US1200788A - Telephone-exchange system. - Google Patents

Description

` S. B. WILLIAMS, 1R.

TELEPH'ONE EXCHANGE SYSTEM. PPLlcATloN FILED Mln/22.1915.'

1,200,788. Patented o@t.10,1916.

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Patented Oct. 10, 1916.

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TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED MAY 22, 1915.vv I 'Patented OQt. 10,1916.

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TELEPHONE EXCHANGE SYSTEM. ,APPLICATION min MAY 22. '1915.

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TELEPHONEAEXCHANGE SYSTEM. -APPLICATISN FILED MAY 22. i915.

Y Patented Oct. 10,1916.

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SAMUEL l:BYRON WILLIAMS, JR., OF BROOKLYN, NEW YORK, ASSIGNOR, BY MESNE ,ASSIGNMENIT 'lO` WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORA- TION F NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specication of Letters Ilatent.

Patented uct. 10, 1915.

Application led May 22, 1915. Serial No. 29,875.

To all 'whom t may concern Be it known that I, SAMUEL B. WILLIAMS,

JR., a citizen of the United States, residing ful in connection with call distributing systems'. Its object is primarily to provide means for furnishing an automatic identification of each line with respect to its class of service, so that the treatment the line is to receive with respect to the manner in which it is handled or extended may automatically be indicated or determined. 20

In the ordinary manual practice of telephone eXchange operation, it is customary to associate with the answering jack and lamp of each'l telephone line certain characters, letters or colors which convey to the answering operator information with respect to the character of the line, such information being necessary as a guide to the operator 'in handling the calls from the particular line. These distinguishing marks associated with the incoming terminal of the line inform the operator whether the line is an individualline, a party line or a private branch exchange line, and whether the line receives a flat rate or message rate charge, or whether it is a line equipped wi fh coinboX or coin-collector mechanism. there is 'also associated with each line a number plate.

upon which appears the number of the line.

` and in writing such tickets and records as There is thus available to the operator all the information that it isnecessary for her to have in the manipulation of her message register and coin collector or return ikeys,

handling of the calls. l

In a call distributing system, the operator who receives the call and extends it tp the called' line does not have access to the incoming terminals of the lines, and, therefore, is not in position to know the {characteristics of the calling line which determine the treatment "that the call must receive. The call comes to the answering operator over trunk circuit, instead of through the may be required in connection with.. the

medium of answering jacks, and is thus-ex# tended to the operator without vany identiication of the line or of the class of, service which it is adapted and intended to receive.

By the application of the invention to a call distributing system, when a call comes to an operator, it comes accompanied by such identiication of the calling line asis 'necessary to determine the manner in which the call is to be handled.

Generally speaking, the invention contemplates the association with all of thelines adapted by certain classes of service of means which impress upon such lines peculiar and characteristic electrical conditions,

different for the different classes of service, which conditions are translated into indications at the operators position that inform the operator of the identity with respect to its class of service of any line that is originating a call. Or this characteristic electrical condition impressed upon a line may bring about the operation of apparatus adapted to automatically determine the character of the circuits with which the calling line is to be associated in the process of extending the call, and thus automatically adapt the connecting circuits to the character of service for which the call originating line is intended.

In the specific embodiment of the invention that is here disclosed, there israt the.

central oilice a device for producing as many sorts of characteristic electrical conditions as are necessary for the identification of the various classes of lines that are served at the central office, and each of the lines has such connection with this device as to impress upon the line the characteristic con-A dition appropriate to the class in which the particular line falls.

In the specific embodiment disclosed, the characteristic condition is impressed upon a conductor of the telephone line which is local to the central oiice. At the operators position there is a device that is selectively responsive to the various electrical conditions that are impressed upon the lines. -In the extension of the line to the operators position, this device is brought into operative association with that conductor of' the eX- tended line upon which the characteristic condition is impressed, and is operated to furnish an indication that identifies the extended line with respect to the service which it is to have. This responsive device at the operators position, furthermore, has con'- trol over certain circuits that are completed by the operator to supply current tothe calling line for various purposes, such as for operating the message register that may be associated with the line, or for operating the mechanism of the coin-box, if the line be provided with suchso that the circuits which the operator controls may automatically be adapted to the class of service for which thev line is intended.

A specific embodiment of the invention is shown in detail in the accompanying drawings, in 'which- Figure l illustrates three telephone lines.

with their central office terminal connections and identifying cirgjsits; Fig. 2 illustrates a line finder and cord finder circuit for eX- tf-:nding a calling line; Figs. 3 and 4 illustrate a cord circuit terminating in a plug, a called line int-o a spring jack of which the plug may be inserted, and a part of the operators circuit; Fig. 5 illustrates the part of the operators circuit that has to do with determining the identity of a calling line with respect to its class of service; and Figs. G, 7, 8 and ffshow details of the common identifying device or commutato: and its connections.

In the particular embodiment of the invention illustrated in the accompanying drawings, I have shown three lines adapted for different galasses of service extending from their respective stations A, B and@ to switch terminals at the central officeli A may be assumed to be a private-branc'h-exchange message-rate station, a party line coin-collector station, and C .an individual fiat rate station. The character and arrangement of aliparatus at such stationsiswell known, and I have not thought it necessary to illustrate it specifically. Cutoff relays 2l, 2,3, and line relays 22, 24, 26 are associated with the three lines in the usual way.

LT he line from station A, lbeing a message -rate line, also has associated with it at the central office a message register.,27.

llachfof the llnes has four conductors, tiro -bei'ng the ordinary line conductors, and thev other two,6l, and 460, being conductors localto the exchange. The local conductor 64 of each line has included init a winding of the associated cutoff relay, while the conductorgfti() 1n each case extends to the common f y identifying device or apparatus for` produc- "ing th.; .`character1st1'c :electrical conditions .whichfserve to identify the various lines. This Adevice 1s represented diagrammatically at the drawing, and is illustrated'as cont rising nine 'paths extending from the free pole of the central battery to nine terminals which are commontofthe lines of the exchangeeandgto one or" another of which current that may liow in each of the paths so as to produce trains of impulses, the impulses of each train being divided into groups and subgroups and the number of impulses y:1n-each group and subgroup being varie yso as to produce different and characteristic combinations. The duration of' the groups and subgroups in each train is determined and limited by piek-up impulses. Each of the suligroups consists of one or more impulses of current, as determined bythe action of circuit changing contacts in the various-paths. A single interruptjon in one of the subgroup periods divides the current flow in that period into two impulses, and two interruptions in the, subgroup period divides the current fiow in that period into three current impulses. To meet the requirements of the present embodiment of my invention, I have 'found it only necessary to provide a maximum of three impulses in each subgroup period, the various combinations of one, two or three impulses in each subgroup of a group af'- fording nine different characteristic combi.- nations of current impulses.

