US1562528A

US1562528A - Telephone system

Info

Publication number: US1562528A
Application number: US674939A
Authority: US
Inventors: John F Toomey; Henry E Phelps
Original assignee: American Telephone and Telegraph Co Inc
Current assignee: AT&T Corp
Priority date: 1923-11-15
Filing date: 1923-11-15
Publication date: 1925-11-24
Anticipated expiration: 1942-11-24

Description

Nov. 24, 1925- 1,562,528

J. F. TOOMEY ET/AL TELEPHONE SYSTEM Filed NQV. 15, 1923 4 Sheets-Sheet 1 hyerrio/a: Jam f 700/226 flew 5 Pie/pa Nov. 24,1925 1,562,528

J. F. TOOMEY. ET AL TELEPHONE SYSTEM giled Nov. 15. 1923 4 Sheets-Sheet 2 Nov. 24, 1925- J. F. TOOMEY El AL TELEPHONE SYSTEM Filed NOV. 15. 1923 4 Sheets-Sheet 5 hue/1mm. Jo/mfl' 7'0omey Hen/315 Pheks by Nov. 24, 1925. 1 1,562,528

J. F. TQOMEY ET AL TELEPHONE SYSTEM Flled Nov. 15 1923 4 Sheets-Sheet 4 Patented Nov. 24, 1925.

warren: stare rare NQT Farce,

JOHN F. TooMEy Am) HENRYLE, PHELPS, or yortrnn, Y,, .a ssronoas; 12o Annexcan TELEPHONE 1am) :TELEGBAI H zooiarAnmn oonronnmron, or 3 TELEPHONE rsrrala Applipat ion filed November 15, 1923-. Serial No. 674,939.

T0 all whom it may concern:

Be it known that we, JoH1 I. F. TOOMEY and HENRY E. PHELPS, residing at New- York and New York, in the counties, ofNew York and Bronx, andstatetof New Yorlo and New York, have invented certaihIniprovements 111 Telephone systems oi' which the following is R SPQCIfiQQlIIOD.

This 7 invention relates to {telephone sys terns, and more part cularly, to' systems feature or the lllYBIllQl-Oll by providing manual switchboard operators with cord less connecting circuits, that is, i'nsteagtl er;

providing the-operator with av number of cordsand jacks with which sheinay coin: plete connections, each position is equipped with key sets, each set comprising a pie rality of mechanically interlocking keys in which the connecting circuits serving that By this arrangement the mere act. of operating-a, key hy an lop erator extends a call incoming to her post position terminate.

tion tothe positionor. switchboard corre sponding tothe key actuated. Cordless connecting cllClllts are part cularly adapted for use at what, are known as recording operators positions.

Another feature of, the invention resides in the automatic distribution of callsinconiL mg to a recording operatofls, pos t on.

W hen a recording trunk. is taken up at its outgoing end for a new call, itsinco-n' ing end is automatically connected to an idle recording operator, by means of a rotary, type select-or swltch. The l ghting of a.

lamp signal indicates to the recording op orator that a call has come 1n onone other,v

idle connecting circuits.

A further feature of the invent on resides The operation of talking key unit of, a connecting key set at arecording operators position completes a circuit for indicating. to.

therecording operator the [calling subscribe crs class of SGFV1C8.,

A still further: feature residesin the auto:

matic selection of trunks -.terminating; at the recording operators position In case a call incoining to a recording operato'rsposi ti-on is of such a nature thattherecording operator inust extendit to some other part ofithe ofli'ce, she may do so by operating the proper-nnitot a connecting key set and an idle trunk'leadinglto the desired positionor de'skf, will then be "automatically selected by a rotary;type selectorswitch; U

Another feature residesfin the prevention of intrusion on a busy opera-tor. When recording operator actuates' 'altalking key" in response to I an incoming call all th'e'icon neoting' circuits serying thatposition are rendered busy; so [that "new "call's are excluded duringcthe time the operator is completing the first connection. A

The above and other features of the inventionwill readily appear'fMriith'e following detailed description madefwith [reference to. the accompanying drawings inv which Figure 1 shows the outgoing end of a; toll trunk line terminating in a semi inecha'nioal oiiice to gether with the associated apparatusior transmitting class or service signals over the trunk line, a calling subscribefls line and a diagrammatic representation of the circuits of a semi-mechanical operators position]for,,

extending a connection from the s ubscriber s lineftoithe toll trunk." Fig, 2 shows the incoming end of the toll trunk line together with the necessary equipment for relaying the class of service signals; and a selector switch in whichthe' cordless connecting circuits leading to recording ope1'ato1l*s "positions terminate; Fig 8 shows'a connecting circuit terminating in a plurality of keys at a recording "operators position" "some of which areemployed in extending an incom ing call to another position such as the soconnecting circult, appearing betorean idle,

called ratequotingT pOsitiOnM by way of the, rotary type selector switch K. The equipment necessary for receiving the class of service signals is al'so shown in Fig, 3. Fig. 4 shows the outgoing end ot a tolltrunk line terminating-in a manual ofiice and the I necessary equipment at that office for transin the provision of class of service signals,

n itting class of; service signals-over the toll trunk line. This figure corresponds to the arrangement showninFig 1,

The following description will trace a call from the originatings ubscribers line A over the toll trunk line B, by We}? Ofa seminiec'hanical office, to the recordingoperators position 0, Fig. 3. Thence the call is ex tended to a special operators position M. Though the following description is directed to a call'handled by a semi-mechanical operator, it is obvious that the multiple terminal shown in Fig. 1 may be seized by a mechanical subscribers machine switching equipment direct, the choice of terminals being dictated by conditions inserted in the subscribers line equipment.

A calling subscriber at A to initiate a call removes the receiver from the switchhook thereby closing the circuit of the line relay 30. This circuit extends from grounded battery, through the left-hand winding of relay 30, the outer armature and back contact of cut-01f relay 31, thence over the subscribers line loop and through the back contact and inner armature of relay 31, to ground, through the right-hand winding of relay 30. Relay 30 energizes in this circuit and closes an obvious circuit for line lamp 32. This line lamp is provided with a distinctive lamp cap 32 which enables the answering operator to determine the class of service to which the calling subscriber is entitled. In the present case it will be assumed that the calling subscriber is entitled to regular toll service.

The semi-mechanical operator on noting the illumination of lamp 32 inserts the answering plug P of an idle cord circuit at her position in the jack J of the calling line whereupon a circuit is established over the sleeve contacts of the plug and jack J, through the win-ding of cut-off relay 31, which relay operates and opens'the circuit of line relay 30 thereby extinguishing the line lamp 32.

