US1617414A - Signaling system - Google Patents

Description

' Feb. 15, 1927.

H. w. O NE ILL SIGNALING SYSTEM 5 Sheets-Sheei2 1 I Filed Dec. 17, 1924 Y 1,e17,414 F 15, H. w. O"NE ILL SIGNALING SYSTEM- Fild Ded. 1924 5 Sheets-Sheet 2 nyz by A77)? Feb. 1927.

15, w. O'NEILL SIGNALING SYSTEM ts-Shet 3 I Filed Dec. 17,

H. W. ONElLL SIGNALING SYSTEM Feb 15,1927 K 1,611,414

Filed Dec. 1 1924 1 5 sheds-sheet 4 ,hvenfaq: Henry VI. flAeM/ by WWW Patented Feb. 15, 1927. r

"HENRY W. ONEILL, OF ELMHU'RST,

YQBK, nssjrenon no WEST N nnne rn rc ooMrAN INCORPORATED, emu-11w 101m; n.-

A eonronn'r-Ion ionqunw Y-QRK.

swimme s-refinemn nc non filed llecember 17, 192 4 ser anuo. ma ce This invention relates to signaling systems :and more particularly to improved methods andmeans .for signaling over transmission :lines. i

5 Under the :present telephone practice involving the use of telephone lines interconnecting .difi'erent exchanges, several diflerent methods of extending connections are employed, such as, manual to manual or in manual to automatic connections; In a manual to manual connection, thesubscriloer in the originating exchange first secures. a connection to a toll operators position in his oWn exchange, ,Who then extends the'con- 13 nectionover a toll lineto a distant exchange and rings up thetolljoperator as \su chejan exchange. ;The toll operator at this eX- change requests ofthe originating toll op erator, the numberof thefdesired lineand then proceedsto extendthe connection to ,the desiredsubscriber. In, a, inanuall to. eutomatic connection, thentoll operator in ,the originating exch ange V dials the desired line in the automatic exchange vvithontth'ejaid Ot'the toll operator at the distentfexehange. Connections o f these types ina y extend through a number o fmanual or. automatic exchanges involving the use of severeltoll lines. 7 n

It is an object of thisinventionto provide I cord circuit and toll line equipments suitahlefor use in e tendingieonnections of the above types. 3

Anothenobject is to provide, meansassociated with such icord circuit and toll line equipments, whereby any one of ,thei wel'l known types of toll 'llllQS;-n1=2ty,b( employed suches, for example, ordinary wn-e itoll lines with or Without repeaters, a channel of a carrier telephone installation, n radio telephone connection, compositewlines or phantom'lines. That is, the'nature of the signals used for performing the, various functions incidental to the extension of a connection 'is such that 3 the ,signals may .be' transmitted over any :toll linethe same distanceand at the same eiiiciency as the ordinary voice-modulated signals and Without in any Way curtailing t -he. nseii'ulnessor efficiency otthese var-ioustypes, ottoll lines.

Another object ,of, the invention is theprovision of a simplified service observing arrangement--.whereby the service observing operaton may ;not only ascertain the various types ofconneetions being established over nections. V

the toll \line' but also observe tl ie progress oi establish n o di es e i hillg s c Another object is the provision ofa simtoll l'inej to accoinplish the :variousisvvitehi lg and supervisory fu c ions F .A com on i l mel t l f e e t; sus f new ,mission oflsignals in either direction over t e t 1 e hd mea s p oi d do t. e

end of the toll lines for automaticnllyiniodns his undam n al equenty with I 't o s le t na ms n nt Oi? qompar tmely l rfiz uen tra m tin th resul n signals ov t l e 11d. jce ii g the ,responding functionjsto bef In the .case' of the swit hing hinctiqns; .i ipu s elere whic a e p ed jr d. by interrupting 'thejtu igl ainentali frequency at de is sl Ano h f nn :v th eproyis on, otm an whe eby th vibratoy in ays ffjfih f hbr circuiting type used combination with a direct 'ciirrenusource iQRthe production of frequencies .rnaynbe of the same type for both the fundamental,alternatingcurrents W hin th voice frequen y rai jgetas W ll a li thealt na ineeleme sof ,lQwiie eeney an whe by re e ting oils QPIE ASfQ i l e a na re edule ing It'h und mentalhigh frequencies by ,tlief low quencies.

f .Another feature is the use of rec eivi g circuits for the arnplificatio nand rectification o'flthe variously modulated high; fretain automatic operations in the establishing of a connection may be insured under the most adverse conditions encountered in the I operationof systems of this type.

Another feature resides in the provision of a circuit arrangement whereby the talking conductors in the cord circuit are completed, either to the operators telephone set should the talking key be operated or tothe connection beyond, between the sending of sets of dialing impulses so that both visual and audible supervisory signals may be received over the toll line during the dialing period.

Anoth'erfeature resldes mthe provision of means in the cord circuit and diahng cir- ,eeit equipment whereby visual supervisory signals. such as busy indications may be received. during the dlaling period regardless of whether or.not dialingimpulses are being sent out over the line at the, moment.

I V The arrangement is such that the line conductors are maintained looped through a repeat ng coil to the dialing circuit durlng the transmission of impulses "so that any ..incoming signal will not be interfered with as might be the casewhere impulses are transmitted .by the openin'g'and closing of the lineconductors.

The nature'of the invention will be more fully understood fromthe following de scription read in connection with the accompanying drawings, in .which Fi 1 shows diagrammatically a connection from a subscribers. line with a toll operators cord circuit and an associated dialing circuit arranged in accordance with this invention and located at one manual exchange.

a By meansofthis equipment, a toll operator 40 may extend connections either to another toll operator. located at another manual ex change'or to a subscriberreached throughan automatic or. machine switching exchange. Fig-2 represents the outgoing end of. a special toll line equipment arranged in accordance-with this'invention and located at the originating exchange and by-means of which voice frequency alternatmg' current signals may be transmitted to and received from thedistant exchange over any type of toll line associated therewith. Fig. 3 represents the incoming end of a special toll line equipment arranged inaccordance with this invention located at a distant exchange and portion of the equipment at this exchange andat an automatic exchange by means i by means of which voice frequency alternating current signals of the type employed in this system may be received from or trans- 'llllttGCltO the originating exchange. Fig. 4

represents the local equipment at' this distant exchange by means of which a manual connection may be extended from the incom ing toll line equipment. Fig. 5 represents a which automatically called subscribers may be reached from the above mentioned toll line equipment. Only a sufiicient portion of V the automatic exchange has been shown to form a basis for a full explanation of the invention involved. 1

Referring 'now to the drawings, trafiic over the system as illustrated and arranged 111 accordance with this invention may be outlined'as follows: If it is assumed that a subscrlber at has established a connection as far as to the toll operators position 100 and the toll operator has inserted the answering plug 12 of the cord circuit shown at 100 into jack 11 and ascertained the number of the desired line, the toll operator will then insert calling plug 15 of the cord circuit into jack 2100f the outgoing toll line equipment 200 which is associated with a toll line 220 leading to the incoming toll line equipment 800 at the distant exchange. The toll operator at then proceeds in either one of two'manners to extend a connection.

