USRE18038E - Ivl schwartz - Google Patents

Description

A '1 7 1931 SCHWARTZ R 1 p INTERCEPTING TRUNK SYSTEM 8038 2 Sheets-Sheet 1 Original Filed Feb. 9. 19 4 I ]fiu5n UT Michael 55771-151322 2 Sheets-Sheet 2 M. SCHWARTZ INTERCEPTING TRUNK SYSTEM Original Filed Feb. 1924 Im/en ur" HmhE/EZ Schwarfk April 7, 1931.

Reiuued Apr.v 7, 1931 mcnam. scnwanrz, or onrcaco, AUTOMATIC ELECTRIC me, or cmcmo,

ILLINOIS,

A OOBPOiB-A'LIQN OI DELAWARE m'rnncnrirme rmmx aye-rim Original application died February 9,1924, Serial No. 881,879. Renewed August, 1987. Original No.

1,005,479, emu awn 10, was.

The resent invention relates in general to telep one systems, but is particularly concerned with the provision of new and improved trunking arrangements for handling 5, calls to lines out of'order, or to lines on which the service has been discontinued, etc., trunks for handling these services bein commonl' known as intercepting trunks, and the broa object of theinvention is to rovide an intercepting trunking system w iich is more flexible, economical, and convenient in practice than any such system heretofore known to applicant.

A particular object is to provide an inter"- cepting trunking system in which, 10' simpl removing battery potential fromt e cuto relay of a line switch of aline in trouble, or an unassigned line, the calls extended thereto are automatically trunked to an intercepting operators position.

Another object is to provide means whereby an interceptin operator, upon answering -a call extende to her osition, is automatically informed that t e number called represents a called working line which is in trouble or is a dead number, as the case be. ther minor features of the invention not specifically pointed out will be brought out in the detailed description which follows.

Referring now to the drawings comprising Figs. 1 and 2, these figures, when arranged with Fig. 1' immediately above Fig. 2, show sufficient of the circuits and apparatus 'of an automatic telephone system to enable the invention to be clearly understood.

Referring to the figures in detail, Fig. 1 shows aconnector H, line switch C, substation A, special high frequency generating equipment T,'and a start relay lOO. The connector H is of the well known Strowger type and is wired in accordance with the usual two-wire practice. Minor circuits additions have, however, been made in accordance with the present invention. These added circuits will be fully described hereinafter. The line switch C is of the well knownKeith or plunger type. The master switch M is of the usual solenoid type used to maintain the plungers of idle line switches "before an idle trunk.

Application for reiuue filed April 7, 1980. SerialKo. 442,432.

I The substation A comprises the usual apparatus tions of automatic telephone systems. The special high frequency generating equipment T consists of' an ordina high frequency buzzer operatingi prefera 1y at about 400 cycles peresecon This equipment is common to anynumb will be clearly brought out hereinafter. The start relay 100 is individual to the connector H, and is for a purpose which willbe subsequently made clear.

Fig. 2 shows a line finder LF, trunk-hunting switch TS, a special A or intercepting operatorsposltion Y, and also an operators cord circuit for answering calls extended to her position. In the cord circuit is included a ver sensitive A. C. relay, disclosed in Patent No. 1,221,299, issue to C. J.- Erickson, April .3, 1917. The line finder, trunkhunting, and finder distributer switches are mechanically the same as line switchesof the well known rotary type having their rlilpers always in engagement with a set of b contacts.