The operator now obtains from the calling subscriber the nature of the connection desired, and assuming that the subscriber desires a toll connection, the operator proceeds to set up on her sender X, the'necessary code for settingthe brushes of the district selector 90, in which her cord circuit terminates, upon the terminals of a toll trunk line extending to the recording operators position at O, Fig. 3. The code which the semi-mechanical operator'sets up upon her keyboard is also determined by the class of service to which the calling subscriber is entitled and therefore the brushes of district selector will not only be set, by the sender X, upon the terminals of the toll trunk line but also upon a particular set of multiple terminals of the toll trunk line for causing the transmission thereover, of a special distinctive'signal to inform the toll operator of the class of service to which the calling subscriber, is entitled For this purpose each toll trunk line terminates at the terminal bank of the district selector 90"in four sets of terminals. In the case assumed the brushes of the district selcctor 9O will be set upon the first set of terminals 9, 10 and 11. A circuit is thereupon established which may be traced from grounded batter through the lower lefthand winding'of repeating coil 12, winding of relay 13, upper normal contacts of relay 14, terminal 11 and the associated brush of the district selector 90, the left-hand normal contacts of key K, through the windings of the polarized supervisory relay 91, righthand normal contacts of key K, brush and terminal 10 of the district selector 90, lower normal contacts of relay 14, through the upper left-hand winding of repeating coil 12, to ground. The direction of current in this circuit is such as to permit relay 91 to operate causing an obvious circuit for the supervisory lamp 92 to be established. The illumination of lamp 92 at this time serves as a guard signal. Relay 13 also operates in this circuit and establishes a circuit extending from grounded battery, through the winding of relay 15, and winding of relay 16, to ground, over the front contact and armature of relay 13. Relays 15 and 16 operate in this circuit. Relay 16 at its inner armature prepares a circuit for the reversing relay 14, the purpose of which will be described at a later time. At its outer armature relay 16 prepares a circuit originating at the positive pole of battery 70 which circuit will be completed presently. Relay 15 operating in series with relay 16 establishes an obvious circuit for the slowto-release relay 19. Relay 19 at its righthand armature establishes an obvious circuit for sloW-to-release relay 20 and at its lefthand armature removes the short circuit from the left-hand armature contacts of relay 15.

The circuit originally started by the attraction of the outer armature of relay 16 is now complete and may be traced from grounded battery 70, resistance elements 17 and 18, conductor 21, front contact and outer armature of relay 16, conductors 22 and 23, back contacts and armature of slow-to-operate relay 24, left-hand armature and front contact of slow-to-release relay 20, left-hand armature and front contact of relay 15, winding of marginal relay 25, lower righthand winding of repeating coil 12, conductor 95, lower left-hand winding of repeating coil 103, through the windings of polarized relay 102, marginal relay 101 and relay 100, upperleft-hand winding of re peating coil 103, conductor 96, through the upper right-hand winding of repeating coil 12, to ground. Relay 25 being marginal does not operate in this circuit.

The current in the circuit just traced is in such a direction and of such strength as to operate only relay 100 of relays 100, 101 and 102 which are bridged across the trunk conductors and 96 through the left-hand iii) windings of repeating coil 103; Relay 100 in operating establishes an obvious circuit for relay 1. Relay 104 operates, and in attracting its outer armature establishes circuits for relays 105 and 100 the former extending from grounded battery, through the winding of relay 105, normal contacts of hand arn'iature and back contact of relay 109, through the winding 01. relay 112 to ground. Relay 112-, operating in this circuit, connects a source of tone current 113 to the main conductors of the trunk to indicate to the calling subscriber that the recording operatoris being signaled as will appear presently.

Relay 105, operating in the circuit hereinbefore traced, establishes a circuit extending from ground, through positive pole or the battery 114, resistance elements 115 and 116, back contact and outer right-hand armature of relay 117, conductor 118, back contact and outer right-hand armature of relay 119, conductor 120, righthand armature and front contact of relay 105, conductor 121, to the mid-point of the right-hand windings ot repeating coil 108 and thence over the tip and ring conductors of the trout: as far as the arniatures of relay 122. This circuit will be completed presently. At its lefthand armature relay 105 establishes a locking circuit for itself extending from grounded battery, through the winding of relay 105, front contact and leftha-nd armature of re lay 105, conductor 128, conductor 108, normal contacts oft relay 109, conductor 110, over the front contact and righthand arniature of relay 104, to ground.

Relay 100 operating in the circuit previously traced, causes the steppin magnet 12% to energize in a circuit extending from grounded battery, through the IQSiSAiDCQ element 125, winding and armature and back contact of magnet 124;, armature and back contact oi? relay 107, both arniatnrcsand front contacts of relay 100, right-hand winding of relay 100, through both windings of relay 107 to ground. The stepping in. net 124, operating in this circuit, causes the selector switch S to start hunting for an idle trunk leading to the recording operations position. As soon as the test wiper 120 of switch S encounters a contact which is supplied with battery, that is an idle trunk, the stepping magnet ceases to operate since it is shunted by the battery 200 (Fig. associated with the idle trunk. Relay 107 now operates in a circuit e:-;tending from grounded battery 200, through the resistance element 201, back contact and left-hand armature of relay 203, back contact and armature of relay 1, upper contact 01 key 205, conductor 200, contact 127' and wiper 120 of the selector switch S, front contact and inner arniatnre of relay 106, therighthand winding of relay 100, through both windings of relay 107, to ground. Relay 10? in attracting its right-hand armature opens the original circuit of stepping mag net 12th it its outer left-hand armature relay 10? 'ranst'ers the ground received from the make contact of relay 10 1 from the win-ding o1 relay 100 to the winding of relay 1 Relay 122 thereupon operates connecting the tip and ring conductors otthe-trunl: to corresponding terminals of the selector switch S. At its two lower arinatures relay 122 connects conductors 128 and 129 to the windings oil? relays 107 and 133 for pun poses which will hereinafter appear. A circuit tor relay 203 now exists which may be,

traced from grounded battery, hrough the winding of relay 203, conductor 202, terminal 130 and wiper 131 of switch S, conductor 128, front contact and lowermost arinature of relay 122, leit't-hand inner armature and contact of relay 102', through the right-hand winding of relay 10?, to ground. Relay 208 in attracting its left-hand armature removes battery 200 from the test terininal 12'? of switch S and substitutes a ground therefor, in order to hold the inult-iplecontacts out other selector switches busy. At its right-hand armature, relay 203 establishes a circuit extending from grounded battery, over the right-lnind armature and front contact GTE relay 203, back contact and inner left-hand armature of relay 207, lefthand arinatrure and back contact of relay 208, through the filament of lamp 20.0, to ground. The illumination of lamp 200 in this circuit indicates to the recording operator that there is a. call awaiting her atten tion and she proceeds to answer it in the following manner.

