US1967848A - Automatic telephone system - Google Patents

Description

July 24, 1934. J, w c s 1,967,848

AUTOMATIC TELEPHONE SYSTEM Fil March 19, 1917 2 Sheets-Sheet 1 HZZQLEQLJ [ILL/BRIEF July 24, 1934. J. wlcKs 4 AUTOMATIC TELEPHONE SYSTEM Filed March 19, 1917 2 ShfetS-Sheet 2 EN F [UL/517227? Patented July 24, 1934 PATIENT OFFICE AUTOMATIC TELEPHONE SYSTEM John Wicks, Chicago, Ill., assignon by mesne assignments, to Associated Electric Laboratories, Inc.-, Chicago, 1ll.,'a corporation oi Delaware Application March 19, 1917, Serial No. 155,040 I 41 Claims. (01.179-27) My invention relates in general to automatic telephone systems, but'is more particularly applicable to 'automatictoll service trunking systems, such for example as the one disclosed in my prior application, Serial No. 124,358, issued as Patent No. 1315,444, Sept. 9, 1919; and the object of the invention is toprovide an improved automatic ringing system of maximum convenience and efliciency.

The particular arrangement employed, its advantages, and its intended mode of operationwill be fully described hereinafter, reference being had to the accompanying drawings, comprising Figs. 1 and 2, which show in diagrammatic form the essential circuits of a system embodyingthe principles of my invention.

For a clear understanding of the drawings they should be placed in order with the lines at the ends thereof in alignment, and when thus arranged there is shown a complete circuit connection extending from a toll operator's cord'circuit to a local subscriber. The connection has been established through the medium of elements of a toll service trunking system comprising a toll first selector V (the circuits of which are not shown), a tollsecond selector W, and a combi nation toll and local connector H.

Inasmuch as a complete disclosure of the general purpose and utility of a toll service trunking system of the character-shown in the drawings has been made in my prior application above referred to, it will be unnecessary to encumber this application with another. It may be mentioned briefly, however, that each toll operator is given access to a system of toll service trunks by means of which she is enabled to connect toll lines with the lines of local subscribers. For example, and referring to the drawings the operator who has the toll cord circuit 0, has in front of her a plurality of jacks, one of which is the jack J, from which trunk lines extend to toll first selectors, one of which is the selector V. The toll first selectors have access to trunk lines terminating in toll second selectors, such as the selector W; and the toll second selectors in turn have access to trunk lines which terminate in connectors such as the connector H. If desired, and it is so illustrated in the drawings, the toll second selectors may also be accessible to incoming toll selector repeaters; while the connectors may be accessible in common to toll second selectors and the second selectors of the regular local trunking system.

The cord circuit 0, of which only the local end is shown, may be of any approved long discord circuit O'is located desires to call the line tance type, except for certain modifications which will be mentioned, and comprises the usual tip-and ring talking strands terminating in the plug P, a combination ringing and listening key K, and a supervisory lamp L controlled by the 9- supervisory relay 2-. The key K is a calling device key and when actuated serves to substitute the calling device CD for the supervisory relay 2 in the sleeve of the cord circuit. The calling device CD may be of any well known two-wire 5 type, such for example as is shown in the British patent to Dicker, #29,654 of 1910; and in addition to the usual break impulse springs is provided with a pair of springs 5 and 6 which are allowed to make contact whenever the dial of the device is turned from its normal position. The function of the relays 3 and 4 is to'start the automatic ringing of the called subscriber, as will be fully explained hereinafter.

The selector and connector switches in the system are of the well known Strowger vertical and rotory type, the mechanical construction of which is disclosed in the U. S. patents, to Keith, Erickson, and Erickson, Nos. 815,321, and 815,176, bot-h granted March 13, 1906. In the selector switches, however, the side switches and private magnets have been omitted, and all circuits, including the connector circuits, have been revised in accordance with modern two-wire practice. Further circuit modificationsrelating to the adaptation of the switches for use in a toll service trunking system, and to the incorporation in such a system of my improved automatic ringing arrangement, will be described in detail in the description of the operation.

The called substation A, the individual line switch C, and the master switch D are of the usual construction and are described and their functions explained in the U. S. patent toNewforth, No. 13,901, reissued April 13, 1915. While I have shown throughout the drawings a plurality of batteries it is to be understood that there is preferably but one battery having its positive pole grounded. Anexception to the above isthe batteryB' associated'with the ringing interrupter IR, which is provided to insure the operation of the ring-cut-oif relay in the connector when the called subscriber answers. The reference character Q indicates a busysignaling machine. I W

Having described briefly the apparatus in- -volved, I willnow proceed to explain the operation of the same, it being assumed for this purpose that the toll operator at whose position the 1m off-substation A to complete a toll connection therewith. v.In the following explanation the operation of the toll first selector V will be neglected entirely and the operations will be considered as though the jack J was connected directly with the toll second selector W, as, in fact, it might well be.

