US1800788A - Automatic telephone system - Google Patents

Description

April 14, 1931. H. M. FRIENDLY AUTOMATIC TELEPHONE- SYSTEM Filed Dec. 22, 1927 4 Sheets-Sheet MRMM 2 April 14, 1931- H. M. FRIENDLY AUTOMATIC TELEPHONE SYSTEM Filed Dec. 22, 1927 4 Sheets-Sheet 2 Invaniur Herhefl-PI-Ffiandl AlludhR D um mifi llll. 3

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April 14, 1931- H. M. FRIENDLY AUTOMATIC TELEPHONE SYSTEM Filed Dec. 22, 1927 4 Sheets-Sheet 3 April 14, 1931- H. M. FRIENDLY 1,800,788

AUTOMATI G TELEPHONE SYSTEM Filed Dec. 22, 1927 4 Sheets-Sheet 4 510525 on I] Else. if

@ ZYZWZZZM/ Patented Apr. 14, 1931 UNITED. STATES PATENT OFFICE HERBERT M. FRIENDLY, OF CHICAGO, ILLINOIS; MILTON S. FRIENDLY AND CENTRAL TRUST COMPANY OF ILLINOIS EXEGUTORS OF SAID HERBERT M. FRIENDLY,

DECEASED AUTOMATIC TELEPHONE SYSTEM Application filed December 22, 1927. Serial No. 241,793.

The present invention relates to'telephone systems; more particularly so-called automatic or machine switching telephone systems.

General objects The general objects of the present invention is to enable a subscriber of the automatic telephone system, who contemplates leaving the location of his telephone, to directively set central office apparatus or call-forwa rding equipment associated with his line, through the agency of his automatic calling device dial on his telephone so that in case any calls are thereafter directed to his line, the latter said calls will be further extended or forwarded to a predetermined random subscribers line or other line of the system.

The latter said line may terminate at the O switchboard of an operator who is charged with responding to such calls and imparting such information to the party calling as instructed by the absent subscriber primarily called. That is, for example, a physician before leaving his office may remove the receiver of his telephone as if to initiate a call, and then operate his calling device dial by placing his fore-finger in a specific depression finger-hold of the dial and then draw the dial until his finger encounters the fingerstop, so that when the dial is released it will send a series of eleven open impulses. After the dial has returned, he will restore the receiver, leaving his central office call-for- 35 warding equipment in the set condition.

General operation As will appear presently, that due to the said set condition, any call extended to the terminals of the said subscribers line will not only ring the bell of his telephone in a peculiar manner because of the set condition, but the call will be thereupon automatically extended or forwarded under directive control of an impulse sending device in accordance with the said set condition to an attendant who may possibly serve many such subscribers, or it may as referred to, and as illustrated herein, be extended to a random subscribers telephone line, as may be predetermined.

It will also appear presently, that the said peculiar ringing of the bell of the subscriber primarily called under the said set condition for forwarding the call will vary dependin upon if the connection has been forwarde to the line intended. That is to say, the bell will start ringing at the time the terminals of the primarily called line are seized, the bell vibrating at a predetermined rate, and intermittently applied at a predetermined rate, so that there are two distinctive characteristics to the signal. When the forwarded extension has progressed to the predetermined line and the central office impulse sending device directing the forwarding of the call has been thereupon excluded, as will appear presently, the rate of vibration of the said bell and the intermittent periods of application of the ringing will change. This is because a specific source of ringing current different from that normally applied from the connector seizing the terminals of the set line is applied at the time the terminals of the set line are seized and a still different source of ringing current is applied at the time the forwarded extension is completed to the predetermined line. The peculiar ringing of his bell under the set condition thus prompts the primarily called subscriber, if he is at his telephone, that his line is set by reason of the change in ringing to forward calls, and it also apprises him in general as to how far the forwarded call has been progrossed.

The primarily called subscriber, if he has returned, may remove his receiver upon hearing his bell ring at any stage until the call is responded to on the said predetermined line and thus eiface the forwarded extension and become in direct tall ring communication with the calling party as if the primarily a his line.

the subscriber sets his line for forwarding calls it will remain so set until hedirectively unsets it, in the manner .as will appear presenty, though he may in the meantime intercept calls which are being forwarded from The present invention. provides for for- I warding calls under the set condition over primarily called subscribers line or group of the same outgoing path from the line primarily calledas if the call originated on the latter said line. It also provides for metering calls so forwarded on the regular line meter of the primarily called line sothatthe operating concern may receive toll for the connection to the primarily called line and may also receive toll'from theprimarily called line to the predetermined line to which the call is forwarded. a

A meter M is provided individual to the lines torecord the number of calls forwarded and responded to. A switch S is provided for readily changing the circuits of the latter said meter so-that it will'record the number of calls forwarded to the line to receive the forwarded call, regardless of whether such calls are responded to over the forwarded extension.

A meter MM is provided to record the number of times the said subscribers line is I selected and seized while it is set for forwardying calls regardless of the fact the calling party may abandon .the call before the call is forwarded. This is having in mind that the tone induced by generator G or G applied to the calling line will indicate that the line called has been set for forwardin and is bemg forwarded, and that the su scriber is probably not at his telephone. The operation of the latter said tone applied from the ringing generator G 'or G, will be further discussed presently.

The subscriber having the line arranged for forwarding calls made thereto will set his line for forwarding calls made to it by removing the receiver as if to initiate a call,

and when he hears the tone from source T through interrupter I, he will know from this [intermittent tone that the first selector F has been seized and that his line extends thereto.-

' He will then operate the dial on his calling device inaccordance with the finger-hold provided for sending a series of eleven open impulses. This will correspondingly operate.

subscriber is thereupon apprised that the set relay C has been operated and locked. The

subscriber may then. replace his receiver and thereby efface the call extension he made to the first selector F, while the set relay :0 remains set due to the locking dog. The subscriber may thereafter remove his. receiver to initiate and thereafter make a call in the normal manner, as if the set condition of his line did not exist. However, when he re moves his receiver he will perceive the tone from the source T applied through the interrupter I to prompt him of the set condition, as he may wish to efi'ace the set condition.

If the subscriber of the set line wishes to etface the set condition he will after initiating a call by removing his receiver in the usual manner and upon perceiving'the tone from the source T operate his dial in the same manner as when setting his line. That is, he will send a series of eleven open impulses to cause the shaft of the first selector F to step up eleven steps and energize a magnet circuit to unlatch the locking dog to permit the set relay C to restore, the subscriber then hearing the tone fromsource T to apprise him of the unset condition existing. The subscriber may now replace his receiver, whereupon the first selector F will restoreand his lineis then in normal idle condition. Incoming calls will not be forwarded and the bell of the sub scribers telephone-will be rung from the connector as E, in place from the source G or G.

Reference is made to my copending application for U. S. Letters Patent,-Ser. No.218,605, filed Sept. 10, 1927. The said copending application refers to an automatic telephone system embodying certain features incorporated in the present application, but there are certain distinctive features of the present application over said copending ap lication which will appear from the descriptions and which will be specifically pointed out in the subjoined claims. 4

Drawings.