It is to be understood that relay 10, re mains operated in series with relay 203. Too recording operator in response to the illumination of lamp 209 actuates the tails ing lrey 210, whereupon a circuit is established extending from grounded battery. through the winding of relay 207, to ground on the lower alternate contacts of lacy 210. Relay 20?. operates in this circuit and performs the following functions: At its outer right-hand armature, it connects ground to the contact of switch S by way of the.

normal contact of key 211, which ground hereinafter to be described.

. 204 in a. circuit connected to battery through the windings of all other such relays that are located in. the connecting circuits to which this operator has access. All these relays will, therefore, operate and connect ground to the test terminals of these connecting circuits at all selector switches associated therewith and thereby causing said connecting circuits to test busy as long as any key, such as 210, at any one of the connecting circuits at this operators position is operated. It is therefore evident that a position will not be selected by any incoming call as long as the operator at that position has one of her talking keys thrown. That is, any relay 207 which is operated causes the operation of all relays 204, as the lead from the inner contact of the outer left hand armature of these relays are multiplied together, as indicated by the taps on this lead. At its middle and upper alternate contacts key 210 bridges the operators telephone set and the simplex circuit including the windings of relay 214, marginal relay 215 and polarized relay 216 across the tip and ring conductors of the trunk.

Upon the connection of ground to the contact 132 of selector switch S as hereinbefore described, Frelay 133 operates and at its right-hand armature establishes an obvious circuit for relay 109, while at its left-hand armature it short circuits the high resistance left-hand winding of relay 100. The shunting of the high resistance winding of relay 100 causes an increase in current in the circuit including the winding of marginal relay hereinbefore traced. Marginal relay 25 thereupon operates and establishes an obvious circuit for relay 60. Relay 60 in attracting its left-hand armature establishes a new energizing circuit for slow-to-release relay 20 which may be traced from grounded battery, through the winding of slow-to-release relay 20, conductor 61, over the front contact and left-hand armature of relay 60, to ground. At its right-hand armature relay 60 establishes an obvious circuit for slowto-release relay 63, and also a circuit for the reversing relay 14 which may be traced from grounded battery, through the winding of relay 14, front contact and inner armature of relay 16, conductor 64, armature and back contact of relay 65, conductor 66, over the front contact and right-hand armature of relay 60, to ground. Relay 14 operates in this circuit and in attracting its armatures reverses the tip and ring conductors of the trunk so that the current from the battery associated with the repeating coil 12 is reversed through the windings of polarized relay 91 so that this relay releases to extinguish the supervisory lamp 92. The darkening of lamp 92 at this time is of no importance as the semi-mechanical operator does not attend further to the connection, unless she is recalled by the calling subscriber, until she receives the disconnect signal.

Relay 63 which operated as a result of the energization of relay establishes an obvious circuit for relay 67 which thereupon operates and locks to ground on the righthand armature of relay 20. In attracting its right-hand armature, relay 67 performs no useful function at this time since the circuit for interrupter 80 is opened at the back contact of relay 63. Since relay 20 is now maintained energized over two circuits, one indirectly controlled by relay 13 in the outgoing end of the toll trunk, and the other indirectly controlled by relay 133 in the incoming end of the toll trunk, the locking circuit for relay 67 is therefore maintained as long as the trunk is held in service at either of its ends, and therefore ground potential is maintained on all multiples of test terminal 9 appearing in all district selectors having access to the outgoing end of the toll trunk. This ground is connected to the test terminal 9 in a circuit extending over conductor 68 to ground on the middle left-hand ill!) armature and front contact of relay 67. The toll trunk is thus made unavailable to other outgoing calls until after it has been released at both its ends. Relay 67 at its outer lefthand armature establishes an obvious circuit for relay 24 which operates, disconnecting battery 70 from the winding of marginal relay 25 and substituting therefor the battery associated with the front contact of relay 24, in order to hold relays 25 and operated.

Relay 109 operating as a consequence of the operation of relay 133 as hereinbefore described, locks up over its outer left-hand armature to battery on the inner right-hand armature of relay 104. At its inner left hand armature relay 109 prepares a circuit for relay 134, the purpose of which will hereinafter be described- At its right-hand armature relay 109 connects ground to the windings of relays 122 and holding them operated independently of relay 104. In opening its left-hand normal contact, relay 109 opens the circuit for relay 112 which thereupon releases removing the tone source 113 from the trunk, which serves as an indication to the calling'subscriber that the recording toll operator has answered the call and also removing ground from the armatures of relays 101 and 102.

As a consequence of the various operations Cit hereinbefore described, a circuit now exists which may be traced from ground,'through battery 114., resistance elements 115'and 116, back contact and outer rightdiand armature of relay 117, conductor 118, back contact and right-hand armature of relay 119, conductor 120, right-hand armature and front contact of relay 105, conductor 121, and thence in parallel through the right-hand windings of repeating coil 103, back contacts and armatures of relay 134, upper and innermost lower armatures and front contacts of relay 122,

wipers

138 and 139, and terminals 140 and 141 of switch S, middle and upper alternate contacts of key 210, through the simplex windings 217. and 218, through the windings of relay 214, marginal relay 215 and polarized relay 216, to ground. The current in this circuit being of such a'polarity and of a relatively low Value does not cause either marginal relay 215 or polarized relay 216 to operate. Relay 214, however, operates causing lamp 219 toglow in a circuit extending from grounded battery, through the filament of lamp 219, back contact and left hand armature of marginal relay 215, back contact and armature of polarized relay 216, over the armature and front contact of relay 214, to ground. The illumination of lamp 219 which is provided with a cap 219 having a distinguishing marking corresponding to the marking on lamp 32, inclicates to the recording operator the class of service to which this particular calling subscribers line is entitled.

Since the operators telephone set is bridged across the main conductors of the connection by the actuation of key 210, the recording operatormay now converse with the calling subscriber. It will 'be assumed that the subscriber desires a connection with some o )erating room desk such as the rate quoting desk and that such a request is made to the recording operator. The operator may'then restore her talking key 210 and actuate the rate quoting key 220. The actuation of key 220 causes cut-off relay 203 to operate in a circuit extending from grounded battery, through the winding of relay 208, conductor 221, to ground over the u crmost alternate contact of key 220. Relay 203 at its left-hand armature cuts off the lamp 209 and at its right-hand armature applies ground to the'terminal 132 by way of the lead 212 to hold busy the equipment in the recording trunk circuit. At its two inner alternate contacts key 220 prepares the tip and ring conductors of the connecting circuit for connectionwith the corresponding terminals of the selector switch K. At its lowermost alternate contact, key 2-20establishes an obvious circuit for relay r222. Relay 222 operates in this circuit and connects ground to the winding ground.