As diagrammatically illustrated at 13 in the drawing, path 1 has one impulse` in each subgroup period; path 2 has two impulses i in the first period arid one in the second period; path 3 has three impulses in the first period and one in the second; path 4L has one impulse in the first and two 1n the second; path 5 has two in the first and two in the second; path 6 has three in the first and two in the second; path 7 has one in the first and three in the second; path 8 has two in the first vand three in the second; and path 9 has three in the first period and three in the second. 'The'marks X placed upon the nine conductor paths indicate interruptions, and the `broken lines extending transversely of thev paths indicate the division of the resulting impulses into groups and subgroups by 4 the pick-up impulses. The classification which I havefound it desirable to provide for in this embodiment of my invention is` a division of the lines into three classes With respect to the character of the line, and into three classes with respect to the nature of the charge that is made for the use of the line. The lines are thus classified as individual, party line and private branch eX- change or P. B. X. lines, and the classifica-ltion of the lines with respect to the charge "vides them into flat rate, message rate and sin collector lines. There are nine possible combinations in this classification. for `cach sub f operated, thus o e1 the su sequent t relay 81 isi up,` relay 81 1n 1 10 relays 78 and 719.

number A shaft is constantly driven by a suitable operating it, the ten associated cams being mounted upon a common shaft`111, which source of power. The shaft andassociated cams lmay be driven to rotate at a rate of say 120 revolutions per minute. Switches 101 to 10S inclusive are normally closed, and are operated by their associated cams to be opened momentarily once in each revo` lution. Switches 109 and 110 are normally! opened, and are arranged to be closed once in each revolution. The cams are cut away to produce the operation of their associated switches at any one of six points sixty degrecs apart inthe rotational cycle. I have indicated these point or positions by the Roman numerals I, II, III, IV,V and VI. The cams associated with switch'springs 110 and 109 are cut away to produce the momentray closure of the switch contacts at positions I. and IV, respectively, in` the cycle of rotation of lthe cam shaft. These switch springs are those which determine the pickup impulses switch 110 controlling pick-up impluse #l and switch 109 controlling pick-up impulse #2. The cams associated with switch springs 102, 104C and 10'?Y are cut away at position II of the cycle; the cams associated with switch springs 101, 103 and 108 are cut away at Vposition'I'II of the cycle; the cam associated with the switch 105 is cut away at position V of the cycle; and the cam associated with switch 106 is cut away at position V I ot the cycle. Thus the complete rotation of the cam shaft with its cams involves thejmomentary closure of pick-up #l switch at position I, the momentary opening of switches 102, 104; and 107 at position II, the momentary opening of switches 101, 103 and 108 at position III, the momentary closure of piclrup #-2 switch 109 at position IV, the momentary opening of' switch 105 at position V, and the momentary opening of switch 106 at position VI. i

The eight switches 101 to 108 inclusive are connected in differentcombinations in the identifying paths 2 to 9 inclusive. Path 2 includes the contacts ot switch 102; path 3 includes the contacts of switches 102 and 101'.; path a includesswitch 105; path 5 includes switches 10:11 and 104; path 6 includes, switches 105,101 and 103; path 7 includes switches 105jand 106; path 8 includes switches 105, 106 and 107'; and path 9 includes switches 106, 107 and 108. Path 1 i'sadaptcd. togrgmain closed in positionsl I I, III, V and and, therefore, does not include any of the switches that are ated in these positions. l vThe resulto't the above described arrangeoperment ot'y cam, switches .in the conducting paths o 't the identifyingdeviceA is that these' paths have produced them thedistinctive combinations 'of interruptions `-illustrated diagrammatically at 13 in Iilig. 1 or the drawing, the impulses produced by the interruptions being divided through the medium of the piclcup impulses `:#:1 and #2 into groups and subgroups,l -The various identifying device paths, thus adapted to produce trains of impulses divided into distinctive groups and subgroups, terminate upon connectors from which connection may be made with the fourth or identifying conductor'60 of any line that it may be desired to identify, the connector to which the identifying conductor of the line isY led depending upon the classification of the line with respect to whether it is an individual line, a.

party line or a private branch exchange line,

and whether it has a flat rate or a message rate, or is equipped with a coin box or collector.

Inasmuch as my invention is not particularly concerned with the character of the circuits over which the calling-line is extended to the operator-s position, and over which the callinglline is extended to the called line after the operator' has obtained such identification of the calling line and such information concerning the called line asmay be necessary for her purpose, I shall describe these intermediate circuits and apparatus lonly to the extent that'they are involvedv in the operation which'has particularly to do with the disclosure of my invention. The organization which 'I have chosen for the purpose of showing a specific embodiment of my invention is one which utilizes automatic linder switches for finding a calling line and for extending the calling line to a connecting cord circuit that is at the time idle and available, and which utilizes a plug terminal for the connecting. cord circuit, which plug terminal is inserted by the operator into the spring-jack of the wanted line. Such systems, with their automatic finder switches, sequence switches and control circuits are well known, and this specification need not be burdened with a particular and detailed description of such a system. Y

In the operation of the particular embodiment of my invention illustrated, when one of the lines calls, the |associated line relay 22, 24 or 26, as the case may be,.1s enelrgiZed, and in closing its contacts closes a circuit which is effective, through intermediate circuits and apparatus that need notf here be particularly described, in permitting cutrrent to flow, by way of conductor 112,

:through one winding of the relay 52 asso- A line finder switch 11 to connect with the vterminals of the calling line. The sequence switch ismaglapted to rest in positions 1, 2, I

ytis

a, 4, e, 7, s, a, 14, 15, 16 and 17. 0f these positions, the following are of interest in connection with this description:

Position l-Normal.

Position 2 -Awaiting starting circuit.

Position 1 -Hunting calling line.

Position Q-Hunting cord circuit.

Position lll-Talking.

Ido not consider it necessary to show the connection of the circuit last traced with the motor magnet of the line finder switch, nor the path over which the iividing of the calling linel results in the sequence switch 36 being advanced through the intermediate stages until it reaches position 9, which is the position in which the connecting cord circuit is hunted. The circuits for accomplishing this are well known in the art.