Having given 'a' laneous equipment shown in Figs. 1 and 2, itis deemed advisable, before going into the detailed description of the invention, to briefly describe the trunkin arrangement of the intercepting s stem; t isassumed, in the present case'tiat the connectors H are divi There are provided four or five fift point line finders LF for each group of fiy con nectors and, of course, since the trunk hunting switches are individual to their associated line, finders, a like numb'er'of these switches are necessary. switches ma point. type trafiic conditions. For eachroup of connectors there is provided one nder distributer FD. This finder distributer has its wipers normally associated with anidle link.

circuit of its associated group and permits the trunk hunting operation and line finding operation to take place automatically when the switching through relay of a connector,

which may be'of t e t pe The trunk hunting be of the twenty-fiveor fifty ependent, of course, upon thenssrcnon', BY KESNE as srem m's, 'ro rumors,

used in substaer of lines and its purpose 7 description of the miscel- 7 previously operated switches a so which has been seized, remains deenergized for a predetermined time after the connector has come to rest on the contacts of :1. called line.

In order to describe the invention, it will now be assumed that a calling subscriber desires to extend a connection to the substation A, whereupon such subscriber, upon removing his receiver and 0 rating his calling device, switch train to extend a connection to the connector H which, it is assumed, is idle, causing the energization of line relay 11 which in turn'completes a circuit for the slow release relay 12. Upon energizing,'relay 12 prepares the connector for operation in its vertical movement in the usual way and at armature 25 connects ground to the release trunk conductor. A holding circuit is thus established which maintains all the in operated position in the usual manner.

When the next series of impulses is transmitted over the control circuit b the calling subscriber the line relay 11 of the connector H is momentarily deenergized a plurality of times and at each deener 'zation transmits an impulse of current to t e vertical magnet 18 .over a path'which extends from ground by way of armature 24 and its resting contact, armature 26 and its workin contact, ofi normal springs 21 and 23, winding of the slow acting series relay 13, and the winding of the vertical magnet'18 to battery. By the operation of the vertical magnet the wlpers -52, inclusive, are raised step .by step until theystand o osite the desired level of bank contacts. l elay 13 is energized in series with the vertical magnet 18 and being slow actingholds up continuously during the vertical operation of the switch.v By the operation of this relay, the vertical ma et circuit is preserved intact, notwithstan iiig the shifting of the ofi normal springs, which occurs at the first vertical step of the switch.

At the end ofthe vertical movement, relay 13 deenergizes and transfers the operating circuit to the rotary magnet 19. g 1

The calling subscriber now transmits the final series of im ulse's of the called tele-f phone number. 1 esponsive to these interruptions the line relay 11 is deenergized a corresponding number of times and now sends im'pulses to the rotarymagnet 19'over the following circuit: from ground by way of armature 24 and its resting contact, armature 26 and its working contact, oil normal springs 21. and 22, armature27 and its restmg contact, resting contact of armature 32 and the said armature, armature 39 and its resting contact, andthe winding of the rotary magnet 19 to battery. By the opera- 1 tion of the rotary magnet the w pers 50-42, inclusive,

and are finally brought to rest in engagecauses I the various switches of a I windin .relay 17 pulls up,

are rotated step by step ment with the particular set of bank contacts in which the line of substation A is terminated, these contacts being'indicated in the drawings by reference characters 53, 54 and 55. The slow acting relay 16 is energized in parallel with the rotary magnet and remains continuously energized during the rotary movement. In operated position, relay 16 connects the test wiper 51 to the winding of the test relay 15 by means of its armature 33 and at armature 35 closes an alternative point in the circuit of the rotary magnet, to ard against the possibility of having this circuit 0 ened by the operation of the test relay w He the test wiper 51 is passing over grounded test contacts.

The final series of impulses has now been received, and the connector wipers have been placed in connection with the terminals of the called line. If the line is busy there will be a ground potential on the test contact 54 and the test relay 15 will be energized. When this rela operates it prepares a locking circuit or itself at its armature 31, which is completed when the slow actingrelay 16 falls back an instant later, opens the rotary 'magnet circuit at armature 32, and at armature '34 connects a lead from the busy'signaling machine to the lower side of the line. -On perceiving the signal, the subscriber will replace his receiver, thereby releasing the connector H and all previously operated switches.