With reference to the accompanying draw- 1n s;

iig. 1 shows a subscribers calling automatic telephone A to which the finder switch FS of a group' (not shown) .has access. 'It also shows certain rel ysauxiliary to the set relay C shown in Fig. 2.

' Fig. 2 shows the set relay C and auxiliary apparatus thereto. It also shows the connector E of a group of connectors (not shown) having common access to the line leading to telephone A shown in Fig. 1.1

gether with a well known telephone, line switch, selectors and a connector of a comprehensive telephone system involving the present invention. 1

Fig.5 shows a preferred modification of Fig. 2, introduced into Fig. 2 where indicated by the dotted line a. The said preferred modification is to be assumed as belonging to the structure disclosed in Fig. 2, it having been deemed more expedient to disclose the preferred embodiment supplemental to the simpler embodiment in Fig. 2.

The Various sheets of drawings are to be assembled so that the lines extending towards the margins register consistent with the reference designations thereof.

Equipment The telephone A in Fig. 1 is the well known common battery series automatic type, but it is equipped with an automatic calling device and dial as disclosed in the said copending application and illustrated in Figs. 7 and 8 thereof. This dial enables a series of eleven open impulses to be sent responsive to operat ing and releasing a specific finger-hold depression positioned after the 0 digit fingerhole. Of course, it is feasible to use a fingerhole in place of the finger-hold depression, but the latter avoids confusion when sending trains of series in interswitching.

The finder switch FS in Fig. 1 is of the class shown and described on pages 55 to 57 of the third edition of the book Automatic Telephope Practice, by Harry E. Hershey. However, modified by the addition of the lower wiper and armature therefor.

The first selector F is of the well-known class as described in the said Hershey book on pages 59 to 61. However, the lower set of off-normal springs, the upper armature of the release relay and the upper armature of the switching relay and associated circuits are introduced, as shown in selector F of Fig. 3 of the said copending application.

The switch elements NO and DF have the same general mechanical structure and operation as the finder switch FS, though the A operating circuits of said elements are specific to the present invention.

The primary line switch LS is of the wellknown rotary class as described in the said Hershey book, page 53.

The selectors G, H, J, N, P and Q. are well known selectors (known as Powell selectors) as disclosed on pages 59 to 61 in the said Hershey book.

The connector E is of the well-known, socalled, group-selecting type as designated Fig. 111 in the fourth edition of'the said Hershey book.

The connector R is like connector E. The connectors E and R are like connector E in Fig. 4' of the said copending application.

It will be understood that any other suitable switches may be substituted for the said well-known switchesmentioned without departingfrom the spirit of the present invention.

Upon removing the receiver from the switch-hook of telephone A, a circuit path can be traced from ground, armature 12, conductor 13, make-before-break spring 201, armatures 202 and 203, conductor 205, telephone A, conductor 14, armatures 206 and 207, make-before-break spring 208, conductor 209, armature 16 of line relay 17, lower winding of the latter said relay, winding of common relay 18 to' grounded battery, the relays 17 and 18 actuating. However, only the armature 19 of the relay 17 will now operate to disengage its resting contact and engage its make contact.

Responsive to the actuation of relay 18, common relay 20 will energize over an abvious circuit path. Ground is applied through armature 21, common conductor 22, armature 23 to'the Winding of slow-releasing relay 24, the latter said relay actuating. Due to the attracted condition of armature 19, ground will not be applied to private bank terminal 25 and its multiples. However, the cor responding bank terminals to said 25 belonging to other normal subscribers lines are grounded because the armatures corresponding to said 19 will be retracted on all but the line or lines on which a call is' initiated awaiting its seizure by a linefinder switch of the group containing switch FS.

In view of the reference, it is thought to be unnecessary to describe the detailed operation of the line-finder switch FS in hunting for and seizing the line leading from telephone A to line relay 17 wherein the relay 26 will actuate and first apply ground from armature 28 and then cause ground from armature 401 in first seclector F, release trunk conductor 402 to be applied through the private wiper 29 and armature 19 to energize the upper winding of relay 17 to opcratively attract the armatures 12 and 16. The ground applied through the armature 19 is also applied to private normal conductor 30. armature 31 to the winding of relay 32, the latter said relay actuating. Ground is now ap plied through armature 33, conductor 34 over an obvious circuit path including a spring on relay 0 to the auxiliary private bank terminal 210 and also directly to the private bank terminal 211 and multiples, to guard the line leading to telephone A against intrusion from a connector of the group contaming connector E.

The connector E is a group-selecting connector, wherein the subscriber having tele-,-

phone A is assumed to have two additional lines, (not shown). The first line corresponding to bank terminal 210 to 213 is assumed tobe. telephone number 22312,-so that the actual numbers of the two following lines of the indicated group are 22313 and22314. However, calling telephone number 22312 will normally cause the first idle line of the group to be selected by automatic selective operation in case the line or the first and second lines of the group are engaged because of a call having been initiated thereon or having been called through a connector of the group containing connector E.

It will be noted in this connectionthat if therelay C is actuated, and the spring 216 is therefore flexed from its resting contact, the tie normally existing between bank terminals 210 and 211 will be opened and thus disable the automatic group selecting operation of the connector E when set upon the bank terminals 210 to 213. That is to say,v

when relay C is operated, for the objectives as will appear presently, the second and third lines, (not shown) of the subscribers group 22312 will be barred under the condition of calling the group number 22312.

At the time relay 26 in the line finder switch FS actuated it completed a circuit path including the telephone A and the windings of the line relay 403 in first selector F, the slowreleasing release relay 404 actuating in a local circuit of 403 to cause ground to be applied back from armature 401 over conductor 402 to sustain the relays 26, 19 and 32 actu-' atccl'. A circuit path can now be traced from ground, oil-normal spring 405, armature 406, start conductor407, lower armature of relay 26, wiper 35, bank terminal 36, conductor 37, make-before-break spring 38 to the winding of relay 39, the latter said relay actuating. The relay 39 will lock through its armature 40 to the grounded conductor 30 for the duration of the call. At the same time that relay 39 actuated the relay 41 actuated, also en ergized from conductor 37.

Responsive to the actuation of relay 41 tone from source T is applied through the spring 217, conductor 218, interrupter I, armatures 43 and 44 to talking conductor 14, audible to the subscriber at telephone A, indicative that the call has been progressed to the first selector F' and that the said first selector is in condition to receive the directive impulses from the calling device of telephone A.

The system location number of the telephone A is 33241, so that the subscriber at telephone A will first operate his calling device dial in accordance with the first digit 3 to cause the first selector to align its wipers 412 to 414 with the bank terminals of the third level and there rotate-in and select the first idle trunk leading to the second selector G, in the well-known manner, in view of the reference to the Hershey book and what is well known in the art. The operation of the second selector G, third selector H and connector R responsive to the sending of the last four digits 3241 causing the line leading modification of the first selector F with relation to the grounding and ungrounding of conductor 407.