Assuming that the cord circuit 0 is to be used in establishing the connection, the operator, after first observing that the toll service trunk with which the busy lamp L is associated is idle, as indicated by the unlighted condition of the said lamp, will insert the plug P into the jack J of the service trunk. Upon the insertion of.

the plug in the jack a control circuit for the line relay 29 of the toll second selector W is completed over the following path: Ground at G winding of supervisory relay 2, contact springs 12 and 13 of the calling device key K sleeve of plug P, sleeve of jack J, conductor 52, armature 54 and its resting contact, and the windin of line relay 29 to battery B". Upon the comp etion of the above circuit, relays 2 and 29 are energized in series, the former relay closing a. circuit for-the supervisory lamp L in an obvious manner. Relay 29, upon energizing, completes a circuit for the slow-acting release relay 30,

which relay, upon energizing in turn, prepares a circuit for the vertical magnet 35 in the usual manner, and also closes a circuit for the busy lamp L and its multiples at other operators positions over the following path: Ground at G,

working contact of armature 55 and the said armature, conductor 51, and the lamp L' to battery B By the illumination of the busy lamps, the other operators are warned that the service trunk terminating in the jack J has been taken for use. A branch of. the. above circuit extends over conductor 51', to the test contact 56' and its multiples in the banks of the toll selector repeaters having access to the toll second selector W, where by a ground potential on these test contacts, the said selector is made busy.

The foregoing operations have occurred in re sponse to the insertion of the plug in the jack. The operator may now proceed to dial the number of the wanted subscriber, but before so doing, she is required first to operate the calling device key the actuation of which results in the substitution of the calling device CD for the supervisory relay 2 in the circuit of the relay 29 of the selector. When now the calling device is actuated in accordance with the first digit of the required number, a series of interruptions is produced in the circuit of the line relay 29. Responsive to these interruptions of its circuit, the line relay 29 deenergizes a corresponding number of times and at each "deenergization sends an impulse to the vertical magnet 35 over the following path: Ground at G, armature 57 and its resting contact, resting contact of armature 58 and the said armature, armature 59 and its working contact, winding of low resistance relay tacts in which terminate trunk lines extending to a group of connectors which have access to the line of substation A. The relay 31 is energized in series with the vertical magnet, and being slowacting retains its armature attracted during the series of impulses. At the first upward movement of the shaft, the off-normal springs '75 are permitted to close, thereby completing an initial energizing circuit for relay 32 as follows: Ground at G, working contact of armature 55 and the said armature, armature '72 and its working contact, off-normal springs 75, and the winding of relay 32 to battery B Upon energizing, relay 32 closes a locking circuit for itself over the following path: Ground at G, interrupter contact of the rotary magnet 34, off-normal springs 75, and the winding of relay 32 to battery B As a further result of its energization, relay -32 prepares at its armature 73a circuit for the rotary 'magnet 34 which, however, is held open during the vertical movement of the switch by the slow-acting relay 31. At this point it should be mentioned that as soon as the off-normal springs 75 are closed, the line switching relay 25 is connected in series with the relay 32 over the following circuit: Grounded conductor 51, wind ing of the said relay 25, interrupter contact of the rotary magnet 34, off-normal springs 75, and the winding of relay 32 to battery B It is noted however, that first ground G and then ground G have been connected to this circuit at points midway in the circuit connecting the two relays; whence it follows that the relay 25 is short-circuited and remains inoperative for the present.

At the end of the series of impulses the slowacting relay 31 deenergizes and completes a circuit for the rotary magnet 34 as follows: Ground at G working contact of armature 55 and the said armature, armature '72 and its resting contact, working contact of armature 73 and the said armature, and the winding of rotary magnet 34 to battery B The rotary magnet 34 is energized over the above circuit and rotates the switch shaft one step, thereby bringing the wipers 90 to 93, inclusive, into engagement with the first set of contacts in the level opposite which they were raised. Near the end of its stroke the rotary magnet separates its interrupter contact, thereby breaking the circuit connecting relays 25 and 32 and opening the locking circuit of the latter relay.

Relay 32, therefore is deenergized and breaks the circuit of the rotary magnet which deenergizes in turn and again closes its interrupter contact. The operation now depends upon whether or not the first trunk line is busy. If this trunk line is busy, the test contact with which the test wiper magnet 34, resulting in the advance of the switch I wipers another step. It will be seen then that the relay 32 will operate as an impulse sender or stepping relay to advance the switch wipers through the medium of the rotary magnet as long as the test wiper 91 continues to engage grounded test contacts. As soon as the first ungrounded test contact isreached, assumed to be the test contact 95, and the rotary magnet 34 deenergizes to close its interrupter contact, the relay 25 will no longer be short-circuited but will instantly energize in series with the relay 32 over the circuit previously traced. Relay 25 is of such high resistance, that relay 32 remains inoperative. Upon of armature 63and connects it instead to armature '64 of relay 26; at its armatures 61 and 62 prepares circuitsincluding the right hand repeating coil windings which will later be explained in detail; and at its armature completes-a control circuit extending to the line relay 100 of the connector H (Fig. 2), which may be tracedasfollows: Ground at G, armature 5'7 and its working contact, working contact of armature 60 and the said armature, wiper 92, bank contact 96, conductor 122, upper winding of relay 106, upper contacts of the answering bridge or reversing relay 102, and the upper winding of line relay 100 to battery B Relays 106 and 100 are energized in series upon the closure of the above circuit and the relay 100 completes in the usual way an energizing circuit for the slow acting release relay 101. Upon attracting its armatures, the s relay 101 prepares a circuit for the vertical magnet 109 at its armature 132, and at its upperarrnature connects ground G to the conductor 124, whereby a busy potential'is established on the test contact 125 and its multiples in the banks of the local second selectors having access to thejconnector H. Sameground also extends byway of the winding of relay lo'land the conductor 121 to test contact 95 and its multiples in the banks of the toll second selectors, whereby the connector H is also made busy to'remaining toll second selectors. The function of the relay 106, which it will be remembered was energized in series with the line relay 100, is to change the characteristics ofthe connector H from those of a local connector to those of a toll connector.

