US1887744A

US1887744A - Automatic telephone system

Info

Publication number: US1887744A
Application number: US346323A
Authority: US
Inventors: Wicks John
Original assignee: Associated Electric Laboratories Inc
Current assignee: Associated Electric Laboratories Inc
Priority date: 1919-12-20
Filing date: 1919-12-20
Publication date: 1932-11-15
Anticipated expiration: 1949-11-15

Description

Nov. 15, 1932. w c s 1,887,744

AUTOMATIC TELEPHONE SYSTEM Original Filed Dec. 20. 19 3 Sheets-Sheet 1 w. l\ t '0 Q t w .fnuenTzT- Jul-m Znfmks mkN kwN DWN M4 H U";

Nov. 15, 1932. J. wlcKs AUTOMATIC TELEPHONE SYSTEM led Dec. 20. 1919 I5 Sheets-Sheet 2 Nov. 15, 1932. J. WlCKS AUTOMATIC TELEPHONE SYSTEM Original Filed Dec. 20, 1919 3 Sheets-Sheet 3 ]nuEn u1" EN QM K RX R kw Jul-m lnfmks HIT:

Patented Nov. 15, 1932 UNITED STATES PATENT OFFICE JOHN 'WICKS, OI CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO ASSOCI- ATED ELECTRIC LABORATORIES, INC., OF CHICAGO, ILLINOIS, A CORPORATION OI DELAWARE AUTOMATIC TELEPHONE SYSTEM Application filed December 20, 1919, Serial No. 346,323. Renewed June 2, 1987.

My invention relates in general to automatic telephone systems but is concerned more partlcularly with the method of handling long distance calls in such systems, and

the object of the invention is the provision of new and improved means for connecting local subscribers in automatic exchanges with long distance lines, either as calling or as called subscribers. In the development of the system herein disclosed certain new features have been invented, all of which will be explained fully hereinafter. reference being had to the accompanying drawings, in which Figs. 1, 2 and 3 are circuit diagrams, while Fig. 4 is a diagrammatic layout of the system embodying the invention.

It is believed that the invention can be best understood by first explaining the general aspects of the system with which it is contemplated to use the invention, and for this purpose reference will be made to Fig. 4. This diagrammatic layout shows in simple form the trunking between local subscribers in the automatic exchange and also the trunking between such subscribers and the long distance operators, together with the trunking between these operators and the subscribers. Considering first the means by which local subscribers are interconnected, let us assume that the subscriber at substation A desires to obtain connection with the subscriber at substation A. The connection may be established by means of the individual line switch C, a first selector switch such as the selector E, a second selector such as the second selector F. and a combination toll and regular connector such as the connector H. With the exception of the fact that a combination toll and regular connector is used instead of an ordiuarv connector switch, this is the usual and well known percentage trunking system. It is customary in order to enable the subscribers to obtain connection with the toll operators to assign a certain level of the first selector banks. generally the tenth level, as term'znals of so-called toll recording trunks. Such being the case, if the subscriber at substation A wishes to call a long distance oporator in order to place a long distance call the connection may be established by means of his individual line switch C, a first selector E, and a toll recordin trunk which terminates in the jack J. onnections in the reverse direction, that is, from the toll operators to the local subscribers, are established through the medium of a system of toll serv-. ice trunks. A certain number of outgoing trunk lines are provided at the toll board which extend to and terminate in toll first selectors. These toll first selectors have access to toll second selectors, which in turn have access to the combination toll and re ular connectors in common with the second selectors of the regular trunking system. In brief, the toll selectors constitute a separate and distinct trunking system similar to the regular trunking system except, of course, that there need not be nearly so many switches of each class; and this special trunking system is merged in the regular trunking system at the connectors, the second selectors of both systems having access to the same connector switches which are accordingly termed toll and regular connectors. The above layout is believed to be clearly shown in the diagram, from which it will be seen that a toll connection, as for example from the toll line terminating in jack J may be extended to a local subscribers line, as for example the line of substation A, by means of an operators cord circuit 0, jack J, toll first selector E,

toll second selector F, and the combination toll and regular connector H.

There is a certain class of long distance calls which are generally known as twonumber calls, which may be handled in a particularly advantageous manner in the system herein disclosed. In this class of calls the local subscriber calls a long distance operator over a toll recordin trunk, and after giving the name and location of the desired party is immediately connected without having to hang up his receiver and wait for the toll operator to call him back. In automatic systems in handlin toll connections of the above character, if t e connections were completed directly it would be possible for the subscribers to defraud the telephone company and secure connections free of charge by giving the toll operator a wrong number,

' the bank thus inducing her to charge the call to a different subscriber. In order to eliminate this possibility it has heretofore been the practice to request the calling subscriber to replace hlS receiver for a moment with the Ob ect of enabling the toll operator to call him back by means of the toll service trunks. Thls procedure gives the toll operator an absolute check on all long distance calls and makes it certain that they are charged to the proper parties. However, it is ob]ect1onable to require the calling subscriber to replace his receiver and wait until he is called back by the operator and since the connection 15 to be established immediately there is no other object in requiring the subscriber to hange up other than to permit the connector switch which is to be used by the toll operator to establish connection with his line. One of the principal ob'ects of the invention is to provide means w ereby the toll operator may call a subscriber who is waiting on a recording toll trunk by means of her servlce trunks without requiring the calling subscriber to replace his receiver, thereby permitting the connection to be established directly and with a minimum of annoyance to the subscriber.

