize the winding of relay 508. The winding of the relay is of sufficiently high resistance to prevent the operation of the supervisory relay 259 when the talking battery is of maximum voltage. The operation of relay 508 establishes a circuit to operate relay 509 from battery through its winding, contact of relay 508, right outer contact of relay 506 to ground to the left outer contact of relay 507. Relay 509 is looked through its left contact to the operating ground above traced. The operation of relay 509 further establishes a circuit to associate the high resistance left winding of relay 511 with the ring conductor which it is assumed is carried to ground at repeating coil 258. This circuit may be traced from battery through the left winding of relay 511, contact of relay 510, right inner contact of relay 509, left inner contact of relay 409, left lower winding of repeating coil 413, left inner contact of relay 404, left normal contact of relay 403, right inner normal contact of relay 402, left normal contact of relay 401, ring conductor of plug 400 and thence over a circuit previously traced to terminal 344 brush 301 to the grounded pole of the talking battery at repeating coil 258. It will be noted that the tip conductor is opened at the right inner contact of relay 509. It remains open during monitoring to prevent operation of supervisory relay 259.

The operation of relay 511 establishes an obvious circuit for the operation of relay 503. The operation of relay 503 which prepares a path for the energization of relay 408 whenever the flashing key 422 is operated. This circuit may be traced from ground at the left inner contact of relay 507, left contact of relay 503, upper ring contact of key 414, left contact of key 422 to battery through the winding of relay 408.

The operation of relay 408 in turn estab-- lishes an obvious energizing circuit for relay 402 and the release of this key releases both relays. This combination of flashing relays is not used in connection with a call through the mechanical switches as hereinbefore described but is used when the circuit is associated with a type of incoming selector switch for a call initiated from a manual oifice. Since this feature is not'a part of the invention it will not be further described herein.

The release of relay 403 upon the operation of relay 409, establishes the talking conductor circuits through the left winding of repeating coil 413. With key 414 actuated the operators headset isv now associated with the calling subscriber who is advised of the condition of the line called.

Assuming that the final brushes 301 and 302 are associated with terminals 303 and 304,v battery is received in the monitoring circuit over the ring conductor.v An energizing circuit for relay 508 is not associated with its winding under this condition. Relay 409 is however operated as before through the right outer contact of relay 502. The ring conductor is. opened at the inner contact of relay 409 and the tip conductor which is associated with ground at the repeating coil 258 is extended through the left middle contact of relay 409, right inner normal contact of relay 509, normal contactof relay 510 to battery through the high resistance winding of relay 511. Relay 511 isthus operated to establish energizing circuits for the flashing relays. The energization of relay 503 opens the locking circuits for relays 500, 504, 501 and 505 to cause their release. Relays 502 and 506 remain operated until the release of relay 507.

The operation of relay 511 in each of the operations described above extinguishes the lamp 410 which lighted upon the operation of relay 404, to advise the monitoring operator that the talking conductors have been "prepared for conversation with the calling 7 establishesa circuit to light lamp 410. The

illumination of lamp 410 indicates to the monitoring operator that the calling subscriber has disconnected which is a signal for said operator to remove plug 400 from Jack 325. The removal ofplug 400 releases relays 405 and 407 whichin turn release the remaining relays operated for the connection.

Should plug 400 be removed from jack 325 by mistake previous to the disconnection of the automatic switches it may again be inserted into the jack and the reoperation of relays in the monitoring circuit Figs. 4

and 5 takes place in the manner previously described with the exception that no ringing circuit is received from the incoming selector switch. The connection of the talking battery to the tip or ring conductor is tested by the monitoring circuit in the manher previohsly described and the operators telephone a circuit may be associated with the calling subscriber. 1 A Let it be assumed that stations 13 and C and the line connected tl'ierewithar'e in conditionfor making a call to the central otiice and thatTthe -subscriber at station B removes the receiver i ronrthe-switchhook. A circuit is established' to' energize'relay 330 frombattery throughits "winding, Contact of jack 326, conductor'322, tip contact of j-ac'k 320 and plug- 814,"conductor 317, springi310 of plug 342, "spring 306 of arrestor 340 and thence over the im loop through the "subscribers station apparatus to spring ofarrest'or 340, spring 309 of'plug'342, conductor'315, tip of plug313 and 'j'ack 319,

v connector 323 toground 't'l'irough the spring of jack326. The operation of relay 330"established a circuit to illuminate red lamp 331 from battery through the right inner contact of relay 329, filament *of lamp 331, normal contact of key '332,"contactiofrrelay 330 to ground through"the'contact 'o'f-jack 826.. .7 i