To explain this briefly, it has been mentioned before, that the connector H is accessible in common both to toll second selectors such as the selector W and to local second selectors comprising part of the regular exchange trunking system. The circuits of the connector H are normally in such condition that the connector will operate as a standard local connector, and when seized by a local second selector these circuits are not altered in any respect. When seized by a toll second selector however, certain of the circuits, as for example, those having to do with the signaling of the called subscriber and testing for a busy line are required to be altered and a relay is therefore inserted in series with the operating lead in the toll second selector trunk to perform these alterations or circuit changes. This relay is the relay 106, which is made slow acting so that it will not respond to impulses received over the operating circuit in which it is included. In its energized position, relay 106 disconnects at its armature 137 the ring cut-ofi relay 105, used on local connections, and substitutes therefore a ring cut-off relay in the toll second selector W over a circuit which will be subsequently traced; and at its lower armature 138. changes the characteristics of the connector from one which will lock on busy to one which will cut thru when the called line becomes idle.

The foregoing operations have occurred in response to the calling of the first digit of the required number (or the second digit, assuming that a first selector is included in the connection) Before proceeding with thejcalling of the remaining digits, it will be advisable to return to the cord circuit first and consider certain operations which take place in response to the actuation of the calling device dial in accordance with the digit of the called number which controls the operation of the toll second selector W. It has been assumed in the previous explanation that the tolloperater desires to have the automatic ringing of thecalled subscriber begin immediately upon' completion of the connection, and this being the case she will have her listening key K in operated-position'as shown in-the' drawings. Now when the dial is turned to cause the actuation of the toll second selector as previously described,

an energizing" circuit is completed for the relay 3 device returns to normal position the contact springs 5 and 6 are separatedagain and the circult of relay 3 is broken. Relay 3, upon'deenerg1zing, breaks the circuit of relay 4, but this latter relay, being slow-acting, does not deenergize at once, whereby for ashort interval the generator Gen is bridged across the tip and ring strands of I the cord circuit asfollows: Upper or tip strand of the cord circuit, armature 14 and its working contact, armature 1'7 and its resting contact, generator Gen, resting contact of armature l6 and the said armature, and the working contact or "armature l5 and the said armature to the lower or ring strand of the'cord circuit. A flow of alternating current is thus set up over the line conductorsof the trunk extending to the selector W to'actuate the bridged alternating current relay 33. Upon energizing, the relay 33 closes a circuit for relay 26 as follows: Ground at G contact and armature of relay 33, and upper winding of relay 26 to battery B Relay 26, upon energizing closes a locking "circuit foritself over the following path: Ground at G working contact of armature 55 andthe said armature, armature 78 and its resting contact, armature '66 and its working contact, and the lower winding of relay 26 to battery B As a further result of its energization, relay 26 disconnects the bridged battery supply relay 28 from the windings of the repeating coil, and for the upper winding of the said relay 28 substitutes the slow acting relay 27, thereby preparing a signaling circuit which will be described later. Relay 26 also disconnects battery B from the test wiper 91 at its armature 64.

We will return now to the connector H and consider its operation in response to the dialing of the two remaining digits in the desired number, whereby the connection is extended to the called line. When the operator turns the dial of her calling device for the next digit in the number, a series' of interruptions is produced in'the circuit of the line relay29 of the toll second selector W Ground at G 2, armature 130 and its resting con I tact, armature 132 and its working contact, windingof low resistance relay 103, winding of the vertical magnet 109, and the side switch wiper 156, in first position, to battery B In response 'to these impulses the vertical magnet 109 is operated to raise the switch shaft step-by-step, until the wipers 150, 151 and 152 arrive opposite the horizontal level of bank contacts in which are located contacts which are terminals of the line of substation A. The relay 103 is energized in series with the vertical magnet, and being slow-acting, retains its armature attracted during the series of impulses to close a circuit for the private magnet 158. At the end of the series of impulses, the relay 103 and the private magnet are deenergized the latter controlling the side switch wipers 156 and 157 to advance them to their secand position in the usual and well known manner.