In order to explain the invention it will first be assumed, referring to Figs. 1, 2 and 3, that the subscriber at substation A desires to call a long distance operator for the purpose of obtaining a toll connection; and the entire process of completing the connection will be explained. Thereafter such features of the invention as have not been brought out will be explained separately. In view of the well known character of the apparatus, only sufficient of the circuits have been shown to enable the various features of the invention to be understood; and reference is made to the following patents as showing the state of the art: U. S. Patent to Keith, Erickson & Erickson, No. 815,321, U. S. Patent to Keith, Erickson & Erickson, No. 815,176, U. S. Patent to John Wicks, No. 1,315,444 and my co-pending application Serial N 0. 155,640.

When the calling subscriber at substation A removes his receiver to initiate a call a cir cuit is completed over the line conductors 11 and 12 for the line relay 15 of the line switch C, Fig. 3. Upon attracting its armature, the line relay 15 closes a circuit for the pull-in winding 16. Upon energizing, the pull-in winding operates both the plunger arm 19 and the armature 18; the former through the medium of its plunger (not shown) forcing springs 30-33, inclusive, into en gagement, respectively, with the contacts 34 37, inclusive; and the latter connecting the private normal conductor 13. By the engagement of

bank springs

30 and 33 with contacts 34 and 37, respectively, the line conductors 11 and 12 are extended by way of armatures 58 and 61 of the switching relay of the first selector the double wound line relay 51.

The line relay 51 is accordingly energized over the loop circuit including substation A, and upon attracting its armature closes a circuit for the slow-acting release relay 52. Upon energizing, relay 52 prepares the usual circuit for the vertical magnet 56 and also completes a holding circuit for the line switch C which may be traced as follows: ground at G, upper contact springs of relay 52, conductor 62, bank contact 35, bank springs 31, and the holding winding 17 of the line switch C to battery.

A branch of the above holding circuit extends by way of contact springs 21 and 20 and conductor 13 to the winding of the cut-off relay 14, which is accordingly energized in parallel with the holding winding 17 to disconnect the line conductors 11 and 12 from the winding of the line relay 15 and from ground, respectivel Conductor 13 is the private normal con uctor and extends to test contact 384 and its multiples in the banks of the connector switches which have access to the line of substation A. A ground potential is thus established on these test contacts and the line of substation A is made busy. By the engagement of bank spring 32 with bank contact 36 a circuit is closed whereby the master switch D is operated in the well known manner to advance the plungers of all the remaining idle line switches into position 1before the terminals of the next idle trunk The foregoing operations whereby the line conductors 11 and 12 have been extended through to the line relay 51 of the selector E have taken place in response to the removal of the receiver at substation ly stated, the tenth level in the selector banks is usually the level which is assigned to the toll recording trunks. It will be necessary, therefore, for the subscriber to actuate his calling device S in accordance with the digit 0 in order to obtain the desired connection. As the result of the operation of the calling evice a series of interruptions is produced in the circuit of the line relay 51 which responds by deenergizing a corresponding number of times and at each deenergizatiou sends a current impulse through the slowacting series relay 53 and the vertical magnet 56 to battery. By the operation of the vertical magnet the switch shaft is raised step by step until the wipers 80-82, inclusive, stand opposite the tenth level. The slowacting relay 53 is energized in series with the vertical magnet, maintaining its armature 63 attracted during the vertical movement of the switch, and at the first upward movement of the shaft completes a circuit which extends by way of the working contact of the said armature, the off normal springs 64, and the winding of the stepping relay 54 to E to the windings of A. As previousbattery. The stepping relay 54 is energized,

reparcs a circuit for the rotary magnet at its armature 66, andcloses a locking circuit for itself at its armature 67.

At the end of the vertical movement of the switch the slow-acting relay 53 is deenergized, and at the resting contact of armature 63 completes the circuit of the rotary magnet 55, thereby initiating the operation of selecting an idle trunk line. Upon energizing, the rotary magnet advances the wipers 82, inclusive, into engagement with the first set of bank contacts in the level opposite which they were raised, and at the same time interrupts the locking circuit of the stepping relay 54. The stepping relay 54 thereupon deenergizes and breaks the circuit of the rotary magnet whichin its turn deenergizes also. The operation now depends upon whether the test wiper 81 is in engagement with a grounded or non-grounded test contact. If the trunk line terminating in the first set of bank contacts is busy the test contact associated therewith will be grounded and a circuit will be completed which extends from the grounded test contact by way of the test wiper 81, armature 68 and its resting contact, interrupter contact of the rotarv magnet 55. oii normal springs 64, and t e winding of the stepping relay 54, to battery. The stepping relay Si is therefore again energized with the result that the rotary magnet 55 is als energized again to advance the switch wipers into engagement with the next set of bank contacts. This operation will continue as long as the testwiper 81 continues to engage grounded or busy test contacts. As soon as a nongrounded test contact is reached which we will assume to be the test contact 84 associated with the trunk line shown in the drawings, the stepping relay M will not again be energized, but the switching relay 5() which heretofore has been short circuitcd will be operated by current flow in the following circuit. Ground-ed conductor (32, winding of the switching relay 50, interrupter contact of the relay magnet 55. off normal contact 64, and the winding of the stepping relay 5 to battery.

