US1718914A - Telephone system - Google Patents

Description

June 25, 1929, J. E. QSTLINE TELEPHONE SYSTEM Filed June 18, 1926 2 Sheets-Sheet 1 John E. UETlma @Mw g:

June 25, 1929. J. E. OSTLINE TELEPHONE SYSTEM 2 Sheets-Sheet 2 Filed June 18, 1926 Patented June 25, 1929.

UNITED .STATES PATENT OFFICE.

JOI-I1\T"E. OSTLINE, 01? LIVERPOOL, ENGLAND, .ASSIGNOR"TOAAUTOMATIG; ELECTRIC INCL, OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE.

' TELEPI IONE SYSTEM.

Application filed June 18, 1926, Serial No.

The presentinvention relates to telephone systems and is more particularly concerned with arrangements for making routine tests of; automatic switching apparatus as used in such systems.

The principal object had .in mind when the invention was devised was the testing of apparatus employed at. a call indicator operatorsposition for effecting" the display ofwanted numbers and enabling theoperator to completedesired connect-ions, but certain of the principles involved are capable of wider application.

Accoriiling to one feature of the invention, a testing. arrangement for call indicators is provided in which on the perforimince a special. operation by an operator a defin te number is transmitted from the test equipruent to the apparatus at the incoming; end

of. a line. to operate the recording; devices.

while on the operator plugginginto a special jack the various operating features ot the cord pircuit are automatically tested. in turn.

Acco iing to another feature of the inventionin atesting arrangement for use in tele )hone s stems an im )ulse sending switch ings, comprising Figs. 1 and'2, which when.

arranged with Fig. 2 to the right-of Figh 1;. with the corresponding lines in allgnmenn #7475373, liled'Nov.:1, 1924, and Serial.

$756,239, liled Feb.'2, 1925. It willhowever be understood that theinveution is not limited to this arrangement and that with com-.

paratively slight modifications, such as would be readily apparent to those skilled in the art,- the general principles of the invention couldbe appliedto call indicator apparatus 1 ct other types.

The routining apparatus, which mayv be 116,768, and. iniGreat, Britain July 30, 1925.

common to the exchange, comprises three switches, TS, CS and SS, and a number of venting the common equipment from being taken into use by more than one operator at once. All'the switches are preferably 25- pointrotary switches with wipers-niovii-ig alwaysin. the same direction, such aspare commonly employed. as subscribers individual line switches.

Thegeneral operation of theequipment will'first be traced through hrieflyf When a routine testis to, be made, the. operator removes the plugnattached. to..the.,headset from the normaljack, thereby busyingher position to incoming calls, and inserts. it instead inthe specialjack J ilf the com mon apparatus is; alreadyin use at this time, she :receives a busy tone, buttif it;is free, sheseizesitto the exclusioniof othenoperators. equipment, the switch SS is startedoperating and a particulannumber is. displayeduon henlamp panel. She: .then. takes up. cord No. 1 and insertsthe attached plug into the routining jack J Won the multiple,.1\vhereupon. she receives ring-back tone indicating two ilJGYiOdS-Of ringing. After this. a test tone is heard for a: short intervahthe cessation of wh ich-indicates that the operator may .now .testthe cord for cutouts onothendetee-ts. As soon as: thistisi completed, the operator. Withdraws the plug .from the routiningjack so as to testthesignal toiawrong disconnect and theuinserts it again, whereupon the .re-ringing,feature comes into operation and. the operator. hears iringnback tone during. another, periodoii ringing. At the end of thisperiod, the operator; hears a diiterenttone, iorinstance of ZLzIllllClLlOWQl frequency, which is to indicate that-proper hattery-reversalhas takenplace for metering; purposes. 'lhistone ceases, after. a .furthe]: shortinterval, and. a disconnectsignal then appears on the. lamp. associated with the cord inruse. This lamp extinguished after .a short: period and, a flashing .re-call signal isr then displayed. This. completes the test of cord N0 1 and the operatorpacv. As .soontas she obtains access to the i cordingly removes the plug and proceeds to go through the same series of tests with cord No. 2. In the arrangement shown..