Assuming now that the called 'line is idle when connection therewith is attempted, under these circumstances there will be no ground on the test contact 54, and the test relay 15 will not be ener ized. Then when the slow acting relay 16 alls back a circuit is completed for the switching relay 17 which may be traced from the grounded 0on ductor 7, by way of armature 31 and itsresting contact, the upper winding of the switching relay 17, resting contact of armature 33 and the said armature, test wiper 51,v test contact 54, contacts of the jack J of the cut-off or switching relay 62 of the line switch C, contacts 71 of jack J, to battery. Relays 17 and 62 are energized in series over this circuit, and the latter relay operates armature 72 to clearthe-line conductors 60 and 61 of their normal'battery and ground connections in the line switch C.

At the connector H, when the switching it establishes a locking circuit for itself at armature 38, grounds the test wiper 51 at armature 37, opens the rotary magnet circuit at armature 39, and at armatures 36 and 40 connects up the two ine wipers 50 and 52. By the latter'operation a signaling circuit is established whereby ringing current from the generator GEN is intermittently projected out over the called-line to operate the bridged ringer at substation A to notify the called subscriber that he is wanted. The return path for the ringing current includes the upper windin of the ring out ofi relay. 14, and when t e called subscriber answers this relay is operated. Upon energizing, relay 14 establishes alocking circuit for itself at its armature 29, breaks the ringin circuit ate armatures 28 and 30, and at t e working contacts of these same armatures finally completes the talking connection.

Current is now supplied to the transmitter at substation A through the windings of the double 'wound back' bridge relay 10 which is accordingly energized. This relay is a reversing relay and has the well known function of reversing the incoming trunk conductors 6 and 8 as regards their connections with the windings of the relay 11.

This reversing operation is a standard op-' eration and is for the purpose of operating subscriberspaystation or metering apparatus, and in some cases is used for supervisory purposes. The subscribers may now converse as desired.

When the subscribers are throughtalking they will replace'their receivers, causing the connector H and all previously operated switches to be released in the usual and well known manner.

of the line switch C. in a'simple manner by merely placing a thin and the said armature,

ing relay 17 does not energize,

There is nothin particularly new in the operations above escribed. t is thought, however, that the above description will be a material aid in making clear the various features of the invention.

It will now be assumed that the subscriber at station A has had his service discontinued, or that the telephone at station A- has been taken out. :Now in order to trunk calls which may be extended to the line switch 0 to a special A or intercepting operators position, it is only necessary that battery potential be removed from the test contact 54 This is accomplished iece of insulatingmaterial between springs 0 of the jack J. When the connector H seizes the line switch-C under these condi-' tions, the test wiper 51 fails to find battery, and when the slow relay 16 deenergizes,"relay 17 fails to pull up and a circuit is completed for'start relay armature 49 and the said. armature, armature 31 and its resting contact, upper winding of relay 17, resting contact of armature 33 and the said armature, armature 37 and its resting contact, armature 43 and its resting contact, resting contact of armature 44 rotary 'ofi normal springs 45, conductor 46, resistance 99, and the winding of relay 100 to battery. Due to the high resistance of relay 100, switchand' relay 100,

100. This circuit may. e traced from grounded working contact of junctions 105 and due to the inclusion of resistance 99, only receives suflicient current to cause it to oper-' ate its armatures 102 and 103. The operation of armature 103 causes ground to be removed from conductor 155 terminating in a bank contact of the line finder LF, at the frontcontact of this same armature repares a new circuit for relay 100 indepen ent the resistance 99, and at armature 102 completes a circuit for slow release relay 110 of the finder distributer. Relay '110, upon operating, at its armature 117 prepares locking circuits for relays 111 and 112, and at armature 116 connects interrupted ground to the windings of relay 111. Interrupter' I is arranged to apply round to conductor 130 for a period of one to remove ground from this conductor for a like period. As soon as ground is connected to conductor 130 relay 111, upon having a circuit completed through its upper winding, operates its armature 118, thereby short circuiting the lower Armature 119 is so adjusted that it will not operate until the current flow is established through both windings of relay 111. As soon as ground isremoved from conductor 130 a circuit is completed-from the grounded working contact of armature 117 and the said armature, armature 118 and its wor ing contact; and the windings of relay lll I A has elapsed relay 112 operates sufficiently to' winding of this relay;