The resistance of the switching relay 50 is so high that the stepping relay 54 is not operated. Upon energizing, relay 50 opens the circuit of the release magnet 57 at its armature 60, switches the test wiper 81 into connection with conductor 62 at armature (i8, and at

armatures

58 and 1 disconnects the incoming line conductors from the winding of the line relay 51 and extends the said conductors by way of the working contacts of the said armatures, wipers 80 and 82, bank contacts 83 and 85. and

trunk conductors

86 and 88 to the windings of the double wound relay 90 at the recording operators position. By the extension of the calling line as above described, an energizing circuit is completed over the line for the relay 90 which is accordingly energized to close the circuit of the slow-acting relay 91. Upon energizing, the

relay 91 completes a holding circuit extending back to the selector E which may be traced as follows: ground at G working contact of armature 93 and the said armature, contacts of key K, conductor 87, test contact 84, test wiper 81, armature 68 and its working contact, junction point (39, where it joins the conductor 62. the selector E, the holding winding of line switch C, and the cut-oft relay 14 of the said line switch are maintained energized over the holding circuit just described after the slowacting relay 52 of the selector E has deenergized.

When the relay 91 was energized it closed a circuit for the lamp signal L in an obvious manner, and the lamp is therefone lighted to notify the toll operator at whose position it appears that a call has been received. The

operator will respond by inserting the plug of t the cord circuit 0 one of her cord circuits, for example, in the jack J, at the same time throwing her key K to listening position. Upon the insertion of the plug a circuit is completed over the sleeve for energizing the I cut-oil" relay 92, thus extinguishing the lamp L. The operator may now converse with the calling subscriber and ascertain his wants, recording the data obtained on a ticket in the usual manner. If we assume that the desired toll connection is one which is handled in accordance with the so called two-number practice the toll operator will ask the calling subscriber to wait a moment on the line and will immediately proceed to obtain connection with the desired party, using for this purpose the calling plug of the cord circuit 0 and the proper outgoing to l line, which may be the toll line terminating in jack J It is understood that the toll connection at the distant exchange may be completed in any desired manner as, for example, by another operator at the distant exchange. \Vhile waiting for the connection to he established the toll operator having the cord circuit 0 will proceed to establish connection with the line of the calling subscriber A by means of her toll service trunking system with the primary object of ascertaining the correctness of the telephone number given by the calling subscriber, although, as will appear hereinafter, other advantages, including an improved talking circuit, are obtained by setting up the connection via the toll service trunks.

Observing that the service trunk terminating in jack J is idle. as indicated by the unlighted condition of the busy lamp L. the toll operator will now remove the. answering plug of cord circuit 0 from jack J and will insert it in the jack J, the key K being leftin listening position. A circuit is thereupon es- The switching relay 50 of tablished which extends from ground G by way of the impulse springs of calhng device S, contacts 0 key K sleeve of the plug, sleeve of the jack, armature 124 and its resting contact, and the winding of line relay 115 to battery. Upon energizing, the line relay 115 completes a circuit for the slow-act ng release relay 116 which, upon energizmg n turn, prepares the usual circuit for the vertical magnet 120 and also connects ground G to the conductor 125, thereby lighting the busy lamp L. i

The toll operator will now operate her calling device S. in accordance with the telephone number given her by the subscriber at substation A. The toll first selector E which responds to the first digit of the called number, is similar to the first selector E, and its operation therefore will not be described in detail. It will be sufficient to say that when the callin device is operated in accordance with the first digit a series of interruptions is produced in the circuit of the line relay 115 which responds in the usual manner to raise the switch shaft through the medium of the vertical magnet 120 until the wipers 140143, inclusive, stand opposite the bank level in which are terminated thetrunklinesleadingto the desired thousands group in the exchange. The slow-acting relay 117 is energized in series with the vertical magnet and closes the initial energizing circuit of the stepping relay 118 which locks itself as usual. At the end of the vertical movement of the switch the slow-acting relay 117 is deenergized and the switch wipers are rotated in search of an idle trunk line by means of the rotary magnet 121 which is controlled by the stepping relay 118 and the test wiper 142. When an idle trunk line is reached, which we will assume to be the trunk line extending to the toll second selector F, Fig. 2, the rotation of the switch will cease, leaving the wipers 140 143, inclusive, in engagement with bank contacts 144-147, inclusive. The switching relay 114 will then be energized with the result that the conductor coming from the sleeve of jack J will be disconnected from the line relay 115 and will be extended by way of the working contact of armature 124, conductor 111, wiper 141, bank contact 145, conductor 149, and the winding of the line relay 205 of the toll second selector F to battery. Upon energizing the line relay 205 closes the circuit of the slow-acting release relay 206, which, upon energizing in turn, prepares the usual circuit. for the vertical magnet 210 at its armature 233, and at armature 232 completes a holding circuit for the switching relay 114 of toll selector E as follows: ground at G", armature 232 and its working contact, conductor 150, test contact 146, test wiper 142, conductor 112, armature 125 and its working contact, winding of the switching relay 114,

ofi' normal contacts 122, and the winding of the stepping relay 118 to battery.

The above circuit serves to maintain the switching relay 114 energized and the busy lamp L lighted throughout the connection. It is understood that the ground potential also extends to multiples of testcontact 146 in the banks of other toll first selectors whereby the trunk line extending to the toll second selector F is made busy.