If the wanted subscribers number can onlybe reached through the service of a toll 'operaton'such as the one at position 410 at the distant exchange, she proceeds to call this toll operator in the usual manner well known in the art except that alternating V currents within thevoicerange offrquencies on which alternating currents of low frequencies are superimposed, are used for the necessary signaling indications. I That is, she causesinstrumentalities in the cord circuit and the outgoing toll line equipment 200 to be operated to transmit voice fre quency alternating currents of, for example, 1000 cyclesmodulated by analternatlng current of 135 cycles over the toll line 220 to the incoming toll line equipment 300 at the distant exchange. Such signals then condi tion the incoming tOll'llIlG equipment 300' for a manual connection and are translated by the receiving circuit equipment 350 into nection, as well as when the connection is established. 7

Similar operations take place in the systern if the toll operator at position llO' desires to call the toll operator at position 100 when, for example, the same type of signals hi are produced at the incoming toll line equipment 300, transmitted over the toll line 220 and translated by the receiving circuit equipment 250 at the outgoing toll line equipment 200 into signaling indications for If the attention of the toll operator at position 100. r

On the other hand, if the'wanted subf s'cribers line may be reached from an automatic exchange, such as the one indicated m in Fig. 5, the toll operator at POSltlOIlalQU proceeds by operating a dialing key to connect the common dialing equipment 150 to the cord circuit and by means of instrumenrents of 1000 cycles modulated by various low frequency currents, to cause various supervisory signal indications 'to be given during establishment and disestablishment of the connection The arrangements of the toll line equipments are such that various signals for the supervision of the automatic connection are transmitted back to the operator at position 100 during the progress of the call as Well as in the breaking down of the connection. Such signals may consist of the fundamental alternating currents of 1000 cycles modulated by low frequency currents of 20 cycles or 135 cycles, or signal indications consisting of the fundamental frequency modulated by low frequency current of 20 cycles transmitted in the shape of impulses at 60 per minute, these latter impulsesbeing used when all of the toll linesare busy; or signal indications consisting of the fundamental frequency modulated by loW frequency of 20 cycles transmitted in the shape of impulses at 120, per minute, Which are used When the called'line is busy. Such signals are all translated bythe receiving circuit equipment 250 at the outgoing toll line equipment 200 into the proper supervisory signal indications for the attention of the operator at position v100. i

It is to be understood that the various frequencies mentioned are simply illustrative and that the invention is not limitedto the employment of these particular values but that any frequency Within the voice range may be used for the fundamental alternating current, and lOW frequency currents of other frequencies more suitable to particular cases in the practice of the inven tion mayalso be selected.

It is believed that the arrangement shown will be more fully understood from the following detailed description of a series of calls of the types that may be completed thereby. The first type of connecti'ons'to be considered Will be calls extending on the so-called ring-down basis, that is, from a subscriber 10, through a toll operatorsposishown as they form no part of this inventlonand as it 1s Well known and understood in the art how manual connections are attended to by outgoing as Well as incoming toll operators,'no furtherexplanation ill be made in this respect. assuming then, that the operator at 100 as inserted plug 12 into jack lllan'd has ascertained thenurir ber of the Wanted subscribers line by the connection of her telephone'set to the. cord circuit, and the operation of listening key 82,'slie proceeds by inserting plug. 15 into jack 210 after having performed the usual busy test. as a'result'o'f this action, relays 24, 23 and 201 are operated'as followszbattery, Winding of relay 245, Winding of relay 23, sleeve contactsofplug .15a1'id jack 210, Winding of relayi201to'ground'f Theop'eration of relays 24fand' 2 3 closes the following circuits: one from battery,,armature and front contact of relay 2fl, Winding'of relay 26, armature-and back contact of relay to, ground, another from battery at any 12 3 lamp 25,.armature and front contact-of relay 23, armature and b ackconta ct ofrel ay 26 to ground at thenormal contactsv Oflistening key 32 and another from battery re lay 2.4, Windingbf relay 2'? to ground: listening key32, these latter tWo circuits are, however, prevented from lighting lamp 25 andoperating relay27 as relay 26 operates ratherquickly. sothat these circuits are almost immediately broken, The operation of relay 201 closes anaenergizirig circuit for relay 202 from battery, outer right hand armature and front contact of relay20l, Winding of relay 202 toground, Relay 202, when operating, closes a'circuit for busy signals 205 as followszbattery, right hand armature and front contact of relay 202, winding .of, signals 205 to ground, operating these signalsto indicate toother toll operators that the toll .line 220' connected tvith this equipment is busy.

The operator now proceeds to ring the operator at the (llStQlllQQXGlltlllgQbY actuat 4 ing ringing key 34. This causes a 20 cycle.

alternating current source to be connected to the ring lead and ground to the tip lead of the cord circuit and the outgoing tolllinc equipment in Which abridged circuit con;

taining an alternating current responsive relay 208 is located. Belay 208 responds to the 20 cycle current andcloses a circuit as follows: battery, armatureand front contact of relay 208, winding of relay 209lo ground. Relay 208 also, by operating this armature removes battery from the 20 cycle alternating current Iresponsive relay 204-111 the receiving circuit 250 in order :that'thisl equipment may not be disturbed the ringing current from the cord circuit; Relay 209 operates in the above traced circuit and closes a circuit for relay 213 as follows: battery, upper armature and front contact of relay 209, winding of relay 213 to ground. Relay 213, in operating, disconnects the outgoing end of the toll line from the tip and 'ringleads to the jack 210 and connects it to the source of fundamental high frequency alternating current on which is superimposed a low'frequency current of 135 cycles. The application of this signal to the outgoing line is accomplished as follows: It should be noted that the fundamental alternating current source 211 of 1000 cycles is connected to one winding of transformer 214 while a source of lowfrequency alternating current 212 of 135 cycles is connected through the lower armature and front contact of relay 209 to another winding of transformer 214 whereas a third winding of this transformer is connectedto the leads now connected tothe upper and inner lower armature and front contacts of relay 213. The signal is, therefore, transmitted over the toll line 220 to the incoming equipment- 300 received at the receiving circuit equipment 350 and 18 there transmitted through the input transformer 326 to the input circuit of the vacuum K tube 327 serving as an amplifier. The plate circuit of the tube 327 is connected through to the grid or lnput clrcuitof vacuum tube 328, whichacts as a rectifier, causing the relay316, whichin turn is connected through r th transformer 329 in the output circuits of the tube to operate in response'to the 1000 cycle current modulated by the 135 cycle current. That is, relay 316 and the circuit therefor are tuned to respond to this type of signals only in a manner well known in the art. As this relay attracts its armature an obvious circuit is closed for relay 217 which in operating closes a circuit to ground for 0 lead 330 to cause the operation of relay 401 as follows: battery, make-before-break contact of relay 408, left-hand winding of relay 401, lead 330, lower armature and back contact of relay 319, outer right hand armature and back contact of relay 307, lefthand ar- 2 mature and front contact of relay 317 to ground. The operation of relay 401 closes a circuit for the busy signals 426 at the jacks 425, 430 and 429 of the toll line as follows: battery, at relay 408, left hand ara mature and front contact of relay 401, busy right-hand armature and front contact of relay 401, left hand armature and back contact of relay 404, right-hand armature and back contact of relay 411, lamp 427 to ground, causing this lamp to be lighted to indicate to the operator at 410 that her attention is desired on this line.

In answer to this signal, the operator at 410 inserts her plug 428 into jack 425, causingrelay 402 to operate over the following circuit: ba tery, sleeve contacts of plug428 and jack 425, right hand winding of relay 402, lead 431, inner right hand armature and back contact of relay 307 to ground. The operation of this relay opens the locking circuit for relay 401 which is presently released on the subsequentoperation of relay 408 causmg the supervisory signal 427 to be extinguished. 'That is, relay 408 is operated by the closing of anobvious energizing circuit at the armature and front contact of relay 402.. The operation of this relay thus in addition to opening the original energizing circuit for relay 401 also closes a circuit for maintaining the busy signals 426 operated over the following circuit: battery, armature and front contact of relay 408, busy signals 426 to ground. The operation of relay 402 also applies battery to the lead 432 which causes the operation of relay 319 as follows: H

battery, armature and front contact of relay 402, lead 432, winding of relay 319 to ground. The operation of relay 319 closes the tip and ring leads of the toll line to the tip and ring of jack 425 at" its upper armatures and front contacts and disconnects the tollline from the leads to the automatic equipment at the back contacts of these armatur-es. The

operation of relay 319 also opens the cir-w cult for relay 401 which, as hereinb-efore listening key connecting her telephone set in the usual manner to the cord circuit and receives the details of the call from the operator at 100 who has also by this time actuated her listening key 32 and connected her telephone set to her cord circuit. The operator at 410 then proceeds to extend the connection to the wanted subscribers line and call the subscriber and the connection with the calling subscriber is also attended by the operator at 100, in accordance with the well established practice in the art of telephony.