of relay 223 and also to conductor 224. It will be noted that sector 228 of the switch K has itsterminals'divided into four groups, with a certain nuniber of terminals allotted to each group'and each group corresponding to one of the keys 227, 220, 226 and 225. 'if he terminals of the sector'228 are allotted in accordance with the tralfic, that is, calls for information "being more numerous than calls for rate quoting, for chief operator or for directory, a greater number oftermina'ls willbe assigned to information 'than to the other desks. The information desk group of'terminals obyiously corresponds to key 225, whereas the key 226 corresponds to the chief operator desk group of terminals, key 220 corre sponds to'the rate-quoting desk group of terminals and key 227 corresponds to the directory desk group ofterminals. The grounding of conductor 224 by relay 222 connects gro'undto the group of terminals 230 which is allotted to rate quoting. The operation of relay 223 as hereinbefore described causes the stepping magnet 231 to energize in a circuit extending from grounded battery, through the resistance element winding of magnet'231, armature and back contact of magnet 231, conductor 233, back Contact andle ft -hand armature of relay L34, conductor 235, over the front contact and outer armature of relay 223, to ground. At its inner armature relay 223 prepares a circuit for'relay 270 aswill hereinafter appear. The stepping magnet231 upon energizing, causes the selector switch K to step around until the group of ground ed terminals 230 is reached, whereupon relay 234 energizes in a circuit extending from grounded battery, through the winding of relay 234-, right-hand normal contacts of relay 234, conductor 236, Wiper'237 of switch K,'to ground on the group of contacts 230. Relay z34 operates and locks itself to ground on the outer armature of relay and disconnects itself from the wiper 237 of switch K. At its left-hand armature relay 234 causes relay 238 to operate in a circuit which may be traced from grounded battery, through the left hand winding of relay 238, back contact and outer left-hand armature of relay 239,1'1101'1t contact and left-hand armature of relay 234, conductor 235, front contact and outer armature of relay 223, to In completing this circuit relay 234 opens theoriginal energizing'circuit for stepping magnet 231. Relay 238 in operating establishes a circuit extending from grounded battery, through the resistance clement232, winding of magnet 231, armature-and back contact of -magnet231,outer right-hand armature and back contact of relay 239, outer. armature andfront contact .of relay 238,"fr.ont contact and inner arma- Lure of relay 238, {gilt-hand winding 01 relay 238,'to ground, through both windings 7 contact and left-hand armature of relay 270,

of relay 239. Owing to theinclusion of re slstance element 232 in this circuit relay 239 does not receive sufficient current to operate at this time. .The stepping magnet 231,

however, operates and causes the selector switch K to hunt for an idle trunk in the group corresponding to the group of terminals 230 leading to the rate quoting desk. The idle condition of the trunk is indicated by the presence of battery on the test terminal 242. vAs soon as such an idle trunk such as L is encountered a circuit is established extending from grounded battery, through the resistance element 240, back normal contact of key 241, test terminal 242 and wiper 243 of switch K, conductor 244,

front contact and inner armature of relay 238, right-hand wmdmg of relay 238, to ground, through both windings of relay 239.

The battery associated with the resistance element 240 shunts out the stepping magnet 231 causing it to release. The current through the windings of relay 239 is sulficient now to causethis relay to operate and lock up in series with relay 270 in a circuit extending from grounded battery, through the winding of relay 270, terminal 245 and wiper 246 of switch K, conductor 247, front contact and inner armature of relay inner left-hand armature and front contact of relay 239, right-hand winding of relay 239 to ground. Relay 239 at its outer lefthand armature opens the circuit for relay the test terminal 242 of switch K and sub- .stltutes a ground therefor, thereby, causing all the multiple contacts of all selector switches such as K to cause the seized trunk L to test busy. At its inner right-hand armature relay 239 causes relay 246 to operate in an obvious circuit. Relay 246 in attracting its armatures connects the conductors of the connecting circuit through to the trunk leading to the f rate quoting desk.

As a result of the operation of relay 246, a circuit is established which may be traced from grounded battery, through the armature and back contact of cut-off relay 300, right-hand Winding of relay 301, ring conductor of the selected trunk leading to the rate quoting desk, ring terminal 290 and wiper 291 of switch K, front contact and lower armature of relay 246, lower normal contacts of key 293, winding of relay 292, upper normal contacts of key 293, upper armature and front contact of relay 246, wiper 294, and tip terminal 295 of switch K, tip conductor of the selected trunk leading to the rate quoting desk, left-hand winding of line relay v301 to ground. Relays 301 and 292 operate in this circuit, the latter and theformer establishing a circuit from grounded battery, front contact and righth'and armature of relay 301', through the lilainent of lamp 303, back contact and righthand armature of slow-to-release relay 304 to ground. The illumination of lamp 303 in this circuit indicates to the rate quoting operator that a call is awaiting her attention. The illumination of lamp 296 as hereinbefore described serves as a guard signal to the recording operator.

The rate quoting operator in response to the illumination of lamp 303 inserts plug P into jack J of the selected trunk, whereupon cut-off relay 300 operates in an obvious sleeve circuit. Belay 300 opens the circuit for line relay 301 and for relay 292 which thereupon release causing the darkening of lamps 303 and 296 respectively, the latter'indicafing to the recording operator the response of the rate quoting operator.

- By actuating her talking key (not shown), the rate quoting operator may converse with the calling subscriber. Assuming that the conversation has ended, the rate quoting operator withdraws plug P from jack J whereupon relay 300 releases opening the circuit for relay 304 and closing the circuit for line relay 301. Relay does not release since itis a slow-torelease relay and its locking circuit will be completedat the left-hand armature and front contact of relay 301 before it has time to retract its armatures so that the operator at position M does not get a false signal when she disconnects.

The circuit for. relay 292 is again established causing lamp 296 to become illun1iated to indicate to the recording operator I nection.

To release the connection the operator actuates a restoring key 262 that is arranged, in a manner well known in the art, to restore any of the keys 220, 225, 226 and 227, whichever one of these keys may be operated. Key 220 which in this instance is operated consequently releases and thereby causes relay 208 to restore thereby ren'ioving ground from terminal 132 of switch S causing the release of relay 133. Relay 33 in releasing, removes the shunt about the high resistance left-hand winding of relay 100 thereby causing the current in the circuit including the winding of marginal re lay 25 to decrease to such an extent as to per mit this relay to release. Relay 25 in retracting its armature causes relay 60 to release. The release of relay 60 causes the opening of the circuit of the reversing relay 14 and also of relay 63. Relay 63 in releasing, causes the interrupter circuit including the winding of relay 65 i? be. completed, it being understood that relay 67 remains 1 through the windings of polarized relay 91.

Relay 91 thereupon causes lainp 92 to flash as a dis-connect signal to the semi-merchant cal operator.