alf second and then cause its armature 125to engage its working contact, and at the termination of another half second interval the short circuit is removed from the lower winding of this relay permitting it to also operate its armatures 120-124, inclusive. I armature 121 completes circuits for relays 113 and 114 The circuit for relay 113 may .be' traced from grounded working contact of armature 121- and the said armature, winding of relay 113, wiper'131 and its associated contact, conductor 145, interrupter springs of the motormagnet 156, and the winding 0 said magnet to battery. The circuit for relay 114 may be traced from the grounded working contact of armature 121 and the said armature, winding of relayf114, conductor 1'08, wiper 133 and its associated contact, conductor 136, interrupter. springs of the motor magnet. 139, and the winding of said magnet tobattery. By the operation of armature 124 a circuit is prepared for the motor magnet 104' of the finder distributer FD independent of interrupter contacts 129,

and by the operation of armatures 120 and 123 test wipers 164 and 153 are cgnnected to.

107, respectively.

Assuming now that i the trun hunting The operation of= switch TS has its wipers'associated with a trunk line which is in use, the contact with,

' and its resting contact, junction 105, wiper 131 ,and its associated contact, conductor 145, interrupter springs of motor magnet 156, and the windin of said magnet to battery. Relay 113 is s ort circuited by ground at junction 105 and cannot operate. Magnet 156 operates and interrupts its own circuit, and upon deenergizing steps the wipers 7163165, inclusive, into engagement with the contacts of the next trunk line. If this trunk line is in use, the above described operation of ma et 156 will be repeated. As soon as the wiper 164 comes into engagement with the test contact associated with. conductor 150 of the trunk line comprising conductors 149-151, inclusive, which it is assumed isidle, no ground potential will be present on conductor150 and the switching relay 113 will no longer be short circuited and will therefore operate. Since the resistance of this relay is very high compared:

to that of motor magnet 156, the magnet is not operated at this time. Relay 113, upon operating, at its armature 127 grounds the test conductor 150 of the seized trunk, to make the same busy to other trunk selecting V switches, and at its armature 126 prepares a pointin the operating circuit of magnet 104, and relays 115 and 140.

Assuming now that the'wipers 152-154, inclusive, of the line finder-are not in engagement with contacts associated with connector' trunk conductors 47, 48 and 155. Under these conditions ground will be present on the contact on which wiper 153 is positioned and, therefore, a circuit will be completed for motor magnet 139, this circuit being traceable from thegrounded test wiper 153, armature 142 and its resting contact, conductor 137 wiper 134, working contact of armature 123 and the said armature,

junction 107 (ground at this point short circuits relay 114. and prevents it from operating), wiper 133 and its associated contact, conductor 136, interrupter springs of the motor magnet 139 and the winding: of

said magnet to battery. The magnet 139 will, therefore, operate and as long as they test wiper 153 comes into engagement with idle connector trunks, will continue to operate in the same manner as explained 1n connection with the operation of magnet.

156. As soon as the test wi r153 comes into engagement with the ban contactwith which the ungrounded conductor 155 is associated, magnet 139 will cease to operate and relay 114, having the short circuit re- I moved from its windin will now energize. Since both switching re ays 113 and 114 are.

now) operated multiple circuits are com cuit divides, one branch extending direct to the winding of relay 115 and to battery,