Conversation between the subscriber at 10 and the called subscriber may then take place. a i

In case the call extended to the operator at 410 is intended for a subscriber that may be reached through the assistance of an operator at another distant exchange, that is, if the operator at 410 is merely employed as a connecting operator fora so-called through supervisory signalsf-rointhe operatorat 100 r at the ori inatin exchan e-oyer the toll line b D 2D 7 220 thro'ughthe incoming toll line e ui ment 300 to the cord circuitof the operatorat-.410

and this may be done by the operation of the ringing key 34 whenever such super- Vis'ory slgnttllllgiS desired. 'The functionof the circuit in this instance is the same as that already described when thekeywas first operated, except that when relay'317 is now operated in response to a signal, over the toll line220, of 1000 cycle alternating current modulated by a 135 cycle current,

the ground 'at the left 1 hand" armature and 1 front contact' of this relay operates relay 320 as follows: battery, winding of relay-320', lower armature and front'cont'act of relay 319,.0uter right: hand armature andback contact of relay 307, left hand armature and front contact of relay 317 to round';cau'sing the operation of relay 320; lhis causes the disconnection of the tip and ringleads of the toll line 220 and connects currentfrom the 20 cycle alternating current source 331" and ground to thetip and ring leads ofthe switchboard endof the incoming toll line equipment through the ack 425 to the cord cir'cuit of the operator'at' 410, causing supervisory signal indications to be displayedi n the cord circuit at 410 and theconnectionmaybe extended further as is welll'znown-in the art. I

In case the incoming operator at 410 at the distant exchange decides to enten'dfa connection to a subscriber that may be attended to by the operator at 100, i. e. a connection in the opposite direction'on the toll line 220, a procedure similar to that described above is followed. Theope'rator at 410 afterinserting her plug 428, into jack 429 causingo'perations totake placeresulting in the op} eration of relay 319; a'ctuates her ringing key (not shown) in the same manner as the operator at'100 operated her ringing key 34:. Twenty-cycle alternating, current and ground ,is thereby connected to the; tip and ring leads of the toll line equipment 300;

causing relay 332 bridged across the lineft-o operate. The operation of this relay closesa circuit for relay 310 as follows: battery, right hand armature and front contact of re lay 332, winding of relay 310' to ground.

This relay after havin disconnected the u i 7 H s a ,i portions of the tip and ring leads connected to jack 4-28, connects at its upper and inner lower armatures and front contacts, leads connected through one Winding of a re eae ing coil 336, another winding of this co'ili'sconnected to analternatin'g current source 33athaying a frequency-of 1000-cycles, while a third winding 1s connectedto an alternat ing current source 335 having a frequency of 135 cyclesandthatis nowconnected through he inner left hand a rest-lire and 'f i ont con-'- mer er-aw 332. Thus, anLimpulseifrom the --1000"cycle source 1 modulated bycurrent from the 135-cycle source'iseffective through the-tip: and 'rin'g leads ofutolliline 220', and;

transmitted at the outgoingtollline equip- 1nent=20'0; through the upper and inner lower a-ri'natures and backcontacts of relay 213 and v at the-receiving circuit250 through the in.-

put transformer 230 to the. input circuit of the v'aeu'uinl-tube 231.: Thisireceiving cir-.

cui'tis similar to the receiving circuit 350, that is, the plate circuit of; the amplifier tube 231'is connected to the grid or lIlPUbClIClllt of a secon'd tube 232, which acts as a rectifier cau's1ngre1ay221 which is l'nturn connected through the transformer 235 in the output circuit of thetube, to operatein response to the 1000 cycle current modulated by the 135 cycle current: The operation of-r el'ay 221 closes. a circuit for. relay 222 .as follows: battery, left hand winding ofI-relay222, inner right-handiarmature and back contactfof relay 201,:ar1nature and contact of relay 221 to ground. Relay 222, in operating, closes, atit's left-hand armature. and' front contact,-

ture and back contact of relay- 227, lamp 226;

to-ground, causing the illumination of this lampa's an indication to theoperator at 100 that the connectionis desired on this line.

In an'sweringothis signal, the operator at 100 inserts-plug. 15'into jack 228 and relays 24, 23 an'd 201 are operated 1n a circuit as hereinbefore traced; the operation of relays 24 and 23in the cord circuit have also the same effect as hereinbefore descrlbed, i. e., tl1at-la1np'25 isnot illuininatedbut the operation of relay 201 by opening 1ts make before-break contacts to battery, causes the signalf226to=be extinguished. The operation of relay 201 also causes the release of relay 222 and the operation of relay 202 which thus maintains busy signals 205 oper ated over anobvious circuit. The operator at 100 now'actuates her listening'key 32, connecting her telephone setto the cord circuit and r'ec'eives the details of the-callfrom the operator at 410 who has already by this time actuated her listening key:correspond-v ingto 32 and connectedzher telephone set 39 '90 acircuit-for'the busy signals 205 as follows:

subscriber in accordance with the well estab lished practice in the art ,of telephony whereupon conversation between the sub- 'scriber at the distant exchange and the subscriber at 10 may take place.

In case the call extended to the operator at100 is intended for a subscriber that may be reached through another exchange in this direction, i. e., if theoperator at 100 is merely employed as a connecting operator for a through connection, it maybe necessary to send supervisory signals from the operator at 410 at the distant exchange over the toll line 220 through the outgoing toll line equipment 200 to the cordcircuit of the operator at 100. This may be done by the operator at 410'actuating her listening key whenever such supervisorysignaling-is desired. The function of the circuits in this instance isthe same as that already described when the ringing key was first operated except that when relay 221 was operated, instead of operating relay 222, a circuit is completed for relay 223 as relay201 is now operated. This circuit may be traced as follows: battery, winding of relay 223,

' inner right-hand armature and front contact ofrelay 201, armature and contact of relay 221 to'ground. The operation of relay 223 connects current from a cycle alternating current source 224 and ground at its armatures and front contacts to the tip and ring leads and contacts ofthe'jack 210 and plug 15 to cause the operation of relay in the cord circuit at 100. The operation of relay known in the manual telephone art.

The second type of connections to be considered are calls extended on the so-called automatic basis, i.'e., from the subscriber at 10 through the toll operators position at 100 at the originating exchange, over the same toll line 220 to the incoming toll line v equipment 300 which will, in this instance,

be prepared to extend the call through an automatic equipment such as is shownin Fig. 5 and through the associated switches to a subscriber such as 510. Asthe automatic exchange equipment does not form any part, of this'invention, only a smallportion has been shown suflicient to illustrate .how it is effected by and how it reacts upon the toll line equipment in accordance with this invention. In fact, any well known type pf automatic equipment may be used as long as the proper signal indications may be sent. or received to perform the proper functlons wlth respect to dialing and signaling super a visory' indications through the toll line equipment.