The operator may now call the final digit in the required number, resulting in another series of interruptions in the circuit of the line relay 29,

which are repeated as before into the circuit of the line relay 100. Now however, the side switch 156 having been advanced to its second position, the line relay 100 transmits a series of impulses to the rotary magnet 110 over a circuit substantially the same as the one described in the case of the verticalmagnet 109. Responsive to these impulses the rotary magnet 110 rotates the shaft of the switch until the wipers 150, 151 and 152 engage the bank contacts 153, 154 and 155 respectively, .in which contacts the wanted line terminates. The slow acting relay 103 is energized as before during the final series of impulses and (assuming that the called line is idle) advances the side switch wipers to the third position through the medium of the private magnet as before.

When the side switch wiper 157 comes into engagement with its third position contact point, a circuit is completed for the cut-01f winding 200 of the called line switch as follows: Ground at G, side switch wiper 157 in third position, private wiper'151, bank contact 154, and cut-ofi winding 200 of theline switch C to battery B By the energization of the cut-off winding of the line switch, the armature 201 is actuated to disconnect the line of substation A from its ground and battery connections in the line switch. Ground G also extends to multiples of contact 154 in the banks of the other connectors in the group, where by a ground potential on these contacts the line of substation A is made busy. A branchof the above traced circuit extends through the winding of the wiper switching relay 108 by way of side switch wiper 156 in its third position to battery B The relay 108 is thereupon energized to extend the talking conductors of the connector through to the line wipers 150 and 152; and as a result of this operation, a signaling circuit for actuating the ringer 202 at substation A is completed as follows: Ground at G, generator Gen,

' contact of ringing interrupter IR, lamp L resting contact of armature 140 and the said armature, resting contact of armature 136 and the said armature, armature 142 and its working contact, wiper 152, bank contact 155, through the ringer 202 at substation A, bank contact 153,

wiper 150, working contactof armature 141 and the said armature, armature 134 and its resting contact, armature 137 and its working contact, trunk line conductor 120, bank contact 94, wiper 90, winding 79 of the repeating coil, armature 62 and its working contact, armature 65 and its working contact, and the winding of relay 27 to battery 3". Relay 27, owing to the provision of a slug of copper on its core, is slow to energize and does not respond to alternating current in the above circuit.

Connection has now been established with the tery B for the generator Gen in the ringing circuit in order to produce an intermittent ringing of the bell at the called substation. In case the called subscriber should respond while alternating current is on the line, the relay 27 at'the toll second selector will be energized by' current from the battery B in series with the generator; but in case the receiver is removed during a silent period, the said relay 27 will be energized by current from the two batteries B and B in series. In any event, when the called subscriber takes 01f his receiver, relay 27 will be operated to open the locking circuit of relay 26, resulting in the deenergization of the latter relay with the following results: At armatures 65 and 67 the answering bridge 28 is bridged across the line circuit in series with windings 79 and 80 of the repeating coil, and at armature 64 battery B is connected to the test wiper 91. The relay 107 of the connector H is now energized over the following circuit: Ground at G armature 131 and its working contact, winding of relay 107, conductor 121, bank contact 95, wiper 91, armature 63 and its working contact, armature 64 and its resting contact and the resistance, 77 to battery B Upon energizing, relay 107 closes at its armature 139 a circuit through the lower windings of relay 106 for a purpose to be described later; and at its lower armature 140 disconnects the lead extending to the ringing apparatus and closes a contact in the talking circuit, whereupon the answering bridge relay 28 will become energized over the heavy line conductors extending to substation A. This circuit, being for the most part drawn in heavy lines, need not be traced in detail.

The energization of relay 28 has the following results: At armature 70 the alternating current relay 33 is disconnected from in bridge of the line conductors; at armature 69, the left hand windings of the repeating coil are connected to complete the talking circuit; at armature 68 ground G is connected to the control circuit extending to the line relay 100 of the connector H as a substitute for ground G removed an instant later by the deenergization of relay 29, as will appear shortly; and at armature 54 the conductor 52 is disconnected from the line relay 29 and is connected instead to the slow acting release relay 30. It should be mentioned at this point that the line relay 29 is of moderate resistance, preferably 250 ohms, while the release relay 30 should be of at least 1300 ohms resistance. The supervisory relay 2 at the cord circuit is marginally adjusted so that it will energize in series with the line relay 29 and will deenergize when connected in serieswith release relay 30. It follows then, that when the called subscriber answers and the answering bridge relay 28 is energized by the process already described, the resistance of the circuit including the supervisory relay 2 at the cord circuit will be sufliciently increased to cause the deenergization of the said relay and extinguishing of the supervisory lamp L.- The operator isthussnotifled'that the called party has answered the telephone. The con nection to the other subscriber may then be completed by means of the other plug uiot' shown) of the cordcircuit inthe-usual manner, and conversation between the twoconnected subscribers may be 'held'over the heavy line conductors. The subscriber at substation A is-of course supplied with talking current through thewindings of the answering bridge relay 28 ofthe toll second selector W; while the other subscriber' may be supplied with talking-current from connective apparatus associated with his line during the connection'in any suitable or desired'ma'nner.