,that for the next test a different number is displayed and thus the display lamps and recording'apparatus. may be tested for. all digit values.

Considering now in detail the operation I of the apparatus shown, when the operator inserts her headset plug in the jack J relay 1 is'operated in series with the transmitterfrom ground on the lowest contact of the jack and this relay by operating its armature 2, prepares a circuit for the relay .4. If the common equipment is already in use, relay 13 will be operated and armature 16 will therefore not be engaging its back contact so that no circuit is completed for relay 4. Moreover, busy tone is now conneet-ed up from thelead BT, armature 15 and its front contact, back contact and armature 11 to the operators headset so that she receives a busy signal. In case the common apparatus is,not in use however, relay 41 operates and at armature 7 completes a locking circuit for itself dependent only on relay 1. The operation of armatures 5, 6,

78,5 9 and connects the individual apparatus wit-l1 the common equipment while at armature 11 the circuit for the busy tone is interrupted. Moreover the operation of armature 10 completes a' circuitfor relay 13, which operates to prepare the equipment for operating, and a circuit is also completed for the interrupter 18 which has a weighted armature 20, and is adapted at its spring 19 to short-circuit itself so that as long as groundis connected up at armature 10, interrupter'18 cont nues 1n operation ELIld'Vlbrates *at a frequency of, conveniently, 20

I pervsecondQ By theoperation of armatures 5' and 6, conductors 39 and 40 extending. 'tothe" trunk relay group are connected up by, way of armatures 32 and 33 and their back contacts, and the normal contacts of Lwipers 29 and 30 and said wipers to the relay 24, and as conductors 39 and 40 are j now connected respectively to battery and ground, relay 24 operates, thereby at its armature25 completing 'acircuit for relay 26 which operates also. When the trunk relaiy group is' connected through to the de- I coder, as fully described in the specifications above referred to, a loop comprising the mpulse-respond1ng relays is placed across conductors 39 and 40 instead of the previous battery and ground connections, and relay 24 theref0re de-energizes, thereby opening the circuit for relay 26. Since however, this relay is slow-to-release, a circult is momentarily completed from ground, armature 25 and its back contact, front contact and armature 27, first contact in the bank of wiper 31 and said wiper, vibrating spring 20, winding of rotary magnet 23 to battery.

'By the operation of magnet 28. the wipers 29, 30 and 31 of the switch are now advanced one step, whereupon wiper 31 encounters ground which is eonluycted to the remainder of its hank contacts, and thus the switch SS continues to advance under the control of the vibrating spring 20. The contacts in the banks of wipers 29 and 30 are wired in a particular manner to the wipers 34, 35, 36 and 37 of the control switch CS, to certain contacts of which battery is connected through either high resistance 4-]. or low resistance 42. The operation of the switch SS therefore serves to send special impulses to the decoder in the manner fully set out in the specifications above referred to, so as to set up the number 1111 on the display lamps. When wiper 31 engages its last contact, instead of finding direct ground it encounters ground through the upper winding of relay 43. Magnet 28 is unable to operate in this circuit, but relay 13 energizes and at armature 15 completes a locking circuit for itself by way of its lower winding and at armature -14 short circuits its upper winding so as to provide direct ground for the operation of the-magnet? 23. Theswitch SS is thus returned to its normal position, in which it remains until the test of the particular cord to be employed is completed. Relay 13 moreover, at armatures 32 and 33 disconnects wipers 2.) and 30 from the switch TRS so as to prevent a false operation of relay 24 and conn cts up instead the right-hand winding of the polarized relay 21 and the retardation coil 23 in series. The operator upon noting the number displayed upon her lamp panel inserts the plug attached to cord No. 1 into the special test jack J, which as previously pointed out, is located along side those ordinarily used for completing connections to subscribers lines.

