US1674916A - Semiautomatic telephone system - Google Patents

Description

June 26, 1928.

V J. E. OSTLINE "s'E'MiAUToMATIc TELEPHONE SYSTEM 8 Sheets-Sheet' 1 Filed Feb. 2, 1925 NEH 5 June 26, 1928, 3,674,916

- J. E. OSTLINE SEMIAUTOMATIC TELEPHONE SYSTEM Filed F .2, 1925 f 'L'ZUE'TZIUZ" Jul-m E2215 UEIZmE June 26, 19 28. 1,674,916

J. E. OSTLINE SEMIAUTOMATIC TELEPHONE SYSTEM 8 Sheets-Sheet 5 F1 FEWE.

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June 26, 1928.

J. E. OSTLINE SEMIAUTOMATIC TELEPHONE SYSTEM Jul-m Ellzs 5.712115 June 26, 1928. I 1,674,916 J. E. OSTLINE SEMIAUTOMATIC TELEPHONE SYSTEM Filed Feb. 2, 1925 v 8 Sheets-Shee't' 5 a Far-7 E ---InuEn UI" .Juhn EH25 55711115 raid June 26, 1928. 1,674,916

J. E. OSTLINE SEMIAUTOMATIC TELEPHONE SYSTEM Filed Feb. 2, 1925 s Shets-Sheet' s F217 5 Far Z /Z6Z 27/ J im 47 i; l

June 26, 1928. 1,674,916

J. E. OSTLINE SEMIAUTOMATIC TELEPHONE SYSTEM Filed Fe 1925 8 Sheets-Sheet' 7 -Inu5n2nr I J Jul-m E1215 UTZZHE aw Wm QMN QR:

26, 19280 I J. E. OSTLINE SEMIAUTOMATIC TELEPHONE SYSTEM Fi ed Feb.2, 192s a Sheets-Sheet' 8 Lf UP- Juhzz E Z125 557172275- Patented June 26, 1928:.

entree s'rrss i M filti JOHN E. OSTLINE, 0F LIVERPOOL, ENGLAND, ASSIGNOE, BY MESNE ASSIGNMENTS, TO AUTOMATIC ELECTRIC INC, OF CHICAGG, ILLINGIS, A CORPORATION OF DELA-' WARE.

'SEMIAUTOMATIC TELEPHONE SYSTEM.

Application filed February 2, 1925, Serial No. 6,235, and in Great Britain February 15, 1924.

The present invention concerns improvements in or relating to semi-automatic telephone systems and more particularly arrangement-e for use at a B operators position in which the operator is informed verbally- .pending Ostline application Serial No.

747,373, filed November 1 1924-. The sequence of operations is that the operator on learning the wanted subscribers number tests his line and if it is free inserts a plug in it whereupon the next line on which a call is waiting completion is automatically connected to her headset. If the required line 'shouldbe busy, she will insert the plug in a busy jack or press a special busy key either of which operations serves to disconnect her from the calling line and to connect up the next line.

It will be appreciated that this arrangement may be provided either separately in place of call indicator equipment or may be provided in conjunction with call indicator equipment and a: reserve set for use in emergency so that if the call indicator equipment should break down, the operator can still deal with incoming calls. The arrangement according to the invention forms a cheap substitute for call indicator equipment whether to serve as a spare to existing call indicator equipment instead of an extra set or for regular working in an exchange where it is not'desired to go to the expense of full call indicator equipment.

According to one feature of the invention an operators headset is automatically con-v nected in turn by means of a control switch to lines previously selected for use in the establishment of a connection.

According to another feature of the invention an operato-rs headset is automatically associated. in turn with calling lines to which connection has been established by a calling party over numericalautomatic switches.

A further feature of the invention is that in a system having connections, from automatic subscribers to manual subscribers com: pleted by operators at call indicator positions switching means are provided to enable the operators headset to be substituted for the call indicator equipment so that in the event of the call indicator equipment failing the operator may be informed orally of the wanted number.

Still another feature of the invention is that where calls are completed at operators positions by means of cord circuits, the op erators headset is automatically associated in turn with calling lines, the operation of placing a plug in a jack in order to complete the connection serving to associate the plug over a hunting switch with the line to which the operators headset is connected.

These and other features not specifically mentioned at this point will be more fully appreciated from the following description of one method of carrying out the invention; It will be understood, however, that this is by way of example only and that considerable modifications could be made in the circuit arrangements without exceeding the scope of the invention.

The arrangement shown is on the general lines of that described in the above mentioned Ostline application Serial NO.74:7,373, filed November 1, 1924, which relates to arrangement for call indicator working, the number-3 to be set up on the call indicator being transmitted. over the line in code.

In the arrangement shown in the accompanying drawings, the connection of the operators headset to the line is arranged to be as substitute for the call indicator appa ra-tus so that it could be used in case the latter breaks down or for any reason is not working satisfactorily. It will be realized, however, that, as mentioned above the arrangement according to the invention could equally well be employed for constant use and not merely as a substitute for call indicator equipment in case of emergency. 7

Referring now to the drawings these are substantially the same as those accompanying the specification above referred to except that the decoder apparatus with which the present application is not concerned has not been shown. Y

Figure 1 shows a special call indicator repeater and a coder; I

ll? ignreflshows .the :relay group associated with :a singleztrunk line at the B operators position together with one marker, the marker distributor and the set up control switch;

Figure 3 shows 'a cord circuit at the operators position and also the necessary keys and supervisory apparatus; and

Figure 4; shows the position load distributin switch, the special service trunk dis tridouting switch, and the distributing switches tor connecting the calls waiting at the position to the operators headset in turn, these latter switches fulfilling the same functions as those in Figure 2, and being provided additional thereto as a further safeguard. against breakdown.