The semi-mechanical operator, noting the flashing of lamp 92 removes the plug P fIOHL jack J of the calling line thereby restoring the calling line to its initial condition and causing the restoration of the district selector switch 90. Following the restoration of switch 90, the circuit previously traced through the winding of relay 13 is opened thereby opening the circuit for relays 16 and 15.. At its inner armature, relay 16 opens the circuit for reversing relay 1%. Relay upon deenergizing, opens'the circuit for relay 19 which in turn opens the circuit of relay 20 and since, at this time the auxiliary holding circuit of relay 20 previously traced over conductor ()1 is opened at the left hand larinature and contacts of relay 60, relay 20 deen'ergizes, opening at its right handarmature, the holding circuit for relay-67 whichrelay in turn opens the circuit for relay 2 1 a11d-re1n0ves busy ground potential from conductor 68 and the multipleterminals of the'toll'trunk. *The release of relay ,lOOas hereinbetore mentioned causes relay lO lto release whereupon the locking circuit forrelay 109 is opened, so that this relay alsoreleases removing the holding ground from the windings of relays 105 and'122. Relays 105 and 122 there-upon release. Relay 122 at its lowermost armature opens the circuit for relays 107 and 203 \vhereupon'these relays release, the latter removing the busy ground potential from the test terminal 127 of switch S and substitutingtherefor battery 200. Relay 122 alsodisconnects the tip and ring conductorsof the recording trunk from the corresponding terminals letO and 141 of switch 53. 'Relay 15 upon deenergizing also opens the circuit previously traced through the winding of relay over the toll trunk and through the windings o'f relays 100, 101

and 102 whereupon-these lastthree relays, it operated, release, relay '25 having been. previously released. The circuits'at the outgoingand incoming ends of the trunk are now in their normal positions.

Upon the release of key 220 at the recording operators position, as hereinbefore mentioned, relay releases removing key 211, whereupon relayJBS 'SGlIll-IHQCll211116211 operator reconnects ground from the winding of relay 223 and also from the group otterniinals 230 of switch K. Relay 223 thereupon releases, opening'tlie locking circuit torrelay 23 1 and alsofor relays 239 and 2T0 which thereupon release. The deenergization of relay 270 removes thebusy condition 1 1O111tl18 trunk'L leading to the rate quoting desk, and again connects'battery to the test terininal 2 12 01 switch K to indicate the idle condition of the trunk. All the apparatus is now in its normal condition and the circuits prepared to receive another call.

If in'the course of a connection, the recording operator at 0 should desire to signal the semi-mechanical operator, she may do so by successively actuating the flashing is intermittently deenergized to alternately remove and complete the shunt about the high resistance winding 01? relay 100 so that the current in the circuit including marginal relay 25 will be varied causing this relay to follow the ,actuations of key 211. The circuit for relay will thereupon be intermittently opened and closed to cause the circuit through slowreleasing relay 63 and reversing relay 1% to be opened and closed at the same rate. Relay 63, being slow-to-release, does not have suliicient time to restore its ELITHZHJUIBS to their initial positions between successive deenergizaatons of relay '25, and therefore, the circuits which are established by relay 63 are maintained intact. lielay l t however, responds to each deenergization of relay and at its armature contacts reverses the current flowing through the windings of polarized supervisory relay 91 at the senaianechanu cal operators position. The lamp 92 which is controlled by relay 91 will, therefore, flash in synchronisni with the actuations of key 211.

In response to this flashing signal, the her telephone with the semi-n1echanical cord and is then in a position to con'nnunicate with the recording toll operator.

Should the originating or semi-mechanical operator desire to signal the recording operator, she may do so by momentarily ac tuating the hey k to disconnect the windings of polarized rel ay 91, from the cord and connect battery and ground to the ring and tip conductors of the cord whereui pon the battery-associated with repeating coil 12 is rendered ineffective to hold relay 1.3 operated.

Relayls thereupon releases causing relays 16 and to deenergize. lit-clay 15 causes the circuit tor relay 19 to be opened but relay 19 being slew-to-release does not have su'tlicient time to retract its ari'n atures. How- 6VG1,Sl1()Ul(l relay 19 restore and open the circuit for relay 20 the slow-releasing characteristic of this relay would tend to maintain it operated. The rhalzicteristics of reto the incoming end of the trunk. fore, in response to the actuation of key 7c, a v circuit for relay 213 is established which may be traced from grounded battery, over the front contact and lower armature of relay 13 1 inner lower armature and front contact of relay 122, wiper 139, and terminal 1&1 of switch S, back contact and inner right-hand armature of relay 207, through the lefthand winding of relay 213, terminal 140 and wiper 138 of switch S, front contact and upper armature of relay 122, upper armature and front contact of relay 13 1, through the resistance element to ground. Relay 213 operates in this circuit and in attracting its armature establishes an obvious circuit for the supervisory lamp 250 and locks itself to ground on the outer right-hand arn'iature of relay 207. In response to the illumination of lamp 250, the recording operator again actuates key 210 to connect her head-set to the tip and ring conductors of the trunk and to establish an obvious circuit for relay Relay 207 thereupon operates disconnecting the left-hand winding of relay 213 from the tip and ring conductors of the trunk and opening the locking circuit of relay 213. This relay thereupon releases causing the darkening of lamp 250.

It for any reason, the rate-quoting operator should desire to recall the recording toll operator, she may do so by successively withdrawing and inserting plug P into jack J. This action causes relay 300 tobe successively deenergized, and to thereby successively disconnect battery from the righthand winding or" relay 301, which relay together with relay 292 are bridged across the tip and ring conductors of the trunk. Relays 292 and 301, therefore, follow the interruptions of the bridge circuit caused by the intermittent actuations of sleeve relay 300. Lamp 296 which is controlled by relay 292, therefore, flashes in synchronism with the connections and disconnections of plug P with jack Q It will be noted, however, that lamp 303 which is controlled by line relay 301 does not flash at this time since its circuit will be maintained opened at the back contact and left-hand armature of slow-to-release relay 304 during this period, relay 1 remaining energized owing to its slow-release characteristic,

The ringing key 298 which is furnished with the recording operators equipment is supplied for the purpose of signaling a special operator whose position may be equipped with a ringdown type of signaling equipment.

. The previous description was directed to a call originated by a subscriber who is entitled to regular toll service. If, however, a subscriber other than the subscriber at station A who is entitled to some other class of service, should initiate a call, the semi-mechanical operator would set up a special code, which would cause the brushes associated with her semi-mechanical cord circuit to come in contact with a. ditierent set of trunk terminals such as a, b or c. Depending-on which of these terminals are employed in the establishment of a connection, currents ofdifierent strengths and polarities are transmitted over the recording trunk from the sources and 99 to effect the operationot relays 100, 101 and 102 in various combinations. Depending upon the combination of relays operated, currents from the

sources

114 and 190 are sent out through

resistance elements

115, 116, 151 and 152 over the outgoing end of the trunk to the recording toll operators position to efl'ect the operation 01' relays 214i, 215 and 216 in various combinations, and depending upon these combinations effected, one of the class of

service signal lamps

257, 256, 255 and 219 will be illuminated, the variously marked caps of which will indicate to the recording operator the class of service to which the calling subscriber is entitled. That is, the class of service to which each subscriber is entitled is indicated by a particular figure or sign on the caps illuminated by the corresponding lamps.