While the other branch extends by Way of wiper 135, conductor 138, and the windin of ,said relay 140 to battery. The result 0 the o eration of magnet 104 and relay 115 will e described later. Relay 140, upon operating, at its armatures 141 and 144 and their working contacts extends the talking conductors of the calling line by way of conductors 146, 148, and conductors 149 and 151 to the intercepting operators position Y, at armature 143 shifts conductor 147 from engagement with -grounded conductor 157 into engagement with grounded con-' ductor 138, and at armature 142 disconnects wiper 153 from engagement with conductor 137 and connects this wiper to grounded conductor. 138. The line relay 11 of the connector is bridged across conductors 6 and 8,'wh1ch are now extended by way of conductors 47 and 48, conductors 146 and 148 to conductors 149 and 151 across which are bridged the windings of relay 172 at the I intercepting operators position. Relay 172 operates in multiple with line relay 11 and at its armature 167 connects interrupted generator to the conductor 149 by way of armature 173 and its resting contact and low capacity condenser 168. Condenser 168 allows just suflicient current to leak back over the calling lineto give the calling subscriber the usual ring-back tone to inform him that the signaling operation is taking place. Relay 172 Yalso, at armature 160, completes a circuit for the call signal lamp L, which glows to notify the interceptingoperator that a call is awaiting her attention, and at armature 159 applies ground through a low resistance retard coil to conductor 150 to maintain the trunk busy to other trunk selecting switches independent of ground supplied by way of wiper 135, and to provide a holding circuit for relays 140 and 100 after the finder distributor has stepped ahead.

At the same time that the circuit for relay 172 was completed, a new circuit was completed for start relay 100 at armature 142 independent of resistance 99 in multiple with the winding of relay 142, permittinfinder relay 100 to operate its armatures 101 an 181. The operation of armature 101 causes ground to be removed from the common start conductor, while armature 181 short circuits high resistance 99. The latter operation continues the holding circuit ground on con-ductor 150 back to the test wiper of the connector, thus shunting the upper winding of relay 17 so that if another connector should connect with the same line relay 17 would not pull in series with the busy test relay of the second connector. 7

It will be recalled that slow release relay 115 and motor magnet 104 were energized in multiple with switching relay 140. The result of the operation of relay 115 and magnet 104 will now be described. Relay 115 operates and opens the circuit of relay 110. Relay 110, upon deenergizing, at its armature 117 opens the locking circuits of relays 111 and 112. These relays, accordingly, deenergize. The deenergization of relay 111 in no way affects the operation of distributor FD. Relay 112, however, upon deenergizing, at its armature '1'21 breaks the circuits of switching relays 113 and 114 and these relays, accordingly, restore to normal. The deenergization of .relays 113 and 114 causes ground to be removed from the common operating circuit of relays 115, 140 and .motor magnet 104.

, Magnet 104 and relay 115, accordingly, de-

" energize. Relay 140, however,

' cuit happens vfor magnet 104 will does not deenergize due to the previously described holding circuit completed for it by the operation of net 104, upon deenergizing, shifts its wip-' ers 131-136, inclusive, into engagement with the next link circuit. If. the next link cirto be in use at this time its associated conductor 138 will have ground potential thereon and an operating circuit magnet 104 the interrupter springs 129 are opened, and this magnet, therefore, deenergizes to advance the wipers into engagement with the next link. It will be quite evident that this operation will be repeated until an idle link circuit is found. Since relay- 115 is connected to wiper 135 this relay receives ground impulses in multiple with. magnet 104 and, being slow to release, will remain operated during the operation of magnet 104 to maintain the relay 110 disconnected from the common start conductor until an idle finder link is found.