The operation of setting up a call means of the call indicator may first be briefly considered. The repeater R with which 'is'associated the selector D is taken into use from the banks of local switches and the coder selecting switch CS then hunts ito find-an idle coder. In response to the first series of impulses sent to the repeater, selector D is operated, but the succeeding series of impulses, in this case four, are sent to the coder and means of the switchDS are recorded on the digit storing relays. hen all the digits have been trans mitted a switching through operation takes place at the repeater and the secondary switch SS at the incoming end of the junctionfline is set in operation to select an idle trunk relay group ata preselected ope1'ators position. A marker such as M preselected by the marker distributor MD is then taken into use and in due course when the operator is ready to deal with the call the set up control. switch .868 associates the trunk line seized with the decoder which is assumed to be located below the right hand portion of Figure '2. The code sending switch CSC in Figure '1 is now started up and sends out code impulses corresponding to the number stored whereby appropriate relays are operatedin the decoder. The wanted number is then displayed on the call indicator lamp panel and the operator tests the multiple jack corresponding to this number with the plugassodiated with a .free cordat her po sition. If it is idle she completes the con nection by inserting the plug in the jack;

if it is busy she replaces the plug and presses the common busy key at her position whereupon the calling party is given the 'busy signal. In either case the call indicator lamps are extinguished and a fresh number isdisp'layed it other calls are awaiting attention.

When the call indicator apparatus is cut out the connections are extended direct to the operators headset under the control of markers and a set up control switch as before. The sequence of operations is substantially the same except that in this case the transmission of the number incode is without function and the operator must ask the calling party for the wanted number. In order to cut out the call indicator appara tus, it is necessary for the operator to depress the key 293, whereby earth is connected over lead 205 to the winding. of *relay 195. This therefore energizes and ope-rating its armatures 196, 1597, 198, 199, 200, 201, and 202, disconnects all the trunk relay groups from the decoder .and its associated switches and connects them to the operators headset by way of the special switches shown in Figure 4:. The setting *up of a connection under these circumstances 7 will now be traced through in detail.

sumed that the call is set up by .m'eans'of'a register translator rather than direct from a calling subscriber, though the application of the invention is "in no way limited to this condition. Suppose 'now that the repeater R is taken into use from 'thebanksofajlocal selector; a circuit is thereupon completed for line relay 4 over conductors 1 and 2*and the normally closed springs controlled by armatures 46 and 47.. Relay 4, upon operating, at armature 5 completes a'circuit for relay 7 and at armature 6 completes a circuit for the line relay of the, selector D which extends as follows battery, resistance, back contact and armature 28, front contact and armaturet, armature31and2its back contact, back contact andarmaturegfi lead 60 and to earth by wayof the lower winding of the line relay of selector D. A branch of this circuit also extends over armature 22 and its back contact and through the'lower winding .of relay '23 but this operation need not be considered further since it is without function at this point. The operation of the line relay of selector D completes a circuit for the release relay and prepares "the selector for operation in the usual manner. Relay .7, upon operating, at armature '8 disconnects armature 12, at armature- 10 prepares a circuit for relay 1-1 and at armature 9 completes a circuit for the right hand winding of relay 42 andalso "for the upper winding of relay '23, whereupon the latter by operating armature 24 connects earth *to release trunk conductor '3 and also prepares a circuit for relay 25. A circuit is also'completed by the operation of armature 9 tor starting the hunting operation of ithe coder selecting switch CS, this circuit extending over the normally closed springs controlled by armature '35, armature '20 and its "back contact, windingof relay 13 to battery. Re-

its

on the contact with which itis now in engagement, relay 16 is again short circuited and the wipers are advanced a further step.

This hunting operation continues until the switch reaches a free coder whereupon wiper 50 no longer finds earth, relay 16 Is no longer short circuited and energizes in series with magnet 48. At armature 17 it opens a point in the homing circuit, at armature 19 completes a circuit for reversing relay 45, at armature 20 completes a locking circuit for itself and at armatures 18, 21, 22 and 96 connects up its wipers. A circuit may now be traced as follows: earth, armature .9 and its front contact, normally closed springs controlled by armature 35, armature 20 and its front contact, front contact and arma ture 96, wiper 50 and the contact with which it is in engagement, lead 55, normally closed springs 97 of the test jack, back contact and armature 62, winding of relay 74 to battery. Relay 74, upon operating, at its armature 7 5 opens a point in a chain circuit extending over lead 77 and connects earth to lead 76 for starting the impulse sending machine. Reversing relay 45 operates when its circuit is completed and at its armatures 46 and 47 reverses the current back tonormal over the calling loop, the leads 1 and 2 being reversed in coming from thebanks of the local switches as shown. This has the effect of operating a polarized relay in the register translator so as to permit the transmission of the next series of impulses, this operation thus being held up until the coder selector CS has found a free coder. This arrangement which forms no part of the present invention is fully described in the copending application of John E. Ostline, Serial No. 755,374, filed December 12, 1924.