At the time the shaft of the first selector F moved off-normal responsive to the first directive impulse sent from the telephone A the ground will be removed from the oilnormal spring 405, causing the conductor 407 to be ungrounded to permit relay 41 to deactuate, the relay 39 remaining locked to the conductor 30. Ground will thereby be applied-through attracted armature 46, retracted armature 47 to the winding of relay 48, the latter said relay actuating and locking through its armature 49 to conductor 30, disconnecting the tone from source -T.

If it is assumed that the party at telephone A responds, and thereby reverses the direction of current traversing the telephone A, the meter M will record-acomplete call from the line belonging to telephone A.

If it is assumed that the party at telephone A restores his receiver to abandon the call either before or after the party at telephone A does likewise, the ground will be caused to be removed from the conductor 30 and the stated relays sustained therefrom will deactuate and cause the apparatus concerned in the stated call to be restored to normal condition for new use, having in mind that the connector R will not restore until the last party to the connection at telephone A or A replaces his receiver, although the switches antecedent to connector R will restore.

Call from telephone A to telephone A under nownal conditions In view of the reference to the third and fourth editions of Hersheys book, it is thought that the extension of a call from the telephone A through the line switch LS,

' first selector J, second selector N, third se- LII derstanding of the operations incident thereto.

If it is assumed that the first line (leading to telephone A) of the group 22312 is idle, and therefore ground potential is not on bank terminals 210 and 211, but on the other hand these terminals constitute battery potential derived through the winding of relay 50, armature 33, conductor 34 to bank terminal 211 and from said conductor 34 through spring 216 to bank terminal 210, the connector E will seize responsive to receiving the said battery potential from bank terminal 211, in the well-known manner. Responsive to the said seizure, ringing current will be applied from the connector E over wiper 222, bank terminal 212, spring 225, armature 203, conductor 205, bell of telephone A, conductor 14, armature 206, spring 226, bank terminal 213, wiper 223 to ground in the connector E.

In this connection, it will be noted that at the time the connector E seized the line leading to telephone A the wiper 221 applied ground potential to the co-operated bank terminal 211, conductor 34, armature 33 to the winding of relay 50, the latter said relay sustaining actuated, having in mind it actuated when current was derived through it to cause the connector E to seize. Armature 31 attracts to disable the relay 32. Ground is applied through armature 51, conductor 52, spring 227, conductor 30 to energize the upper winding of relay 17 to operatively attract all its armatures and to place ground potential on bank terminal 25 and multiples thereof to guard the line leading to telephone A from being seized by a line finder switch of the group containing switch FS.

In this connection, it will also be noted that while a path was traced from bank terminals 212 and 213 to the telephone A and involving conductors 205 and 14, a path may also be traced from conductors 205 and 14 through retracted armatures 202 and 207 springs 201 and 208, conductors 13 and 209, bank terminals 53 and 54 to wipers 55 and 56. The conductors 57 and 58 are free due to the deenergized condition of relay 26. This is having in mind that the wipers 55 and 56 may not be resting upon the bank terminals 53 and 54 they are shown resting upon, in service operation; in fact, the finder switch FS may be in service in a call with respect to some other line of the group containing the line leading to telephone A, but not shown. The branch leading to bank 1 terminals 53 and 54 will be open and therefore have no operative effect on the call to telephone A from the connector E.

Setting line leading to telephone A so that calls directed thereto will be forwarded to telephone A, the number of which is 33241 Let it be assumed that the subscriber of telephone A dmires to have all calls directed to his line group number 22312 forwarded to telephone number 33241, for example. The latter number is tributary to a diiferent central ofiice from that to which the line to telephone A is tributary, though the call may in like manner be forwarded to a random line of any central oiiice of the system, as if the call were being directed from the calling device of telephone A.

Remembering that the dial on the telephone A has provision for sending a series of eleven impulses responsive to operating it in accordance with a specific finger hold, it being like the dial shown in Figs. 7 and 8 of the referred to copending application, the subscriber at telephone A will remove his receiver from the switch-hook as if to initiate a call, causing the telephone A to be extended through the line finder switch F S (or one of its group) to first selector F (or one of its group), and the relays 32, 39 and 41 to actuate for the objects before mentioned.

The subscriber at telephone A will now apply his finger to the finger-hold of the dial specific to the sending of eleven open impulses and set the dial and release it. The shaft of the first selector F will now be operated into alignment with the eleventh level of bank terminals where it will close the eleventh off-normal shaft springs 420 and rotate-in and select the first idle slow-releasing relay 422. Armature 423 will apply ground through bank terminal 424, wiper 412, armature 426 to the release trunk conductor 402 to maintain ground potential on conductor 30.

When the shaft of the first selector F first moved from its normal resting position the spring 405 disengaged and thereby ungrounded the conductor 37 so that the relay 41 deactuated and the relay 48 actuated and locked to the conductor 30 in the manner as has been explained wherein the selector F was operated to select the trunk leading 'to the second selector G in the call from telephone A towards telephone A. However, at the time the shaft reached its eleventh vertical off-normal position and operated the springs 420, and before rotating-in, ground from the release trunk conductor 402 was applied through armature 428, shaft springs 420, conductor 407, conductor 37, to cause relay 41 to be again operatively energized. The relay 41 will remain energized only until the armature 428 attracts from its resting contact when the relay 422 is seized. A circuit path can now be traced from ground, armatures 46, 47, 61, conductor 62, spring 230, conductor 231, armature 63, make-before-break spring to the winding of relay 66, the latter said relay actuating and looking through armature '67 to conductor 30. Ground from armature 68 applied over conductor 69 will operatively energize relay O. The dog 233 will latch the 'armaturepro- 'ection 234 to: retain thesprin sof relay C 1n. their operated positions. 1 round from armature 68;. will also operatively energize the meterM' to-register a set condition of r the relay C- When relays 66 and actuate, continuous tone from source T is applied'through spring 217, conductor 218, armature .70 to the talking conductor 14 audible in the telephone A to apprise'thesubscriber thereat holding the receiver ofi' the'switch l ookthat the set. relay has been actuateda'nd latched in said actuated condition.

The'subscriberat telephone A may now replace his receiver onthe switch-hook, causingthe relay 422 todeactuate' consistent with its slow-releasing characteristic and thereby remove the 'und from conductors 30 and 37 so that the relays 32, 39, 41, 48 and 66 will deactuate. g I

Mahi/n-g call from telephone A to telephone line group 252312, the first line of which extends to telephone A under the condition that set relay 0 is in its set condition The wipers 220 to 223 of connector E will be now again assumed as being set upon the bank terminals 210m 213 respectively. Due

to the relay 0 being latched in its operated state there will be no tie through spring 216, so had the line leading to telephone A been busy when the wipers. 220 to .223 were last assumed set on the bank terminals 210 to 213 the connector E would not operate oft said terminals in group selection to test the succeeding bank terminals corresponding to the second and third lines of the group.