Referring now to Fig. at taken in connection with Figs. 2 and 3, a subscriber at substation B on initiating a. call removes the receiver from the. switchhook whereupon a circuit is established for line relay 400, this circuit extending over the subscribers line loop. Relay 4:00 operates in this circuit and establishes an obvious circuit for line lamp 102. The lamp 102 is provided with a distinctive lamp cap which designates the class of service to which the calling subscriber is entitled. In response to the illumination of lamp 402 the A operator inserts plug P of of jack J, and plug P upper left-hand winding of repeating coil 405 to ground. Supervisory relay 404 operates in this car causing the darkening of lamp 402.

The r-i operator 'llO'W aetuates key 410 in order to connect her telephone set with the talking strands of the cord circuit. The operator now learns from the calling subscriber the nature of the desired' connection. It will be assun'ied, as in the previous case, that the calling subscriberdesires a connection with therecording toll operator.

The A operator tests for an idle recording trunk in the 'well-knoivn manner. Assuming that the trunk-L is the first idletrunk encountered and thatthe calling subscriber is entitled to the-class of service correspond ing to jack J the operator will insert plug P into this itClI J whereupon a circuit is established which may be traced from grounded battery through the filament of lamp 408, sleeve contacts of plug 1, and jack J -,,-Wind1ng of relay 500, conductor 520, left-hand armature and-back contact of-relay 501, resistanceelement 502 to {ground The lamp "108 energizes in this =circuit'an'd servesas a guard signal tothe Acpera-tor. Relay 500 also operates in this circuit and in attracting its innerarinature performs no iiul'nediate function. However, at its outer armature, relay 500 establishesacircuit extending from grounded-battery 503, through the resistance element 504, outer armature and front contact of relay 500, conductor 50.3, winding of marginal relay 506, back contact and lower armature of relay 507, lower lefthand Winding of repeating coil 103, windings of polarized relay 102, marginal relay 101 and relay 100, upper lefthand windingof repeatingcoil 103, upper armature and back contact of relay '507 to ground. The current in the "circuit just traced is of such strength as toqprevent marginal relay506'fr0m'energizing at this time, but of sufficient strength and proper polarity to-cause relays 100 and 101 to operate. Relay 100 in operating establishes an -ob- YlOUS circuit for relay 104:. Relay 101 in operating establishes an obvious circuit for relay 117.

it its outer armature, relay 104 establishesan obvious circuit for relay 105; at its inner armature relay 10lcauses the energization of relay 12toconnect the tone source 113170 the tip and ring-conductorsofthe trunk in order to indicate to the calling subscriber that the recording operator is being signaled. ltelay 117 and relay 105 in operating both lock up to 'ground on the outer armature of relay 104 by Way' of the normal right-hand contacts of relay 109. As a-result of theenerg-izat-ion-of relays 117 and 105, a circuit now exists extending from grounded battery 11%, through resistance element 115, front contact and outer right=hand armature of relay 117, conductor 118, back contact and right-h-aml armature of relay 11-9, conductor 120, right-hand armature and front contact of relay 105,001 1ductor121 to-th'e midpoint of the right-hand windings of repeating coil 103 and thence over thetip and ring conductors ofthe incomingend of the recording trunk as faras the upper andlower inner armatures of --relay-122. Itis believed unnecessary to repeat the pperations which extend the incomingend of the trunlgcircu-it to the --recomli-ng operatorls position 0 since these steps were described in detail-in the previous description. HoWeVeTr, it will be assumed that the lamp 209 -hasbeen illuminated as a signal-to the recording-operator and she has responded tothe call by actuating talkinglreyQlO,

11s a result -0f the actuation of talking key 2 10, relay 207 is operated for the par-- poseshereinbefore mentioned, One effect of the operation of relay 207 is to connect ground to "the terminal 1320f switch-S by Way of conductor 21-2 Thisground causes relay 133 to operate Which in attracting its right-hand armature performs the same function-as it did in the preceding case. In attractingits left hand armature, relay 133 again shunts the high resistance left-hand Winding of relay 100 so that the current in the circuit including marginal relay500, previously traced, is increased suflieiently to permit relay 506 to operate. Relay 606 in operating establishes an obvious circuit for relay '508 Which thereupon operates and locks itself to ground on the-inner -=a11nature of relay -500, at its right-hand armature relaytOS'establishes'an obvious circuit for relay 507 which in operating disconnects the circuit including the marginal relay 506 fromthe trunk circuit and bridges'the condensers510 and 51 1 sothat acireuitmow'exists which may be traced from igrounded battery through lower right-hand Winding of repeating coil 405, Winding of relay 406, ring'contacts of plug P and jaclrJ front contact and lower armature of relay 507, lower left-hand Winding of "repeating coil 103, windings-of polarized relay 102, marginal relay=101,'righthand Winding of relay 100, left-hand armature and front contact of relay'133, upperleft hand Winding of repeating coil 103, "upperarmature and front contact of relay 507, Windingof marginal relay 509, tip contacts of \jack J and plug P through the upper right-hand Winding ofrepeating cell 405 to ground. Relays'106 and 509 operate in this circuit, the former shunting out the lamp 408 as an indication to the A operator that the recording operator has responded to the call, while the latter establishes an obvious circuit for relay 512. Relay 512 in operating shunts the resistance element 502 and the right-hand winding of relay 501 so that relay 501 energizes over the sleeve circuit through its lefthand winding to ground on the alternate contacts of relay 512. Relay 501 in energizing in the sleeve circuit prepares a peremptory disconnect signaling circuit which will be completed hereinafter.

As a result of the actuation of talking key 210 at the recording operators position O, and as a result of the extension of the trunk circuit as far as the recording operators posit-ion, the circuit which was previously traced from grounded battery 114 as far as the upper and inner lower armatures of relay 122 is now completed over the wipers 188 and 189 and terminals 140 and 141 of the selector switch S, over the upper and middle alternate contacts of key 210 through both simplex windings 217 and 218 through the windings of relay 214, marginal relay 215 and polarized relay 216 to ground. The current in this circuit is such as to cause only relays 214 and 215 to operate, so that a circuit may now be traced extending from grounded battery through the filament of lamp 255, front contact and left-hand armature of relay 215, back contact and armature of relay 216, armature and front contact of relay 214 to ground. lhe lamp 255 energizing in this circuit indicates to the recording operator the class of service of the calling subscriber.