When the brush 30 of the line finder 11 comes into engagement with the corresponding terminal of the calling line, a circuit is completed that includes battery, resistance 43, sequence switch contacts 42, brush 30 and its coperating line contact, and the cut` loff relay 21, 23 or 25 `ot the calling line. This energizes the cutoH relay and causes it to disconnect 'the associated line relay branch from the line.

When the sequence switch moves into position 9, the motor magnet of the cord finding switch 12 is made active, over circuits which need not be described, to cause the brushes 32, 33, 34 and 35 of the cord finder switch to engage corresponding contact terminals ot' an idle connecting cord. Whenv the idle connecting cord is found, the* sequence switch 36 is moved, by the closureaf circuits that it is unnecessary to describe, into position 14, which is the talking position. In this position of the sequence switch, the two talking conductors and 66 ot the finder circuit are connected through from brushes and 29 of the line finder switch to brushes 32 and of the cord iinder switch, by way of contacts 39 and 40 of the sequence switch, which contacts are. closed in position' 14. The third conductor A64 of i "-he circuit is closed, in this position, *from brush 30 ot' the line finder switch to brush 34 ot' the' cord finder switch by way of contacts 4'! -otf the sequence switch, one of the windings ot' relay 52, and contacts 50 and 51 of the sequence switch. The fourth or identit'ying conductor 60 -is closed from brush 31 ot the line finder switch to` brush 35 of the cord finder switch by way of contacts 44 of the sequence switch, contact-s 53 ot' relay 52, and contacts 46 and 47 otl the sequence switch.

I l will be noted that the motor magnet ot' thc sequence switch, whiley the switch is i resting in the talking position 14, is under the control ot' contacts 54 ofthe .relay 52 by way of contacts 3S of the sequence switch closed in position 14; so that in the talking position relay 52 acts as a holding relay, the denergization of which causes the sequence switch to move to its next position.

The circuits of the connecting cord are vgoverned by a sequence switch 165 which Vits No. 9 or hunting position to its No. 14

or talking position by well-known circuits which need not be particularly illustrated or described and as soon as sequence switch 36 leavesits No. 9 position, it completes a circuit which may be traced from ground through resistance coil 114, sequence switch contacts 49 and 51, brush 3ft-and its correspondingcord circuit contact, conductor 64, contact 67 of relay 68, sequence switch contacts 69 and winding of relay 113 to battery. Relay 1.13 in operating closes a circuit for the energization ofthe motor magnet of sequence switch 165, by Way of sequence switch contacts 115, contacts of calling plug sequence switch 118 closed in posi tion N o. 1 of that switch, and contacts 117 of relay 113, which movesl the sequence switch to its No. 7 orlistening-in yposition.

In order to avoid unnecessary confusion in the circuits, I have adopted the expedient, of showing, by means of circles with appropriate numbers inclosed therein, the positions of the calling plug sequence switch 118 in which this switch acts to close the path upon which the numbered circles are placed. Otherwise, in order to indicate the control (if the conductors by sequence switch 118, it would be necessary to extend them in each case to the vicinity ot' that switch, which is at a point somewhat remote in the drawing.

As' soon as sequence switch 165 moves out of position 1, itcloseis an energizing circuit for relay 6.8,as vfollows: battery, winding of relay 68, contacts 119 of sequence switch 165 to ground. The operation of relay 68 closes a locking circuit for the relay as follows: battery, winding of relay 66, contacts 120 of that relay, and contacts 11.) closed in position 1 to 7 ot' sequence switch 165 to ground. Subsequently theievljf; an alternative path closed in positions lto 179l ot thc calling plug sequence switch 11S to ground. This locking circuit provides for the continued energization of relay 68 from the time the connecting plug 14 is inserted the circuit.

in the spring jack of the called line until it is removed.

'Relay 68 in operating disconnects the sleeve strand 64 from the relay 113 and connectsit with the relay 121. This closes the path of the third strand 64 of the connecting circuit that remains normally completed during the period of extension of the ca-ll- 4 ing line to the operators circuit and to the called line. This path is as follows: :battery, winding of relay 121, backcontacts 122 of relay 123.-front contacts 67 of relay 68, contact ,terminal and brush 34V of the cord finder switch 12, contacts 51 and 50 of sequence switch 36, winding of holding relay 52, sequence switch Contacts 41, brush 30 of line finder switchl 11 and the associated line contact, winding of cutoff relay 21, 23 or 25 to ground. The relay 121, the holding relay 52, and the cutoff relay are thus kept energized while the line is extended.

When sequence switch 165 moves into position 7, it breaks the direct talking path through conductors 65 and 66 of the connecting cord circuit, and substitutes a loop which passes through contacts of certain of the operators control keys 124 and 125 and has connection with the operators telephone set 16. This loop is controlled in the contacts 126, 127, 128 and 129 of sequence switch 165. The operators key 124, thus brought into circuit in position 7 of sequence switch 165, is for the purpose of connecting high-voltage current of negative polarity with the calling line to bring about the return of a coin which may be held in the coin box of the line; while operators key 125 is for the purpose of ringing back on the calling line circuit.

The movement of sequence switch 165 into position 7 brings the operators telephone into circuit, as above described, and

also brings the operators class-o`fservice`v indicating mechanism into association with The latter is accomplishedby the closure in position 7 of the sequence switch contacts 130 and 131. Theclosure of contact 130 completes a path for the flow of current through conductor 61 including relay 70 ,of the class-of-service indicating apparatus, and the closure of sequence switch contacts 131 extends the fourth or identifying conductor of the line circuit to the class-of-service indicating apparatus. This automatically causes the indicating apparatus to operate to apprise the operator of the characteristics of the calling line with which the apparatus has Just acted to connect her. The manner in which the appa ratus acts to effect this result is as follows:

The closure of conductor 61 causes the energization of relay 70, which operates to close.