When the connector E seizes, ground potential is applied therefrom through its wiper 221, bank terminal 211," conductor 34, armature 33 to the winding of relay 50, ar-

mature. 31 of the latter-said relay'operating to disable relay 32. The ground applied." through armature 51, conductor 52-to-spring' 227'is not applied to conductor 30 sincethe spring 227 is flexed out of engagement with its resting contact which attaches to conductor 30, so that the upper winding of. relay 17 is not energized responsive to the seizure of the line leading to telephone A by a connector. asE under the condition of the set relay 0 being in its operated state. HOW? ever, the ground applied through armature 51, conductor 52, spring 227 is applied through armatures 237, 238 to the winding of relay 239, the latter said relay actuatlng. The actuation of relay 239 causes by its ounded armature 240 the meter M1! to leg l'ster, that a call has been forwarded in. the

direction of the telephone A.

A circuit path can now be traced from ground, .armature 12, conductor 13, spring 201, armature 241, conductor 242, armatures 301 and 302 in multiple, conductor 303, ar-

mature 243,'spring 208, conduc tor 209, ar

mature 16, lower winding of relay 17, windthe finderswitch FS. Only the armature 19 of relay 17 is now operatively attracted from its resting contact into engagement with its make contact'to' incidentallyunguard terminal 25. That is to say, the finder switch FS will operate as if there was a call initiated at telephone A in place of'the connector E having-seized the bank terminals of the line leading to telephone-A. a Q

When the first selector F is reached re- .sponsive to the seizure by the finder switch FS the talkin conductors 13 and'209 are completed to t e lower and upper winding ing of common relay 18 to battery, the relay 18 actuating to operativelyenergize the relay 20 in a local circuit to startthe operation 01E).

terminals of line relay 403 in first selectorF.

A circuit path can now betraced from ture 307 applies its ground through wiper 308, conductor 309, bank terminal 310, wipers 311 and 312, bank terminal 313, armature 314 to the winding of relay 315, the latter said relay actuating and locking through its armature 317 to grounded armature 318. It will be noted, in this connection, that unless the wipers 308, 311 and 312 are in the drawn position, which is their normally resting position, the circuit for primarily energizing th relay 315 cannot be completed.

For warding the call The ground interrupter I revolves at the rate of approximately twelve times persec- .ond, so that the first ground impulse applied through armature 320 to armatures 321 and;

322 in multiple will cause relay 325 and the motor magnet 326 to energize and operate correspondingly. The operation of relay 325 will not have any operative effect at this time because the armature 302 is retracted. The motor magnet 326 upon deenergizing at the termination of the said ground impulse applied through armature 320 will cause the wipers on the shaft 327 toadvance one step whereat ground will be applied through wiper 328, armature 330 to the relay 332, the latter said relay actuating and remaining so until the wiper 328 has been restored to its drawn position.

Successive ground impulses from the interrupter I will be applied efiective to relay 325, so that for each groundimpulse applied by the interrupter I through armature 320, an open impulse will be applied by armature 301 eflective to line relay 403 in first selector F, remembering that armature 302 is held attracted from its resting contact by the ground received over wiper 328. The ground impulses applied through armatures 320 and 322 will cause the wipers on the shaft 327 to correspondingly step advance.

Sending first digit series at the same time deenergizing the relay 332 to hold the circuit including conductors 242 and 303 closed regardless of the condition of armature 301. Armature 343 now applies ground through the interrupter armature 344 to the winding of the motor magnet 326, the latter said magnet operating by interrupter action to restore the wipers on the shaft 327 to the drawn position, unlocking the relay 342 and causing it to deactuate consistent with its slow-releasing characteristic.

As long as'relay 342 is actuated the sending of open impulses by relay 325 to line relay 403 in first selector F is disabled, in order to make sufficient pause between impulse series of a train to permit selector F to automatically operate selectively along its (third) level its wipers were directively operated into alignment with before the next succeeding impulse series of the train is sent.

- This also applies to subsequent series of the train with respect to the concerned switches. Sending second digit series At the time relay 342 actuated its armature 346 applied ground to the winding of motor magnet 347 to energizeit preparatory to causing it to step the wipers on shaft 348 one step so that wiper 308 will rest upon bank terminal 350 responsive to the deactuation of relay 342, at which time the terminal 341 will again constitute ground potential; this time received over jumper 336.

When the next ground impulse is applied from interrupter I the relay 325 will be operated and the motor magnet 326 will be energized in preparation for advancing the wipers on shaft 328 one step when the ground impulse terminates, and in view of the same bank terminal 341 being grounded as when the first digit series was sent by armature 301, a like series of three open impulses will be sent by armature 301 effective to second selector G to effect the selection of third selector H.

At the termination of the second series of three open impulses sent by armature 301 the relay 342 will actuate and lock and the wipers on shaft 327 will be restored to their drawn positions and the wiper 308 will be advanced a step to bank terminal 351 so that bank terminal 352 will constitute ground potential when said relay 342 deactuates consistent with its slow-releasing characteristic following the restoration of the wipers on the shaft 327.

Sending third digit series The mechanism in F ig. 3 will perform in the same manner to send the third series of two open impulses from armature 301 eifective to the third selector H as when sending the first two series of three open impulses each from said armature 301. In the latter instance the number of impulses (2) is determined by the ground potential on bank terminal 352.

At the termination of the third series of two open impulses sent by armature 301 the relay 342 will actuate and lock and the wipers on shaft 327 will be restored to their drawn positions and the wiper 308 will be advanced a step to bank terminal 354 so that the bank terminal 355 will constitute ground potential when said relay 342 deactuates consistent with its slow-releasing characteristic following the restoration of the wipers on the shaft 327.

Sending fourth and fifth digit series It is thought, in View of the foregoing, that the sending of the fourth and fifth digits 4 and 1, respectively, will be clear without detailing the operation of the apparatus in Fig. 3. However, it is pointed out that at the time the fifth digit constituted of one impulse is terminated and the wiper 356 steps from bank terminal 357 to bank terminal 358 a circuit path can be traced from ground applied from armature 318, armature 317, bank-terminal 358, wiper 356, conductor 360 make-before-break spring 246 to the winding of relay 247, the latter said relay actuating. The winding of relay 239 will be disconnected at armature 238, while the relay 247 will be locked actuated through the said armature 238 to ground applied through armature 51, conductor 52, spring 227 and arma ture 237. Relay 239 will retract its armature.

The retraction of armature 244 will cause relay 305 to deactuate, deenergizing relay 315 so that armature 361 will apply ground through wiper 362, interrupter armature 363 to the winding of the motor magnet 347, causing the wipers on the shaft 348 to be reoperated, and slightly slow-releasing relay 252 will be sustained actuated, now energized The retraction of armature 365 will cause" in a local circuit of relay 251 by its attracted ground to be applied through the wiper 366 interrupter armature 344 to the winding of the motor magnet 326, causing the wipers on the shaft 327 to be restored to the drawn position.