\Vhen the plug is inserted in the jack J. a circuit is completed over the sleeve of the plug for the relay 46 which therefore operates; armaturcs 47 and 48 connect up the operators speaking set to the trunk conductor; armature 49 opens a point in the circuit of magnet and prepares a locking circuit for relays 4.3 and 73, and armature 50 removes ground from certain cow tacts in the bank of wiper 56 for a purpose which will he explained in due course. The operation of the sleeve relay in the cord circuit when the plug is inserted in the jack J starts the trunk finder switch associated with the cord hunting in the usual manner to find the trunk relay group with which the de-coder is associated and when it is llt) found the transmission of ringing current is started. In this case the circuit for the ranging current is from the tip spring of i the jack J armature 65 and its back coning the circuit of relay 58 and when this deenergizes in consequence, the circuit for magnet 57 is opened and it releases and advances the Wipers 55 and 56 of the switch TS into engagement with the second con tacts in their respective banks.

When the next period of ringing currentcoinmences, relay is again operated and when it terminates, relay 50 deencrgizee, and, consequently, another impulse is sent to magnet 57 and the switch TS is advanced a further step. Since the operatoifsspeaking set is connected to the conductors 39 and 1-0, she receives ring-back tone during the ringing periods in the same way as would the calling subscriber. When wiper 56 engages the third contact, the fol lowing circuit is completed: ground, armature 17 and its front contact, wiper and the third contact in its bank, upper winding of relay 59 to battery.

Relay 59 is now operated and at arn'uiture 60 disconnects relay 50 and places a direct loopacross the springs of the jack by way of the secondary winding of the induction coil IO. This corresponds to the reply of the called party and the operator now given a tone, which extends from. a high frequency source over lead HT, front contact and armature 61, armature 74; and its baclr contact, back contact and armature 71, primary Winding of the induction coil to earth. Moreover at armature 62, the interrupter (53 is connected up by way of armature 75 and its back contact sot-hat when theinterruptcr :ontacts next close, a circuit is CUIHPlClZQLl for relay 53, which operates as before to advance the wipers of the switch TS one step. hen this occurs the circuit for relay 59 is open-ed and it Clo-energizes, thereby removing the tone. A. circuit is now completed, however, for relay 64C and this relay upon operating at its armatures (35, 66, 67, 68 and 69 changes over the connections to the operatorsheadset so as to establish the ordinary test conditions for testing the cord circuit for cutouts and similar defects. The operator thus proceeds with this as soon as the circuits are prepared as indicated by the cessation of the tone.

\Vhen this test is completed, the operator withdraws the plug, thereby de-energiaing relay -16 which at armature 50 completes a circuit for advancing the switch TS a further step. Since the re ay 2i is-still connected across the line representing a calling subscriber, the signal on wrong disconnect is now given to the operator on the lamp associated with the cord and she then rc-insorts the plug. 'lhereupon the re-ringing feature comes into operation and ringing current is again sentout and this operates relay 50 as before to effect the stopping of the switchTS.

When the wiper engages the seventh contact in its bank, a circuit is completed for the lower winding of relay 59, and also for relay 70. Relay 59 by operating its armature again places a loop across the springs of the jack J, thus simulating the response.

ofthe called party but in this case the high frequency tone which was previously connected up at armature 71, is cut oil at armature 71 and in its place a low frequency tone from lead LT is connected by way of arm-a ture 22 and its front contact, front contact and armature 71, primary winding of the induction coil ill to ground. llt should be explained that when the conditions reprc senting the reply of the called party are.

produced, a reversal of current back over the connection is ctl'ectcd from the cord circuit and this brings about the operation of relay 21. This operation moreover took place in the earlier stage of the test also but was then without effect in connecting up a tone since relay had notbeen operated. The operator therefore hears now a low fre piencytonc to indicate that the reversal for effecting metering has taken place satisfactorily. Relay 70 at armature "72 connects up the interrupter (53 to relay 5;} so that the wipers of the switch T5) are ad vanced two further steps under the control of the interrupter.

