US1778319A - Telephone metering system - Google Patents

Description

0a. 14, 1930. A. E.'HAGUE 1,778,319

TELEPHONE METERING SYSTEM Filed June 7, 1929 4 SheetsSheet l l 4 /NVEN7'0/? A. E. HA GUE ATTORNFV Oct. 14, 1930.- A. :E. HAGUE 1,778,319

TELEPHONE METERING SYSTEM Filed June 7, 19/29 4 Sheets-Sheet 2} IIHI'I 0 Q a; m & fa F, E: E Q E Q w R {I- N B QL L QR I N N INVENTOR A. E.YHAGUE" ATTORNEY Oct. 14, 1930. HAGUE 1,778,319

TELEPHONE METERING SYSTEM Filed June 7', 1929 4 Sheets-Sheet 3 A.E.HAGLIJE By Oct. 14, 1930.- A. E. HAGUE 1,778,319

TELEPHONE METERING SYSTEM Fil ed June 7, 1929 4 Sheets-Sheet 4 llll llll INVENTOR A. E. HAGUE Patented Oct. 14, 1930 UNITED STATES PATENT OFFICE ALFRED E. HAGUE, OF WEST ORANGE, NEW JERSEY, ASSIGNOR TO BELL TELEPHONE LABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK TELEPHONE IMETERING SYSTEM Application filed June 7, 1929. Serial No. 389,028.

This invention relates to dial telephone eX- change systems and particularly to metering arrangements applicable to party lines.

' It has for its object economy in the amount of equipment necessary for such metering.

In accordance with one embodiment of the present invention means is provided com mon to a plurality of district selectors for testing the calling line to determine the calling substation and-to establish a record in the district selector of that substation. Several identification circuits are provided each normally serving a singlegroup of district selectors, but capable, should one or more of them fail to function properly, of serving more than one group of selectors. A timing arrangement is provided and means for dis criminating whether a delay is due to faults in the identification circuit or in the district selector and in response to such discrimination to release the district selector or to con nect it with a different identification circuit. l he testing of the line involves reversal. of current flow over the line. In order to reduce the clicks produced by this reversal a network is provided in each identification circuit. This network is connected in parallel with tie talking circuit by the same operation that associates the district selector with the identification circuit after which the talking circuit is opened and the network thereby inserted therein. The network remains in position during the performance of the tests and until after the line has been reclosed.

The invention will be more clearly understood from a consideration of the following: description in connection with the attached drawings in which Fig. 1 shows a portion of a district selector; Fig. 2 shows fourparty line, an individual line, and the common meter control equipment; Fig. 3 shows one complete party identification circuit; Fig. 4 shows portions of two other identification circuits; and Fig. 5 is a diagram indicat an idle sender and the wanted line number is recorded in the sender which thereupon controls the selective operations of the district selector nd other switches. lVhen selections have been completed a relay is operated which connects an idle identification circuit with the calling line. The operation of this relay connects a network in parallel with a section of the talking circuit as it extends through the district selector and then opens the talking circuit to insert the network therein. The identification circuit then connects a relay to both sides of the line in parallel to detern'iine whether the substation. calling is grounded and then in effect applies battery first to one side of the line and then to the other to operate the polarized relay at the substation which, by its response, de ermines the registration. Following the reg stration the line is reclosed and the identification circuit is disconnected from the selector. lVhen the called subscriber answers and the charge relay operates as an indication that the call has been successful, a meter control circuit is associated with the district selector under the control of the registration set up by the identification circuit. The meters of the corresponding party of all lines located on the same frame are connected to the respective meteringterminals of the line. For example, if the calling substation were substation #1, then the :ttl meter for c cry party line appearing in the same panel would be connected to the metering terminal of the correspondin ine. Thisoperation i i pplica o ring curl terr .al for a measured inte"- val after which the current is *ovcd and t'.. cr control ci t selector.

l y 100, thus initiating the op- These eration of a trio, start and link circuit. circuits in turn bring about the operation of a particular line finder and district selector for the purpose of extending the call. The line finder, for example line finder 101, counects with the calling line, after which The the line is associated with a sender.

mt to lower back-contact of relay 105, upper contact of relay 112, to ground at the baclr 'eloses'a. circuit tron operation of the dial on the calling line registers the number of the wanted subscriber in the sender in accordance with which the sender controls the operation of the district selector 102 and other switching apparatus for completing the connection. The sequence of operations of the district selector is guided by a sequence switch which advances from position to position as the circuit functions. Since the foregoing operations are merely incidental to the present invention, no attempt has been inade to either show or describe the apparatus and its functions in detail. Reference is hereby made to U. S. Patent 1,589,402, granted January 22, 1926 to G. H. Kopp, for a detailed description of the establishment of'a connection through equipment of the type shown. 7