path is as follows: ground, commutator switch 110, contacts 132, back contacts 133 of relay73, and winding of relay 71 to bat-l tery. When the tirst'pick-up #l impulse flows, after relay is operated, relay 71 operates, and closes a locking circuit forv itself in its contacts 134. Vhen the con ltacts 134 close, a path is completed for the flow of current through the winding of rei .lay 73 to ground by way of contacts 135 of relay 70. But as long as the'pick-up #1 impulse persists, no current viows through the wirfding of relay 7 3`v because this path is short-circuited by the direct path from the winding of relay 71 to ground byk way of the pick-up commutator 110.' 'But the' termiuation of the pick-up #l impulse 'and the opening of the' direct path to ground at 110, permits the current through the winding of relay 71 to be diverted into the path including the winding of relay 73 and contacts 135 of relay 70. Thus, upon the. termination of the first pick-up #l impulsen relay 73 is operated, and thereafter relays 71 and 73 remain locked up as long as c ontacts 135 of relay 70 remain closed. Relay 73 in operating closes its front contacts 133 and 136. The opening of the back and closing of the front contact of 133 transfers the path through the pick-up #l commutator 110 fro-m relay 71 to the winding of relay 74 by way of normally closed contacts 137 of the last mentioned relay. The closing of contacts 136 of relay 73 connects the commutator switch 109 of pick-up #2 with the winding of relay by way of normally closed contacts 138 of that relay. Relay 73 thus operates to make ready the pathslover which the pick-up `#2 impulse and the second pick-up #l impulse' subsequently operate to control the operation pf the indiof relay 74 to ground. This impulse causes relay 72 to close its contacts 141 and complete a circuit for the'=y operation of relay 76, which circuit may be traced from battery thro-ugh the winding of relay 76, resting contacts 241 of relay 77, restingcontacts 142, 143 and 144 of relaysk 81, 79 and 77 respectively, in series, resting contact 1'45 of relay 96 and Contact 141 of relay 72 to ground. Relay 76 in operating closes its contacts 146 and completes a locking path for itself to ground by way of the winding of relay eating device. e. p

77, resting contacts 147`fof relay 79 and con-` facts 1535 of relay 70. rlhe previously traced path from the winding of relay 7o to ground -closed in contacts 1-l-1 of relay 72, shortcircuits the path last traced; -but at the interruption in the flow of' current which marks the end oftlic first ii'npulse, relay 72 permits contacts 141 to open, thus breaking the short-circuitJpath about relay 77 and causing that relay to operate.. rlhere- 'after relays 76 and 77, constituting the first pair of the selected relaysQarc held operated. subject to the control` of the resting contacts 147 of relayy 79 and `the contacts 1255 of relay 70. lelay 76 in its operated position closes a path for the How of' current to the tirstjlainp H2 of the first group of three lamps, subject to the control of normally open contacts 14S of relay 96, which contacts are closed at a later stage of the operatirn by the passage of the pick-up #2 impulse, as will hereinafter be described.

Relay 77 in operating, moves its contacts 144 to switch the circuit controlled by relay @from the winding of relay 76 to the winding of relay 7 8. Therefore, the second impulse of current that flows over conductor (30 in the first subgroup period and operates relay 72, closes a path for the energization ot relay 7 8 that may be traced from battery through the winding of relay 7 S, vfront contacts 144 of relay 77, back contacts 145 of relay 96, and front contacts 141 of relay 72 to ground. The flow of current over this path operates relay 78, which relay closes a locking circuit for itself by way of its con tacts 149, the Winding of relay 79, resting contacts 150 of relay 81, and front contacts 135 of relay 7U to ground. Current is diverted from the path last traced by the short circuit path. completed by way 4of contacts '-1-5 of relay 96 and 141 of relay 7:2. Upon the termination of the' impulse this shortcircuit path is Ainterrupted andi-clay 79 is operated. Thereafter relays 78 and 7 9 are. both held up, subject to the control of resting contacts 150 of relay 81 and contacts 1535 of relay 70. Relay 78 in operating closes, in its contacts 151, a path for the s'ub'V sequent flow of current through the second lamp S3 of the first group, under the control of.' contacts 148 of relay 96, which are closed at a later stage of the operation. Relay 79 in operating opens its contacts 147, thus.

l'n'eaking the locking circuit for the pro`- viously operated pan' of' relays 76 and 77 and permittingr those relays to fall back.

- The falling back of relay 76 opens the circuit o f lamp 82, so that, that lamp will not be lighted when contacts 14S of relay 9G are subsequently closed; and relay 77 in falling f back disconnects relay 7 8 from the controllinlircircuit and connects 1n its place relay 8() by way of the-back contacts 144 of relay `77 and front contacts 143 of relay 79, which is one relay of the pair that is now energized. 4

.lhe above `described operation places relay SO of the third pair in position to be energized by the closure of contacts 141 of relay 72 resulting from a` third impulse of current over the conductor 60. 1V hen relay 72 closes its contacts 141 upon receipt of the third impulse, a. path, like that previously traced for the operation of relays 76 and 78, is closed for relay 80 of the third pair; and relay S0 closes a locking circuit for itself in its contacts 152, which locking circuit includes the winding of relay 81 and contacts 135 of relay 70. Relay 81 is short-circuited and prevented from operating as long as the shortcircuiting path by Way of contacts 145 of relay 9G and contacts 141 of relay 72 is closed, in the manner previously described, and is operated as soon as the short-circuiti ing path is broken. Relay 80 in operating closes a path in its contacts 153 for the flow of current through the third lamp`84 of the first group, subject to the closure of contacts 148 of relay 96; and relay 81 in operating opens, in its contacts 150, the locking circuit for the previously operated pair of relays 78 and 79, and permits these relays to fall back and open the path prepared for the flow of current through the second lamp 83.

The first subgroup period is terminated by the production of pick-up #2 impulse by the momentary closure of contacts 109 of the commutator. It Will be remembered that relay 7 had previously been locked up to prepare a path for the flow ofjthe pick-up :#:2 impulse by Way of the Winding of relay 75.` Upon the passage of the picl up. #2 impulse, relay operates, closes a locking circuit for itself by way of its-make contacts 154, subject to the control of contacts 135 of relay 70, and also closes its contacts 155 to operate relay 96. Relay 96 in operating disconnects the circuit controlled by contacts 141 of relay 72 from the path leading to the relays 76, 77, 78, 79, and 81 of the first group, and connects, it to the path which leads to the relays 86, S7 88, 89, 9,0 and 91 of the second group. It also closes in contacts 14S the circuit for the flow of current over whichevercf the lamps S2, S3 or S4 of the first group has its circuit left closed in the contacts of' the associated relay 76, 7S or 30. i

Assuming that three impulses of current are caused to pass to the second group of relays by way of the path controlled in the :front contact 145 of relay 91'. -the selective opta-ation ol" these relays by the successive impulses is'the same as has been described in detail for the first group of rela'ys, and needs no further description. The only point which needs to be noted in connection with the action in the second group of re- 20 the last mentioned relay. f Relay days, as distinguished from ad desde in l acciones the rs't group, is that relays '88 and'90 operatingl do not prepare;directly thecir- 'ouits for` the' vsubserpi'ent illumination off their associated'lanips 93 andf94, respectively, but closethe circuits ofxthese lamps throughl thef'i'nediurn of the relays'v 85 and and which relays .85 and 9 5 also .control cir- T.cuits `governing ,the-operation of message ratei and coin collector appara-tus, which circuits will bev-traced hereinafter.