. Assuming now that no other connector, of the group to which connector H belongs, has in the meantime been positioned on contacts of a line in trouble, etc., no others'tart relay, such as 100, will be operated, and

armature 159 of relay 172. Magagain be completed by way of wiper 135, interrupter contacts 129,

since, as previously explained, armature 101 of relay 100 is now. operated no ground is present on conductor 17 5 and relay 110, therefore, does not again'operate. If, how-.

the meantime been positioned on contacts of ever, it beassumed that a connector. has in a line in trouble, etc., its associated relay 100 will be energized and therefore conductor 175 will have ground potential thereon and relay 110 will again operate to inidescribed. The intercepting operator, upon observing the lighted condition of lamp L inserts the plu P .of her cord circuit in the jack J, there y closing a circuit for relay 17 4.- Relay 174, upon operating, removes ground from conductor 150 and completes a circuit for relay 158. Relay 158, upon operating, at itslower armature opens the circuit of lamp L, and 'locks itself up through its u per winding and the working contact 0 this same armature, and at its armature 173 disconnects interrupted 'gen-. erator tone from the upper line conductor. When the plug was inserted in jack J sleeve relay 170 in the cord 0 energized in series with relay 140. Relay 170 in pleted a circuit for slow relay 171. This latter relay in operating prevented the lamp L from being lighted. Since the lamp L fails to low the operator knows that the call, has een extended to adeadnumber. The sleeve of-the plug applies ground to operating corn:

the sleeve of the jack J via low resistance..-

to maintain the trunk busy may now operatekey K scriber replaces his receiver,- resulting in the release of the connector H and'all previously operated switches. Since relay 172 is connected in multiple with relay 11, relay 172 also restores and in so doing opens the locking circuit of relay 158. During the restoring operation of connector H of! normal springs 45 open the holding circuit, andas a result these relays restore to normal. Since ground is now removed from the conductor 138, the finder link, comprising switches LF and TS is-again rendered selectable by the wiper 135 of the'finder distributer FD.

The operator uponremoving the plug from the associated jack causes'relays 174 1 When 'the line switch C. Upon a connection being attempted with 'the working line A in trouble,the operations. reviously described will again take place, ut this time, since the high frequency apparatus '1 is associated with the line called, the operations which take place, when the operator answers, will be slight] different,

e operator plugs intojack J, a circuit is completed for A. C. relay 162. This circuit may be traced from high frequency apparatus T, lug P, upper. one of the springs 70, ba contact 54, wiper 5 armature 37 and its resting contact, armature 43 andits restin contact, resting contact of armature 44 an the saidarmature, rotary of! normal contact 45, conductor 46, armature 181 and its working contact, working contact of armature 103 and the said armature, conductor 155, wiper 15 3, armature 142 and its working contact, working contact of armature 143 and the said armature, conductor147, wiper 164, conductor 150, sleeve of jack J, sleeve side of plug P, condenser 163, and the winding of relay 1621.0 ound; Relay 162'therefore operates at t e same time as does relay 170, thereby'preventing the operation of relay 1Z1. Lam fore 1i hted to immediately in orm the operator o the character of the called line thereby enabling the operator to convey such information tothecalling subscriber without delay.

After conversation has been completed,

release is bro ht about in the same 'manner as lpereviously ascribed, v

fore c oncluding, it is thought advisableto explain the" reason for provIidin the ui ment com rising internupter an twot ep relays 111 and 112 'for delayin the operation of the switches'LF and T It will be noted that a connector, such as H, upon switching through, transmits amomentary ground impulse to its associated start relay 100 over a circuit-extending. from grounded conductor 7, armature 31 and its resting contact of armature 33 and the said armature, armature 37 and its resting. con-1 tact, over the previously traced circuit through the associated start relay. The possibility of a number of connectors, switching since the holdin L is therein linewith said switchboard. resting contact, upper winding of relay 17 through in close se uence, resulting in'the starting of a finder link is made impossible by the useof this delayin mechanism.

' Attention is also calle to thefact that circuit used for the transmission of the igh frequency currents to 'theoperator is nowhere connected direct to ground or battery, even before the operator plugs in to answer the call, it is possible for the operator to test for the presence of these signalling currents on the sleeve of the jack before plugging in, the same as when testing a line to see if it is busy. \Vhen this" method of operation is followed the'special eguipment s own in the cord circuit 0 is 0 course not needed and-a standard subscribers operators cord circuit may be used.