The selector F is now ready to operate in response to interruptions in the circuit of its line rela 205 caused by the operation of the calling device S in accordance with the second digit of the number. The interruptions cause the line relay to deenergize a corresponding number of times to raise the selector shaft through the medium of the vertical magnet 210 until the wipers 260263, inclusive, stand opposite the bank level in which are terminated the trunk lines leading to the combination toll and regular connectors which serve the desired hundreds group. The slow-acting relay 207 is energized in series with the vertical magnet maintaining its armature attracted throughout the vertical operation of the switch, and at its armature 235 completes a circuit which extends from ground by way of the working contact of the said armature 235 and the lower winding of the ring cut-oil relay 203 to battery. Upon energizing, the latter relay closes a locking circuit for itself which extends from the grounded conductor 150 by way of armature 213 and its resting contact, armature 222 and its working contact, and the lower winding of the said relay 203 to battery. The other circuit changes caused by the energization of relay 203 will be considered hereinafter. Returning to the series relay 207, this relay, upon energizing, also closes the initial energizing circuit of the stepping relay 208 which prepares the usual circuit for the rotary magnet 212 at its armature 236, and establishes a locking circuit for itself at its armature 237. At the end of the vertical movement of the switch the series relay 207 is deenergized and closes the aforementioned circuit of the rotary magnet 212 to start the operation of selecting an idle trunk. Upon energizing, the rotary magnet advances the wipers 260-263, inclusive, into engagement with the first set of contacts in the level opposite which they were raised, and also interrupts the locking circuit of the stepping relay 208. The relay 208 is accordingly deenergized and breaks the circuit of the rotary magnet which deenergizes also. As ex lained before in the case of the selectors d and E the operation now depends upon whether the test wiper 262 is in engagement with a grounded or non-grounded test contact. If the test contact with which the test wiper 262 is in engagement is grounded a circuit will be established for again energizing the stepping relay 208, this circuit bein traceable over the following path: grounded test contact, test wiper 262, conductor 258, armature 224 and its resting contact interrupter contact of the rotary magnet, oil normal springs 238, and the winding of the stepping relay 208 to battery.

Upon energizing again the stepplng relay again closes the circuit of the rotar magnet 212 and the switch wipers are a vanced into engagement with the next set of contacts, the stepping relay and rotary magnet. being thereafter deenerg zed as before. This operation will continue as long as the test wiper 262 continues to engage grounded or busy test contacts. As soon as a non-grounded test contact is reached, which we Wlll assume to be the test contact 266, associated with the trunk line extending to the connector H, Fig. 3, the stepping relay will not again be energized and the wipers 260-263, inclusive, will be brought to rest in engagement with bank contacts 264267, inclusive, respectively. The switching relay 204, which has been short circuited during the operations just described is now energized over the following circuit: grounded conductor 150, winding of the switching relay 204, interrupter contact of the rotary magnet, ofi normal springs 238, and the winding of stepping relay 208 to battery.

The latter relay is not operated because of the high resistance of the switching relay. Upon energizing, the switching relay 204 connects the double wound battery feed relay 202 to the outgoing section of the line at its armatures 226 and 229 over circuits which will be described hereinafter, and at its armature 225 completes an operating or control circuit for the connector H, as follows: ground at G, armature 230 and its working contact, armature 225 and its working contact, conductor 257, wiper 261, bank contact 265, trunk conductor 277, upper low resistance winding of relay 305 of the connector H, contact springs controlled by armature 321 of relay 300, and the upper winding of the line relay 301 to battery.

Upon thecompletion of the above circuit the line relay 301 and relay 305 are energized in series, the former relay closing the usual energizing circuit for the slow-acting release relay 302, and the latter relay altering certain circuits in the connector switch for the purpose of enabling it to function as a toll connector rather than as a regular connector as will be more fully explained hereinafter. When the release relay 302 is energized it prepares a circuit for the vertical magnet 311 at its armature 327 and at its armature 325 connects ground G8 to conductor 274. Ground potential is thereby placed upon the test contact 271 and its multiples in the banks of the regular second selectors which have access to the connector H for the tpu ose of making the connector busy to sue se ectors. A circuit may be traced from ground G back to the selector F which extends as follows: from ground G, armature 325 and its working contact, winding of the low resistance relay 304, conductor 278, test contact 266, test wiper 262, conductor 258, armature 224 and its working contact, armature 220 and its working contact, and resistance X to battery.

By the closure of the above circuit relay 304 is energized and at its armature 333 completes a circuit through the lower winding of relay 305, this circuit serving to maintain relay 305 energized while the connector H is being operated by interruptions in the circuit which includes the upper winding of relay 305 and the line relay 301. It should be stated at this time that relay 305 is not a slow-acting relay, but is provided with a slug or sleeve of copper for the purpose of reducing its impedance to increase thereby the efliciency of the control circuit as much as possible.

The relay 304 also disconnects the ringing apparatus at its armature 336 and closes a contact in the lower line at the same armature. The resistance of relay 304 is so low that the test contact 266 and its multiples in the banks of the other toll second selectors having access to the connector H are brought near enough to ground potential to make the connector busy.