WVhen relay 45 operates after the switch CS has come to rest the next digit in the required number will be sent out from the register translator and a corresponding number of interruptions will. accordingly be produced in the circuit of line relay ,4. This will therefore release its armature 6 a corresponding number of times, thus producing a similar number of interruptions in the circuit of-the line relay of the selector D. The selector D is therefore operated in well known manner to raise its wipers to the required level and on the termination of the train of impulses the hunting operation is initiated and continues until an idle trunk line is found, for instance that comprising conductors 119 and 120. VVhen the selectorswitches through the circuits of its line and release relays are opened and upon the deenergization of the latter dead earth is removed from release trunk conductor 26. The upper winding of relay 25, which has previously been short circuite'd, is now able to energize the relay in series with the switching relay of the selector D. Relay 25, upon operating, at armature 27 short circuits its own upper winding by connecting direct earth to release trunk conductor 26, at armature 29 completes a locking c1r-- cuit for itself through its lower winding, at armatures 30 and 81 prepares the impulsing circuitfor repeating impulses to the coder and at armature 28 prepares a circuit for relay 32.

When the next digit is transmitted, relay 4 is deenergized a number of times" as before and on each 'deenergization a circuit is completed as follows: eartl'narmature 9 and its front contact, front contact and armature 30, back contact and armature 6, armature 31 and its front contact, armature 21 and its front contact, wiper 51 and the contact with which it is in engagement, lead 56, armature and its back contact, winding of relay 68, first contact in the bank of wiper 80 and said wiper, winding of stepping magnet 76'to earth. Relay 68 is energized in this circuit and being slow to release maintains its armatures operated throughout the train of impulses. At 'armature 69 a circuit is completed for relay 71 and at armature a further circuit is completed for stepping magnet'76 so that it is operated by the succeeding impulses after wiper 80 has been stepped off its first contact. Wipers 77, 78, 79 and 80 of the switch DS are thus advanced, a number of steps corresponding to the digit dialled. At'the end of the series of impulses, relay 68 releases and at armature 69 and its back contact connects earth over armature 72 and its front contact to wipers 77, 78 and 79 which earth is extended over one or both of wipers 77 and 78 and armatures 89 and 90 and their back contacts to relays 100 and 101. As more fully explained in the before mentioned Ostline application Serial No. 7 47,373, filed November 1, 1924, these relays are compensating relays and-their function is to adjust the resistance of the code impulse sending circuit to a substantially constant value'so as to permit the reliable operation of a marginal relay in the decoder over lines of different length. When energized,.they operate their armatures 104 and 106 so as to include resistances 105 and 107 respectively in the sending circuit for the code impulses. It should be mentioned .fi' ailso that :the appropriate compensating tacts of "relay 92.

digit is generated automatically by :the regis-' ter translator :and is additional to the digits diailleLd-aby the calling subscriber. "Acircuit is also completed on the deenergization of relay .68 byway O'fii armature 73 and its front contact andrarmature 8'8 and its back-contact for the rapper winding o'l. relay S6 which'is of the tin -step type and at the moment only Operates its light armature 87' thereby short circuiting its lower winding. YVhen relay 71 .deenergizes after a short interval, earth is removed from the unction of the wmdlngs of relay 86- and it thenoperates fully, there- 1 by transferring the operating circuits to the first set of storage relays over the back conlVhcnarmature engages with its back contact, earth is extendedethrough the lower winding of relay 65,

' interrupter contact '81, multipled contacts in the bank of wiper and said wiper :to stepping magnet 76.. VJipers 7780 are thus stepped onto one ot'thc normal positions in which wiper 80 engages contact '82 and therefore no longer finds earth. Relay :65

is operated at this time and at armature 66 serve to energize successive groups of stor-. age relays in approprlate ficomblna tions, Relay '92'is operated at the .GDd Of the sec-.

ond train of impulses, relay '93 after the third series and relay 94' after the fourth;

When the relay 68 deenergizes after the last serles of impulses, a circuit is completed as follows earth, back contact and armature 69, :armature 73 and its front contact, armature 88 and its front contact, similar armatures and front contacts of relays 92, '93, 94, armature 98 and its back contact, low-er winding 01 relay 83 to battery. 'Relay 83, upon operatin at armature opens a point in the circuit for starting the code sending switch, another point in which circuit is closed a moment later at armature 99 and at armature .84 completes a circuit which extends as follows: earth, back contact and armature 130, lead 120 of the junction line, selector D, lead 60, armature 36 and its back contact, arn'lature 22 and its vfront contact, wiper 52 and the contact with which it is in engagement, lead 57, armature 84 and its front contact, upper winding of "relay 83, lead 58, contact on which wiper .53 is resting and said wiper, front contact and armature 18, back contact and armature .33, lead 159, selector D, conductor emme 119 of t'he junction line, -armatune-129 and its hack contact, winding of relay 121 to,

hatter 7 Relay 83 is maintained energized moved-as about to be explained: Switching relay 125 there-upon -operates,-zat armature 126 completes a circuit over-lead 127 ,-inc'lud-- ing'armatnre 122 and its frontcontaotato operate a meter tor.:recordpurposes, at m matui-e' 128 completes a locking circuit for itself and at armatures' 129 and 130 switches the speaking conductors througlr- Since relay 83 is slow to release, it is'ma'intained energized at this time, its circuit now ex tending from battery, winding ot'relay 148, back'cont-act and armature 175, ibackcontact and armature 154, back c'ontactandarmature 18.6, contact 150, front contact and armature 129 and thence as previously traced to armature 130' and its front contact, contact 152, armature 190 and back contact, armature 159 and its'bacl: conta ct, armature 1.76 and its back. contact, armature 1'83 and its back contact to "ear h.