Having fully described the invention,

what is considered new and is desired to have protected by Letters Patent will be pointed out in the appended claims.

What I claim is:

1. In a telephone system, acalling line, called lines, unassigned called lines, other called lines assigned but temporarily out of service, means including automatic switches for extending a connection to any of said called lines, means responsive when a connection is extended to either of. the latter type of called lines for automatically trunking the call to an operators switchboard, and means whereby an operator upon answering is immediately informed of the class of line called.

2. In a telephone system, acalling line,

unassigned called lines, other called lines assigned but temporarily out of service,

means including automatic switches for exat sald switchboard, means operative when an operator answers a call for causing the o rationof said signal if the line cal o the latter type, and means operative preventing the operation of said signal in case the called line is of the first type.

,3. In a telephone system, a called line temporarily out of service, a connector ing line to connect with said called line, an

operators switchboard, a' link circuit comprising a finder switch and a hunting switch, and a start; relay associated with said connector operative when'said line is called for causing said link circuit to connect the call- In a tele hone system, a connector switch, wipers or said switch adapted to be positioned on terminals of called lines, a Witching "when a relay in said connector operative me is called, means for preventing the operation of said relay should the line ed isswitch adapted to be controlled over a call called be in trouble, and means operative should the switching relay fail to operate within a predetermined period for causing said connection to be extended to an oper-. ators switchboard.

5. In a telephone system, a calling line, called lines of difierent classes, an automatic switch having access to said lines, subscriber controlled means for causing said automatic switch toextend connections tosaid lines as desired, an operators switchboard, means for automatically trunking calls extended to certain of said called lines to said switchboard, a visual signal at said switchboard, means 'thereat operated when the operator answers the call if the called line is of one class for causing the operation of said signal, and means operated if the called line is of a difi'erent class for preventing the operation of said signal.

6. In a telephone system, an automatic switch, subscriber controlled means for con trolling the operation of said switch to extend connections to called lines of different classes, an operators switchboard, means for trunkin connections extending to called lines of certain classes to said operators switchboard, a call signal at said switchboard operated when a connection is extended thereto, a cord circuit, and means associated with said cord operated or not operated dependent on the particular class of line called when the operator answers the call to inform such operatorof the particular class of the called line.

7. In a telephone system, a calling subscribers line normally having direct accessv via automatic switches to other subscribers lines, means for temporarily plugging any line out of service, an operators switchboard having a plurality of trunks terminating therein, a trunk huntin switch, a line finder switch, a finder distri uter switch, circuit arrangements uter switch to operate responsive to any calling line extending a connection to a called line out of service, and means in said distributer for controlling said trunk hunting switch to find an idle'switchboard trunk and said line finder switch to find the extended calling line and connect it to said idle switchboard trunk.

8. In a telephone system, a calling line,

' a connector switch, a called line terminating in a line switch, a plu ending tone machine for plugging out saiddine switch, subscriber controlled means for causing said connector switch to extend said calling line to said called line, an operators switchboard, means responsive to the attempted extension of said calling line to said called line if the line switch has been plugged out, for trunking said calling line to said switchboard, a plug ending cord circuit including a signal, and means in said cord circuit responsive to said for causing said finder distribtone machine for controlling the operation of said signal when the operator plugs into said trunked line to inform her of the particular class of the called line.

9. In a telephone system, an automatic switch, subscriber controlled means for controlling the operation of said switch'to extend connections to called lines of different classes, a plug ending tone machine for plugging out lines of one-class, an operators switchboard, means responsive to the extension of a calling line to'a plugged-outline for trunkin said calling line to said operators switc board, a call signal at said switchboard operated when a connection is extended thereto, and a cord circuit for testing for the presence of saidtone machine and answering said call.