'ond pick-up 1 impulse ,.'110 of 4the commutator.

-Way of'contacts 132'l of relay 70,' front contacts "183' -c'ffirelay 723, resting contacts'- the cycle are lternlii'iated' by the production of a sec. in. switch contacts Thisirnpulse flows 'The 'secondsubgroup period and 13 7 ofrelay-74 and throughthe winding of 'operated,- closesa locking" circuit for itself 140 completes apath for the illumination 2,5"01' whichever lamp 92,- 93 or 94 of the second f group is held in circuit by the energization y y of its associated relay 86, 88 or 90.

in opening .its baci' Rela 74 in operating also, contacts 140,' opens the path for the How of current',throughrelay (2, so that that relay thereafter' is unresponsive to the opening and closing Vof the 'identifying circuitj-60 associated with the oal1ing"line.- The;com- ISE- pletion of the cycle or. .group period lof the identifying device' thusleaves the lcircuit oi 'the'.identifying'conductor 60 open incon- .xilnpulse open incontacts 137 of relay 74,v 'the 'path-of pick-up #f-impulse. open in con-I tacts .138 of'relay 75,

" 'I5' and96 locked up subject tothe control of contacts` 135 of 'relay 70. I f 'it be as-l sumed that therevvere `three 'impulses in cach subgroup. period', it also leaves' relays yandf 9 1 ofthe second group locked up over 8O and 81 of the firstV group .and relays 9 0 the! locking circuitpeontrolled in contacts and -94 burning'. Itf also, under thesame as. sumption,

collector controlling path 't 63 yclosed The 'actions described above were under the assumption thateach of the two'sets of' counting relaysy received three im the path of`pick-up #1- relays 76 and 7 7,jso that -tvvo impulses dur- `ing the iirst .subgroup periodleavevthe secF d and relays 7.1, e, 74,-

.' their `associated lamp' .83.illuminate and 'of relay "70, anldwthje associated lamps 84" 'leaVesrelay 95 held operated the energzation o tgelay v90,'`a`nd the coin" to" .place if only one or tivo impulses ivere received ina subgroup period. 4In such' a Case, the iow of currentthroug'h identifying conductor 60, following the passage of thefirst. pickup :#:1 impulse acts, throu h the mediurngof .the relay 72,130v close t e energizing circuit of the relay'76. 4But, a'scurrentcontinues and contacts` 1410i relay 72 are y'heldclosed throughout the Whole of -the vfirst subgroup period, and While' this suming that there-is but a single iin-pulse -in' the first' 'subgroup period, this .flow of 96, as 'previously described,and relay 96 in operating opens its back contacts 145.v This A1.'eu'ioi-festhe short circuit from relay .7 7, and lterminates the-first' subgroup period "with l74 is'thus'yl'elays and?? locked up and lamp-.82

l 1ghted;-. fIf. thereare assumed to be two' inits contacts' 156, and in its :liront:contacts impulses' in therst subgroup period, the

TSbythe second impulse. Relay 79fof`the second pair is keptf 'short circuited, as

. alreadydescribed during'the passage 'of the second impulse; butvthe short circuit is re- 'moved-and 'relay 79 operates when pick-'up #:2, inkipulse 4 operatesrelay 96"to fopen itsre'sti-ng contacts 145 at thev end ofthe first subgroup perlod. In operating, relay 79 ,opens the locking' circuit of vthe first pair of ond pair of relays 78 and 79 locked u "and loe the other two Apairs ofrelays'denergized' one or two impulses in the second subgroup period, are exactly. the same' :as the actions described-above astaking' place in the relays',

of'therst group'. The result is that the.. lamp which is left lighted 'in each ofthe two Y 'groups corresponds with the number. of irn` pulses` Whichare received'. during that v sub# group period,' t`he operator bein informed bythe particular lampllighted-in the first` i yidual line, a' party line or a private branch. i 1

groupA Whether thecalling line" 1s -anindiexchange line, and by the particular lamp lightedin second group Whether the line l' receives 'flat rate, message rate or coinj collector"service. Thus, when the operators set 16 is automaticallyconnected with `the cord' circuit to which the calling line is eX-` ulses" in its res ecti've'subgroup period. I s all no vv descri 'e' briefly the'jaction thatvvv'ould .take

tended and 'the 'relay' l()` is operated, the

' class-of-service 4indicating apparatus is made 1 cate to the operator, by means of the particular lamps lighted, the class of service fer which the calling line is adapted. Thus informed, the operator is enabled to write' such tickets or memoranda or give such service as her instructions require for this sort of a line.'-

Having l'earned the number of the line that the calling line desires connection with, the operator completes the connection by inserting plug 14 into the sprin -Jack 15 of the desired linut-,The circuits o the calling plug end of the connecting cord circuit are controlled by a sequence switch 118, the

principal .resting positions of which, as d'e- 4 termined by the master contact 157, are as follows: e. Y I

Position. l-NormaL Position 2-Awaiting listening key se'- quence switch. Y ,i

Position -Ringing on tip conductor. Position .B-Ringing lon tip conductor. Position 11-Ringing on ring conductor. Position l8r-Ringing on lring conductor. Position 16Awaiting supervisory relay. Position 17-Talking- The sequence switch 118 remains in posil tion No. 1 until plug 14 is inserted, when it moves into position No. 2, and there waits upon certain actions in' the associated connecting cord circuit, which are not particularly concerned with this invention and need not be described, and presently is moved into position 5L -In this position, ringing current may be applied to the t1p` conductor of the cord by way of sequence switch contacts 158, the ring strand of the cord being connectedK to ground by way of contacts 159. In position 8 ci' the sequence switch, ringing current of a. dill'erent sort 4may be applied to the tip strand and the ring strand grounded by way ofthe same 163 and 164 of sequence switch 118.

sequence switch contacts. In positions Nos. 11 and 13, ringing current of dilerent sorts may be applied to the ring strandand the tip strand grounded by way oi sequence switch contacts 160 and 161 closed in these positions. Sequence switch .118 then moves to position 16 where it awaits the response ofthe called subscriber; and upon the subscriber taking his telephone from its hook, the sequence switch moves to position 17, which is the talking position.