The connector H is now ready to be operated. When the toll o erator actuates her calling device in accor ance with the third digit of the number, thereby producing as be ore a series of interruptions in the circuit of the line relay 205, these interruptions are repeated at armature 230 of the said relay 205 into the circuit of the line relay 301 of the connector H. Relay 301 accordingly deenergizes a corresponding number of times and at each deenergization sends an impulse through the vertical magnet 311 over the following path: ground at G, armature 324 and its resting contact, armature 327 and its working contact, oil-normal springs 330 and 328, winding of the slow-acting series relay 303, and the windin of the vertical magnet 311, to battery. The above is the circuit over which the first impulse is transmitted. At the first upward step of the shaft however, the circuit is altered by the shifting of the off-normal springs so that it extends from the working contact of armature 327 by way of off-normal springs 330 and 329 and the armature 332 of relay 303 and its working contact to the said relay, relay 303 having energized in series with the vertical magnet. By the operation of the vertical magnet the switch shaft is raised step by step until the wipers 380-382, inclusive, stand opposite the level of bank contacts in which are located the terminals of the line of substation A. At the end of the vertical movement of the switch the slow-acting series relay 303 is deenergized and the operating circuit is altered to provide for the rotary movement of the switch. When the next and last series of impulses are received over the line the line rela 301 will transmit a series of impulses to tli e rotary magnet 312 over the following circuit: ground at G, armature 324 and is resting contact, armature 327 and its working contact, ofl' normal springs 330 and 329, armature 332 and its resting contact, resting contact of armature 343 and the said armature,armature 354 and its resting contact, and the winding of the rotary magnet 312 to battery. By the operation of the rotary magnet 312 the wipers 380-382 are advanced until they come to rest in engagement with the bank contacts 382-385, inclusive, which contacts are the terminals of the line of substation A. During the rotar movement of the switch the slowacting re ay 308 is energized in parallel with the rotary magnet 312 and maintains its armatures attracted while impulses are being received. At its armature 346 relay 308 connects the test wiper 381 with the test relay 307 and at its armature 347 closes an alternative circuit for itself and the rotary magnet in case the test relay 307 should attract its armature 343 during the rotation of the switch. When the test wi er 381 arrives at test contact 384 it will fin a ground potential, for, as already explained, the line of substation A is busy, and test relay 307 will therefore be energized over the following circuit: grounded test contact 384, test wiper 381, armature 346 and its working contact, resting contact of armature 352 and the said armature, and the winding of the test relay 307 to battery. When the slow-acting relay 308 deenergizes an instant later the test relay 307 will remain locked up over the following circuit: rounded test contact 384, test wiper 381, wor ing contact of armature 335 and the said armature, working contact of armature 342 and the said armature, normally closed contacts controlled by armature 346, resting contact of armature 352 and the said armature, and winding of the said test relay 307 to battery.

The required connection has now been completed over the toll service trunks to the line of substation A, but since the called line is busy, for the calling subscriber is still waiting on the toll recording trunk, the test relay 307 of the connector was energized and the connection was not finally completed. The operator is given the busy signal in the following manner: When the test relay 307 is energized, a circuit is completed for the lower winding of the double wound battery feed rela 202 of the toll selector F, which exten s as follows: ground at G, lower winding of relay 202, working contact of armature 229 and the said armature, resistance X, lower right hand winding of repeating coil R, conductor 259, resting contact of armature 242 and the sald armature, line wiper 263, bank contact 267, trunk conductor 279, resistance X", armature 345 and its working contact, and the low resistance secondary winding of the induction coil of the signaling machine Q to battery. By the closure of the above circuit relay 202 is energized and completes a circuit in an obvious manner for the relay 201. When connection was first established with the selector F the relay 94 in the cord circuit was energized over the following circuit: ground at G", resistance X, armature 215 and its resting contact, upper left hand winding of repeating coil R, conductor 148, bank contact 144, wiper 140, conductor 110, tip spring of jack J, tip of plug, contacts of key K winding of relay 94, contacts of key K ring of plug, ring s ring of jack J, conductor 113, wiper 143, 147, conductor 152, lower left hand winding of repeating coil R, resting contact of armature 216 and the said armature, and the resistance X to battery. Now when the relay 201 is energized, as before stated, the armatures 215 and 216 are retracted and the circuit of the supervisory relay 94 at the cord circuit is broken, with the result that the supervisory lamp L, which heretofore has been lighted, is extinguished. At the same time the operator is given an audible signal emanating from the busy signaling machine Q and which produces a tone on the line in a well understood manner which notifies her that the line is busy.

In the present case the busy signal merely indicates to the operator that she has called the correct number, for inasmuch as the subscriber at substation A is already connected by Way of the toll recording trunk, it is to be ex ected that his line would be found busy.

e may now consider how the operator substitutes the connection by way of the toll service trunks for the connection by way of the toll recording trunk. To do this it is only necessary for her to actuate the key K associated with the jack J, Fig. 1. By this operation ground G is disconnected from the holding circuit which extends back over the conductor 87 to the selector E and line switch C, and which until now has been effective to maintain

relays

50 and 14 energized and which also served to maintain the line of substation A busy by means of the ground potential on test contact 384 and its multiples. When the holding circuit is broken, therefore, relay 50 and the holding winding 17 are deenergized and selector E and the line switch C are released and restored to normal condition in the well understood manner. When the circuit of the cut-off relay 14 is broken this relay does not retract its armatures at once because it is slow-acting, and it remains in operative position until a new ank contact circuit is established from the connector ,H, thereby preventing the line switch C from being again operated It has been described how the test relay 307 of the connector H is locked up to ground on the test contact 384.

Now, when this ground potential is removed the test relay 307 deenergizesand closes the tery. The above circuit is established before the cut-ofi relay 14,has time to retract its armature and is efi'ective to retain the said cut-off relay 14 energized and also to operate the switching relay 309. Upon energizing, relay 309 connects direct ground to the test wiper 381, establishes a locking circuit for itself at its armature 353, and at armatures 349 and356 completes the talking circuit connection to the

line wipers

380 and 382, respectively.

he connection has now been re-established by way of the toll service trunks. Talking battery is supplied to the transmitter at substation from the battery feed relay 202 in the toll selector over the following path: ground at G, lower winding of relay 202, working contact of armature 229 and the said armature, resistance X the lower right hand winding of repeating coil R, conductor 259, resting contact of armature 242 and the said armature, wiper 263, bank contact 267, conductor 279, working contact of armature 336 and the said armature, Testing Contact of armature 340 and the said armature, working contact of armature 356 and the said armature, wiper 382, bank contact 385, to and through substation A. returning on the other side of the line to bank contact 383, whence it extends by way of wiper 380, armature 349 and its working contact, armature 337 and its resting contact, armature 334 and its working contact, conductor 276, bank contact 264, wiper 260, armature 240 and its resting contact, conductor 256, upper right hand winding of repeating coil R, resistance X, armature 226 and its working contact, armature 221 and its working contact, and the upper winding of relay 202 to battery. When the called subscriber responds the conversation may proceed as desired, the path for voice currents being shown in heavy lines. Since the relay 202 is now energized by a flow of current through the substation A, the supervisory relay 94 at the operators cord circuit will be deenergized and the supervisory lamp L remains extinguished.