A brief description .may :be givenat this pointol the nature and method of operation of the a-ppartus for distributing calls to the various operators positions-thisapparatus being used both tor normal call indicator and for emergency working; The principle is that earth is normally connected to'the release-trunk conductors and test contacts ot' alljuncti'on lines associated with all the positionsexcept one, each position becoming in turn the'one selectable unless no operator is present theparticul'ar posi tion or she has more than apredeterminedv number of calls awaiting attention or for any other reason 1s unable to receive further calls; thus the tratlic 'IS distr buted evenly,

A pair of relays such as 351 and 354, Fig

ure 4, are associated with each position, while the switch comprising wipers 360 and 361 is common to all the positions. W th the appartus in the position shown a circuit will be completed from earth, armature 358 and its back contact, wiper 360 and the contact on which it is standing, winding of relay 354 to battery. Relay 3'54 upon oper ating, at armature 356 prepares .a locking circuit for relay 351 and at armature 355 removes earth from common lead 167 so as to make the position selectable and at the front contact of this armature prepares an deenergiz'ed, a circuit is momentarily completed from earth,tront con-tact and arma- .lar position considered.

ture 123, wiper 132, contact 151, normally closed springs controlled by armature 166, lead 167, armature 355 and its front contact, winding of relay 351 to battery. Relay 351, upon operating, at armature 352 completes the previously prepared locking circuit and at armature 353 completes a circuit for relay 357 which extends over wiper 361. Relay 357 at armature 358 opens the circuit of relay 354 and completes a 011'- cuit for magnet 359, so that the wipers 360 and 361 are advanced one step. No more calls can be received by the position shown until the distributing switch has allotted a call to each of the other positions or found them busy.

To return now to the operations of the trunk relay group, relay 148 operates when the secondary switch SS switches through and at armature 149 completes a circuit for relay 160. Relay 160 now, operates and at armature 161 completes a circuit for relay 165 which, upon operating, at armature 166 disconnects conductor 167 and connectsearth to test contact 151. Relay 160 also at armature 162 prepares a circuit for relay 153, at

armature 163 removes earth from the con-- tact associated with the trunk relay group in the banks of the markers and at armature 164 completes the following circuit: earth, armature 170 and its back contact, front contact and armature 164, armature 202 and its front contact, lead 209, armature 368 and its back contact, winding of relay 362 to battery; this is assuming that no calls are waiting attention at the particu- Relay 362 thereupon by operating its armatures 363 and 364 completes the usual circuits for switching relay 365 and magnet 371 for initiating the hunting operation of the switch. When wiper 372 encounters the contact from which earth has been removed by the operation of armature 163, switching relay 365 is no longer short circuited and operates, thereby at armature 366 preparing a busy circuit and at armature 367 completing a locking circuit for itself to earth on lead 205. Relay 365 also at armature 369 completes the following circuit: earth, armature 363 and its front contact, front contact and armature 369, wiper 372 and the contact on which it is resting, lead 208, armature 163 and its front contact, Winding of relay 168 to battery. Relay 168 at armature 169 removes earth from the back contact of armature 163, at armature 170 removes earth from lead 209 so as to prevent another marker being started up and at armature 171 completes a locking circuit for itself through the normally closed springs controlled by armature 182. Relay 365 moreover at armature 368 transfers the starting circuit to the second marker, and at armature 370 completes a circuit which extends from the earth on lead ing leads through to relay 385 by way of I armatures 197 and 201 and conductors 203 and 206 at the same time disconnecting relay 148. Furthermore,'at armature 156 it completes a locking circuit for itself and at armature 158 completes a circuit for the lower winding of relay 178. The operation of armatures 155 and 157 is without function when the decoder is cut out by the operation of relay 195. Relay 178 operates when its circuit is completed and completes the following circuit: earth, armature 188 and its back contact, back contact and armature 17 4, upper winding of relay 178, front contact and armature 179, armature 198 and its front contact, lead 204, Winding of relay 374 to battery. Relay 374 thereupon 0perates to connect earth from lead 205 by Way of front contact and armature 375 and armature 383 and its back contact to the left hand winding of relay 379. Relay 379 is a twostep relay and for the moment only operates its light armature 382, whereby earth from lead 205 is connected to the other terminal of its right hand winding so that this Winding is for the present short circuited. Relay 178, furthermore, at armature 180 prepares a circuit for relay 185, at armature 181 removes earth from test contact 192, at armature 182 connects a further earth to the release trunk conductor, at armature 1'83 prepares the connection of battery to the lower trunk conductor for a purpose which will be described subsequently and at armatrpe .184 prepares a circuit for busy relay 1 2.