Assuming then, as hereinbefore, in connection with calls extended on the ring-down basis that the toll operator at 100 has inserted the plug 15 into jack 210 and relays 201 and 202, signals 205', relays 23, 24 and. 726 have all been operated and that the,

contacts, of relay 38. Relay 37 in operating disconnects the tip and ring leads'of the cord circuit from the plug 15 and connects thereto leads 40 and 41, the other ends of which are connected through right-hand windings of transformer 42. Another circuit is completed for the operation of relay 43 as follows: battery, winding of relay 43, inner left-hand contact of relay 38, upper contacts of dialing key 35 to ground. Relay 43, inoperating, closes a circuit for relay 38 as follows: battery, winding of relay '38, right-hand armature and front contact of relay 43 to ground at the upper contacts of dialing key 35, causing this relay to operate. It should be noted that when the dialing key was operated, a circuit for the upper lefthand winding of transformer 42 was closed as follows: from battery at the alternating current source 44, upper. left-hand winding of transformer 42, contacts 48 of dial 46, upper contacts of dialing key 35 to ground. As this source 44 includes a vibrator operating at, for example, 1000 interruptions per second, a 1000 cycle alternating current is inducedin the upper left-hand winding of transformer 42 and transmitted to the tip and ring contacts of plug 15 to the toll line 220. This impulse of high frequency alternating current is, however, discontinued the moment relay 43 is released which takes place as soon as relay 38 is operated. Relay 43 is released by the opening of the inner left-hand make-before-break contactsof relay 38, whereas relay 38, in operating, pro- Vides a locking circuit for itself through its inner left-hand armature and front contact to the ground at the upper contacts of dialing key 35. On the operation therefore, of relay 38 and release of relay 43 a circuit is completed from the alternating current source 44, through the lower left hand windg of transfo r the r ght armatur l er-7541 4.

passing through the two left-hand windings of the'tra-nsformer 4:2 in opposite direction and consequently no inducedcurrent is effective through the secondary windings of the transformer under this condition. The

cycle'of operation of these relays therefore providesthat the imp'ulseproduced in this manner is of a sufiicient duration to'insurc that the required operations willtaken place under all circumstances even though the functioning of the individual devices and circuits may not be entirely up to the standard, that is, the operation hereinafter described will have suficient tirne to'be performed. It should be pointed out that the length of this impulse is always the same andis produced by this simple cycle of operations of the above mentioned two relays a3 and 38 only without the use of any involved ti'rning' relay combinations. This high frequency alternating current impulse at a frequency of l000cycles is'now received at" the incoming toll line equipment 300 through transformer 3 26 bridged across the tip and ring leads. After having been transmitted through the amplifying tube 327 and rectifying tube 328, thisiinpulse causes the operation of relay 301, which responds to a rectified current "from an alternating current at this frequency only.

The operation of relay 301 closes a circuit for relay 302' as follows: battery, right hand armature and back contact of relay 317, winding-of relay 302, oute'r'left' hand armature and back contact of relay 306, annature', front contact of relay 301 to ground at outer left hand armature and backv contact of relay 332, causing'the operation of this relay. Relay 302 in turn closes a circuit for busy signals 426, from battery righth'a'ntl armature and front contact of relay 302, lead436, signals 426 t'o' ground, making the manual end of this trunk circuit busy. The operation of relay 302'also opens a circuit normally extending through the right hand winding of polarized relay eoawhieh niay be traced as follows: battery, left hand armature and back contact of relay 302, arn'iature and back contact of polarized relay 303,v right hand Winding of relay 303 to ground. This circuit iiorinally holds relay 303 in'the non-operated position shown, asthe current through a circuit closed for the left hand winding of relay 303 from battery, armature and back contact of relay 305, Wind ingot relay 304:, left hand winding of relay 303 to'ground'normally opposes this current through the right hand winding of this relay and relay 303 is therefore now per mitted to operate. The operation of relay 303 applies, atits armature and front contabt as Soon as-the inipu1se fronr the" di'aliii g circuit' ceases and relays 301 and 3021bleasefa short circuit forrelay' 304 which-, it should be noted, isnerman'y operated, i. e.- the current from the left hand amimtare amr back Contact of relay 302 now passes tlireuglr the armature and "front Contact of relay" 303 to the left hand 'winding of relay 303 to ground.- Relay 304, the'refore, in I releasing, follows: battery, 'lnake before-brealr contacts of relay 108,-le'ft hand armature and 'back' closes-a circuit for relay 305,-" as' contactof relay 401, 'le'ad '4aaae'maaae and back contact of relay 304, winding of relay 305; left hand winding of relay 3 03- to ground. The operation" of relay 305 closes ac'ir'cuit for relays 306' and 307-as follows: battery, arniature and front contact of relay 305, windings of relays 306 and 307 in series to groundi The operation of relay 307 by closing its'left hand armature to the corresponding front contact, retains the busy signal 426 operated after-relay 302is released through a circuit as follows z'battery, left hand ari'na'ture and front contact ofrela'y307, lead eeemgroma at thebusy signal 426. The operation of relay 307 also includes a resistance to bat tery in the lead 431by removing the ground 7 at its inner right hand armature and" back contact as"follows: battery, armature and front contact of relay 305, resistance335 and lead 4531, to make the sleeve" leads of jacl'rs' 4'25 and 429 busy. The ground atthe' innerright hand arina'ture of relay 307 is now applied at the front contact therefor'to a conductor 550 leading to the autninatic equipine'nt shown-'injFigJ 5. The result of thhigh frequency alternating? current iinpulse sent fron'i dialing" equipment 150* is therefore that a ground is" applied on lead 550 to prepare the automatic equipmhtforthe reception of directive and supervisory impulses and when this equipment is se'i'z'ed as hereinafter described a signal is returned therefrom and the'dialiiig inayba gin. 1 The effect of this ground on lead 5f'50is as follows: Relay 511 is' operated over the following circuit: battery, winding of relay 511 to ground at lead 550. The operation ofrelay 511 closes a circuit as follows: battery, relay 512; inner right hand arii'iature; and contact of relay 514, armature andback contact of relay 522', left hand armature and" front contact of relay 511 to ground. This causes the operation of relay 512 which in turn closes an obvious circuit for rotary magnet 518 of the finder switch F. The rotary magnet 518' in operating, c'au'ses'the line switchFtostar-t hunting for an'idle district switch in a manner Well known in the art.

Nith an idle district switch, such as is diagrammaticall illustrated at G and the idle condition which is designated by the presence of battery on the test terminal 520, relay 522 is operated in a circuit extending from battery, sequence switch contact 540, armature and back contact of relay 525,

terminal 520 and wiper 521, right hand arcuit for relay 514 as follows: battery, wind ing of relay 514, armature and innerfront' contact of relay 522 to ground at the left hand armature and front contact of relay 511. Relay 514, in operating, closes a locking circuit for itself through its inner left hand,

armature and inner front contact to the ground on lead 550. Relay 514, at its two outer left hand armatures and front contacts closes the tip and ring leads from the brushes 598 and 545 of the switch F to relay 527 and lead 552 for purposes hereinafter to be set forth. Relay 514 at its left hand inner armature and one front contact closes a circuit for relay 525 as follows: battery,

winding of relay 525, brush 541 of switch F, left hand inner armature and said front contact of relay 514 to ground on lead 550, causing the operation of relay 525. Relay 525, in attracting its armature, removesbattery from the test terminal 520 of switch 1 whereupon relay 522 releases, and as relay 514 is held operated, the ground from the left hand armature and front contact of relay 511' through the armature and back contact of relay 522ihas no effect on relay 512 .or magnet 518.