lVhcnwiper 55 engages its ninth contact, the circuits for relays 59 and 70 are opened and instead a circuit completed for relay 73. This relay upon operating, at armature 77 completes a locking circuit for itself dependent upon relay ill; at armature closes apoint in the circuit of niagne' 80,

i and at armature 79 alters the lockii'ig circuit of relay l3 so as to make it dependent upon relay 46 rather than upon relay 13. Relay '73 moreover at armature T4: disconnects the lead HT; at armature 75 again connects up the interrupter 63 to relay 53, and at armature 76 opens the circuit of polarized relay 2i and retardation coil 23. This o icration corresponding to the cilling subscriber rcplacing his receiver; consequently the appropriate lamp associated with the cord circuit in use is new lighted to indiiate cleaning, down by the calling party. it icn the switch cuitis completed: ground, armature 17 and its front contact, wiper 55 and the tenth contact in its bank, armature 12-and its v front contact, winding of magnet 81 to battery. This circuit is opened when wiper makes a further step and. magnet- 81 then releases and advances the wipers of the switch TBS into engagement with the next trunk relay group. It should be mentioned that the test contacts en aged by wiper 83 are normally left dead, but in case any of the trunk relay sets are not equipped, the test contacts such as 82 corresponding to such sets are connected to ground and it will be seen that when wiper 83 encounters such grounded contacts, a local circuit is completed for magnet 81 over its interrupter contact so that the switch is advanced over such contacts until it reaches the next trunk relay set that requires'to be tested.

. It should be mentioned also that, though with the arrangements shown a different trunk relay set is employed for each test, this is not essential, and if desired the same trunk relay set could be used for testing with each separate cord. This could conveniently 'be efiected by the use of an addi tional jack similar to J the insertion of a plug in which would. operate a relay performing similar functions to the relay 46 and in addition opening the above circuit for magnet 81. When the switch TS takes afurther step relay 59 again energizes 'thereby again operating armature 60 and completing a bridge acrossthe tip and ring contacts of the jack J This corresponds to the called party removing his .receiver while his multiple jack is still plugged up and is intended to test the flashing recall feature.

The test is now completed and the open tor accordingly Withdraws the plug, thereupon releasing relay 16 which at once deenergizes thus opening the circuits of relays 73 and 43. Since relay 7 3 is slow to release however, the following circuit is now completed: ground, armature 19 and its back contact, armature 78 and its front contact, winding of .magnet 80 to battery. 'Conse quently, magnet 80 receives an impulse of sufficient length to cause it to advance the wipers 3438 of the control switch CS into the next position in which the connections to the bank of the sending switch. SS are altered in such a manner that upon the next operation of the switch SS impulses are sent out corresponding to the number 2222. Upon the deenergization of relay 43, which takes place after a short interval, a circuit is again completed at armatures 32 and 33 for relay 24 which accordingly operates and in its turn operates relay 26. Thereafter 'when the circuit of relay 24 is opened due to the connection of the seized trunk relay set with the de-coder, the sending switch SS is set in operation and the number 2222 is displayed on the lamp panel.

The operator will now proceed to make the same series of tests with cord No. 2 and thereafter with each of the cords at her position. In case there should be more trunk relay sets than cords and it is desired to test. all the trunk relay sets, one or more cords will have to be employed over again. \Vith the wiring of the control switch CS, as shown, the numbers displayed in successive tests are 1111, 2222, 3333 and so on, so that if ten or more tests are made all the indicating lamps are tested.

The leads Set and extend to a jack adapted to receive a plug attached to a handset with the transmitter and receiver in series. Hence when this plug is inserted relay S6 is operated and at its armatures 87 and 88 connects up the handset in parallel with the regular operators set.

Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is 1. 111 a telephone system in which line designations are displayed before an operator by means of a call indicator mechanism under control of calling lines, a plurality of cord circuits accessible to said operator for completing connections to lines whose numbers are displayed on said indicator, trunk lines having access to said indicator mechanism, a testing device, means in said device responsive to the performance of a special operation of the operator for automatically seizing an idle trunk line and for automatically operating said indicator mechanism in simulation of actual service conditions to display a definite number, a special test jack associated with said device, and means operable automatically upon the insertion of one of said cords into said special jack for successively testing the various operating features of said cord, simulating the functions of said cord under actual service conditions.

2. In a telephone system in which line designations are displayed before an operator by means of a call indicator mechanism under control of calling lines, a plurality of cord circuits accessible to said operator for completing connections to lines whose numbers are displayed on said indicator, trunk lines having access to said indicator mechanism, a testing device, means in said device responsive to the performance of a special operation of the operator to automatically seizing an idle trunk line and for automatically operating said indicator mechanism in simulation of actual service conditions to display a definite number, said number consisting of a plurality of digits each of the same numeric value, a special test jack associated with said device, means operable uUl'OIHELtlCtLllY upon the iinsertionro'li 1, one of SHNlGOl'LlS lHLO SfLlLl special ackliori successwely testlng the various operatmg.

features o'l said cord, simulating-thefunctions olnsaid cord under actual serv1ce con? with said indicator mechanisnrrwcr a ditterent trunk line to prepare for a subsequent test.

3. In a telephone systel nuiniiwhichaline.

designations are displayedcbei ore an operator by means of a callindicator mechanismi under control, of calling lines, a plurality of cord circuits accessible to said operator for completing connections to lines Whose numbers are displayed on said iindicator, trunk lines having access to said indicator mechanism, a testing device,means in said device responsive to the performance of a .-:pe 'ial operation-of the operator for automatically seizing an idle trunk line and for automatically operating said; indicator nu-chanisin in simulation of actual service conditions to display a definite number, said number consistingof a pluralityof Ldigits each of the same numeric value, a special test jack associated With said device, means operable automatically upon thcinsertion ot' one of said cords into said special jack for subjecting said cord to 'a series of tests in simulation of the functions of said cord under actual service conditions, and auto matic means operable upon the 'WllJhClIL'Wttl. oi said cord when the test is completed,rf0r associating said testingdevice with; said indicator over1a different trunk line and tar automatically operating said indicator to display adefinite number consistingof: a plurality oi": di its each of the t same but dillerent numeric value from the digits. displayed at theprevious tcst,mthe series of tests applied. to a cord inserted responsive to the display o'f thesecond number being identical to the one appliedto the-first cord.

4.111 a telephone system in WhlChRlllM-l designations are displayed: before an operator by means of a call'indicator mechanism under control of calling lines, a plurality of cordcircuits accessible to said ioperator for completing connections to lines Whose numbers are displayed on said indicator, trunk lines having access to said indicator mechanism, a testing device,1neans in said device responsive to the performance of a special operation of the operatordtorautomatically seizing an idle trunk line aud tor automatically operatin said indicator :mechanism in simulation ot actual service conditions to display a definite number, said number consisting of a plurality of digits each of athe same numeric value, a-special test jack associated with said device, means operable automatically upon the insertion of one of said cords 1nto said SPGCItLls jack for subjectingsald cerdto a serlesof test-s in simulation of the functions of said cord under actual, service conditions, and means-for transmit-- ting; an audible; check signal, to the operator,

forieachtest said cord is subjected to.

5..In a telephone system in which line designations are displayed before 1 an operaton by meansof a call indicator mechanism under control of calling lines,a plurality of cord circuits accessible to sa'id operator for completing connections to lines ,WlIOSG numbers are displayed on said indicator, trunk lines having, access to 1 said iindicator mechanism, a tcstingdevice, means in said device responsive to the-performance ota specialoperation ofathe operator for automatically seizinganidletrunk line and for automatically operatingssaid indicator mechanism in simulation of actuali service conditions-to display a definite number, saidnumber con-i sisting Off a.1 )lurality,of digits each ofthe same numeric-value, a spccialtest :jackiassociated Withcsaid device, meansioperable automatically uponthe iHSGltiOllnOf zone of said cordsinto said special jack forrsubjcctingasaid cord to a series .of tests in simulatiion of the functionsnof said -cord under actual service conditions-none, of said tests being the transmissiom of-y ringing {current andiitripping of "the ringing; relay innsaid cord, and means,forctransmit-ting acharacteristic audible check signal tothe operator for each'test said cordis subjected to. y