Uallz'ng subscriber abandons call It will be noted, in this connection, that should the calling party at telephone A have restored his receiver and thus abandoned the call, causing the connector E to'restore while the wipers on either or both shafts 327 and 348 were off the drawn position, this latter would not in itself prevent the connector E or another connector of its group from forthwith seizing the line leading to telephone A since there would be no guarding potential on the private bank terminal 211 and its multiples. In order to prevent confusion, the sending of impulses from the armature 301 will be disabled until the relay 315 is first caused to actuate, and this latter cannot occur until the circuit path is completed from armature 307, Wiper 308, conductor 309,'b'ank terminal 310, wipers 311 and 312, bank'terminal 313, armature 314 to the winding of relay 315. That is to say, the armatures361 and 365 will remain retracted to restore the wipers on the shafts 327 and 248 after they once retract and the relay 315 cannot reactuate to start an impulse train until the circuits shown in Fig. 3 become in the drawn position. This is having in mind that the relay 305 may be reactuated from a new call ,without vitiating the new call, although the shafts 327 and 348 may be off-normal when the relay 305 is caused to actuate.

Gall fmwahded'to telephone A The foregoing described sending ofthe train of impulse series constituting digits 33241 from the impulse sending device in Fig. 3 effect the linking of a connection to the line leading to telephone A in the same manner as if this train came from the calling device of telephone A, which latter operation has been referred to.

The line leading to telephone A 1s now seized by connector R, and ringmg current from the latter said connector isoperating' the bell of telephone A. The conductors 13 and 209 are 'continued through springs 201 and 208, armatures 202 and 207, respectively,

to the winding terminals of the polarized I :5 dition the slow-releasing relay 251 will be locked thereto will deactuate.

inside armature before relay 252 has had time to retract its armature 253 in view of the deactuation of relay 239.

Subscriber at telephone A responds It will now be assumed that the subscriber at telephone A responds to the call, wherein the operation of the back-bridge relay in connector R reverses the direction of current traversing the polarized relay 250. This will cause'the armature of the latter said relay to be tilted clockwise into the designated Ans. pos.. Relay 255 will operate under the condition, and relay'251 will deactuate consistent with its slow-releasing characteristic.

During the time relay 251 sustains after relay 255 is actuated, ground is applied through armatures 256 and 257, make-beforebreak spring 258 to the winding of relay 259, the armature 260 causing the meter M to register an answered forwarded call, the relay 259 being locked to conductor 34 to prevent more than one registration by the meter M Also, tone from source T will be applied through armatures 262 and 263, audible to the calling and called parties over the obvious path involving conductor 209 and bank terminal 212. This apprises both parties that the call'is one that has been forwarded from the. primarily called line. The latter comprehends that the ring-cut-off relay and the back-bridge relay in the connector E oper-' ate responsive to the actuation of relay 255 wherein armature 265 connects the retardation coil 266 across the conductors leading from bank terminals 212 and 213. The calling subscriber at telephone A and the called an scriber at telephone A are in talking relation wherein the condensers 268 and 269 are vinterposed serially; one'in each side of the talking path denoted by the heavy lines.

If it is assumed that after the termination of the converation between telephones A and A the subscriber at telephone A hangs up his receiver before the subscriber at telephone A does so, the connector E will restore its wipers from the bank terminals corresponding to the line leading to telephone A. This will remove the ground from conductor 34, whereupon all relays dependent upon being The latter includes relay 247, which will cause the windings of the polarized relay 250 to be removed from the bridge between the conductors 13 and 209 so that the front-bridge relay of connector R will deactuate removing the ground from conductor 30 so that the relays dependent upon ground received from the latter said conductor will deactuate. All apparatus antecedent to connector R is now restored to normal, and subject to new use. When the party at telephone A replaces his receiver the connector R will restore in the Well-known manner, subject to new use.

Subscriber at telephone A abandons call first If it is assumed that after the termination of the conversation between telephones A and A the called subscriber at telephone A replaces his receiver before the calling subscriber at telephone A does so, the deactuation of the back-bridge relay in connector R will cause the current traversing the windings of the polarized relay 250 to be reversed. This will cause relay 255 to deactuate to remove the winding of the retardation coil 266 from the series path of the back-bridge relay of connector E to reverse the direction of current traversing the telephone A. Relay 251 will reactuate, but to no operative efiect in the circuits. In this connection, it will be remembered that relay 252 deactuated when the response at telephone A occurred causing relay 251 to unlock relay 252.

If the party at telephone A now replaces his receiver, the connector E will restore its wipers from the bank terminals 210 to 213 in the Well-known manner, whereupon ground will be removed from conductor 34, causing relay 247 to deactuate to remove the windings of the polarized relay 250 from the path including the front-bridge relay of the connector R. Ground will now be removed from conductor 30 and the relays dependent upon the latter said conductor will deactuate. The connector R will restore responsive to the deenergization of its front-bridge relay. The circuits and apparatus involved in the call are now at normal and subject to new use.

Bell of telephone A rings de'stz'netz'rely while call is being forwarded to telephone A 'lVhile the relay 239 is actuated and relay 252 is operatively energized from grounded armature 240 on relay 239, and the forwarding of the call to the line leading to telephone A is progressing, intermittent ringing current is being applied from ringing generator G through armature 270 on interrupter relay IR, armatures 271, 272 and 273, conductor 205, bell of telephone A, conductor 14, armature 274, make-before-break spring on ring-cut-ofi' relay 275 to the winding thereof, the latter said relay being inoperative from the said ringing current due to having a shielded core and having special adjustment. However, the bell at telephone A will ring in a peculiar manner responsive to the ringing generator G.

When the forwarded extension of the call has been completed to the line leading to telephone A the relay 247 will be actuated and locked by ground over conductor 52 applied through spring'227, armature 237 and armature 238 on relay 247. The relay 239 will then be deenergized. Under this condition relay 252 is locked energized from the attracted inside armature of relay 251. However, since armature 271 is now retracted, the ringing current applied to operate the bell at telephone A is now derived from ringing generator G, which causes the bell of telephone A to ring differently from when it was rung from ringing enerator G, due to the different character 0 the current and the periodicity thereof.

The subscriber at telephone A will thus be apprised by the sound emitted by the bell thereof, if e hears it, what stage of the call ensues. If he wishes to respond to the call he will remove his receiver from the switchhook in the normal manner and close an energizing circuit from rounded negative battery, or from ground applied through the source G or G as the case may be, armatures 271, 272, 273, conductors 205 and 14, armature 274, make-before-break spring and winding of relay 275 to grounded positive battery. Relay 275 will actuate and lock through armature 276 to conductor 34, opening the traced path from armature 274 to the winding of relay 275.

If the relay 239 is actuated, the connection not having progressed to the line leading to the telephone A when relay 27 5 actuates, the attraction of armature 237 will deenergize relay 239, which will in turn deenergize the relay 252. The attracted armature 272 disconnects the ringing current from the line leading to telephone A before relay 252 has had time to deactuate so the called party will not be annoyed by it. If the relay 247 is actuated when relay 27 5 actuates, (the connection having progressed to the line leading to telephone A), and relay 247 is therefore locked through its'armature 238, armature 237, spring 227, conductor 52, armature 51 to ground, the armature 237 will deactuate. The deactuation of relay 247 will in turn deenergize the polarized relay 250 and also the latters dependent relay 251 in order to deenergize relay 252.