The operation of relay 525 of the selected 7 district switch causes an idle sender to be selected in a well known manner, and when relay 500 operates from the ground at relay 332 over lead 552, relay 501 is also operated through int ermediate'relays (not shown) to cause a dialing signal to be given to theop- .erator at 100 in the following manner. Relay 501, in operating, places a ground on the tip conductor of the switch Th s ground causes relay 527 to operate in a c1rcu1t extending frombattery, outer right hand an mature and back contact of relay 528,winding of relay 527, left hand outer armature and front contact'of relay 514,, brush 598, sequence switch spring 580 to ground at the armature and front contact of relay 501. Relay 527, in operating, causes the ground on l ad 55!) t9 be c nne ted t9 con uct r 55? 310, in operating, closes a circuit through its upper and inner lower armatures and front contacts from the left hand winding of transformer 313 to the incoming tip and ring leads of toll line 220, thus transmitting an impulse from the 1000 cycle alternating current source 334 modulated by current from the cycle source 331 by means'of the upper right hand winding of trans former 336. -This impulse, however, is of short duration as the operation of relay 310 closes at its outer lower armature and front contact a circuit to ground at right hand armature and back contact of relay 404 for the left hand coil of relay 311 from battery at the right hand armature and front contact of relay 309, causing relay 311 to operate its armature in the opposite direction and thus opening the energizing circuit for relay 310 which is thereby released and causes.

the impulse to cease. This modulated signal causes the lamp to become illuminated to indicate to the operator at that dialing may, begin. The impulse is received at the receiving circuit equipment 250 over the following circuit: from the left hand winding of transformer 313 through the tip and ring conductors of the toll line 220 to the incoming winding of transformer 203 andis effective through the receiving equipment 250 in the manner hereinbefore described for other signals to cause the operation of relay 204. The operation of relay 204 opens the closed circuit from battery at the left hand armature and front contact of relay 7 201 through the left hand winding of polarized relay 203 to ground, causing this relay to operate as the current through the closed cire cuit through the right hand winding of relay 205 normally opposes the current in the left hand winding. This latter circuit may be traced as follows: from battery, left hand armature and front contact of relay 201, left hand armature and back Contact of relay 207, winding of relay 200, right hand wind in of relav 203 to round. In oan/rating this relay provides a locking circuit for itself through its right hand winding, armature and front contact to battery at the left hand armature and front contact of relay 201 as soon as relay 204 is released when the impulse from the incoming toll line equipment 300 cea e Thelast mentionedv cir it flows short circuits relay 1206 which istherehy dcenergized. AlCltGLllt is now closed forrelay 207 follows: battery at relay 201, arrnat11I'-8:3,'I1 Cl back contact of relay 206, inding of; relayi207, leftzhand inding of relay 203 to ground. opens ia shunt .circuit through its right-hand The operation of relay 207 armature and baclrcontact, {or the left hand high resistance winding of-grelay 2.0-1 1thusincreasing the resistance for thesl-eeVe-Acircuit sufiic ently to cause relay 23 to release and close .a circuit for lamp at its arina-ture and hack contact [to ground from battery ,at relay 24. I his s gnal, tnow indicates to the operator :that diahng operations nlay beg n.

Current from the 1000 cycle source 44 at the dialing circuit l50is now inposition to he connected-to the receiving-circuit 3.50as a pulsing current. When,-therefore,the operator at 100 operatesthe dial 46in accordance Withthe number of the desirevd line, ground is connected-to the Winding of relay 37 fro m the off-normalcontacts 47 of'the dial, caus-' ing relay '87 to operate-over obvious cir- 1 suit. The operation of this relay closesa circuit from the leads 40 and {ll of the toll line/i22 t th upp end-lo e igh ihand' windings of transformer 42' the left hand windings of which are closed from the source 44 to thesgroun daat the upper contacts of di ling ikey i3 2, e l r winding th ug the .right;ha11d armature and front contact of relay38, which .is operated at this tirne,

and thenthrough the right hand armature and hack montaot of .relay' Q3 and 1 the upper wvinding throughthe pulsingmontacts 48 of dial 46. lrnpulses of lOOOcyclecurrent from this source are therefore now ready to be transmitted to the receiving equipment :350

at 300. The pulsing contacts 48 of=the dial are opei atedduring the return of therclial to normal in accordance with the desired numherand therehy cause an interruption of the circuit through the upper left hand Winding .ogftranstormerlQ-to the; source 4& and in this manner pulses of lOOOcycle current :are transmitteditogthe distant end each pulse beingjeq-ual intin e to theopen periodof the pulsing contacts 48 of-the dial. SVhem-therefore, the 100.0 cycle pulsesare received over the line afromthe outgoing end, they are transmitted through the receiving equipment 350 v, as hereinheforedescribed ttO cause relay 30l1t0 operateand release ata ,ratecorresponding .to the rate of interruptions of the pulsing contacts 48. Relayv301 thusdi-sconnects at its armature and back-contact the ground at .relay 332 from lead 552-to cause selecting operations v to he performed by the automatic exchange. equipment shown in Fig.

5. That is, arelayi50O is caused :to respond to filfielllllllllSGS over a circuit as follows:

attery, nd n of ra sins ay equence switch 58y1,-=Wiper 545, of switch :F, middle upper. armature and ifront contact: or

1th? c r u o re-l y 5 4c, inn-er sinne ar atur 59n bask ont c z re ay 2 .28,, lsefl1 52 a mament back cont c 'd-rel y tats-re ed a th ne I uppe a m u and ack n ni -firs .e rel y 2- inatic equipment when t-l1B pUle5- Lr6 registered in the sender ground is removed from th ip lea-d lay: 01, Eth hy a ing ir ey .2 to re a wh ch i tern 91 1 1 1 9 circuit to ground over :lead for -.relay 399- ;R lay 5 09, n re eas n sqlo e a' r ui To turn now to the operationrof tlie autof r re ay 101 fqllowsat er y, f ight iha t ar u Eaid ba k $01 M 6 Err et 3 9 been registered on the sender f It isjhou ldibe stead that in this ase on, th Operat i ay 2 cm l th wirin eau pm n vzfim r ilay 205 :is;pern 1 itted to: release. Eh en tliis mp lse cea es and r ay 2 1 315 'QSi l n rmal, a shun ieu s establishe 2 i armatu an aback c tes -1f0 r lay 2 aus ng th re ay to rele se, her by e ta lishingqthe unt ir ui or it ilet han winding o t -r lay 2 r a t agai we th margina relay 2 t iepe at d ope iba-ek contact. r y

QWhen the wanted subscribers line a tL5,10

is reach-ed, ground;isconnecteil atijtlhe contact 52 .tB- m Seq enc wi ch on c towiper 538 genie switch E; whereupon ,relay 528 isoperated in a circuit Wl11f l1111ay;b

7 signa a its a ma u and I traced from hattery, Winding of relay 528,

nialreebeforeehreak colltactsfloif relay 528, Outer right hand armature and 'ba'ck con gtactpf relay 515i, brush538 =.to thegground' at contacts .582. {At-itsinner rightlhandarniaim an i n te act, r ay 28 stablish ..;a locking circuit iorlitself to the groun d ,on

.iconductor ,550. ,At ,its outer iright hand armature .anchback contact thisitelay opens the energizing circuit "for .r lay 2 and a it inner left hand armature :Iand'back contact, rela-y,528 opens the d aling:concluctor'552 ior ,pulsingxrelay' 500.7 :At ,its outer leftjhantl armature and front contact, relay 528 establishes a circuititrom groundat conductori'fioll to the ,con'ductor 553, thus closing cuit ;forrelay 318 ,as ''follo s hatter-y, nd-

"ingnof relay 318, makeThefore hIfeak contacts I of relay 31S, conductor .outer left hand ,arniatnre :and' front contact of relay 528, to ground-ion conductor 550. Belay 318, an

operating, closes at locking circuit for itself ,throughiits Qleft -handflarnjia'ture and front a contact directly to ground at conductor 550 and'at its right hand armatures and front contacts extends the tip and ring leads from the toll line equipment 300 to the tip and ring leads connected at brushes 598 and 545 of the switch F.