The operation of armatures 154 and 159 disconnects the battery feed from the circuit of relay 83 in the coder, Fig. 1, so that this relay is now released and at its armature 85 completes a circuit which extends from the earth on lead 55, back contact and armature 62, armature 99 and its front contact, armature 85 and its back contact, first contact 114 in the bank of wiper 113 and said wiper, lead 116, interrupter springs 117, stepping magnet 115 to battery, the interrupter having been previously started up over lead 7 6'. A branch of this circuit extends from lead 116 through the upper winding of relay 65, which operates with the results previously described. Stepping magnet 115 is therefore intermittently energized and wipers 111, 112, and 113 are accordingly advanced step by step over their respective banks of contacts. During this movement combinations of code impulses determined in accordance with the operated. relays of the digit registerin'g sets are sent out over the trunk line as fully described in the applica tionof Ostline, Serial No. 747,378, filed November 1, 1 924:,- variations in strength being produced by including either the high resistance 108 or the low resistance 109 in the circuit.

"In" the case under consideration, however, since the callindicator apparatus has been cut out, these impulses clearly serve nouseful purpose and must be absorbed, They are transmitted over leads 203 and 206 to relay 385, which therefore operates and at its armatures 386 and 387 opens the circuit to'the operators headset by wayof 1eads308 and 309 so that she does not hear objectionable noises in her receiver. 'When wiper 113 of 'the'code' sending switch reaches contact 133, a circuit is completed for relay 61 in series with relay and stepping magnet 115 in parallel. armature 62 removes the holding earth on lead 55 from the operated relays in the coder, at armature 63 completes a metering circuit over lead 118 and at armature 6t) completes the following circuit; earth, front contact and armature 60, lead 56, contact on which wiper 51 is resting and said wiper, front contact and armature 21, front contact and armature 31, armature 6 and its front contact, armature 28 audits front conta'ct, relay 32 to battery. Relay 32 now operates and at armaturesg and 36' switches through the speaking leads, at armature 3 completes a locking circuit for itself, the same time cutting out line relay 13 so as to prevent renewed operation of the coder selecting switch CS, at armature 18iprep'ares acircuit for busy relay and at armature closes an additional circuit for reversing relay 45. V The removal of earth from lead releases the coder selecting switch and the wipers 505e' are returned to normal by means of eartl'iencountered by Wiper '54 eX- tending over back contactand ari'nature 17, back contact and armature 15 to rotary magnet 48.

The operator will now ask the calling subscriber for the number required and on being informed will select the most convenient idle plug at her position and test the wanted line bytouching the tip of the plug against the sleeve of the required subscribers jack; Suppose first that he is busy, that is to say, a plug at some other operators position has been inserted in the corresponding multiple jack. Now when the operator touches the tip of the plug 288 for instance, against the sleeve of the sub scribers multiple jack at her position, a circuit will be completed from battery, i'vind ing of relay such as 282, in the other cord circuit, sleeve of plug, sleeve of jack, plug tip 288, normally closed springs controlled by armature 283, 'l'ead 2'90, lower Winding of Relay 61 upon operating at the operator will insert the plug into the v jack whereupon the sleeve relay 282 is energized in. series with the cut oil relay associated with the subscribers line. Relay 282 at armaturcs'283 andv 285 preparestheringing circuit at armature completes a circuit for the supervisory lamp.- 287'and at armature 284; completes a circuit which ex tends over the normally closed springs controlled by armature 271, armature 256 and its back contact, winding of relay 252=to battcry. Relay 252' by operating ari'natirres 253 and 254i completes the usual circuits for switching relay 255 and magnet 260 so that the finder switch F S associated with the cord circuitcommences hunting for the trunk line overwhich' the call is being-ens tended. I 'When it finds it, that is, when test wiper 25-1enga'ges with contact 192from which earth has been removed by the operationof armature 181', switching relay 255 is no longer short circu ited and energizes. Thereupon' at armature 256 it com-plctes a locking circuit for itself, at armatures 258 and 259 connects the speaking leads through and at armature 257 connects earth to wiper and its front contact, winding of relay 185 to battery. Relay 185 thereupon: energizes, at armatures 18-6 and 190 disconnects the operators headset frOm-thelin'e, at armature 189 completes locking circuit for itself, at armature 187 connects earth to the release 251, which: earth extends over ari'naturc 180 trunk conductor to rcplacethat which "will shortly be removed at armature 183, and at armature 188 opens the circuit through the upper winding of relay 178 ander-clay 37a whereupon both these relays release. Nhen relay 37 1 deenergizes, armature 375 leaves its front contact, right hand winding of re lay 379, is no longer short cireuited and it therefore energizes fully, therebyoperating all its armatures. At armatures 380' and 381 the control circuits are transferred to the second marker, at armature 383 an energizing circuit is prepared for'the two-step relay 376 and at armature 384C a locking circuit is prepared for this relay. In case a call has been set up on the second marker in the meantime, the: calling line is new connected to the operators headset since earth from lead 205 is now extended over wiper 398 to, the lead corresponding to 207 associated with some other trunk relay group, whereupon the operator may deal with the next call. The operation of armature 380 opens the locking circuit of relay 365 so that the first marker is released and may he used for setting up another call.