When the conversation is flnishedj' the subscribers will replace their receivers. By the re-:

placement of the receiver at substation A the relay 28 at the toll sec'ond'selector is 'deener"- gized, whereby the linerelay 29 is againconnected in thecircuit of the supervisory relay 2,

andthe 'latter relay isenergized'to illuminate the lamp L. Being informed 'b'y the lighting of l the lamp that the conversation terminated,

the operator will takefdownthe'cord circuit, the

' removal of iplug P from jack J being effective to break the circuit of the line'relay 29 of the selector W. The consequent deenergization of line relay 29 is followed by-the deenergization' of the release relay30, and results also in the breaking of the control circuit including the line relay 100* of the connector H.- B'y the former operation ground G is 'disconnected from'conductor 5l whereby'thebusy-lamp L and its multiples are extinguished, andthe'circuit of the line switch relay25 is broken-to' permit it to de--* energize. At the same time -a circuit is-closedfor the release magnet 36 of the-"selector over' the following path: Groundat'Ga'armature 57 and its resting contact, resting contact of armature 58 and the said armature, armature '59 and its resting contact, off 'normalsprings' 76, and the windings: of the release magnet 36 to battery B By the energization'of-"the'release magnet,

the selector W is restored to normal position in xtheusual and well understoodmanner; "the re lease magnet circuit being opened'at the oif nor-- mal springs 76 when'the shaft reaches its lowermostposition. At the connector H, the deenergization of the line relay l00'is followed by the deenergization of the release-relay 101. When relay 101 retracts its armatures, ground (2& is disconnected from the multiple testcontacts in the selector banks and is connected instead to the release'magnet 159, whereupon the connector H is restored to normal position in substantially the same manner as was described in the case of the second selector "W.-"The circuit through the lower winding of relay 106 is provided'to guard against a momentary ringing of the'called subscriber during the release of the connector. This circuit is not broken until relay 107 deenergizes which occurs-when the slow-acting release relay 101 deenergizes: and sincere lay 106 is made slow-acting it retainsits armature until after thereleasemagnethas restored the side switchwipersto normal-' positionand the wiper switching relay 108 has deenergized.

In. the operation of the system'as 'ju'st'described theautomatic ringing of the called subscriber is started immediately' upon connection being completed =to his line,'-and this is the -usual'o'pera tion. If "the operator so 'desires however; she

can call a "subscriber v withoutfhav ing" {the signaling operation 'startat" oncerand it'is'this option which the operator h'as 'of either automatically ringing the called'party immediately upon connection being established, or oi deferring the ringing operation" until later, whenitfmaybe started at will,- which is theprincipalfeature of my invention. It occurs quite frequentlyflthat the, operator in order to save time will flndit convenient to establish the local connection over the service trunk while waiting forthe party in the distant exchange to answer histelephone.

"Not knowing the length of time which will be.

required for an answer'to be obtainedyand in cases where a particular person is wanted, not

being atall certain that suchfla person will be immediately accessible by telephone, the opera-" tor will not wish to have the local partyywit h whom connection is established viathe service" trunk, signalled "at oncej' for if "he answered before the required distant connection wasready',

it might benecessary to havewait for an unreasonable length of time, or even-to have him hang up his receiver again. In such cases as these then it is extremely'desirable thatthe op- 1 erator should beable to establish connection with a called line and defer the signaling operation until the'desired toll connection is ready. When the operator desires to postpone the automatic ringing of the called subscriber she dials the number substantially as previously described, ex cept that her listening key K is not'actuated. It follows therefore, that when the calling device is operated'the're is no circuit closed for the relay 3. in the cord circuit, and no ringing impulse from the generator Gen is projected over the trunk line conductors by the operation of relays 3 and 4 when the calling device returns to normal, as is the case when the listening key isin operated; position. Consequently the alter-" nating current relay 33 in the toll second selec-' tor W is not actuated to cause'the energization of 'relay 26, the latter relay therefore remaining deenergized. Thebattery B not being disconnected from the wiper 91, as soon as the connection is extended to the connector the relay' 107 will be energiaedto disconnect the ringing apparatus, from which it follows that when the connection is completed no ringing operation will take place. Under these circumstances, when the operator gets ready to signal the localsubscriber she will throw her key K to ringing position momentarily, thereby manually projecting an impulse of ringing current out'over the trunk line. The alternating current relay 33 now responds as previously described to energize relay 26, resultingin the disconnection of battery 13 from thecircuit of relay 107 in the connector H.

Relay lfl'ltherefore, deenergizes and the signalling circuit is closed over the path previously traced.

Ithas been'mentioned before that the toll secconnector H,'one-of which sets is shown at'the upper left hand corner of Fig. 2. These trunking arrangements, together with the operation of the toll second-selector andof the connector H when seized by a toll selector repeater and by a local secondselector, respectively, have been described fully in my prior 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:

application previously 1. In a telephone system, a called telephone line, operator controlled automatic switching mechanism for extending a connection to said line, automatic ringing equipment for signalling the called subscriber upon the completion of the connection, manual apparatus at the operators position, and circuit connections whereby the starting of said ringing equipment is made dependent upon the position of said apparatus.

3. In a telephone system, means including an operators cord circuit for connecting a calling and called line, means outside the cord circuit for signalling the called subscriber, comprising also means for automatically starting the signalling operation upon the completion of the connection, and means within the cord circuit operated prior to the establishment of the connection for determining whether or not said starting means will be operated.