WVhen the recording operator actuates key 210, her telephone is connected across the main conductors of the trunk so that she may converse with the calling subscriber to ascertain the nature of the call. It will be assumed that the calling subscriber requests a connection with information, whereupon the recording operator actuates the key 225 at her position which is designated information. She also restores her talking key 210. As a result of the actuation of key 225, relay 208 operates as in the previous connection. At its lower alternate contact, key 225 establishes an obvious circuit for relay 260 which corresponds to relay 222 in the previous description. At its outer righthand armature relay 260 establishes a circuit for a relay similar to relay 223, whereas at its inner armature it connects ground to the conductor 261, leading to the group of terminals 265 of sector 228 of switch K, which group is allotted to information.

As in the preceding connection, the stepping magnet 231 causes the wipers of switch K to advance over the terminals until, in this instance, the grounded group of terminals 265 is reached, whereupon similar operations as described in connection with the rate quoting group 230 are performed, so that the selector switch K hunts for an idle trunk leading to the information operators desk.

The remaining operations which take place in the case of a call for information are similar to those described in connection with the call described for the rate quoting operator so that these operations need not be repeated. However, the manner in which a disconnect signal is given to the A operator differs and this operation will now be described. The recording operator at the termination of the connection, actuates the re store key 262, whereupon key 225 is released. The release of key 225 deenergizes relay 208 whereupon ground is removed from the winding of relay 133 so that this relay releases, removing the shunt from the high resistance left-hand winding of relay 100. The removal of this shunt causes the current in the circuit including marginal relay 509 to decrease to such an extent as to deenergize this relay. The deenergization of relay 509 removes ground from the winding of relay 512 whereupon this relay releases so that the circuit for interrupter 515 is now completed. The reduction of current in the above mentioned circuit also causes relay 406 in the A operators cord to release. The operation of the interrupter 515 causes relay 516 to intermittently attract and release its armature so that the sleeve circuit including the lefthand winding of relay 501, winding of relay 500 and the filament of lamp 408 is intermittently opened so that the lamp 408 flashes synchronism with the interruptions caused by the interrupter 515.

The A operator upon noting the flashing of the lamp 408 proceeds to take down the connection by withdrawing plug P from jack J whereupon relays 500 and 501 release. The release of relay 500 opens the locking circuit for relay 508 which in turn releases relay 507, restoring the outgoing end of the recording toll trunk to normal. In withdrawing the plug P from jack J the circuit for sleeve relay 401 is opened whereupon the line relay 400 is again connected to the conductors of the subscribers line in preparation for another call. The release of the remaining apparatus is effected in the same manner as described in the preceding description.

Keys such as 205 at the recording operators position are provided in the leads from the armatures of the relays 204 of the connecting circuits at this position so that when the position is unattended these keys will be actuated to place a busy potential on all test terminals such as 127 of connecting circuits leading to these positions and thereby rendering the position unavailable to incoming calls. Keys such as 241 serve the same purpose for the trunks leading to the special operators desk.

WVh-at is claimed is:

1. In atelephone system, a trunk circuit terminating in a plurality of terminals, an operators position, a group of connecting circuits terminating in keys at said position, a signaling device at said position for each of said trunk terminals, means responsive to the seizure of said trunk by Way ofone ot saidterminals for selecting an idle one of said connecting circuits, and means l8SPO1l sive to the actuation of one of said keys at said position for actuating the signali device corresponding to the trunk terminal taken for use.

2. In a telephone system, a trunk circuit terminating in a plurality of terminalsan operators position, a signaling device thereat, a plurality of connecting circuits terminating in keys at said position, means responsive to the seizure oi said trunk by way of one of said terminals for associating said trunk with an idle one of said connecting circuits and operating said signaling device, indicating means at said position corresponding in number to said trunk terminals, and means responsive to the actuation of one of said keys for operating the indicating means corresponding to the trunk terminal taken for use.

(3. In a telephone system, atrunk circuit terminating at its outgoing end in a plurality of terminals, an operators'position, a plurality of connecting; circuits terminating at said position in keys, asignaling device for each of said connecting circuits, means responsive to the seizure of: said trunk by way oi one of said terminals for automatically connecting the incoming end of said trunk with an idle one of said connecting circuits to cause said signaling device to be actuated, indicating means at said position corresponding in number to the terminals of said trunk, and means responsive to the ae tuation of one of said keys for restoring said signaling device to normal and actuating the indicating means corresponding to the trunk terminal taken for use.

l. in a telephone system, a trunkcircuit,

first and second operators positions, a plurality of connecting circuits terminating at said first position in keys, a switch for said connecting circuits, means responsive to the seizure of said trunk for causing said switch to hunt for and connect said trunk with an idle connecting circuit and extend said trunk to said first position, and means responsive to the actuation of one of said keysat said lirst position for extending the selected connecting circuit to said second position.

In a. telephone system, a trunk'circuit, a first operators position, a signaling device thereat, a second operatonsposition a sigtion of one ots-aid keys tor eirtending the selected connecting circuit tosaid second operators position and actuating the signaling device there-at.

(i. In a telephone system, a trunk circuit terminating in aplurality .oi tern'iinals,an

operator's position, a group ;oi connecting circuits terminating in keys lat said position, a signaling device'at said position for each of said trunk terminals, means responsive to the seizure of said trunk by way of one of said terminals tor selecting zone of said connecting circuits and extending said trunk to said position, means responsive to the actuation of one 01": said keysat said position for actuating the signaling device corresponding to the trunk terminal taken for use, a second operators position, and means responsive to the actuation ofanother of said keys for extending the selected connecting circuit to said second position.

7. In a telephone system, a trunk circuit terminating in a plurality of terminals,an operators )osition, a signaling device there at, a plurz ity of connecting circuits'terminating in keys at said position, means responsive'to the seizure ot-said trunk by way of one of said terminals for associating said trunk with an idle one oi said connecting circuits and operating said signaling de vice, indicating means at said position corre sponding in number to saidtrunk terminals, means responsive to the actuation of one of said keys for operating the indicating means corresponding to the trunk terminal taken for use, a second operators position, a signaling device thereat, and means responsive to the actuation of another oi? said keys for extending a selected connecting circuit to said second position and actuating said signaling device.