It willbe' noticed that in this case as there all) are only two markers it in unnecessary to provide a marker distributor as the functions of this switch can quite well be -performed by contacts on the switching relays of the markers such as 368 and 394. v The functions of the set-up control switch are in this case performed by the two two-step relays 376 and 379, this arrangement being more economical for such a small number than the provision of a rotary switch. It will be noticed also that since the time required forsetting up a call will not be considerably increased owing to the fact that the operator has to inquire for the wanted number instead of having itdisplayed before her, it is considered desirable to provide for only two calls to be awaiting attention at any position instead of live as was allowed when the call indicator was being used. It will moreover be understood that it would be quite possible to employ the same markers, marker distributor, and set-up control switch as are used for regular working, means being provided if necessary to insure that not more than two markers can he used simultaneously but it was considered desirable in the present case to have a completely separate set of distributing arrangements so as to be independent of any breakdown of the distributing switches.

Returning now to a consideration of the circuit changes which take place in the cord circuit, upon the operation of armatures 258 and 259, a circuit is completed for line reay 247 by way of the left hand repeating coils and the normally closed springs controlled by armatures 262 and 265. Relay 247, therefore, operates and at armature 248 completes a circuit for relay 266. Relay 266 at its armature 267 removes earth from lead 292 for a purpose to be described subsequently and at the front contact of this armature completes a circuit for relays 270 and 274, at armature 268 extinguishes the supervisory lamp 287 and at armature 269 completes the ringing circuit. Relay 270 energizes when its circuit is completed, at armature 272 completes a locking'circuit for itself which is dependent on the sleeve relay 282, at arn'iature 271 shifts the control of the locking earth for maintaining relay 255 op .erated-from the sleeve relay 282 to line relay 266 and. at armature 27 3 prepares a locking circuit for the ringing trip relay. Relay 274, upon energizing, at armature 275 prepares a further circuit for supervisory lamp 287 and at armature 276 completes a locking circuit for itself dependent on armature 274 of back bridge relay 261.

Ringing .of the called subscriber now takes place and the calling party receives in duction by way of a small condenser 281 which is connected across armature 278. Then the called party replies, ringing trip is deenergized also.

relay 277 'is energized and at armature 279 completes a locking circuit for itself, at armatures 280 and 278 opens the ringing circuit and at the front contact of the latter armature completes the speaking circuit. Back bridge relay 249 is now energized and at armature 250 completes the circuit of relay 261. Relay 261, upon energizing at armature 263, alters the circuit of supervisory lamp 287, at armature 264 completes a locking circuit for relay 274 and at armatures and 265 reverses the currentfiow back over the calling line. The eflect of this is to reverse the current in the left hand winding of shunt lield relay 42 so that this relay cannow operate its armature 43 whereupon the circuit of reversing relay 45 is opened. Upon the release of relay 45, current is reversed baclrover the called partys loop at arn'1atures46and 47 so as to effect supervision or I metering inwell known manner.

The two subscribers may now converse as desired, and when theyhave finished they will both replace their receivers. WVhen the receiver is replaced at the. called substation, lraclebridge relay 249 deenergizes and by releasing armature 250 opens the circuit of relay 261 which then at armatures 262 and 265reverses the current flow over the line to normal and armature 264 opens the look ing circuit of relay 274. When the calling party hangs up his receiver, line relay 4 is deenergized and at armature 6 opens the circuit of release relay 7 V A circuit is thereupon moi'nenta'rily completed for relay 11 which being slow to release remains energized for an instant and. operates its armature 12. Earth is thus removed from release trunk conductor 3 for a short period and the preceding switches employed in the connection are thus restored to normal. The release of armature 9 opens the circuit of relays 42, 32 and 23 and the latter releases armature. 24. The elfect of this is to release relay 25 and to remove earthfrom release trunk conductor 26 so that the selector D is released and restores to normal in the usual manner. The release of relay 32 opens the loop across the outgoing trunk whereupon relay 247 is deenergized, and by the falling away of armature 248 relay 266 This then at armature 267 opens the initial energizing circuits of relays 270. and 274 and the lockingcircuit of relay 255., and at armature 268 lights the supervisory lamp 287. The operator seeing the clearing signal removes the plug trom the jack, whereupon sleeve relay 282 is deenergized and the lamp 287 extinguished. The release of armature 284 opens the circuit of relay 270 which thereupon deenergizes; The release of relay 255 removes earth from test wiper 251 so that relay 185 and switching relay" B25 of the line switch are released and all the apparatus is restored te -normal;

It will be noticed that relays which are operated over a loop from the battery at the manual exchange are provided with Assuming that the calling party hasreplaced his receiver by this time, a circuit Wll-l now be completed as follows: battery,

supervisory lamp 287, armature 286 and its front contact, back contact and armature 268', armature 263 and its front contact, armature 275 and itsback contact, lead 291, relay 326, interrupter 327 to earth- The lamp is thus caused to flash under the control of the interrupter 327 and relay 326 is intermittently energized and at armature 318 prepares a circuit for re-cal l buzzer 3138 which is operative if the key 332 has prev iousl y been pressed. Furthermore if the terminals 330 and 33 1- areconnected together" an audible signal. will be given to the operator over armature 329 and the lower winding of the induction coil 307. Thel'am-p 287 is shuntedby a resistance in order that the audible recall feature may still be operative even if the lamp should be burnt out.