4. In a telephone system, means including an operators cord circuit for connecting a calling and called line, means outside the cord circuit for signalling the called subscriber, comprising also means for automatically starting the signalling operation upon the completion of the connection, means within the cord circuit operated prior to the establishment of the connection for determining whether or not said starting means will be operated, and means whereby it the said starting means is not operated at once it may be operated subsequently at the will of the operator.

5. In a telephone system, means comprising a selector switch and a connector switch for extending a connection to a called line, automatic ringing equipment individual to the connector switch for signalling the called subscriber, and a relay in the selector switch responsive to the removal of the receiver on the called line for stopping the signalling operation.

6. In a telephone system, means comprising a selector switch and a connector switch for extending a connection to a called line, automatic ringing equipment, a ringing relay in said connector having contacts for connecting said ringing equipment with a conductor of the said connection to the called line to form a signalling circuit, said circuit including a trunk conductor extending between said switches, and a relay in the selector also included in said circuit, and means for operating said ringing relay to cut oil the ringing cun'ent from the called line.

'7. In a telephone system, means comprising a selector switch and a connector switch for extending a connection to a called line, automatic ringing equipment, a relay in said connector having contacts connecting said ringing equipment with a conductor of the connected called line to form a signalling circuit, said circuit including a trunk conductor extending between said switches, a relay in the selector also included in said circuit, said last relay being responsive to the removal of the receiver on the called line, and a circuit for said first relay controlled by said last relay whereby upon the response of the called subscriber said first relay is controlled to disconnect the said ringing equipment.

8. In a telephone system, a trunk line, automatic switching mechanism forextending said trunk line into connection with a called telephone line, apparatus for automatically and intermittently signalling the subscriber on the called line, and a relay in bridge of the the conductors of said trunk line and responsive to currents projected thereover for starting the operation of said'signalling apparatus, and a condenser in the energizing circuit ol. said relay in series therewith and with the source of current.

9. In a telephone system, a trunk line, automatic switching mechanism for extending said trunk line into connection with a called telephone line, apparatus for automatically and intermittently signalling the subscriber on the called'line, means for projecting ringing current over the conductors of said trunk line, and an alternating current relay in bridge of said conductors and responsive to said current to start the operation of said signalling apparatus.

10. In a telephone system, a trunk line extending from an operators cord circuit and terminating in an automatic switch, a calling device for producing current impulses in one conductor of said trunk line to operate said switch, and means in the cord circuit automatically controlled by the operation of said calling device to transmit ringing-current over other conductors of said trunk line.

11. In a telephone system, a trunk line extending from an operators position and terminating in an automatic switch, a calling device for producing current impulses in a conductor 01' saidtrunk line to operate said switch, and means eifective each time the calling device is operated to automatically project ringing current over said trunk line, said means including'a quick and a slow relay.

12. In a telephone system, a trunk line extending from an operators position, automatic switching mechanisms operable in response to a plurality of operations of a dial for extending said trunk line to the line of a called subscriber, a calling device at the operators position for controlling the operation of said switching mechanisms, and automatic means controlled in the operation of said calling device upon the first dial operation for projecting'ringing current over said trunk line when all the dial operations are completed.

13. In a telephone system, means comprising selector switches and connector switches for extending connections to called lines, automatic ringing equipment individual to each connector switch for signalling the called subscribers, and a relay individual to each selector switch responsive to the removal of the receiver on the called line for stopping the signalling operation.

14. In a telephone system, aselector switch and a connector switch for connecting calling and called lines, a ringing relay in the connector for applying ringing current to the called line, a cut oif relay in the selector operated when the called subscriber answers for controlling the operation of said ringing relay to cut of! the ringing current to the called line.

"15. In a" telephone system,' a selector switch having alternative-sets or incoming terminals, means for seizing either set or terminalsaand means operative according to the set of terminals seizedjto, automatically project signaling current, or not automaticallyproj'ect' signaling current from said selector.

16. In a telephone system, a selector switch having alternative sets of incoming terminals, and means'operative toefiect automatic ringing control or not effect automatic ringing control by said selector according to the set of terminals connectedwithj 17. In a,j telephone system, an automatic switch which will junction as a selector, 9) ringing current source, alternative sets of terminals leading in to the said switch, called lines,,m'eans for seizing the said switch through either set of terminals at will, means for directing the switch for seizing a called'line', means operable when a specific one ofthe sets of said terminals is seized forcausing ringing current to be projected on a called line, and means operable when a specific one of, the said sets of terminals is.

seized whereby ringing current is not projected on a called line. I

18. man automatic telephone system, a switch which will functionas a selector, alternative sets of incoming terminals for the switch, a

source of signaling current in the switch, means for seiz'ng either set of terminals by an antecedent switch, and means respectively operative according to the set of terminals seized to adapt the switch to project signaling current from the said source or not project signaling current to a connected line.