10. In a telephone system, a line having a ending trunk, means including another automatic switch for extending a branch of said connection to said trunk, and a signalling circuit extendin from 1 said test contact thrfiugh all sai switches to the sleeve of said we I 11. In a telephone system, a line having a test contact, a source of signalling current connected to said contact, means including an automatic switch for extending a connection to said line, said switch having a test wiper for engaging said test contact, a trunk line extending to an operators switch-board,

means including another automatic switch" for extending a branch of said connection to said trunk, a non-talking conductor extendmg from said test contact through both said switches to said switch-board and a signalling circuit includingsaid conductor.

12. A telephone s stem as set forth in claim 11 in which tlie said second switch includes a relay energized over said conductor for maintaining the connection.

13. In a telephone system, lines to which service is denied and linesto which service is given, both. accessible by way of an automatic switch, means for operating the switch to extend a call to either class of lines, means responsive-to the calling of a line of the first mentioned class for extending the call to an operators switchboard, the lines of the first eating to the operator the particular subclass of the called line.

14. In a telephone system, a line including talking conductors and a, test conductor, means for establishing a connection to the line, means for testing the busy or idle condition of the line, means effective if the line is idle for completing the connection, and

. a test conductor, means for establishing a venting the operation of the relay, and means effective in response to the failure of said relay to operate. for causing the calling connection to be extended to an operators switchboard.

16. In a telephone system, a line including connection to the line, a plurality of trunks extending to an operators switchboard, and time delayed means effective-if the test conductor is open to seize any idle trunk in said group of trunks and extend the-call thereover.

17. In a telephone system, a line including a test conductor, means for establishing a connection to the line, a plurality of trunks exfending to an operators switchboard, time de ayed means for extending the call to any idle trunk in said group of trunks, and means controlled over the test conductor for rendering said last named means inefiective.

18. In a telephone system, a line including a test conductor, means for extending acall to the line, a trunk terminating at an operators switchboard, means including a finder effective when operated to extend the call over the trunk, time delayed means for starting the finder to operate, and means controlled over the test conductor for rendering the second named means ineffective.

19. In a telephone system, a trunk extending to a connector switch, a branch of the trunk accessible to a finder switch, a starting relay for the finder switch, a test relay and a switching relay in the connector, circuit connections for the starting relay established when the connector has been operated if the test relay and the switching relay are not operated, and means controlled by the starting relay for starting the finder switch to hunt for the branch of the trunk.

20. In a telephone system, a trunk extending to a connector switch, a branch of the trunk accessible ma finder switch, a starting relay for the finder switch, a test relay and a switching relay in the connector, circuit connections for the starting relay established when the connector has been operated if the test relay and the switching relay are not operated, means controlled by the starting relay for starting the finder switch to hunt for the branch of the trunk, and means for extending a connection from said branch by way of the finder switch to an operators headset.

21. In a telephone system, a trunk, a connector including a testing relay and a switching lines and various types of called lines,

automatic switching mechanism for interconnecting calling' and called lines, an operators position with signals thereat, means for automatically intercepting the connection for the called line and extending it to said operators position, and means after such connection is extended to operate said signals to indicate the type of the called for line.

23. In a telephone exchange system, calling lines and classified called lines, means for extending connections between said lines, an operators position with signals thereat, means for automatically extending said lines -to said position in lieu of called lines, and

means to operate said signals to indicate the classification of the called lines.

24. In a telephone system, callinglines and 4 Various types of called lines, means for extending connections between said lines, an operators position, means for automatically extending a connection to said operators position instead of a called for line, and means for notifying the operator of thetype of the called for line.

25. In a telephone system, calling lines,

classified called lines, automatic switching mechanism for extending connections from said calling lines to said called lines, an operators position, means for automatically intercepting a connection and extending it to said operators position instead of the called for line, and means for informing the operator of the classification of the called-for line.

In witness whereof, I hereunto subscribe my name this 31st day of March, A. D. 1930.

MICHAEL SCHWARTZ.

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