When the subscribers are through talking they will both replace their receivers. By the replacement of the receiver at substation A relay 202 of the selector F is deenergized,

thereby again closing the circuit of super 9 visory rela 94 at the operators cord circuit. The lamp 2 is accordingly lighted to give the operator a disconnect signal, and she will respond by pulling down the connection. When the plug is removed from the jack J the control circuit extending over the sleeve of the jack to the line relay 205 of the selector F is broken. This relay is therefore deenergized and breaks the circuit of the slow-actin release relay 206 and also brcaksthe contro circuit extending to the line relay 301 of the connector H. The release relay 206, upon deenergizing, closes the circuit of the release magnet 211, whereby the toll selector F is restored to normal; and also breaks the holding circuit extending back to the toll first selector E, which is also restored to normal through the medium of its release magnet 119. At the connector H when the line relay 301 deenergizes it breaks the circuit of the slow-acting release relay 302, which accordingly deenergizes and brings about the restoration of the connector to normal through the medium of the release magnet 310. All the switches have now been restored to normal position and are ready for use in establishing other connections.

In my issued Patent No. 1,315,444, previously referred to, I have described a system using combination toll and regular connectors which except for minor circuit improvements, are substantially the same as the connector H; and I explained fully therein the purpose of a connector of this type and how it functions differently when used as a toll connector from what it does when used as a regular connector. Hence it will be unnecessary to make a detailed explanation of this subject matter herein. Also in my pending application Serial No. 155,640 I have described a ringing system for toll service trunks characterized principally by a circuit arrangement in which the ringing current is applied to the called line at the connector switch and the ringing operation is stopped by a ring cut oti relay located at the preceding selector switch, and in which the operator is enabled to start the automatic ringing operation at any time she desires. The ringing system in the present case operates in very much the same manner but the circuits have been somewhat improved. When the toll operator establishes a connection through the medium of her toll service trunks and the connection is finally completed by a connector switch such, for example, as the connector H, the automatic ringing does not start immediately, due to the fact that the ring out off relay 203 at the selector F is energized and locked up by the first movement of the switch, as already explained. Assuming that the called line is idle, when the operator desires to signal the called subscriber, she will actuate her ringing key momentarily thereby connecting a source of ringing current to the line which will actuate the alternatin ringing current relay 200 at the toll se ector F. When the rela 200 attracts is armature 213 it breaks the loc 'ing circuit of the ring cut off relay 2033. Upon deenergizing, relay 203 connects its upper winding to the upper line conductor extending to the connector H, the circuit being readily traceable by way of the resistance X and the upper right hand winding of the repeating coil R; and also breaks the circuit of the relay 304 at the connector H. Relay 304 therefore deenergizes, and at its armature 336 connects the lead from the ringing current generator Gen. to the lower line conductor. The called line is now rung automatically. It should be mentioned that there is a shunt path for the upper right hand winding of the repeater R at the toll selector F which includes the resistance X.

Most of the ringing current returning on line conductor 256 will pass by way of this resistance X and the upper winding of the ring cut off relay 203 to battery instead of over the alternative path through the repeating COll winding, the resistance X, and the upper winding of the ring out off relay. However, just enough current flows over the latter route to give the operator an audible signal which advises her that the ringing operation is proceeding satisfactorily. This is the well known ringing current induction. When the called subscriber answers the ring cut of]? relay 203 is operated either by current from the generator Gen. or by direct current from the battery associated therewith, and upon energizing re-establishes its locking circuit and again closes the circuit of relay 304 at the connector. Relay 304 then disconnects the ringing current and closes the lower line.

In addition to the foregoing improvements the system herein disclosed comprises an auxiliary ringing system which is believed to be entirely novel. In all systems in which the ringing is automatic it is necessary to employ a ring cut ofi relay which operates responsive to the removal of the receiver from the hook at the called station. It follows therefore that when the receiver is off the hook it will be impossible for the operator to project ringing current out over the line for any purpose whatsoever. She may wish to do this to attract the attention of a subscriber who has left his telephone for a moment without hanging up the receiver, and also in some intercommunicating or P. B. X. systems the attending operators cord circuit normally has a bridged relay across the talking conductors which would have the same effect as the substation bridge in the case of a called telephone, and would prevent the toll operator from signaling the operator at the P. B. X. In order to enable the toll operator to ring on a closed called line I provide at the toll selector F an auxiliary ringing relay 209 cut oil relay 203 at the toll selector will be energized and locked. Also the battery feed relay 202 and the relay 201 will both be energized. Now, if the toll operator wishes to connect ringing current to the called line, regardless of the fact that the receiver is off the hook, she will actuate her ringing key as before. Responsive to this operation the alternating current relay 200 at the toll selector is again actuated, but does not in this case cause. the ring out off relay 203 to deenergize, for an alternative locking circuit for the ring cut oil relay has been established at the armature 214 of the relay 201. Instead, since relay 201 is energized, a circuit for the ringing relay 209 is completed as follows: grounded conductor 150, armature 213 and its working contact, armature 217 and its working contact, and the winding of the ringing relay 209 to battery.