If the wanted subscribers line is idle, the

ground connected at contact 529 is now completed at the middle upper armature and front contact of relay 528 to conductor 551 causing the operation of relay 309 which through operations as hereinbefore described causes an impulse from the 1000 cycle source modulated by cycle current to be transmitted to the toll line 220 through the receiving equipment 250 and causes the sequenceof operations of relays 204, 203, 206

and 207 as hereinbefore described to light the lamp to indicate to the operator'at 100 that the called subscriber is idle and that ringing operations may begin. 1

When, therefore, all the digits corresponding to the'number of the desired-line have been dialed, the operator at-100 may a restore the dialing key and ther b lease relay 39 and disconnect the dialing circuit 150 from the operators cord circuit.

As the operator at 100 is now connected to the wanted subscribers line she may sig nal the subscriber by theoperation of key 34 and circuits are established in the same manner as described with calls established'on a ring-down basis, i. e., an impulse from the i 1000 cycle source 211 modulated by current from the 135'cycle source 214 is transmitted from' the outgoing toll line equipment 200 over the toll line 220 to the receiving equipment 350, causing the operation of relay 316 and through the contacts and armature of this relay, relay 317 is operated over the following circuit: battery, winding of relay 317, contact and armature of relay 316, armature and back contact of relay 315, outer left hand armature and back contactiof relay 332 to ground. The operation of relay 317 closes .a circuit to ground for conductor 554 causing the operation of relay 599 over the following circuitzbattery, winding of relay 599, sequence switch 594,brush 597 of switch F over lead 554, outer right hand armature and front contact of relay 307, to the ground at the left hand armature and front contact of relay 317. The operation of relay 599 1000 cycle source 334, modulated by current from the 20 cycle source-331, to be, transmitted to the cord circuit at to cause lamp ground.

25 to be extinguished by a series of operations as hereinbefore described, to indicate to the operator that the subscriber has answered. Conversation may now begin between the subscriber at 10 and the subscriber at 510 as the operator at 100 will,as is well known in the art, establish a connection through plug 12 and jack 11.

At the termination of the conversation, the subscriber at 510 upon replacing the receiver on the switchhook again causes ground to-be placed at contact 529 of switch F from contact 582 thereby operating relay 309 and an impulse of 1000 cycle current modulated by current from the 20 cycle source to be therei by transmitted as hereinbefore described to light lamp 25 as a disconnect signal. The operator at 100 now proceeds to take down the connection by withdrawing plug 15 from jack 210. As a result-of this action, l relays 24, 23 and 201" are immediately released; -The release of relay 24 causes the release of relay 26 and the extinguishing of lamp 25. 'The' release of relay 201 causes a signal from the 1000 cycle source modulated V by current from a 20 cycle source to be transmitted'to the incoming toll line equipment 300 as follows: When relay 201 releases, and before relay 202 has time to release, a circuit is closed from battery atthe make-before-break contacts of'relay 201 through the left hand armature and front contact of relay 202 through the winding of relay 213 The operation of relay 213,

to ground. which is slow to release, closes the toll line 220 to the upper winding of transformer 214 and an impulse from the 1000 cycle source at 211 modulated by current from the 20 cycle source224 is transmitted to the receiving equipment 350. This causes-the operation in this equipment ofrelay 301, in the manner as 'hereinbefore described by the 1000 cycle current and the operation of relay 322 through transformer 311 and these relays in operat ing close a circuit for relay 302 as follows: battery, right hand armature and back contact of relay 317, winding of relay 302, armature and front contact of relay 315, outer left hand armature and front contact of relay 306, armature and front contact of relay 301 to ground at the outer left hand arma ture and back contact of relay 332. The operation of relay 302 removes battery from the left hand winding of relay 303, permitting this relay to release and cause the op eration of relay 304 and consequently the release of relay 305 which breaks the energizing circuit for relays 306 and 307. Relay 307 in releasing disconnects ground from lead 550 which thereby effects the release of relay 31.8 and the'automatic switchingequipment as it will benoted that relays 511, 514

and 528 are respectively locked from this The release of relay 307 also releases the busy-signals 426 at the manual end of the toll line at this exchange and removes in conjunction with relay 305 the busy potential on the sleeves of jacks 425 and 429.

if, in the course of completion of the connection by the automatic exchange equipment the trunks through the switches 508,

509 and 511 for extending the connection are found busy, intermittentground is'connected to the terminal 529'from an interrupter, such as 583, or any other suitable means at a certain rate, for example, 60 interruptions per minute. The first impulse to ground will operate relay 528 and the following interruptions will release and operate relay, 309,

at a corresponding rate to alternately close and open the circuit for relay 310 through the operations of relay 311 as hereinbefore described. This causes impulses from the 1000 cycle source modulated hycurrent from the cycle source to be sent at the rate of per second. These impulses will'ther fore intermittently light lamp 25 at. this rate in a manner which is nowbelieved to be obvious. Thefiashing of lamp 25 indicates to the operator that all trunks are busy.

In the same manner, if the called sub,- scriber is found busy, ground will be con nected to terminal 529 at a different rate,

such as will produceim example impulses per minute from an interrupter such as 584 and the flashing of thelamp 25 at this rate will indicate to the operator that the wanted subscribers line is busy. As is well known in the art,-both trunk "busy and subscribers line busy signals may arrive'over the linewhile the-dialingis taking place. In accordance with this inventio-nsuch busy signals may be effective in theqcord circuit during dialing; that is, for example, incase abusy signal should arrive-at the cord circuit while the talkingkey is operated not only will the lamp 25 indicate this condition but also as soon as relay 3'? is released after a set of impulses representing'one digit is completed and the "talking conductors extended to the subscribers telephone circuit, this busy condition will be aud'ibly indicated at the operators receiver. The different typesof busy signals will, of course, in this case be identified by the operator by the rate at which the signals are interrupted. On the other hand, in case a set of impulses rep-- resenting asingle digit are in process of being transmitted the fact that thetal'king conductors are not interrupted but maintained as aclosed loop through repeating coil, thebusy signals will'be receivedwithout interference through the receiving circuit 250 and operate the lamp 25 accordingly. Therefore, regardless of whether or not dialing is taking place, a busy signal will be indicated at the operators cord circuitin one form or another or both visually and audibly. This may be of particular importance when numbers containing a large num her-.oikligits are in process of being transmitted as in such cases the operators time will be saved and a call abandoned at'the first indicationof a busy. condition of the path selected.

lit should also-be noted -that lamp- 25 may be flashe'd by the called subscriber at the rate at which the switchhook is moved up and down. Relay 309- will then be operated-when the switchhoo-k is down and release when the switchhook is up. L

[If the operator at 100 desired to rering the called subscriber after he 'hasreplacedhis receiver on the switchhoolr, she operates the ringing key '34 and-the circuitsi'itunction in exactly the same :manner as when the wanted subscr'ibemwasfirst called, i. e., impulses from the 1000 cycle source modulated by current {from the cycle sou-roe causing theoperation ,of relay "31 7 which in turn causes the operation of relay 599 which applies ringing current from source 3 592 through the establ shed con-nectionto rering the wanted subscriber;

It now only-re1nai11s-to consider one more type of-connections that may be extended by the use of this-tol llineequipment, namely,

a call intended iorWhat is commonly-known as the out delayed or repe atei"" operator, i. e. an operator-haying equipment arranged similarly to the 1operator at/410 only that this op'e-rator is reached'bv having the operator at "100 dial a certain toll or special code number. In this case,*the operator-at 1'00 proceedsin the same manner as when dialingfior an automatic subscriber such the oiie located at 51 O.'0n ly instead-of-reaching this subscribers line terminals she will be connectedto terminals such as 010 connected directly to groundand battery. This battery and lground are t1*ans1nitted*b ackover the line and will causethe operation of relay 516. Relay 516, in operating, causes ground to be connected mead 55Tresulti-ng in the-operation ofrelays and 401. "The operation of "these relays ca-uses the j lighting of signal lamp 405 as well as-the operation of thebusy signals 426. Relays 404 and 409 in operating provide locking circuits for themselves to the battery at-relay 402 and the operation of relay 404 provides a circuit from this battery for signal 405, which in lighting calls the out-delayed operator's attention'to this trunk line, Relay401 closes a circuit for the busy signal 426 as shown.