[nterceptz'ng forwarded call from telephone on line primarily called lVhen the relay 275 actuates and locks by its armature 276 responsive to the subscriber at telephone A responding, and thereby intercepting the forwarded call, there will be no conductive path between the conductors 13 and 209, so that the forwarded extension will be destroyed and ground will be thereby removed from the conductor 30 so that relay 17 will be deenergized and the finder switch FS is then subject to use in a new call.

The telephone A and the telephone A will be in talking relation over the path involving bank terminals 212 and 213, springs 225 and 226 and their respective make contacts, attracted armatures 277 and 278 and conductors 14 and 205, respectively. The path 1nvolving conductors 13 and 209 is disconnected from the said talking path between telephones A and A because of the attracted condition of armatures 203 and 206, since the relay 255 is energized by the attracted armature 280 on relay 275. The receiver of the telephone A is in series with the back-bud e relay in connector E, so that connection will be destroyed by the calling party replacing his receiver, having in mind that the connector E willremain in seizure until the last party to the connection replaces his receiver. When the Wipers of the connector E restore from the bank terminals 210 and 213, ground will be thereby removed from conductor 34. Relays 275 and 255 will deactuate under this condition, so that the circuits and apparatus involved in the call is then at normal and in condition for new use.

'It will be noted that if the relay 275 is caused to actuate while the relay 239 is actuated, meaning that the impulse train for forwarding thecall has not been completed,

the relay 305 will deenergize, followed by dependent relay 315, causing the wipers on the shafts 327 and 348 to restore to the drawn position.

meter M will not be operated unless the call has been forwarded to the line leading to telephone A as relay 255 will not be operated otherwise, so if the forwarded extension is in tercepted by the response at telephone A before the line leading to telephone A is seized, the meter M will not operate.

Preferred embodiment Fig. 5 shows the preferred embodiment for applying the ringing current introduced where indicated by the dotted line a in Fig. 2. The interrupters I and I operate at different rates so that the ringing current from source G will be applied by interrupter relayIR' at difierent rate of live applications from that of source G. While the ringing generators G and G preferably supply current at different periodicity, this is not essential as the different rate of live applications would enable the subscriber at telephone A to discern which said generator was operating the bell and therefore indicate at what stage the forwarded call was.

Unsetting the relay 0' under directive control of the subscriber at telephone A The subscriber at telephone A may at'any time unlatch the dog 233 from projection 234 which retains the set relay C actuated so that thereafter calls directed to the line lead- 1,soo,7es

ing to telephone A, will not be forwarded,

the bell of telephone A being rung directly cordingly, relays 32 and 41 will actuate,

wherein the relay 39 will be locked to conductor 30.

Tone indicative of set condition The subscriber at telephone A will now perceive the intermittent tone from source T applied through interrupter I indicative that the set relay C is set and that the first selector F is in condition to receive directive impulses to unset the relay C or to make a call to any line of the system. However, the subscriber at telephone A desires to unset the set relay C. To accomplish the latter he will operate his calling device dial in the same manner as when causing the relay C to be operated and latched. That is, send a series of eleven impulses to cause the shaft of the selector F to align its wipers with the eleventh level of bank terminals and rotatein and seize the first idle relay 422 in the manner before described.

Tone indicative of unset condition When the shaft of the selector F moves off-normal ground is disconnected from conductor 37 by the operation of the off-normal spring 405 so that relay 41 will deenergize, while the relay 39 remains locked to conductor 30. Relay 48 actuates and locks as described. When the shaft of selector F reaches the eleventh vertical position and the springs 420 operate to again apply ground to conductor 37, causing the relay 41 to reactuate to apply ground through armatures 46, 47, 61, conductor 62, spring 230, conductor 283, armature 64 to the Winding of relay 75, the latter said relay actuating and look ing through its armature 76 to conductor 30. A circuit can now be traced from ground, armature 77, conductor 78 to the winding of magnet 285, the latter said magnet operating to unlatch the dog 233 from projection 234 and thus permit the springs on relay C to restore to the drawn position. Intermittent tone from source T will be applied through the interrupter I, armature 80 to conductor 14 audible to the subscriber at telephone A to apprise him that the relay 0 has restored to normal position. He may now replace his receiver, causing the first selector F to restore in the obvious mannerand to remove the ground potential from conductors 30 and 37 to deenergize the relays dependent thereon, whereupon the circuits and apparatus are at normal in condition for new use.

introduction of speech amplifier in the talking path intermediate of the terminal telephones where call has been forwarded It will be evident that if the line to which the call is to be forwarded, as telephone A,

for example, is located a considerable distance tributary to another central oifice of the system, with respect to the line leading to telephone A, and a call originates in the same. exchange district with telephone A, the connection in that case will double back and under the condition speech may be unduly attenuated on such calls. To overcome this any suitable amplifying speechrepeater may be introduced in the two talking conductors between the condensers 268 and 269 and the point on said conductors where the winding of retardation coil 226 attaches to these conductors. Under this condition, speech from the respective telephones A and A, when connected, will each receive amplified currents constituting speech and this will overcome the excessive distance. Of course, the latter expedient would not be required unless the distances which may be involved is considerable, that is, beyond the standard speaking range established for the system. 'The location of said repeater 1s 1ndicated by the dotted rectangle designated Z.

While any suitable, well-known or other speech repeater may be employed, under the last mentioned condition, reference is made to the patent to Shubert No. 1,029,724, granted June 18, 1912, as disclosing a suitable one for this purpose. The two heavy conductors leading upward at the top of the drawing, Fig. 1, would be attached to the lower term1- nals of the condensers 268 and 269 of the present disclosure, while the two heavy conductors leading downward at the bottom of said drawing would be attached where the winding terminals of the retardation coil 266 attach to the talking conductors of the present disclosure. would be opened to the lower terminals of the said condensers so that the talking path will be through the said speech, repeater. The sources of battery in said Fig. 1 would be applied through normally open contacts to be provided on the relay 247 of the present disclosure in order to have no battery current flowing when the repeater is not being employed in a connection.

I claim 1. In a telephone system, a calling line, a first called line, a second called line, a first switch mechanism for extending a connection from the calling line to the terminals of the first called line, a second switch mechanism for extending connection from the terminals of the first called line to the second called line, a signal device on the first called line, means for causing the first switch mechanism to extend a connection from the terminals of the first called line to the second The talking conductors called line to complete a connection from the calling line to the second called line res nsive to efi'ecting connection to the terminals of the first called line, means for causing the signal device to operate in a predetermined manner responsive to effecting connection to 1 the terminals of the first called line, and automatic means rendered effective responsive to completing the operation of the second switch mechanism in elf the second called line for causing the signal device to change the specific operation to another operation so that the operation of the signal device at a random time will indicate the progressed state of the callextension.

2. In a telephone system, a calling line, a first called line, a second called line, a first switch mechanism for extending a connection from the calling line to the terminals of the first called line, a second switch'mechanism for extending connection from the terminals of the first called line to the second called line, means for causing the first switch mechanism to extend a connection from the terminals of the first called line to the second called line to complete a connection from the calling line to the second called line responsive to effecting connection to the terminals of the first called line, a speech amplifier, and means controlled over the second called line for rendering said amplifier energized and efi'ective intermediate of the first called line and the second called line.