Upon energizing, relay 209 projects ringing current from the generator Gen. over the called line in an obvious manner and at the same time at its armature 241 completes a circuit for relay 201 to prevent the latter from deenergizing during the ringing operation. The ringing in this case is, of course, not automatic, the relay 209 remaining energized only while the ringing key at the cord circuit is in operated position. While the complete circuits for the generator current have not been traced it is believed that they will be readily understood in view of the publications previously referred to.

Having described my invention, what I consider to be new and desire to have protected by Letters Patent will be pointed out in the appended claims.

What I claim as my invention is:

1. In a telephone system, a subscribers line, automatic switches controllable thereover for completing telephone connections, means for making said line busy when calling, and means under the control of a party who has been called by the subscriber on said line for rendering said line non-busy before connecting therewith.

2. In a telephone system, a subscribers line, automatic switches controllable thereover for completing telephone connections, means for making said line busy when calling, means under the control of a party who has been called by the subscriber on said line forrendering said line non-busy, and an automatic switch controllable by the said party for completing connection to said line in the geverse direction only while said line is nonusy.

3. In a telephone system, a calling line and an operators position, an automatic switch Assuming that a connection has controllable by the subscriber on said line to extend a connection to said operators position, means for rendering the said line busy when calling, and means in said extended connection controlled by the operator independent of the calling subscriber for rendering said line non-busy.

4. In a telephone system, a calling line and an operators position, an automatic switch controllable by the subscriber on said line to extend a connection to said operators position, means for rendering the said line busy when calling, an automatic switch controllable by the operator for connecting with said line over another path, means for preventing said switch from connecting therewith while the line is busy and means under control of the operator for rendering said line non-busy to permit said last switch to establish connection therewith.

5. In a telephone system, a calling line and an operators position, an automatic switch controllable by the subscriber on said line to extend a connection to said operators position, means for rendering the said line busy when calling, an automatic switch controllable by the operator for connecting with said line over another path, means responsive to the busy condition of said line for holding said last switch in a condition of suspended operation, and means under the control of the operator for rendering said line non-busy to enable said last switch to complete the connection.

6. In a telephone system, a calling line and an operators position, an automatic switch controllable by the subscriber on said line to extend a connection to said operators position, means for rendering the said line busy when calling, an automatic switch controllable by the operator for connecting with said line over another path, means responsive to the busy condition of said line for holding said last switch in a condition of suspended operation, means under the control of the operator for rendering said line non-busy to enable said last switch to complete the connection, and means for giving the operator a signal while the said last switch is held on the busy line.

7. In a telephone system, a subscribers line, a trunk selecting switch for use by said line when calling, a line relay for controlling the .operation of said switch, a cut-off relay for disconnecting said line relay, a circuit for said cut-off relay closed after the switch has operated, means for breaking said circuit thereafter at one point, means for making said cut-ofi' relay slow to deenergize whereby the said line relay is maintained disconnected for a brief interval after the circuit of the cut-ofi' relay has been broken, and means for again closing the circuit of said cut-off relay at another point prior to its deenergization.

8. In a telephone system, means including a plurali? of serially related automatic switches or extending a connection to a called line, a ringing relay in one of said switches for initially ringing the called sub-' scriber, a ringing key, and a ringing relay in another of said switches operable in response to the operation of said key for applying ringin current to the line while the recelver is o the hook.

9. In a telephone system, means including a selector switch and a connector switch for extending a talking connection to a called line, means in said connector for applying a source of ringing current to the called line, means for disconnecting said source when the called subscriber answers, a rin 'ng key, and means in 'said selector operabe in response to the operation of said key for a plying a source of rin ing current to t e called line after the tal ing connection has been established and while the receiver is off the hook. a

10. In a telephone system, means including a selector and a connector switch for extending a connection to a called line, a ringing key, and ringing relays in both the selector and the connector operable in response to the operation of said key, one or the other of said relays operable at any time after the connection is established whereby ringing current can be applied to the called line from either of two difierent points.

11. In a telephone system, means for extending a connection from an operators position to a called subscribers line comprising a plurality of serially related automatic switches, ringing equipment for projecting generator current out over a called line after connection therewith has been established, a ring out OK relay operated when the called subscriber removes his receiver to disconnect the ringing current, a ringing key at the op erators position, and an auxiliary ringing relay in one of said switches controllable in re- .sponse to the operation of said key by the operator to project ringing current out over said line at any time while the receiver is off the hook.

12. In a telephone system, means for extending a connection from an operators position to a called subscribcrs line comprising- 13. In a telephone system, means comprising a plurality of automatic switches for extending a connection from an operators position' to 0. called tele hone line, automatic ringin equipment, a ring cut-ofi' relay in one of sai switches, means for energizing said relay upon the initial movement of the switch to prevent the ringin oi the called subscriber after the connection has been completed, and

means controlled by the operator thereafter for deenergizing said relay to render said ringing equipment effective.

14. In a telephone system, means comprising a plurality of automatic switches for, extending a connection from an operators position to a called telephone line, automatic signaling equipment, manual signaling equipment, a cut-off relay in one of said switches, a signaling relay in another of said switches,

means for energizing said cut-off relay upon sources to the called line, a second means for connecting the second of said sources to the called line, a ringing ke at the operators position for operating either the said first means or said second means for causing either one of said sources to be connected -to the called line, the source connected depending on the condition of the called line.