6. In a telephone system in iwhichnline designations are displayed before an opera tor by means of a call. indicator mechanism under controlot. calling lines, a-plurality'of cord :circuits accessible to i said operator for completing connections: to lines :Whose numbers are displayed on said indicatorstrunk linesahaving access to said indicator mechanism, attesting device meanszinisaid device responsive to the performance i of a special operationsot, the -:operat.or :for automatically seizing "an idle trunkslme and for automatlcally operating said indicator mechanism; in simulation: of actual serviceconditions to d1splay a definite number, sald number consistingwofita plurality of idigits each-of the tests insimulation of-athe; functions of said cord under actual-:yservice conditions, said tests 1nclud1ng 3theitransmis'slon of ringmg current; the trippmg, ofthe rlnglng'relay -1n said: cord, lprematuro Withdrawal of the cord,

and re riinging', andzmeans for transmitting a characteristic audible-checksignal to the -operators-toreach test satisfactorily completed.

7. In a telephoneiwsystemlnLW-hlCh line designations are displayed before an operator by means of a call indicator mechanism under control of calling lines, a plurality of cord circuits accesible to said operator for completing connections to lines whose numbers are displayed on said indicator, trunk lines having access to said indicator mechanism, a testing device, means in said device responsive to the performance of a special operation of the operator for automatically seizing an idle trunk line and for automati cally operating said indicator mechanism in simulation of actual service conditions to 1 display a definite number, said number conupon the withdrawal of said cord when all tests are completed, for associating said testing device with said indicator over a different trunk line and for automatically operating said indicator" todisplay a definite number consisting of a plurality of digits each of the same numeric value but of a different value than the digits displayed at the preceeding'test, the series of tests applied to a cord inserted responsive to the display of the second number being identical to the one applied to the previously tested cord.

8. In a telephone system, .an operators position, a call indicator for displaying designations of called lines to said operator, a testing device, means for associating said device with saidindicator, and means in said device operated automaticallyupon such associations for successively operating said indicator to display a series of definite and predetermined line designations simulating the functions of said indicator under actual service conditions.

I '9. In a telephone system, an operators position, a call indicator for displaying designations of called lines to said operator, a

testing device, means for associating said device with said indicator, and means in said device operated automatically upon such association for successively operatin said indicator'to display a series of definite and predetermined lme designations simulating the functions of said indicator under actual SGIVJCB conditions, each designation displayed consisting of a plurality of digits of the same numeric value.

10. In a telephone system, an operators position, a call indicator for displaying designations of called lines to said operator, a testing device, means for associatin said device with said indicator, and means in said device operated automatically upon such as sociation for successively operating said indicator to display a series of definite and predetermined line designations simulating the functions of said indicator under actual service conditions, each displayed designation being different from the preceding and succeeding designation.

' 11. In a telephone system, an operators position, a call indicator for displaying designations of called lines to said operator, a testing device, means for associating said device With said indicator, and means in said device operated automatically upon such association for successively operating said indicator to display a series of definite and predetermined line designations simulating the functions of said indicator under actual service conditions, each displayed designation being different in numeric value from the preceding and succeeding desigl'lationand each designation comprising a plurality of digits of the same numeric value.

12. In a telephone system, an operators position, a call indicator for displaying designations of called lines to said operator, a testing device, means for associating said device with said indicator, means in said device operated automatically upon such association for successively operating said indicator to display a series of detinite and predetermined line designations simulating the functions of said indicator under actual service conditions, and automatic means in said device for determining the numeric value of the designations to be displayed.