3. In a telephone system, a calling line, a first called line, a second called line, a first switch mechanism for extending a connection from the calling line to the terminals of the first called line, a second switch mechanism for extending connection from the terminals of the first called line to the second called line, a signal device on the first called line, means for causing the first switch mechanism to extend a connection from the terminals of the first called line to the second called line to complete a connection from the calling line to the second called line responsive to effecting connection to the terminals of the first called line, a plurality of sources of signaling current, means for causing the signal device to operate in a predetermined manner by a first one of the sources of signaling current responsive to effecting connection to the terminals of the first called line, and automatic means rendered effective responsive to operation of the second switch mechanism for causing the signal device to operate in a specific manner by another one of said sources of signaling current so that the operation of the signal device will indicate if the connection made to the terminals of the first called line has or has not been extended to the second called line.

4. In a telephone system, a calling line, a first called line, a second called line, a first switch mechanism for extending a connececting connection to tion from the calling line to the terminals of the first called line, a second switch mechanismfor extending connection from the terminals of the first called line to the second called line, a signal device on the first called line, means for causing the first switch mechanism to extend a connection from the rendered effective responsive to operation of the second switch mechanism for causing the signal device to operate in a specific manner by another one of said sources of signaling current so that the operation of the signal device will indicate if the connection made to the terminals of the first called line has or has not been extended to the second I called line, and means controlledover the first called line after the call extension has been progressed by the second switch mechanism from the terminals of the first called line towards the second called line for preventing the extension being further extended towards the second called line without disabling the second mechanism from thereafter extending the calling line to the second called line responsive to again extending the calling line to the terminals of the first called line in a new call.

5. In'a telephone system, a calling line, a first called line, a second called line. a first switch mechanism for extending a connection from the calling line to the terminals of the first called line, a second switch mechanism for extending connection from the terminals of the first called line to the second called line, a signal device on the first called line, means for causing the first switch mechanism to extend a connection from the terminals of the first called line to the second called line to complete a connection from the calling line to the second called line responsive to effecting connection to the terminals of the first called line, a plurality of sources of signaling curbeen extended beyond the first called line.

6. In a telephone system, a calling line, a first called subscribers line, a second called line, a first switch mechanism for extending a connection from the calling line to the terminals of the first called line, a second switch mechanism for extending a connection from the terminals of the first called line to the second called line, a set relay, means controlled over the first called line for setting the set relay by operating and maintaining the operation of said set relay, means responsive to extending the calling line to the terminals of the first called line only if said set relay is in operated condition for causing said second switch mechanism to further extend the calling line to the second called line, and means controlled over the first called line while the call is being extended by the second switch mechanism for efl'acing the operated state of the second switch mechanism and for causing a talking relation to exist between the calling line and the first called line without restoring the operated state of the set relay.

7. In a telephone system, a calling line, a first called line, a second called line, a first switch mechanism for extending a connection from the calling line to the terminals of the first called line, a second switch mechanism for extending a connection from the terminals of the first called line to the second called line, a set relay, means controlled over the first called line for setting the set relay by operating and maintaining the operation of said set relay, means responsive to extending the calling line to the terminals of the first called line only if said set relayis in operated condition for causing said second switch mechanism to furthm e\tend the calling line to the second called line, and means including a ring out ofi relay located on the first called line controlled over the first called line while the call is being extended by the second switch mechanism for efiacing the operated state of the second s itch mechanism for causing a talking relation to exist between the calling line and the first called line without restoring the operated state of the set relay.

'8. In a telephone system, a calling line, a first called line, a second called line, a first switch mechanism for extending a connection from the calling line to the terminals of the first called line, a second switch mechanism for extending a connection from the terminals of the first called line to the second called line, a set relay, means controlled over the first called line for setting the set relay by operating and maintaining the operation of the said set relay, means responsive to extending the calling line to the terminals of the first called line only if said set relay is in operated condition for causing said second switch mechanism to further extend the call- 45 i nals of the first called line to the second called ing line to the second called line, means controlled over the first called line while the call is bein extended by the second switch mechanism or etlacing the operated state of the second switch mechanism for causin a talking relation to exist between the cal ing line and the first called line without restoring the operated state of the set relay, and means controlled over the second called line only after the calling line has been extended thereto :for preventing the first called line from pecoming in talking relation with the calling 9. Ina telephone system, a calling line, a first called line, a second called line, a first switch mechanism for extending a connection from the calling line to the terminals of the first called line, a second switch mechanism for extending a connection from the termin'als of the first called line to the second called line, a set relay, means controlled over the first called line for setting the set relay by operating and maintaining the operation of the said set relay, means responsive to extending the calling line to the terminals of the first called line only if said set relay is in operated condition for causing said second switch mechanism to further extend the calling line to the second called line, means con trolled over the first called line while the call is bein extended by the second switch mechanism fir etfacing the operated state of the second switch mechanism for causing a talking relation to exist between the calling line and the first called line without restoring the operated state of the set relay, and means controlled over the first called line for directively restoring the set relay to normal unset condition.

10. In a telephone system, a calling line, a first called line, a second called line, a first switch mechanism for extending a connection from the calling line to the terminals of the first called line, a second switch mechanism for extending a connection from the termiline, a set relay, means controlled over the first called line by manual operation for setting the set relay by operating and maintaining the operation of the said set relay, means responsive to extending the calling line to the terminals of the first called line only if said set relay is in operated condition for causing said second switch mechanism to further extend the calling line to the second called line, means controlled over the first called line while the call is being extended by the second switch mechanism for etfacing the operated state of the second switch mechanism for causing a talking relation to exist between the calling line and the first called line without restoring the operated state of the set relay, and means controlled over the first called line for directively restoring the set relay to normal unset condition by a manual operation on the first called line like the operation used in setting the set relay.

11. In ,a telephone system, a calling line, a first called line, a second called line, a first switch mechanism for extending a connection from the calling line to the terminals of the first called line, a second switch mechanism for extending a connection from the terminals of the first called line to the second called line, a set relay, means controlled over the first called line for setting the set relay by operating and maintaining the operation of said set relay, means responsive to extending the calling line to the terminals of the first called line only if said set relay is in operated condition for causing said second switch mechanism to further extend the calling line to the second calledline, and a tone source to indicate to the subscriber on the first called line when initiating a call thereon by removing his receiver if the set relay is set.

12. In a telephone system, a calling line, a first called line, a second called line, a first switch mechanism for extending a connection from the calling line to the terminals of the first called line, a second switch mechanism for extending a connection from the terminals of the first called line to the second called line, a set relay, means controlled over the first called line for setting the set relay by operating and maintaining the operation of said set relay, means responsive to extending the calling line to the terminals of the first called line only if said set relay is in operated condition for causing said second switch mechanism to further extend the calling line to the second called line, and specific tone sources for indicating to the subscriber on the first called line whether or not the set relay is set.

13. In a telephone system, a called line, switch mechanism for extending connection to the near end of the called line, an unenergized speech amplifying repeater for amplifying telephonic currents to and from the called line and said switch mechanism, the said repeater being located intermediate of said switch mechanism and the far end of the called line when said connection exists, and means for energizing said repeater to en able it to operate responsive to eifecting connection by said switch mechanism to the called line.