16. In a telephone system,a subscribers line, automatic switches controllable thereover for-completing a telephone connectionto a called party, means for making said line busy when calling, and means controlled line, a trunk selecting switch for use by said solely by the called party over said connection for rendering said line non-busy.

17. In a telephone system, a subscribers line when extending a connection, a line relay for'said switch, a slow acting relay for disconnecting said line relay, means controlled by a subscriber in calling for closing .a circuit for said slow acting relay, and means controlled over the extended connection independent of the calling subscriber for opening the circuit of. said slow relay, the said slow-acting relay being efiective to maintain said line relay disconnected for a brief interval after said circuit has beenopened.

18. In an automatic switching system for handling toll calls, a toll switchboard, automatic switching apparatus for extending-a calling line to said switchboard, a test contact for said line, means for placing a busy test potential on said test contact, means including an automatic switch for extendin a connection from said switchboard to said line, means in said switch responsive to said test potential for preventing the completion of the second connection, and operator con trolled means for changing said test potential to permit the second connection to be completed.

19. In an automatic switchin system for handling toll calls, a toll switch oa'rd, automatic switches for extending a callin line to said switchboard, a circuit for making the line busy, automatic switches for extending a 'connection from said switchboard to said line, means controlled over said circuit for preventing the completion of the second connection, and operator controlled means for altering said circuit to simulate an idle condition of said line, whereupon said second connection is finally completed.

20. The methodof handling two number toll calls in an automatic telephone system which consists in extending a connection from the calling line to the toll switchboard by automatic switching mechanism under control of the-calling party, in extending a new but incomplete connection from the switchboard to the calling line by automatic switching mechanism under control of the toll operator while the calling party waits on the line, and in then removing the busy condition on the calling line under operator control to permit the partially established second connection to be completed, whereby the second connection is substituted for the first without the knowledge of the calling party.

21. In a telephone system, means including an automatic switch for extending a connection from an operators switchboard to a called line, automatic ringing equipment, a ring cut-01f relay in said swltch, means for energizing said relay before the said connection is completed, means for locking said relay to prevent said equipment fromringing the called line when said connection is completed, and means controlled b an operator at said switchboard for unloc ing said relay to render said ringing equip, ent efiective.

22. In a telephone system, m ns including an automatic switch for extending a connection from an operators switchboard to a called line, automatic ringing equipment. a ring cut-off relay in said switch, means for energizing said relay before the said connection is completed. means for locking said relay to prevent said equipment from ringing the called line when said connection is completed, means controlled by an operator at said switchboard for unlocking said relay to render said ringing. equipment effective, and means controlled by the subscriber on the called line for again energizing said relay to stop the ringing operation.

23. In an automatic switch havin primary and secondary movements, a c ange over control relay, a ring cut-ofl' rela and an initial energizing circuit for sai rin cut-off relay controlled by said change over control relay.

24. In an automatic switch, a relay included in a series circuit with the operating magnet oi the switch and maintained energized while the operating magnet of said switch is being actuated, a ring cut-off relay, and an energizing circuit for said ring cutoil' rela completed by said first relay.

25. 11 an automatic switch havin primary and secondary movements, a c ange over control relay, a ring cut-ofi relay, an initial energizing circuit for said ring cutoff relay controlled by said change over control relay, and a locking circuit for said ring cut-ofl relay independent of its initial energizing circuit.

26. In a telephone system, a calling and a called line, a train of switches for linking a connection from the calling to the calle line, an impulse contact of the calling line for operating the switches to efl'ect the said connection, means for applying sustained signalling current from the last switch of the train to the called line controlled from a said switch antecedent thereto, a relay in the antecedent switch, means for actuatlng and locking the relay to disconnect the signalling v current consequent to a response on the called line, means including the relay for preventing the reapplication of signalling current to the called line regardless of the ,termination of the responded condition of the called line, and means controlled over the calling line for restoring the relay to reapply and automatically sustain the application of the signaling current to the called line while maintaining the first established connection.

27 a In a telephone system, a calling line, a called line, a train of switches means at said callin line for operating said switches to exten a connection to said called line, a signalling current source associated with the last switch of said train, a relay and circuit connections in said last switch for controlling the application of si alling current from said source to said ca led line, means in the switch antecedent to said last switch for controlling said relay a relay in said antecedent swltch, means for actuating said relay consequent to a response on said called line to disconnect said signalling current, means for locking said relay, means including said relay for preventing the reapplication of signalling current to the called line regardless of the termination of the responded condition of said called line and means controlled over the calling line for releasing said relay to reapply signalling current to said called line without releasing the established connection.

28. In a telephone system, a plurality of serially related switches for extending a connection from an operators position to a called 4 line, two sources of ringing current for signalling the called line, a relay associated with the last of said switches for controlling the application of the first of said sources, a second relay associated with another of said switches for controlling the application of the second of said sources a ringing key at the operators position, and means controlled from said operators position by the operation of said key for operating one of said relays to connect one of said sources to the called line, the source connected depending on the responded or non-responded state of the called line.

29. In a telephone system, a subscribers line, a trunk selecting switch for use by said line when extending a connection, a line relay for said switch, a cut-off relay for disconnecting said line relay, means controlled by the su scriber in extending a connection to a called line for closing a circuit for said cut-off relay, a connector accessible to said called line and havin access tosaid calling line, means controlle from said called line for operatin said connector into connection with said cal ing line, means controlled from said called line for opening the circuit of said cut-ofi' relay to release the first established connection, and means in said connector for closing a circuit for said cut-01f relay to maintain the second established connection.

Signed by me at Chicago, Illinois, this 16th day of December, 1919.

JOHN WICKS.