The operation of relay 404 also removes the ground from the conductor 489 and applies this ground on conductor 434-while the operation of relay 40-1 intermpts the battery; normally connected to -lead 433 to effect-the release of the automatic equipment; that the removal of battery 1" :0111 lead 433 causes relays 305,, 30,6 and 807 to releasea-nd the ground for lead 550,-to be removed, Whereas the application of ground atlead-4'84 operates the relays 309 and 310 to send a signal as hereinbefore described and light lamp at the operators position at 100 to indicate that the lamp405- at the out-delayed operators position has been lighted. The

V removal of ground from the lead 439 serves the purpose of preventing relay 331 from operating and releaserelay 310 until this out-delayed operator answers the call as will hereinafter be described.

In answering this call the plug of this op- .erato rs cord circuit (not shown) will be inserted in the jack 430. Relays 407 and 402 will now be operated over an obvious circu'it through the sleeve contacts of the outback contact locking'circuits for relays 401 and 404 and closes at this armature and front contact obvious energizing circuits for relays 408 and 319. The operation, of relay 319 connects the toll line conductors to the jack 430 While relay408, by operating its armature, prevents battery from being connected to the lead 433 andconnects this battery to the circuit for signals 426 to maintain these signals operated after relay 401 is released. Relay 404 in releasing opens the ground connection for relay 409 and reestablishes the ground for relay 311 which will now operate as it will be remembered that relay 309 is maintained energized by groundvat relay 407 and relay'310 will therefore release upon the operation of relay 311 and cause the signal lamp 25 at the operators position at 100 to be extinguished to indicate that the out-delayed operator is ready to communicate with this operator.

When the out-delayed operator disconnects by removing her plug from jaclc430,

relays 407, 402 and 408 are released and all circuits arerestored to normal condition, relay 30 9 naturally being also released causes the signals to be transmitted as hereinbefore described to light lamp 25 as disconnect sig nal for the operatorat 100.

It should be noted that in the event of the out-delayed operator is used in a through connection, the operator at 100 may send supervisory signals to this operators cord circuit by virtue of the operation of relay 317 and in case the out-delayed operator desires to call the operator at 100 she may do so by moving the plug in and out of jack 430.

'There is another phase of this invention, namely a service observing circuit arrangement the principal parts of which are shown at 380 and the operation of which will now be described; It should be noted that in the case of a ring-clown connection when relay 401 operates to light signal 427, the service observing signal 321 is also lighted over a circult as follows: battery, relay 402, right hand armature and front contact of relay 401, conductor 438, inner left hand armature and jack 324 totoll line 220 through thecontacts and iii-matures of relay 323. When lelay 401 is released at the time the call is answered by the toll operator at 410, the service observing lamp 321 is extinguished while the busy signal 322 is maintainedoperated with busy signals 426 through the operation of relays 402 and 403 until the connection is released. These operations in the service observing equipment 380 therefore indicate the progress of a call on the ringdown. basis. i I r I On the otherhand, in case a connection is extended on the automatic basis, the service observing equipment .380 operates in a different manner to indicate the progress of an automatic call. It should be noted that when relays 302 and 306 and other relays associated therewith. operate when a preliminary impulse of alternating current of 1000 cycles is sent out from the dialing equipment 150 to prepare the automatic equipment for the reception of directive impulses, these relays close a circuit for the service observing signal 322 as follows: battery, right hand armature and front contact of relay 302, busy signal 322 to ground and another circuit for signal'321 as follows: battery, right hand winding of transformer 340, left hand armature and back conlill tact of relay 309, inner left hand armature and front contact of relay 306, lamp 321 to ground. It should be noted that the left hand winding of transformer 340 is connected to the 20 cycle source 331 and consequently the circuit for signal 321 is effected by an induced current from the transformer in such a manner that a corresponding so-called quiver effect will be perceptible in the illumination of the lamp.

. This distinctive effect is taken by the service observing operator as an indication that a connection over the toll line 220 is to be extended on the automatic basis while the busy signal 322 indicates that theline is engaged. The service observing operator may now connect her set to the toll line but as soon as the dialing begins, relay 323 is operated to disconnect the operators set in order to insureagainst interference on the line during the dialingperiodo Signa1 321'- is lighted at this tinie u ith? a: steady illumination to -'-in'-' chcate the dialing period. It should bere-' membered that at this" time ground from conductor 550" is connected to c'onductor 551" through the'operation of relay 527 and that relay "309 is'operated'inthis circuit. Circuits for signal 321 and relay 32'3are,therefore,

closed as follows: battery,-right hand 'arma VVhe'n I the dialing is completed, relay. 527 1s released and ground on' conductor 551 is" removed so that relay 309 is'rele'ased" at this t me. vThe circuit for relay 323 is; there fore, broken and the'c'irouit for signal 321* ist-ransfer'rd 'tothe right hand Winding of transformer 340; This stage inttlieprogress Y Qfi pa 'll'is, therefore, indicated y-" quiver indlcationof signal 321;

In case the trunk lines leading to the" wanted subscribers line are busy-or the- Wanted subscribers' line itself-is busy; signal" 321 will alternately be'flashed from uiver to steady, respectively atth'erateof 6001 120interrupt1ons per minute; due to the cor responding operations'of relay 309i on the other hand, when w the Wanted--subscribers line has been reached, the"illuminationpf 1; signal 321 will be' steady and when the celled subscriber hasanswered the-call sig= nal 321'Will quiver. At this" time, the" service observing operators telephone 'setis" connected'to the toll line. In'case the called subs'crib'er operates" his switchhook to recall the subscriber at 10st the operator at 100, the signal 321 alternately quivers or is made steady inplia'se with the release and" operati'o'n of relay 3091 1 When the disconnection tallies place tl'; tl1e called subscribers station," signal 321 will ifuiver and the service observingoperators" telephone set is disconnected to insure against interference Withthe disconnect sig n'al, Thus, it willibe seen that a convenient and simple method of indicating and following the progress of an extension of either type of calls over the toll line available in this service observingequipment;-

hat is claimedis:

1. In a telephone system,"tliecombination of subs'oribers stations'with a 011 line ter-' initiating in means for extending the-line both 'manua'lly and automatically to a; sub scribers station, a i service observing system comprisingmeans responsive "during th op-' eration" of the said manual extensiom'means toindicate the progi'essof the manual con ne'ction over saidlinei an'd means responsive to the operation of thesaid autornatic eX tension means for indicating in a different manner the progressof'tlie automatic eXten sionover said line: I 1 y 2; In a teleph'one' system;- meansi for es-' tablishingi connections on a" manual basis, and means for employing alternating cur rents in establishing"connections ona'an automatic ba'sis, serVice observing-equipment in eluding: signaling means to indicate Whether ac onneoti'on is being established on a manual-or on an automatic basisand also the progressof" a connection being; established onthe automatic basis: an; atelephone exchange system, a'line' circuit" opaque to low frequency currents,

means for establishing a connection either onamahualoran automatic basis over said line, apliirality of low frequency current sources, receiving? equipments responsive re spectively' to"cdrrents"frorn said sources, a; carrier frequency current for rendering said loW frequency current effective over; said line to control said rec'eiving equipments in automatically establishingaconnection;