14. In an automatic telephone system, a first called line, switch mechanism for extending connection to said first called line, a second called line, automatic switch mechanism for extending connection from the first called line to the second called line responsive to extending connection to the first called line, means for applying signaling current to said first called line responsive to effecting connection thereto, a ring 'cut ofit' relay energized over only'first called line for stopping the application of signaling current to said first called line, means whereby a response on said first called line will operate the ring cut off relay to thereby stop the application of mgnaling current to the first called line, and other means operated by a response on the second called line for also stopping the application of signaling current to the first called line, but without operating the r1ng cut off relay.

15. In an automatic telephone system, a called line, a signal device on the called line, switch mechanism for extending connection to the called line, switch mechanism for extending connection over a plurality of link circuits from said first called line responsive to effecting connection to said first called line, and automatic means for operating said signal device at different rate of active intervals depending upon the degree of progression of the said extension.

16. In an automatic telephone system, a called line, a signal device on the called line, switch mechanism for extending connection to the called line, switch mechanism for extending connection over a plurality of link circuits from said called line responsive to effecting connection to said called line, and automatic means for differently operating said signal device in accordance with the degree of progression of the said extension.

17. In an automatic telephone system, a plurality of circuit links, switch mechanism for linking said links in tandem, a signal device on the first one of said links to be connected to, and means for causing said signal device to vary its indication in accordance with the progression of the linking so that the signal device will indicate how far the connection has been linked from time to time.

18. In a telephone system, a connector for connecting to a called line, a source of signaling current applied back from the connector by the connector for indicating that a called line is connected to and that the called line is in a predetermined condition, and another source of signaling current applied over the called line back through the connector to indicate another predetermined condition of the called line so that both said indicating conditions are manifested in the same call while a non-talking condition exists over the the called line so that both said indicatin conditions are manifested in the same ca while a non-talking condition exists over the connection, means controlled over the called line by a response thereon for stopping the said application'of both said sources, and means operated over the called line before the connection thereto is effected for establishing or effacing said another predetermined condition while the line remains idle after said operation and also in condition for being connected to by said connector.

20. In an automatic telephone system, a called line, another line, switch mechanism for extending connection to said called line, switch mechanism for further extending the connection established to said called line to said another line in stages, responsive to effecting said connection to said called line, and means for breaking down the extended connection towards said another line by a re sponse oversaid called line, only in the event that last said extended connection has not yet been extended up to said another called line and a response is gained on said another called line. i

21. In an automatic telephone system, a called line, another line, switch mechanism for extending connection to said called line, switch mechanism for further extending the connection established to said called line to said another line ,in stages, responsive to effecting said connection to said called line, and means for breaking down the extended connection towards said another line by a response over said called line, the effective operation of last said means being dependent upon the stage of the call extension from said called line.

22. In an automatic telephone system, a 1 presetting device, automatic switch mechanism, means for causing the switch mechanism to extend a call by successive advance stages under the direction of and with correspondence to the pre-set condition existing 110 in the pre-setting device before the extension is started, and a signal means on the extension that will constantl manifest by its variable operation the a vance stage of the call extension.

23. In an automatic telephone system, a presetting device, automatic switch mechanism, means for causing the switch mechanism to extend a call by successive advance stages under the direction of and with correspondence to the pre-set condition existing in the pre-setting device before the extensionis started, and a signal means on the extension that will constantly apply back over the extension current that will vary in character 125 in accordance with the advance stage of the call extension.

24. In' an automatic telephone system, a presetting device, automatic switch mechanism, means for causing the switch mechaand source of si nismto extend a call by successive advance stages under the direction of and with correspondence to the pre-set condition existing in the pre-setting device before the extension is started, and a signal means on the extension that will constantly apply back over the extension alternating current of varying periodicity, the eriodicity varying with the advance stage 0% the call extension.

25. In an automatic telephone system, a presettingdevice, automatic switch mechanism, means for causing the switch mechanism to extend a call by successive advance stages under the direction of and with correspondence to the pre-setcondition existing in the pre-setting device before the extension is started, and a signal means on the extension that will apply back over the extension interrupted current that will vary in rate of interruptions in accordance with the advance stage of the call extension.

26. In a telephone system, a terminatinglinkin'g switch, a called line directly accessible from the switch, a ring cut off relay and aling current applied through contacts 0 the relay for application to and disconnection from the called line at a oint'in the connection successive to the switch, means for causing current from said source to be applied back to the switch to indicate that'said source is being applied over the called line, and means for operating the relay by control over the called line to disconnect the si called line an back to the switch.

27. In a telephone system, a plurality of circuit sections connected in tandem, a ring' out 01f relay for each of said sections, a source of'signaling current for each said ring out oil relay, means for causing each of said sections to be traversed by signaling current specific to the said source for the corresponding ring out off relay, and means whereby control'over one of the sections will cause all 'exist over the sections in tandem while the relays are in said operated condition.

28. In a telephone system, a lurality of circuit sections connected in tan em, a ring out off relay for each of said sections, a source of signaling current for each said ring out ofi relay, means for causing each of said sections to be traversed by signaling current specific to the said source for the corresponding ring out 01f relay, and means whereby control over one of the sections will cause a. the ring cut oil relays to operatively energize and actuate to thereby disconnect the various signaling current sources from the corresponding sections.

29. In a telephone system, a plurality of circuit sections, sources of alternating current of different frequencies, respectively aling current applied to the.

to the said sections, a relay for each section for disconnecting the respective source from the corresponding section, and means for' causing all said relays to operatively energize to disconnect their corresponding sources from the corresponding section responsive to control applied over the sections in tandem, wherein the relays are operatively energized successively.

31. In a telephone system, a Y connection of three line sections, means for simultaneously applyin respective signaling current sources over the respective ends of two of said three sections from a point located on the corresponding sections, and means operated by a party respondin on one or the other of said two sections or stopping the application of said signaling current over both of said two sections.

32. In a telephone system, a Y non-talking connection of three line sections, means for simultaneously applying respective signaling current sources over the respective ends of two of said three sections from a point located on the corresponding sections, and means operated by a party responding on one or the other of said two sections for connecting the section upon which the res onse occurred in talking relation with the third one of said sections and for also thereupon disablin the other one of said two sections from eing placed in talking relation with the third one of said sections.

33. In a telephone system, a Y connection of three line sections, a ring out ofi relay on each said sections, a source of signalin current applied through a contact of t e respective said relays, and means controlled over either of two of said sections vfor operating the cut ofl relay of the corresponding sectlon, and the third section in common, responsive to said control to disconnect the corres onding applied signaling current. 34. n a telephone system, a called line, means for extendin connection to a point on said line, a plura ity of sources of signaling current for application to said line Without traversing the point of said connection in reaching the line, and means operated responsive to'efiecting said connection for successively applying the sources to the line. In witness whereof, I hereunto subscribe my name this 17th day of December, 1927. HERBERT M. FRIENDLY.

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