19. In a telephone system comprising a local trunking system for use by local subscribers and a toll trunking system for use by toll operators,

a final connector switch commonto bothtrunking systems, meansfor operating said switch to complete a local connection or a toll connection to a called line, automatic ringing equipment normally connected to automatically ring the called line connected with in either type of connection, means for automatically disconnecting said ringing equipment during the establishment of the toll connection whilepermitting the same to remain connected to'startthe automatic ringing at once when the local connection is established, and means brought into use during the toll connectionfor again connecting said ringing equipment under operator control to start the automatic ringing. v t

20. In a' telephone'system comprising a local trunking system for use by local subscribers and a toll trunking system for use by toll operators, a final connector switch common to both trunking systems, means for operating said switch to complete a local connection or. a toll connection to a called line, automatic ringing equipment normally connected to. automatically ring the called line connected with in either type of connection, means for automatically disconnecting said ringing equipment during theestablishment of the ,toll connection while permitting the same to, remain connectedtostart the automatic ringing at once'whenthe local connection is established, and means controlled by an operator after the toll connection is established for disabling said ringing equipment disconnecting means in order to start the automatic ringin at will.

21. In a telephone system com 4, trunking System use y local subscribers and a toll trunking system for use by tolloperator's, a final connector switch common to both trunking systems, means for operating said switch to complete a local connection or a toll connection to a called line, automatic ringing equipment normally connected to automatically ring the called line connected with in either type of conscriber on the called .inecan stop the automatic ringing when he answers,. regardless of whether the connection to his line is"a 'toll'or a'local con-'" nection.

22. In a telephone system comprising a local trunking system for use by local subscriber and a toll trunking system for use by toll operators, a final connector switch common toboth trunk ing systems, means, for operating saidswitch to complete a local connection or a toll connection to a called line, automatic ringing equipment normally connected to automatically ring the called line connected with in either typeof connection, means for automatically disconnecting said ringing equipment during the establishment of the toll connection while permitting the same to remain connected to start the automatic ringing at once when the local connection is established, means controlled by an operator after the toll connection is established for disabling said ringing equipment disconnecting means in order to start the automatic ringing at will, and means whereby the subscriber onithe called line can stop the automatic ringing when he answers, regardless of whether the connection to his line is a toll or a local connection.

23. In a telephone system, a subscribers line, a switch controlled by an operator for connecting with said line, a relay in said switch, a ringing circuit including normally closed contacts of said relay, means for automatically energizing said relay during the establishment of the connection to open said ringing circuit before the connection is completed, operator controlled meansfor deenergizing said relay to close said ringing cir-' cuit, and means controlled by the subscriber on the called line for again energizing said relay to open said ringing circuit.

24. In a telephone system, a subscribers line, a switch controlled by an operator for connecting with said line, means for ringing the called line, ringing prevention means operated automatically during the establishment of the connection for rendering said ringing means inefiective, operator controlled means operable at any time after the connection is completed for restoring said ringing prevention means to cause the said ringing means to become effective to signal the called line, and means controlled by the subscriber on the called line for again operating said ringing prevention means to stop the signalling operation.

25. In a telephone system, a subscribers line, I

an operators switchboard, means including an automatic switch for extending a connection from said switchboard to said line, automatic ringing automatically signal the called line, and means controlled by the subscriber on the called line for again energizing said relay to stop the signalling operation when the called subscriber answers.

26. In a telephone system, a subscriber's line, an operators switchboard, means including an automatic switch for extending a connection from said switchboard to said line, automatic ringing equipment, a relay in said switch energized before the operation of said switch is finished in order to prevent said equipment from signalling the called line when the connection thereto is completed, means controlled by the operator at said switchboard for deenergizing said relay to cause said ringing equipment to automatically signal the called line, and means controlled by the subscriber on the called line for again energizing said relay to stop the signalling operation when the called subscriber answers.

27. In-a telephone system, a calling station, a telephone line involving near and remote sections thereof, a junction point of the sections, a first relay controlled from the remote section and a second relay controlled from the near section together operative to join the sections at the junction point, first and second signalling current sources, said first source being of a character erate the second relay to apply the second source to the remote section after the last directive operation has been transmitted to the selective switch mechanism, and a circuit connection madeoperative consequent to the operation of the second relay whereby the first relay will become in control of the remote section to join the sections.

28. In a telephone system, a calling station, a telephone line involving near and remote sections thereof, a junction point of the sections, a first relay controlled from the remote section and a second relay controlled over the near section together operative to join the sections at the junction point, first and second signalling current sources, said first source being of a character to which a condenser is transparent, the second relay responsive to the first source applied overthe near section to apply the said second source to the line, and to prepare an operative circuit pathfor controlling the first relay for joining the sections, selective switch mechanism, means for directively operating the selective switch mechanism to complete a connection from the calling station to include the line, means for initially applying the first source over the near section after the last directive operation has been transmitted to the selective switch mechanism to apply the second source to the remote section and to prepare the said circuit path for the first relay, whereby the first relay will become in control of the remote section to join the sections.

29. In a telephone system, a calling station, a telephone line involving near and remote sections thereof, a junction point of the sections, a first relay controlled from the remote section and a second relay controlled over the near section together operative to join the sections at the junction point, first and second signalling current sources, the second relay responsive to the first source applied over the near section to apply the said second source to the line and to prepare an operative circuit path for controlling the first relay for joining the sections, selective switch mechanism, means for directively operating the selective switch mechanism to complete a connection from the calling station to include the line, means for initially applying the first source over the near section after the last directive operation has been transmitted to the selective switch mechanism to apply the second source to the remote section and to prepare the said circuit path for the first relay, whereby the first relay will become in control of the remote section to join the sections, and disconnect the said relays from the connection.