45;111". a telephone exchange} system, line circuits opaq'ne to currents of lowfrequency, aplurality of low frequency current sources, a" source of" carrier frequency current and Ineans'for reiidering said currents effective, v

toestablish' a connection either ona manual an automatic basi s'oyersai-d line; circuits. 5:11; atelephone system, line circuits, opaque"tocurrentsof'low frequency, equip-Y. Inent forenqoloyinfg lowfrequency currents in 'estajblishing- 'connection's either on a'rnanw' ali orionan automatic basis 'over said line circuits; and a'carrier current at audio frequency 4 for" transmitting? said low frequency currents over said lines; I

7 6." In atelephonesystem for handling-long distanc'e traffi'c, lines opaque tolow frequency currents; sources of'low frequency currents, a" source of high=frquency current, equip ment for rendering said low frequency currents effective in signal control for handling connections on a manual basis over lines, means: for employingsaid low and said high'frequer'fcy currents in establishing con nection'son an automaticbasis' also Over said lines, -and-means for employing the high frequency'current as 'a c'arrier agent for the low frequency currents for the signalingrelative v to said inanual connections and; also as a carrier agent for the low frequency currents when" they are required in said automatic connections: 7 I

7'. In aitelephone distance traffic, a line circuit opaque ,to; low frequency currents, sources of low frequency current, a' source of; audio frequency carrier cur'r'en't for transmitting said loW' frequency currents over said line, -me,a1is for-employing said carrier frequencyalone and also as a carrier ,forsaid-low frequency currents Q'dlltlillling; respective OPGmtion's'm the" automaticestablishment of connections in a first direction over said line, and means to render.

signals effective in the opposite direction over said line circuit durmg per1ods signals may be under transmission in the first direction over the same line circuit.

8. 1 In a telephone system for handling connections, a long line circuit substantially opaque to low frequency currents, sources of low frequency current and audio frequency responsive to demodulated low frequency currents, and means jointly under control of said master relayand said low frequency relays for rendering said signaling current effective to automatically extend a connection from said line circuit.

9. In a telephone system for establishing connections either on a manual or an automatic basis, a long line substantially opaque to currents at low frequencies, a transmitting system comprising sourcesof low frequency currents and a source of audio frequency carrier current in which the phenomenon of modulation is established when said low frequency currents may be connected thereto,

a receiving system comprising demodulator means, rectifier means and relays respectlvely responsive to rectified carrier current and to demodulated or low frequency currents, automatic switching means for extending a connection from said line, manual switching means including signals for manually extending connections from said line, and

means included with said transmitting system for selectively applying said currents over said line in rendering the receiving equipment effective to establish an automatic connection or to control said signals of the manual switching means.

10. In a system for automatically establishing telephone connections, a line substantially opaque to currents of low frequency, a source of voice frequency alternating current at one end of said line, a source of audio frequency carrier current and a source of low frequency current at the other end of said line, a receiving system comprising rectifier means, demodulator means, and relays respectively responsive to said carrier current and said low frequency current, an automatic switching system undercontrol of said receiving system, means for applying said carrier current to said line in seizing and conditioning said automatic switching system for the reception of selective impulses, means to automatically apply an impulse formed of said carrier current modulated by said'low frequency current over said line, and signal means controlled by said opaque to direct currents and to low frequen-' cy alternating currents, a source of carrier current of audio frequency, a source of low frequencycurrents for modulating said carrier current, a receiving system for said modulated currents and said carrier current, automatic switching means controlled by said receiving system, and transmitting meansfor selectively applyingsaid currents over said line to respectively control said automatic equipment in the operations of seizing, dialing and ringing inautomatically extending a connection from said line.

12. In a telephone system, a calling and a. called station, a line circuit opaque to direct current and to alternating currents of low frequency, an automatic switching system including a source of audio frequency current and a low frequency modulating current therefor, means for controlling said switching system from said callingpoint in I connecting said line to said called station, a signal and control means therefor at said calling station, and means responsive on said connection being established to said called station to apply an impulse of said modulated current over said line to energizesaid signal. 13..In a telephone system, a calling and a called station, a line circuit opaque to direct current and to alternating currents of low frequency, a signal and control means therefor at said calling station, an automatic switching system including a source of audio frequency carrier current and a source of low frequency current for modulating said carrier current, means for dialing over said line in controlling said switching system to connect the line to the called station, and means responsive during the operation of said switchingsystem and following establishment of a connection to apply a single impulse of said modulated current over said line at different times in controlling said signal to respectively indicate that dialing may be proceeded with, dialing has been completed, the co-nnectionhas been established with the called station, the called. station has responded and finally that the called station has disconnected.

14. In a telephone system, the combinalea terminating end for transmitting to the I originating end signaling currents from alternatlng current sources operat ng when the path being selected by the automatic extension means is busy, a signal at the originating end, means at the originating end for operating said signal responsive I to said signaling currents incoming during the sending of dialing impulses over the toll line.

15. In a telephone system, the combination of a toll linewith means for extending the line automatically, alternating current sources, means at the originating end of the line for producing and transmitting dialing impulses from a current source to control the automatic extension i means comprising a pulsing circuit, a transformer, means for switching the toll line conductors to the secondary of the transformer and the pulsing circuit through the primary of the transformer when the pulsing device is operated, means at the terminating end for transmitting over the toll line conductors to the originating end signaling current from alternating current sources indicating that the path being selected is busy, a signal at the originating end, and means at the originating end for operating said signal responsive to said signaling currents incoming while the toll line conductors are closed through the secondaryof said transformer.

16. In a telephone system, the combination of a toll line with means for extending the line automatically, high frequency and low frequency alternating current sources, means at the originating end of said line for transmitting dialing impulses from an alternating current source for controlling the automatic extension means, means at the terminating end for transmitting to the originating end signals comprising alternating current from a high frequency source modulated by alternating current from a low frequency source operated when the path being selected by the automatic extension means is busy, a signal at the originating end, and means at the originating end for the operation of said signal responsive to the modulated signal incoming during the sending of dialing impulses over the toll line. 7

17. In a telephone system, the combination of a toll line with means for extending the line automatically, high frequency and low frequency sources, means at the originating end of said line for transmitting dialing impulses for controlling the automatic extension means, an operators telephone circuit connected to the originating end of the line, means for connecting the dialing means to the originating end of the line and disconnecting the operators telephone circuit from the line, a visual signal at the originating end, means at the terminating end for transprising alternating current from a high frequency source modulated by alternating cur- A rent from a low frequency source operating when the path being selected by the automatic extension means is busy, and means at the originating end responsive to said modulated signals for the operation of said visual signal when the dialing means is operating and for operating the visual signal and for transmitting audible indications to the operators telephone set when the dialing means is disconnected from the line.

18. A telephone system, including transmission circuits and a source of modulated alternating currents for signaling over said circuits characterized in this that said currents are produced by means comprising a source of direct current, a vibratory relay of the sh'ort-circuiting type connected to said source of direct current, sai'd relay provided. with an armature having a natural period of high frequency for the production of'high frequency alternating current, and a vibratory relay of the same type connected to said direct current source and provided with an armature having a natural period of low frequency for the production of low frequency alternating current, and a transformer having a winding associated with each vibratory relay and a third or output winding for supplying said modulated currents to said transmission circuits.

19. In a telephone system, the combination of subscribers stations with a toll line terminating in means for extending the line au tomatically to a subscribers station, high frequency and low frequency alternating current sources, a supervisory signal at the originating end for indicating the progress of an automatic connection, means at the terminating end for transmitting to the originating end an impulse of current comprising alternating current from a high frequency source modulated by alternating current from a low frequency source at intervals during the operation of the automatic extension means, and means at the originating end responsive to said impulses to actuate said signal on the receipt of thefirst impulse and to restore said signal to its normal condition upon the receipt of the second impulse and thereafter alternating operating and restoring the signal in response to sueceeding impulses.

In witness whereof, I hereunto subscribe my name this 13th day of December, A. I). 1924;. Y

HENRYW. ONEILL.

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