The connection from the back contact of armature 269 to the upper speaking cond uctor is to take care of a special condition. Suppose that the called subscriber does not reply at once and the calling party hangs up, whereupon ringing will ceaseand the supervisory lamp 287 will be lighted. Suppose further, that the operator does not immediately withdraw the plug and the called party wishes to initiate a call, and therefore, removes his receiver; with the arrange ment shown a circuit is now completed from battery, armature 285 and its: front contact, back contact and armature 280, ring 315 of plug, subscribers loop, tip 288 of plug, front contact and armature 288, armature 278 and its back contact, lower winding of ringing trip relay 277, armature 269 and its back contact, upper right hand winding of repeating coil, upper winding of back bridge relay 249 to earth. The ringing trip relay I and the back bridge relay energize in series and the latter is then maintained energized acetate over the subscribers loop. The operation of armature 2631 then. renders eii'ective the visual andv audible recall in. the mannerjust described. v

The operation of the various supervisoryand special control features provided: may now be considered briefly, a somewhat fuller description of these features: being given in. ()stline application Serial No. 747,313, fil'e'di November 1,. I924, previously referred to. Consider first the casein which the operator tests a line and finds it busy; she will not in this case plug in but instead will press: the common busy key 318 associated; with her position. Over one of the springs of this key a circuit is completed for the busy callsmeter 31-9, While over another spring and lead- 299 a circuit is completed for effecting the proper operation of the decoder; Furthermore over the lead 298 a circuit: is completed which extends over armature 184; and its front contact to-the winding ofrelay 1-72; Relay 172 upon operating armature 1'73 places a guarding earth on the release trunk conductor, at armature 17% opensthe circuit of relays 178 and 374 Relay 374 in deenergiziug' permits rel aiy- 379 to operate all its arniatures, which turn causes the release of relay 153- as previously de scribed. Armature 1T7 of-relay 172', in releasing, connects busy tone and busy flash battery to the lower trunk conductor: so as to inform the calling party that the line he wants is busy, and armatures 17:5 and 1-76 connect relay 21% across the calling loopi Relay 21 1 upon energizing at armature 21 5 completes a further circuit for relay 1372, so that both relays then remain energized until. the calling party hangs uphis iccci yer. Owing to the release of relay37'4 and the subsequent operation of relay 379, and re;-

lease of relay 1 53, another call may thus at once be extendedto the operations head set. The connection of relay 214 across the trunk line serves to energize relay lhbu-tnot relay 41-2" since no reversal has taken: place. When. battery is connected to the lover speaking lead as happens intermittentky, relay 40 is shorted out and decnergizeshen relay 4 0 first operates, a circuit is completed as follows: earth, armature 5 and its front contact, armature 4 4 and its back contact, front contact and armature 1 34, front con-.- tact and armature 491', armature 38 and its back contact, lower winding of busy relay 37 to battery. Relay 37 is the two+step type and under these circumstances only operates its light armature 39; Upon. the succeeding deenergizationof relay 49- and the release of armature 41, however, the upper windingof relay 37 is no longer short circuited and it operates fully. Consequentl 'y when relay 4 0 again operates the earth from armature 5 is extended-' over armature 38 and its front contact and armature 46 LOO and its front contact to lead 1 and thus the busy flash signal is repeated back to the calling party. The tone is of course transmitted through the speaking condensers without ditficulty.

In case the selector D should be driven to the 11th contact owing to all the trunks in the required level being busy, the operation is substantially the same. Under these circumstances relay 25 is operated by battery through a busy meter so that succeeding impulses are routed to the coder as before. Owing to the connecting up of busy flash battery in the selector D, however, relay 83 cannot remain energized and the transmission of code impulses takes place imn'iediately, though of course without eittect. Relay 32 then switches through as before and busy tone and busy flash battery are transmitted back from the selector D in the manner just described.

In order to permit of handling special service calls, it is arranged that these are trunked to a special service operator so that the ordinary operators work shall not be slowed up. This is done by pressing the special service key 320 whereupon at the right hand springs the special service meter 321 is operated and at the left hand springs a circuit is completed over lead 316 for init'i ating the operation of the special service distributor shown in Fig. 4. This serves to distribute the special service trunks among the various operators and when a trunk has been assigned, the special service tinder SSF, Fig. 2, is started up and oper ates in a manner similar to the regular tinder switch FS. The call is then extended over a special service selector SSS, Fig. 3, to a special service operators position as fully described in the application ot Ostline, Serial No. 747,373, filed November 1, 1924. In case all the special service trunks are busy, earth will be connected to lead 335 and lamp 334 will be lighted and the operator will then know that it is use less to press the special service key and will press the busy key instead.

The third meter 322 is for counting the total number of calls which come to a position and is operated by armature 324- of relay 323 which is energized over lead 325 in series with the call indicator lamps. The meter thus records the number of calls which are displayed to the operator and with the arrangement shown it the call indicator apparatus is not used this meter clearly becomes ineffective.