30. In a telephone system, a calling and a called line, automatic switch mechanism for connecting said lines, a source of signaling current for application to the called line, a source of inductive current, means for at will applying the inductive current over the calling line after the said lines are connected for applying the signaling current to the called line, and automatically applied means for maintaining the said application of thesignaling current.

31. In a telephone system, a calling and a called line, automatic switch mechanism for connecting said lines, a source of signaling current for application to the called line, a source of inductive current, means for at will applying the inductive current over the calling line after the said lines are connected for applying the signaling current to the called line, and automatically applied means for maintaining the said application of the signaling current regardless of the termination of the application of the inductive current.

32. In a telephone system, a calling and a called line, automatic switch mechanism for connecting said lines, a source of signaling current for application to the called line, a source of inductive current, means for at will applying the inductive current over the calling lineafter the said lines are connected for applying the signaling current to the called line, automatically applied means for maintaining the said application of the signaling current regardless of the termination of the application of the inductive current, and means on the called line for terminating the application of the signaling current.

33. In a telephone system, a calling and a called line, automatic switch mechanism for connecting said lines, a source of signaling current for application to the called line, another source of current, means for at will applying the said another source of current over the signaling line after the said lines are connected but before any operation has thereafter occurred on the called line for applying the signaling current to the called line, and automatically applied means for maintaining the said application of the signaling current. I

34. In a telephone system, a calling and 2. called line, automatic switch mechanism for connecting said lines, a source of signaling current for application to the called line, another source of current, means for at will applying the said another source of current over the talking conductors of the calling line after the said lines are connected but before any operation has thereafter occurred on the calling line for applying the signaling current to the called line, and automatically applied means for maintaining the said application of the signaling current.

35. In a telephone system, a calling and a called line, automatic switch mechanism for connecting said lines, a source of signaling current for application to the called line, another source of current, means for at will applying the said another source of current over a talking conductor of the calling line after the said lines are connected but before any operation has thereafter occurred on the called line for applying the signaling current to the called line, and automatically applied means for maintaining the said application of the signaling current.

36. In a telephone system, a calling line, a called line, switching mechanism for extending a connection from the calling line to the called line, a source of signaling current for application to the called line, a source of current to which a condenser is transparent, operator directed means controlled over the calling line for operating the switching mechanism to extend a connection from the calling line to the called line, operator directed means for thereafter at will applying the second said source of current over the calling line effective to first apply first said source of current to the called line, automatically applied means for maintaining the application of current to the called line, and means controlled over the called line for disabling the said automatically applied means.

37. In an automatic telephone system, a called line, first and second calling lines, automatic switches for linking connections from the respective calling lines to the called line, a connective switch of said switches for completing connections to the called line common to connections from said calling lines to the called line, a selective switch of said switches for completing connections to the connective switch common to connections from the said calling lines to the called line, specific selector switches for completing connection from the respective said calling lines to the selective switch, and means involving one of said selector switches depending upon which said calling line is extended to the connective switch for determining what specific operation the connective switch will be enabled to thereafter perform.

38. In a telephone system, a called line, a first automatic switch having selective access to the called line, a second automatic switch having selective access to the said first switch, calling lines, switch elements for extending connection from a random one of said calling lines to said second automatic switch, the calling line determining which of said elements will be employed in the extension, means thereupon operable over the said extension from the random calling line applied through the concerned said element and said second automatic switch for selectively opcrating said first automatic switch to select the called line, and means the operation oi which is determined by the particular said element em ployed in the extension to the said first automatic switch for determining what particular variable behavior said first automatic switch will be en-- abled to manifest.

3&9. In a telephone system, a called line, a first automatic switch having selective access to the called line, a source of signalling current for 8 application to the called line, a second automatic switch having selective access to the said first switch, calling lines, switch elements for extending connection from a random one of said calling lines to said second automatic switch, the calling line determining which of said elements will be employed in the extension, means thereupon operable over the said extension from the random calling line and through the concerned said element and said second automatic switch for selectively operating said first automatic switch to select the called line, and means the operation of which is determined by the particular said element employed in the extension to the said first automatic switch for determining whether or not said source of signalling current will be applied to the selected called line responsive to said selection.

40. In a telephone system, a called line, a first automatic switch having selective access to the called line, a second automatic switch having selective access to said first switch, calling lines, means for extending connection from the respective calling lines to the said second switch in a different manner specific to the calling lines, means for extending connection from a random one of the calling lines to the called lines wherein the first and second switches are links in the connection, and means depending upon from which said calling line the connection is extended from for determining what behavior the said first switch will be enabled to manifest.

41. In a telephone system, a called line, a first automatic switch having selective access to the called line, a second automatic switch having 120 access to the said first switch, a plurality of other switches having selective access to the said second switch, a plurality of leading-in paths to said second switch, means for extending connection over a random one of said plurality of paths to 25 manifest.

JOHN WICKS.

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