',In the talking position, the conversational circuit is completed between the calling and the called subscribers by way of the windings of the repeating coil 162 and contrafts e tip strand of the talking circuit also passes through contacts 175 of relay176, which relay, with relay 167, is included in a conductor` extending from 'battery to the sl J'eve 14, and thence to gro .nd

of connectin plu g relay of the called line.

through the cuto Answering supervisory relay 168and calling `supervisory relay 169 are included in the `positions, to designate to the operator the I Connecting cord to which the calling line has been' extended, and. being thereafter caused to glow steadily untilthe called subscriber has answered, an'd the sequence switch 118 has moved into its talking position 17.

l/Vhen the sequence switch 118 moved to position 2,'at the time thevoperator inserted the calling plug 14 into the spring-jack 15, it closed contacts which completed a circuit that moved the sequence switch 165 out of its listening-in position 7, in which it had been standing, and into its listening-out position 15. This circuit is as follows: battery, motor magnet of sequence switch 165, sequence switch contacts 172, contacts of sequence switch 118 closed inthe second position, back contact 117 of relay 113 to ground.

In moving out of its listening-in position 7, sequence switch 165 opens, in sequence switch contacts 131 and 130, the circuit of conductors 60 and 61 extending to the class-off service responsive apparatus. The opening of conductor 61 allows relay 70 to fall back and open the locking" and lamp circuits it controls. This extinguishes the lamps and restores the class-of-service apparatus to its normal condition.

When it is resting in its listening-in posi tion 7, the sequence switch 165 may also be moved into its listening-out position over a circuit which passes from battery through the motormagnet of sequence switch 165, contacts 173 of the sequence switch and contacts of the masterv listeningout key .174. If the sequence switch 118 as sociated with the calling plug is in its iii-st position -when the master listening-outkey 174 closes the circuit traced above, the sequence switch 165 finds a circuit .to ground in its 15 position by way of contacts 177 of in l sequence switch 165, and contacts of the 'v sequence switch 118 closed in the normal position of that switch. This condition causes theV sequence switch 165 to pass thrlough its 15 position and return to norma A Assuming that the calling plug 14 has been inserted, 'and that the called subscriber has been signaled ing this telephone versational circuit called subscribers from its hook, the lconstations Vis completed by way of the talking conductors 65 and 66,--i

sequence switch 36 standing in its talking position 14, sequence switch 118 standing between the calling andy and has responded by vtak- L sequence :switch'118, ground. ,'Thiscircuit phone setan'do thegclass-of-service inditheir associated supervisory lamps.

`in its .talking position v17',v ,and sequence switch 165 standing in its listening-out posi sive apparatus are 'disconnected from'` the clrcuit.

' When the subscribers have finished their conversation they` hang up their 'telephones,' as a 'result of which-the answering super` Upon receiving this disconnect signal, the operator may listen-in on the circuit by pressing her listening-in key 180. The pressing of this key closes' the following circuit: ground, contacts 116 of sequence switch 165, motor magnet ofsequen'ce switch 165, battery This ene'rgizes` the sequence switch and causes it ;to move out of its listenirg-out position 1 5.'

*But'instea'd of stopping in' position 1, .the

sequence switch finds a circuit in that po`si tion as follows: battery, motormagnet of. sequence'switch 165, contacts 181, contacts .closed-in .positions 2 tcl8 of the calling 'plug causesv the sequence'switch 165v to move through position 1 andcozne to rest in'its listening-1n position 7, Ars 'a resuit, byl

pressing lher listening-in key 180, the operaf torgrestablishes the connectionl of her telecating apparatus with the connecting cord circuit,fand= the last mentioned apparatus thereupon' operate s,'in`the manner already described, 'to 4indicate' lagain thecla'ss of. serv ice of thecal'ling line'.

lf forany reason the `oper'atci'n' wishes to ,5dt'ggso', she may listen-in and listen-out on the- .-connectionas many times as she Acaresl -to ,while the conneetionis established .between thetwo; subscribers. lines, by merely press- .ingher listeningin key'180 and her master listeningo'ut' key l174, the sequence switch ff 1565 being-thus correspondingly-moved toits listeningin position `7 4.or it's listening-out position 15; Tand each time the sequence switch moves to 'the listening-in position,l the' lamps of lthe class-of-service responsive device.,againindicatethe class of service of thefcalli'ng. line. At the conclusion of the causestheapplication o current to the connecting cord circuitin a manner which is.

automatically' predetermined .by the operal tion of the class-of-serviceresponsive appa to adapt the cir'- ratus, this apparatusacting k h ergeey ,to t e cuits controlled" by the .c

. class-.oii-servlce of the calling line in a inanner which I shall nowdescribe. 4 When the- -charge key 179 is pressed,`it causes the operation. of two '.relays, v189 vand 123, the

- 64 with switch' 118, so that the charge key has -con- `trol-over the relay 123. only whenthe calling jplug'sequerice sij'vitchl is in its talking posicompleted 'with 'the called line. Assumingl that this is thecondition, and that the relay visoryrelay `168 andthe calli-'ng supervisory4 relay 169 of the' connecting c'ord circuitI are" denergized and cause the illumination of" 123 is' operated,it moves its switch contacts `12.2-t'o disconnect the relay 121 from the tion, that isonly when a connection has been thirdxconductor 64101:' the'connectingcord' "circuit, and to 'extend the conductor 6 4, .without interrupting it to a circuit havin`g two branches controlled'inl the contacts 1-84 and 185'ofrelay196. The branchV normally closed isfby way of contacts 184, and includes the winding of a relatively higlrresistance and sensitive'relay 186 and a battery oir', say, twenty-four volts; while theother branch,

by way of contacts 1 85, which is closed when the relay 196 is operated, includes a rela- Vtively low-resistance and insensitive relay 187 anda battery of, say, forty-eight volts. Each of .the relays 186 and 187,When it op`- erates, is 'adapted to operate a position register 18,8, and this position register, -inop-- erating, registers the connection and lights an associatedpilot lamp; The 'conductorwhich one or the other of 'these branches is connected .when 4the relay 123 is operated, is the third strand of the connecting cord ciruit,.and is an extension of :the conductor 'ofthevcalling'l line which in- ,cludes the cutoff relay, If the calling' line is-a flat rate or coin collector line, its-third` conductor. 'includesonly thecutoi relay.`

ter 27 isalso' 'connected lwith the third coni known type'having two windings in series', one of `which windings -is short-circuited If it is a messagejrate line,a message regisi vwhen the register operates Ato permitan inj creased flow of current over the circuit. When the line is a message rate line with the vmessage register 2 7 connected, 'the'branch that includes the windi'gotrelay 187'and thefforty-eight volt battery isincluded in the circuit. The relay 187 iso such low vresist- .an'ce that it is 'not operated by .the current which flows when both win'dngsof` the mesv conve'rsati'ol'i between` the s lbscribers, and j sage register y27 are includedjin the circuit.