The illumination of red la1np"331"is a signal to them'onitoringoperator'that a call 'hasbeen'initiated :iron 1 -iine associated therewith. Thisjcall' oi ginating from station'BTn'ay be initiate'dby a test man or may have beenmade by a mistake'oi the subscriber whose 'l'ine has been taken"out of service. The monitoring operatorflinserts plug 400 intojack-326 which establishes an energizing. circuit. for relay'405 from batt erylthrough its winding, sleeve of plug-400 and jack326 resistance 550 to ground. It willbe "noted that 'relay'407 is included in "this circuit, but since it is marginal it does not receive suiiicientcurrentthrough resistance 350 to cause'its Operation. V

The operation of r elay405 establishes: an obvious circuitto o i'erate'frelay 507,. The operation of relay 507 establishes a circuit through its right outer contact to energize the winding of relay 404. 1 Relay 404 operates and establishes a circuit from ground through its rightinner-contact, lejft normal contact of relay 406,- winding of relay 401 to battery. 'The operation of relays '404;'and 401 associates the line conductors from plug 400 through the contacts of relay 401, contracts of keys 412, 411 and 415, normal contacts of relays 402 and403, contacts of relay 404, left upper and lower. windings of re .peating coil 413, the tip conductor being carried to-ground through the left middle conitact of relay 409 and the ring conductor through the left inner normal contact of relay 409, right winding ofrelay 511 to battery. Thei'ight winding of relay 511 is of low. resistance in order that talking battery Jmaybe'supplied over the line loop from the circuit'traced. The operation of relays 401, 404, and 511 takes place in rapid succession which is known.

which does not allow sufiicient time for lamp 410 to become illuminated when its circuit is closed through the right outer contact of relay 404. v

The operationof the talking key 414 now associates the operators head set with the subscribers station to permit conversation. If a test man has initiated the call he may request the monitoring operator to ring the substation bell. i'ieys 411 and 412 are included in the circuit for this purpose. Key 411 is for associating ringing current with the subscribersstation of the party requiring connection of ringingcurrent to the ring conductor and key 412 is for associating ringing current with the second station associated with t-lie line'requii-ingringing current on the tip conductor.

When the receiver is replaced upon the switchhook at the 'calling station relay 511 i is released which establishes an obviouscircuit to illuminatelamp410. Plug 400-is then removed from jack 325 by the monitoring operator and the relays oi the monitoringcircuit'are released.

The monitoring operator may be required to make tests upon the line other than described above, such'as tests for, grounds c011- .nected to the tip or ring conductor, short circuits on the line or in the station apparatus or other tests that may be made with a' voltmeter. For such tests plug'400 is inserted into jack 326 which causes the operation of relays as previously described for the operation of the monitoring cir'cuitin answering acall from station 13 or G. The operation ol key 415 now associates the voltmeter circuit with the line conductors. A test for a short circuit may be made by the operation of key 416 to assoeiate'iground with the conductors of the line. If a short circuit exists the deflection of the meter is not changed when key 417 is operated to transfer the ground from the tip to the ring conductor. A test for extraneous-ground .or battery is made by associating the voltmeter with the line conductors, the resistance of The n'ionitoring operator notes the deflection oi thejvoltmeter needle and operates key 418 which includes resistance 430 to vary the voltage associated with the line conductors to make further voltmeter readings. Other tests \vell known-in the art may be made by the use of this voltmeter. v

Upon the completion of all tests plug 400 may be removed from jack 326 to restore the monitoring circuit apparatus to normal.