13. In a telephone system, an operators position, a call indicator for displaying designations of called lines to said operator, a testing device, means for associating said device with said indicator, means in said device operated automatically upon such association for successively operating said indicator to display a series of definite and predetermined line designations simulating the functions of said indicator under actual service conditions, and means for automatically changing the numeric value of said designations for each display.

14. In a telephone system, an operators position, a call indicator for displaying designations of called lines to said operator. :1 testing device, means for associating said device with said indicator, means in said device operated automatically upon such association for successively operating said indicator to display a series of definite and predetermined line designations sinullating the functions of said indicator under actual service conditions, and means for automatiignations for each display, each designation displayed comprising a plurality of digits of identicalnumeric value.

15. In a telephone system, an operators position, a call l1'1(l.l02Lt-O1' for displaying designations of called lines to said operator, a testing device, means for associating said device with said. indicator, means in said device operated automatically upon such association for successively operating said in dicator to display a series of line designations simulating the functions of said indicator under actual service conditions, and means for antomatically changing the nu ineric value of said designations for each display.

16. In a telephone system, an o1' era;tors position, a call indicator for displaying designations of called lines to said operator, a testing device, means for associating said device with said indicator, means in said device operated automatically upon such association for successively operating said indicator to display a series of line designations simulating the functions of said indicator under actual service conditions, and means for automatically changing the numeric value of said designations for each. display, each designation displayed compris ing a plurality oi. digits of identical numeric value.

17. In a telephone system, an operators position, a call indicator for displaying designations of called lines to said operator, a plurality of trunk lines having access to said indicator, a tinting device, automatic means in said device for succe 'vely seizing said imlicator over a different one of said trunk lines, and automatic means for o ierating said indicator upon each seizure to display a line designation in simulation of actual service coiulitions,

18. In a telephone system, an operators position, a call indicator for displaying designatimis of called lines to said operator, a plurality of trunk lines having access to said iiulicator, a. testing device, automatic means in said device for successively seizing said indicator over a different one of said trunk lines, automatic means for operating said indicator upon each seizure to display a line dcsi n ration in simulation of actual service conditions, and means for automatically changing the numeric value of said designations for each display.

19. In a telephone system, an operators position, a call indicator for displaying designations of called lines to said operator, a iilurality of trunk lines having access to said indicator, a testing device, automatic means in said device for successively seizing said indicator over a different one of said trunk lines, automatic means for operating said indie tor upon each seizure to display a line designation in simulation of actual service conditions, and means for flllllOllltlljlCtllly changing the numeric value of said dcsigg nations for each display, each designation displayed comprising; a plurality of digits of identical numeric value.

20. In a telephone system, an operatoNs position, a plurality of cord circuits for establishing connections between calling and called lines, a testing device, means for associating any one of said cords] with said device, means in said device operated automatically upon such association for subject ing an associated. cord to a series of functional tests in simulation of actual service conditions, and means for trimsinitting to the operator a characteristic audible signal upon the sz'itisfactory completion of each test.

21.. In a telephone system, an operators position, a plurality of cord circuits for eslttllllfililfitf connections between calling and called lines, a testing device, means for associating any one of said cords with said dovicc, means in said device operated automatically upon such association for subjecting an HSSOt'tlttQtl cord to a series of functional tests in simulation of actual service condh tions, said tests incliuling the transmission of ringing current, the tripping of the ringing relay, pren'uiture Withdraival of said cord, and ire-ringing, and means for transmitting to the operator a characteristic audible signal upon the satisfactory con.1 )lction of each test.

22. In a telephone system, an operators position, a plurality of cord circuits for estahlishing connections between calling and called lines, a testing device, means for a sociating any one of said cords with said device, means in said device operated automatically upon such association for subjecting the associated cord to a series of functional tests in simulation of actual. service conditions, including a testfor the transmission. of ringing current, for tripping the ringing relay, for prematin'e witlulrawal of the cord, and. for reringing, and means for transmitting to the o icrator a different and characteristic audible signal upon the satisfactory completion of each test.