Key 317 is the decoder release key and is not concerned with the present invention. As above mentioned, when a position is to be rendered no longer selectable if for any reason calls cannot be completed thereat, earth is connected to lead 210. It will be 1 3 talzt 5;

the load distributing switch is stepped on without a call having been assigned to the position in question. Owing to a circuit bein completed over wiper 361, earth may be connected to lead 210 for various reasons; for instance, it bot-h the markers associated with the emergency apparatus are in use, earth will be connected up by way of armatures 392 and 366'; again, if relay 211 is operated due to all of the five regular markers being in use, earth is connected up at armature 212. Furthermore, at armature 213 a circuit is completed over lead 340 for the lamp 336 at the supervisory operators position, so that lamp 336 lights to indicate that a position is overloaded; moreover relay 337 is operated and at armature 338 completes a circuit for the buzzer 339. If the operator leaves her position the plug 306 will be withdrawn from its associated jack and in this case the transmitter feed circuit which includes relay 310 is no longer completed. Relay 310 therefore releases armature 312 whereupon earth is connected to lead 210 with the results previously described. Suppose, however, that the operator is at her position but that all, her cord circuits are in use. In this case all the multiple earths are removed from lead 292 at armatures similar to 267 and relay 313 is therefore deenergized and at armature 3ltconnects earth to lead 210.

The lamp 300 is individual to the marker shown and this or asimilar lamp and also the lamp 303, which is common to all the markers, are lighted whenever a call is wait ing attention other lamps similar to 300 being also lighted if a number of calls are waiting. Lamp 303 is connected up at armature 302 of relay 301, which is energized in series with the marker pilot lamps over lead 297. Similar circuits for the markers in the emergency operators circuit are not shown but could equally well be provided in a similar manner. Key 294 is a marker busy key and when operated removes earth from lead 296 which is included in the circuit of the pilot lamp 300 and connects it to lead 295 so as to make that particular marker busy in the bank of the marker distributor.

- The object of the battery connection to the front contact of armature 183 is to prevent the repeater R being seized before it has restored to normal. Suppose that the decoder is in use and that the wanted number has been displayed but that the operator for some reason does not complete the connection immediately and that the calling subscriber hangs up in the meantime. Under these circumstances it no special provision were made, the repeater R and the selector D would release completely and the junction line would be rendered tree at the out going end while still in use at the incoming Jli. tin-- wri i e when relay 153 deenergizes, the following circuit is completed; battery, front contact and armature 188, back contact and armature 176, back contact and armature 159, back contact and armature 1'90, contact 152, front contact and armature 180, lead 120, selector D, armature 36 and its back contact, armature 22 and its back contact, lower winding of relay 23 to earth. Relay 23 is thus main tained energized and at armature 24- maintains the guarding earth on release trunk conductor 3.

What is claimed is:

1. In a telephone system, an automatic exchange, a manual exchange, means for ex tending calls from said automatic exchange to said manual exchange, an operators position, call indicator apparatus at said position for displaying called numbers, an operators head set, and operator controlled means for substituting said head set for said call indicator apparatus to enable the operator at said position to be orally informed of called numbers.

2. In a telephone system, a plurality of calling lines, an operators head set, means for automatically associating said heat set with said calling lines in turn, cord circuits for extending connections between said calling lines and called lines, and means responsive to the placing of the plug of a cord into the jack of a called line for associating said plug with the calling line to which the operator head set is connected.

3. In a telephone system, an automatic exchange, a manual exchange, means for ex tending calls from said automatic exchange to said manual exchange, an operators position, call indicator apparatus at said position for displaying called numbers, an operators head set, operator controlled means for substituting said head set for said call indicator apparatus to enable the operator at said position. to be orally informed of called numbers, means for distributing calls to said call indicator apparatus in the order in which they are received, and separate means for distributing calls to said head set in the order in which they are received.

t. In a-telephone system, an automatic exchange, a manual exchange, means for extending calls from said automatic exchange to said manual exchange, an operators position, call indicator apparatus at said position for displaying called numbers, an operators head set, operator controlled means for substituting said head set for said call indicator apparatus to enable the operator at said position to be orally informed of called numbers, means for distributing calls to said call indicator apparauts in the order in which they are received, and means comprising a group of relays for distributing calls to said head set in the order in which they are received.

5. In a telephone system, an operators position, call indicator apparatus at said position for displaying called numbers, means for extending calls to said position, means for rendering said position inaccessible after a predetermined number of calls are awaiting attention, an operators head set, operator controlled means for substituting said head set for said call indicator apparatus to enable the operator at said position to be orally informed of called numbers, and means made eii'eetive responsive to said substitution for rendering said position inaccessible after another predetermined number of calls, less than said first predetermined number, are awaiting attention.

6. In a telephone system, an operators switchboard, means for extending calls to said switchboard, call indicator apparatus at said position for displaying called numbers, an operators head set by which the operator at said switchboard may be orally informed of called numbers, and operator controlled means for making either effective and the other ineffective at will.

7. In a telephone system, a trunk line, means for extending a connection to said trunk line, an oper'ators head set, means for automatically associating said head set with said trunk line when a connection thereto is extended, a cord circuit for extending connections to called lines, and means responsive to the placing of the plug of the cord into the jack of a called line for associating said plug with said trunk line and for disassociating said head set from said trunk line.

8. In a telephone'system, a calling and a called line, a trunk line, means for extending a connection from said calling line to said trunk line, an operators head set, means for automatically associating said head set with said trunk line responsive to the extension of a connection to said trunk line, a key, and means responsive to the actuation of said key for disassociating saidhead set from said trunk line and for giving the party on the called'line a characteristic signal.

In witness whereof, I hereunto subscribe my name this 12th day of January, A. D.

JOHN E. osriiinn'

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