'But when Athe message register acts and 'short-circuits one of its'.windings, the-increased flow ofcurrent 1s sufiiclent to oper- /ate the` relay 187. As 'a' result, the relay 187 acts to operate the position register`188 -and the associated ilotl lamp onlyfafter the message `regi'ster'2 'has operated.

If the calling'line' is not a message rate' the depression of the charge key^179,` the relay 186 acts to operate the position register 188 and light the associated pilot lampwithout waiting for the 'operation of some other device such as the message register 27. Thus'one ot the branches, that Which includes the contacts 185, the windingof the relay 187 and lthe forty-eight volt battery,` is

adapted to the circuit conditions present in message rate lines; while the other branch,

that which includes the contacts 184, the

winding of relay186 andthe twenty-four volt battery., is adapted for rthe circuit con-J ditions that are present in lines other 'than message rate. Which one of these branches 'is operatively associated with the circuit at the time the operator. presses her charge key 179, is automatically -determined by the class-of-servce responsive device, throughtlie mediunr` of the relay 196, which controls the two branches. If the calling line is not av message rate line, the relay 196 is not energzed. But if the calling line is a message rate line, when it is first brought i1ito operative relation with the classofserv1ce indicating apparatus, that apparatus operates,

as hereinbefore set ortln, to leave the relay 85 energized at the end of the cycle of operation, and thus to complete the circuit of conductor 62 in which the relay 196 is'included. This path for the operation of the relay 19,6 is -as follows: battery, winding of relay 196, contacts 182 of said relay, 'contacts 183 of sequence switch 165, conductor 62, contacts of relay 85, front contacts 1.10 of relay 7l,

to ground. The closure ot' this circuit oper-` switch leaves its normal Aposition until it moves' out of its talkingr position. Thus thel Aidentification of the calling line. as a measured service line kcauses the relay 196 to operates-1nd rcu'iain operated thereafter until the connection is taken down, and in its `operation to connect in circuitI the particul' lar apparatus that isadapted for copera- Ation with thc'charge mechanism oi message rate lines. Returning now to the other relay 189 which is operated when the operator de-` presses lier `charge key 179, this relay, in its contacts 190, breaks the tip conductor 6G ot the connecting v'cord circuit, and connects the portion that extends tothe calling line with a branch which includes normally open contacts 191 ot relay 192,'the-winding of a pilot relay 193, and al protective lamp, and extends to the positive pole of a high potential source'lof current.

The current thatI Hows vby "way of this path to the tip conductor of the callingline is for the purpose of operating the. coin-box mechanism at the subscribers station to collect the de` posited coin.

0. The mechanism at the/Sub?.-

scribers-station involved in this operation,

and in the operation of returning the,coin

when high potential current of the opposite polarity is appliedl to the calling line by way of the operators key 124, under control of the relay 194 operated in the listening position of the sequence' switch 165, is well known in the art, and need not be 4particu-V i larly shown or described. f

Vliether or not current for collecting the coin is applied by relay 189 when the operator presses lier charge key 179, is determined.

by whether or not the relay 192 is operated;

and this in turn is determined by Whether or` notv the conductor 63 has been closed in the operation of the class-of-service indicating apparatus. The closure of conductor 63 is ei'ected by the operation of the relay 95, and this in turn is brought about by the action of. the class-of-service responsive apparatus hereinbefore described if the calling line is a coin collector line. If it is, a circuit is closed for the energization of the relay 192 as follows: battery, winding of relay 192, contacts 195 of that relay, contacts 198 of the sequence switch 165, conductor 63, front contacts of relay 95, front contacts l-LO of relay 74, to ground. The operation of the relay 192 opens the path traced above, and closes a `locking path by way of contacts 197 of the relay and contacts 119 of the sequence switch 195, to ground, an alternative path to ground being provided by way of locking contacts 120 of relay68 and contacts closed in position l to 17?,- of the calling plug sequence switch 118. Thus, if the calling line is a coin collector line, the path for the application of the coin collecting current is automatically prepared by the action of the class-of-service responsive device, so that ,i rwhen the operator presses her charge key `179 and th'us operates yrelay 189, the coin collecting current flows out to the calling subscribers station and there operates the coin mechanism; whereas; if the calling line is not a coin collector line, the operation of the chai-ge key does not apply the lilgh potential coin collecting current. operator has pressed the charge key, which brings about in the inannci' ydescribed the application of the sort ot' charge current to v. the calling line Jfor which the class of scrvice of the line adapts it, she withdraws the i incense I 13- 1 'What is claimed'isi l 1. In -a-telephone system, thecombination With a plurality of telephone lines, an ide'n" tifying device, means -for causing said device to produce a pluralityof` different characteristic groups of iinpulses',each of said groups 'of impulses being impressed uponthe lines of-a particular class to distinguish and idenineansfor causing the temporary association of said indicating device with any of said -tifythem from the lines of another class, and an indicating device selectively responsiveto the different groups of impulses and lines. f

2. In a telephone system, the combination4 with a plurality of lines'divi'ded into groups, ,of a device for producing diiierent charac: teristic groups of impulses and to apply said groups to the different-,groups of lines to distinguish the lines of one group from the v lines of another, an operators position, means for extending any one of said lines to said operators positiongand anjinldicating4 'device at said position arranged to" display av different signal for each 'of said character,-

" istie groupsof impulses and means for cans-- ing said indicating device to be brought teinporarily into association with any-of said 3, In a telephone system,the combination with a plurality o f lines adaptedforfdifer- "ent classes ofservice, class-oY service identifying means associated with each of said lines, a classici-service responsive device, 'means for bringing said class-of-service re-A sponsive device temporarily into association with any'o'f saidIines, and signal mechanism v controlled inits operation by said class-0i* 40 4 I with a `plurality' of telephone lines, 'of 'an service responsive device.