2 3. In :1 telephone system, an operators position, a call indicator for displaying designations of called lines to said (u'icrator, trunk lines having access to said indicator, cord circuits for completing calls to said called lines, a testing device, an operators telephone, plug and jack switches for associating said telephone with said device, antomatic means responsive to said association for extending a connection from said device to said indicator over one of said trunk lines, means responsive to said connection for antomatically operating said indicator in simulation of actual service conditions to display a definite poly-digit number With digits of identical numeric value, a special jack switch llt) for associating one of said cords with said testingdevice, and automatic means for applying to said'cord a series of functional tests in simulation of actual service conditions,

24. In a telephone system, an operators position, a. call indicator for displaying designations of called lines to said operator, trunk lineshaving access to said indicator, cord circuits for completing calls to said called lines, a testing device, an operators telephone, plug and jack switches for associating said telephone with said device, automatie means responsive to said association for extending a connection from said device to said indicator over one of said trunk lines, means responsive to said connection for autoinatically operating said indicator in simulation of actual service conditions to display a definite poly-digit number with digits of identical numeric value, a special jack switch for associating one of said cords with said testing-device, automatic means for applying to said cord a series of functional tests in simulation of actual service conditions, and means for difierently and'characteristically signalling to the operator to indicate the satisfactory, completion of each of said tests. a

255111 a telephone system, an operators position, a'call indicator for displaying designations of called lines to said operator, trunk lines having access to said. indicator, cord circuits for completing calls to said called lines, a testing device, an operators telephone, plug and jack switches for associating said telephone with said device, antomatic means responsive to said association for extending a connection from said device to said indicator over one of said trunk lines, means responsive to said connection for automatically operating sald 111- dicator in simulation of actual service condit ons to display a definite poly-digit number with digits of 1dent1cal numeric value, a

.7 special jack switch for associating one of said cords with said testing device, automatic means for applying to said cord a series of functional tests in simulation of actual service conditions, automatic means for transmitting to the operator different and characteristic audible signals upon the completion of each test to indieate the condition of said cord with respect to each test, and automatic means operable upon the withdrawal of said cord for releasing the connection between said testing device and said indicator.

26. In a telephone system, an operators position, a call indicator for displaying designations of called lines to said operator, trunk lilies having access to said indicator,

cord circuits for completing calls to said called lines, a testing device, an operators simulation of actual service conditions to display a definite poly-digit number with digits of identical numeric value, a special jack switch for associating one of said cords with said testing device, automatic means for applying to said cord a series of functional tests in simulation of actual service conditions, automatic means for transmitting to the operator different and characteristic audible signals upon the completion of each test to indicate the condition of said cord with respect to each test, and automatic means for releasing said indicator upon withdrawal. of said cord and for re-estab lishing said connection over a different one o't said trunk lines.

27. In a telephone system, an operators position, a call indicator for displaying designations of called lines to said operator, trunk lines having access to said indicator, cord circuits for completing calls to said called lines, a testing device, an operatofis telephone, plug. and jack switches for associating said telephone with said device, automatic means responsive to said association for extending a connection from said device to said indicator over one of said trunk lines, means responsive to said connection for automatically operating said indicator in simulation of actual service conditions to display a definite poly-digit munber with digits of identical, numeric value, a special jack switch for associating one of said cords with said testing device, automatic means for applying to said, cord :1 series of functional tests in simulation of actual service conditions, automatic means for transmitting to the operator different and characteristic audible signals upon the completion of each test to indicate the condition of said cord with respect to each test, automatic means for releasing said indicator upon satisfactory completion 01 said tests and withdrawal of said cord and for reestablishing said connection over a different trunk line, and means for comlitioning said. testing device to rc-operate said indicator to display a poly-digit number with digits of a different numeric value from the digits displayed in the preceding test.

In witness whereof, I hereunto subscribe my name this 1st day of June, A. D. 1926.

JOHN E. OUTLINE.

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