8. In a telephone system, a trunk circuit terininating at its outgoing end in a plurality of terminals, an operators position, a plurality ot'connecting circuits terminating at said position in keys, a signaling device for each of said connecting circuits, means re sponsive to the seizure of said trunk by Way of one of said terminals for automatically connecting the incoming end of said trunk with an idle one of said connecting circuits to cause said signaling device to be actuated, indicating means at saidpositioncorresponding in number to the terminals of said trunk, means responsive to the actuation of one of saidkeys for restoring saidsignaling device nae to normal and actuating the indicating means corresponding to the trunk terminal taken for use, a'second operators position, a signaling device thereat and means responsive to the actuation of another of said keys for extending the selected connecting circuit to said second position and actuating the signaling device thereat.

9. In a telephone system, a trunk circuit terminating in a plurality of terminals, a first operators position, a connecting circuit terminating in keys at said position, a signaling device at said position for each of said trunk terminals, means responsive to the seizure of said trunk circuit by way of one of said terminals for extending said trunk circuit to said first position by way of said connecting circuit, means responsive to the actuation of one of said keys for operating the signaling device corresponding to the trunk terminal taken for use, a second operators position, and means responsive to the actuation of another of said keys for extending said connecting circuit to said second position.

10. In a telephone system, a trunk circuit terminating in a plurality of terminals, a first operators position, a connecting circuit terminating in keys at said position, a signaling device at said position tor each of said trunk terminals, a selector switch responsive to the seizure of said trunk circuit by way of one of said terminals for seizing said connecting circuit and extending said trunk'circuit to said first position by way of said connecting circuit, means responsive to the actuation of one of said keys for operating the signaling device corresponding to the trunk terminal taken for use, a second operators position, and a selector switch responsive to the actuation of another of said keys for extending said connecting circuit to said second position.

11. In a telephone system, first and second operators positions, a trunk circuit, a plurality of connecting circuits terminating at said first position in a plurality of keys, means including a switch associated with said trunk and responsive to the seizure of said trunk at its outgoing end for causing said switch to hunt for and connect said trunk with an idle one of said connecting circuits to extend said trunk to said first position, a group of trunks leading to said second position, and means responsive to the actuation of one of said keys for selecting an idle one of said group of trunks and extending the selected connecting circuit to said second position.

12. In a telephone system, a trunk circuit, a primary operators positions, a group of connecting circuits terminating in keys at said primary operators position, a switch responsive to the seizure of said trunk for hunting for and connecting said trunk with an idle-one of said connecting circuits to extend said trunk to said primary operators position, secondary operators positions corresponding in number to said keys, groups of trunks, each group serving a corresponding secondary position, a switch associated With each connecting circuit and in which all of said groups of trunks terminate and means responsive to the actuation of one of the keys in the selected connecting circuit for operating the corresponding switch to select a group of trunks corresponding to the actuated key and seize an idle trunk in that group whereby said connecting circuit is extended to the secondary position corresponding to the key actuated.

18. In a telephone system, a trunk circuit, primary and secondary operators positions, a plurality of connecting circuits terminating at said primary position in keys, said keys corresponding in number to said sec-- ondary positions, means responsive to the seizure of said trunk for selecting one of said connecting circuits and extending said trunk to said primary position, a group of trunks serving said secondary positions, said group being divided into sub-groups and each sub-group serving a particular secondary position, a switch associated with each connecting circuit in which all of said subgroups of trunks terminate, means responsive to the actuation of one of the keys ot the selected connecting circuit for actuating the corresponding switch for the selecting of the corresponding sub-group oi trunks and for seizing an idle trunk in said group whereby the selected connecting circuit is extendedto the secondary position corresponding to the key actuated.

14. In a telephone system, a trunk circuit, first and second operators positions, a group of connecting circuits terminating in keys at said first operators position, means responsive to the seizure of said trunk for selecting one of said connecting circuits and extending said trunk to said first operator-s position, means responsive to the actuation of one of said keys for rendering said first operators position inaccessible to calls incoming over the remaining connecting circuits and means responsive to any one of the remaining keys for extending the selected connecting circuit to said second operators position.

15. In a telephone system, a trunk circuit, first and second operators positions, a group of connecting circuits terminating in keys at said first opera-tors position, means responsive to the seizure of said trunk for selecting one of said connecting circuits and extending said trunk to said first operators position, means for causing said first operators position to test busy to calls incoming over the remaining connecting circuits when the first call is answered and means responsive to the actuation of one of said keys for extending the selected connecting circuit to said second operators position.

16. In a telephone system, a trunk circuit, first and second operators positions, a signaling device tliereat, a group of connecting circuits serving said first operators position and terminating thereat in a plurality of keys, means responsive to the seizure of said trunk for selecting one of said connecting circuits and extending said first operators trunk circuit to said position whereby the signaling device thereat is actuated, means responsive to the actuation of one of said keys for disabling said signaling device and for rendering said position busy to the re maining connecting circuit as long as said key is actuated and means responsive to any one of the remaining keys for extending the selected connecting circuit to said second operators position.

17. In a telephone system, a plurality of classes of telephone lines, a trunk circuit terminating at its outgoing end in as many terminals as there are classes of lines, an operators position, means thereat responsive to a call incoming over one of said lines for indicating the class of service of the calling line, switching means at said position for connecting the calling line with said trunk by way of the terminal corresponding to the class of the calling line, a second operators position, a signaling device thereat for each of said classes of telephone lines, a group of connecting circuits serving said second operators position and terminating thereat in keys, means responsive to the actuation of the aforesaid switching means for selecting one of said connecting circuits and extending said trunk to said second position, means responsive to the actuation of one of said keys for connecting said signaling devices with the selected connecting circuit whereby the signaling device corresponding to the class of the calling line is operated, a third operators position, a group of trunks serving said third operators position, and means responsive to the actuation of another of said keys for selecting one of said trunks and extending the selected connecting circuit thereover to said third position.

18. In a telephone system, a trunk circuit: terminating in a plurality of terminals, operators positions, connecting circuits terminating in keys at said positions, a signaling device at each of said positions for each of said trunk tern'iinals, means responsive to the seizure of said trunk circuit by Way of one of said terminals for selecting one of said connecting circuits, and means responsive to the actuation of one of said keys associated with the selected connecting circuit for actuating a signaling device corresponding to the trunk terminal taken for use.

19. In a telephone system, trunk circuits, first and second operators positions, a plurality of connecting circuits terminating at said first operators position, a plurality of keys associated with each connecting circuit, an individual switch associated with the incoming end of each trunk circuit for connccting an idle one of said connecting circuits thereto operative in response to the seizure of a trunk circuit at its outgoing end, a telephone circuit at said first operators position, means for associating said telephone circuit with any one of said connecting circuits, means for preventing the selection of any connecting circuits by any of said switches operative in response to the connecting of the telephone set to any one of said connecting circuits, and means responsive to the actuation of any one of said keys of a selected connecting circuit for extending it to said second operators position.

In testimony whereof, we have signed our names to this specification this 14th day of November, 1923.

JOHN F. TOOMEY. HENRY EVPHELP'S.