4. In a telephone system, the combination identifying device common to said lines for` A producing trainsof impulses, each train con sisting 'of a succession of characteristic` groups of impulses, said trainsof impulses being impressed uponthe various lines to identify them, a responsive device, means for bringing said Vresponsive'vdevice temper rarily into associationwith any one of said lines, and' means for making the; responsive I period of said'responsive device coextensive 'with the "period 'of production df a single .group of a train.

A 5. Ina telephone system',- thecdm'bination With a telephone line, an :operators position,`

land a trunk for extending said line to said 6. In a telephone system, the combination with `a telephone line, an operators position and' a trunk for extendingsaid line-tov 'said operators position-,of anidentifying device for producing'and applying to saidvline a responsive device at the operators position,

means for bringing said responsive [device y temporarily into association with the trunk Aextension of said telephone line, and'means train of characteristic groups of. impulses, a

to render, said responsive device responsive. Y

"during the periodof production of a'single' group of impulses of said train.

l In a telephone system, the combination With a telephone line adapted for temporary Aextension to an operatonspositiorl of an' identifying device for producing an apply ing to said line a train of characteristic groups of impulses, each of said groups -being` made up of subgroups of impulses,'a're sponsive device at' the operators position,

temporarily into association with said line, means for 'making the operative period of said"responsi.v e device coextensive with the period of production of a single group of impulses of said train, and means for rendering said device selectively responsive with respect tothe subgroups of impulses.' 8. In a telephone system, the combination With-a plurality of telephone'lines adapted for different classes of service, of aclass-oil service identifying device common to said lines for producing a pluralityl of.charac teristic trains of impulses, each of saidtrains being divided .into groups and subgroups by'pickup impulses, and said different char- A acteristic trains being applied to the v,diierent lines to identify 'them' with respect 'to l their class ofservice, a class-oi-.service responsivezdevice, means for bringngsaid class'- of-service responsive device temporarily into association with any line, 'and means controlled:A by said pick-up impulses for making the operative period of said' responsive'demeansfor bringing said responsivedevice ico los

vice coextensive with' the period'of production. of a single group of said series, and for making said responsive device selectivelyv re- 1spin 'sive with. respect to the-subgroups 'o f.

eachroup.. i

9.v n a telephone system, .the combination with aplurality. of .telephone lines differing in -their characteristics, identifying means associated with each line, and an indicating device responsive to said identifying -i'ne'ans' and means,'forbringing said indicating device intotempo'rary association With any of said lines, said indicating device comprising a plurality of'signals. and electrically ac tuated mechanism for-selectively displaying. the same under the control of said identify'- ing meansul0. In a telephone system, the combination with a plurality oflines adapted for' different-classes of. service, of means for im! pressing upon each line an electrical condition characteristic of the class of service for which said line is adapted, a class-of-service responsive device, means for bringing said class-of-service responsive device into temporary association with an of said lines, and signals controlled there y, said responsive device being operated, under the control of the characteristic electrical current flow in the particular line with which it is associated, to selectively display signals corresponding to the'class of service of said line.

l1. In a telephone system, the combination with a plurality of lines having different characteristics and adapted for temporary extension to an operators position, of a group of signals at the operators position for indicating the characteristics of an extended line, an identifying device forimpressing upon cach line an electrical condition corresponding to the special characteristics of said line, and electrically actuated mechanism responsive to said electrical condition of an extended line for selectively controlling said signals.

12. In a. telephone system7 the combination with a calling line, class-of-service identifying means associated with said line, an operators position, operators equipment including a class-of-service indicating device at said operators position, automatic means made operative in the calling of said line for `extending the line to 4said operators equipment to produce a class-of-service indication at said position, a called line, means under the control of the operator for extending said calling line to the called line, automatic means for disconnecting the operators equipment and rendering the class-of service indicatingr device inoperative up'on the extension of the calling line to the called line, and a switch under the control of the operator for reconnecting the class-of-service indicating `device to the calling line to bring said indicating device again under the control of said identifyingmeans.

13. In a telephone system,r the combination with a plurality of telephone lines, an operators position, and means for extend-` ing any one of said lines to said operators position, of a class-of-service identifying' device for producing and applying to said lines different trains of characteristic groups of impulses, cach of said trains being `divided into groups and subgroups by pickup impulses produced by said device, a class-of-service indicating device. means for bringing said class-of-servlceindicating device temporarily into association With the' extended line at the operators position, said indicating means comprising a group of signal devices divided into subgroups corresponding with the subgroups of impulses in altrain, an electrically actuated switch actuated by the first`pick-up impulse received after the indicating device is brought into association with the `line forrendering the first subgroup of signal devices selec-` tively responsive to the first subgroup of impulses, an electrically actuated switch operated by the second pick-up impulse for rendering the second subgroup of signal devices selectively responsive to the second subgroup of impulses, and an electrically actuated switch operated by the pick-up impulse at the end of the group of impulses ior rendering the vsignal devices unresponsive to further impulses in the train.

14:. In a telephone system, the combination with a telephone line, an operators position, and means for extending said line to said operators position, of a class-of-service identifying device for producing and applying to said line a train of impulses dividedby pick-up impulses into groups and subgroups, a switch operated as an incident to the connection of the operators equipment with the extended line, and a classof-ser'vice indicating device at the operators position brought into operative association with said extended line in the operation of said switch, said class-of-service indicating device comprising a group of signal devices Y group of signal devices selectively responsive to the lirst subgroup of impulses, an electrically actuated switch operatedby the' second pick-up impulses for rendering the second subgroup of signal devices selectively responsive to the second subgroup of impulses, and an electrically actuated switch operated by the pick-up impulse at the end of the `group of impulses for rendering the signal devices unresponsive to further impulses in the train.

15. In a telephone system, the combination with a plurality of terminating telephone lines, means for extending the circuit of any one of said lines, a class-of-serviee identifying means associated with each line, a class-o-service responsive device, means for bringing said device into temporary association With the extended line and responsive to the identifying means associated with said line, and a switch for controlling the circuit of said line, said switch being controlled in its operation by' said responsive device.

16. In a telephone system, the combina'- tion with an operators position, oi' a telephone line temporarily extended thereto,

- class-of-service identifying means associated

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