\Vhat is claimed is:

1. In a telephone exchange systenna line, a link circuit, switching means ii'oreonnecting either conductor of said link circuit with either conductor of saidiine, a loop circuit including battery having one pole grounded extending over the conductors of said line and link circuit, responsive means in said loop circuit and a testing relay in said line for determining to which oonducv tor thereof the ungrounded pole of said battery is connected without operating said responsive means.

2. In a telephone exchange system, a line, a link circuit, switching means for connecting either conductor of said link circuit with either conductor of said line, a loop circuit including a battery having one pole grounded extending over the conductors of said line and link circuit, responsive means in said loop circuit, means in said line for determining to which conductor thereof the ungroundcd pole of said battery is connected, monitoring means, and means responsive to said determining means for connecting said monitoring means with said link without operating said responsive means.

3. In a telephone exchange system, aline, a link circuit, switching means for connecting either conductor of said link circuit with either conductor 01' said line, said switching means being controlled from a calling station having call charging apparatus associated therewith, a loop circuit including a battery having one pole grounded extending over the conductors of said line and link circuit, responsive means in said loop circuit for actuating said call charging apparatus, means in said line for determining to which conductor thereof the ungrounded pole of said battery is connected, monitoring means, and means responsive to said determining means for connecting said monitoring means with said link without operating said responsive means.

4. In a telephone exchange system, a trunk arranged for differing connections with an automatic switch having a loop circuit including a battery with one pole grounded, responsive means in said loop circuit, and means in said trunk for detecting the ungrounded battery pole in order to prevent operation of said responsive means.

5. In a telephone exchange system, a trunk, a loop circuit including a battery having one pole grounded, switching means for connecting either conductor of said loop to either conductor of said trunk. responsive means in said loop circuit, and means in said trunk for determining to which con ductor thereof the ungrounded pole of said battery is connected in order to prevent the operation of said responsive means.

6. In a telephone exchange system, a trunk associated with party line terminals, means in said trunk LO receive party line calls initiated by a station having call charging apparatus associated therewith, a selector switch under the control of said station for selecting party line terminals, auxiliary apparatus associated with said switch for controlling-said call charging apparatus, and means in said trunk for differentiating between party calls in order to prevent the actuation of said auxiliary apparatus.

7. In a telephone exchange system, a trunk associated with party line terminals, means in said trunk to'receive party line calls initiated by a stat-ion having call charging apparatus associated therewith, a selector switch under the control of said station for selecting party line terminals, auxiliary apparatus associated with said switch for controlling said call charging apparatus, and means automatically operable in response to the association of said switch with said trunk for differentiating between party calls in order to prevent the actuation of said auxiliary apparatus.

8. In a telephone exchange system, a trunk associated with party line terminals, means in said trunk to receive party line calls initiated by a station having a call charging apparatus associated therewith, a selector switch under the control of said station for selecting party line terminals, auxiliary apparatus associated with said switch for controlling said call charging apparatus, means in said trunk for dift'erentiating between party calls in order to prevent the actuation of said auxiliary apparatus, monitoring means, and means responsive to said dilierentiation for connecting said monitoring means in operable relation with a calling station.

9. In an automatic telephone exchange, a monitoring system, means to connect the apparatus of said monitoring system with a party line in such manner that calls for said line terminate in said apparatus, means in said monitoring system to receive ringing current for the parties of said line, and means to determine which party is caller independent of the kind of ringing current received.

10. In an automatic telephone exchange, a monitoring system, means to connect the apparatus of said monitoring system with a party line in such mannerthat calls for said line terminate in said apparatus, a link circuit, switching means for connecting either conductor of said link circuit with either conductor of said monitoring system, a loop circuit including a battery having one pole grounded extending over the conductors of said link and monitoring system, and means in said monitoring system for determining to which conductor thereof the ungrounded pole in said battery is connected in order to determine which called. I

In witness whereof, I hereunto subscribe my nan 1e this 12th day of November A. 1).,

ARNOLD S. BERTELS.

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