As set forth in the above identified patent, the operations of the line inder 101 and districtrselect-or 102 take place in positions 1 to 9 inclusive of the sequence switch while those of the switching apparatus to which the district selector has access, take place with the district selector sequence switch in position 10. When the selections have completed, indica't-ion'of this is returned to the sender which advances the district selector sequence switch fromposi-uion 10 to position 12. As soon as the sequence switch leaves position 10, a circuit is closed from ling of relay. 103,

battery, through the w i lower contacts of sequence switch cam 10 1, baci;

contact of relay 300. This circuit also e tends to ground at the back contact of relays 400 and 150 so thatshould relay 300 b e.op erated because of a failure of the identification circuit, as will he described hereinafter, relay 103 will nevertheless be operated. Re

lay 103 looks over its lower front contact and the back cont-act of relay 112 to ground at the back contact of relay 300, thus'rendering itself independen of the sequence switch and of relay 105. relay 103 in o iiere.

ba zteiyiv throng sf its upper frontcontact, lower winding of relay 303, lo"er back contact of contact, inner back contact of of the dist 'ict sequence switch selections and conversation .while' 'the identification is being made. itelays 106and 107 complete connections from 106, lowerback contact of relay 801, lower back contact'of'relay 302, to ing o r i.-

ground. Relay 1 06 operates, '1 its upper winding and over its inding of relay 30%, upper back relay 302 to ground. per contact of relay 106 also completes a circuit in parallel with the upper winding of relay 106 for relay 10?,which also opera s after an interval. Relays 106. and 107' are held operated independent of the position so that tall:- may proceed and the district selector as well scribers line are uninte The 01681110111 the upthe identification circuit to the district selector. The four uppermost contacts of relay 107 serve to connect network 310 in parallel with a portion of the talking circuit, namely, that part passing through the contacts of relay 105. These circuits may be traced: From the tip brush of the line finder, fourth contact of relay 107, upperback contact of relay 800 to the upper right terminal of the network, through the upper retardation coil, uppermost back contact of relay 311 upper back contact of relay 307, sixth contact of relay 107, to the tip conducuor of the talking circuit at a point beyond the Contact of relay 105; 'rom the ring brush of the line finder, third contact of relay 107, inner back contact of relay 306, to the lower right terminal of the network 810, lower retardation coil, middle back contact of relay 311, through the winding of relay 312, inner back contact relay 307,'upper normal contact of relay 316,

lower winding of relay 315, upper back contact of relay 307, sixth contact of relay 10?, upper back contact of relay 109, upper left indingfof repeating coil 108 to ground.

Relay 315 o ierates in this circuit and initiates the testing of the calling line. operat on of relay 815 completes. a circuit from ground at its upper front contact, inner back Contact of relay 309, middle lower frontcontact of relay 106, upper wading of relay 105 to batoc Relay 105 operates, opening thetalking circuit atits contacts andthiis introducing the network 310 into thetalking circuit so that the subsequent tests may produce no unpleasant clicks or ther noises to 0 disturb the conversation. ll the inclusion of'the network in theta hing circuit y is includedin a :ircuitfed by battery through the repeating coil 108 and extQ-EK ng over the subscribers line, in which circuit relay 312 operates provided the cone ductors connecting the identification circuit The closure of'the locking circuitof relay 106 causes the opei iion of relay 301 which in turn operates relay 301; to prevent the transfer of the call to another, identification circuit. RelayBOl also closes acircuit over its lower front contact, lower baclrcontact of relay313, windingof relay 314 to batt ry, preparing a timing circuit for determining whether tie tests are completed properly. It also connects ground Over conductor 32 to the armature of relay 312. V j

1:30 7 The Assuming that relay 312 operates, a circuit is closed from battery, through the winding of relay 313, lowermost back contact of relay 311, contact of interrupter 317, front contact of relay 312 to grounded conductor 320. Relay 313 looks through the winding of relay 311, over the upper front contact of relay 313 to grounded conductor 320. Re ay 311 does not operate until interrupter 317 opens its contact to open the shunt around the winding of relay 311. lVhen relay 311 operates the subscribers line is disconnected. from the repeating coil, but relay 315 remains bridged across the repeating coil holding the connection. The two sides of the subscribers line are then extended over the upper front contacts of relay 311 and the back contacts of role 318 to the winding of relay 319 and battery, to determine whether the calling party is one identified by ground.

Examining Fig. 2 for a moment it will be apparent that each party 210, 220, 230 and 240 has a polarized relay and a grounded contact associated with the substation. ith the receiver removed from the switchhook the substations 210 and 220 are not grounded while substations 230 and 240 have ground connected through the winding of the polarized relay to the line. In the case of substation 230 the ground extends over an auxiliary Contact of the switchhook, back contact of pole i/ied relay 231, retardation coil 232, upper winding of polarized relay 231, through the switchhook, transmitter and dial contacts 236 to the ring conductor, and through both windings of the polarized relay and one winding of the substation repeati coil to the tip conductor. In the case of n 21-0 the ground extends over the a V co: act of the switchhook, back contact'of re y 2 11', retardation coil 242, upper winding of relay 241,,left Winding of coil 24:4: to the ti conductor while it extends through bo h w VllllflfS of the polarized relay throu 'lie switchhook, transmitter and dial contacts the ring conductor. Since the subscriber at substation 220 was assumed to be calling, ground will not be connected. to either tip or rip; conductor and relay 319 will not be operated. It should be noted that the battery connected to relay 319 is the re verse of that used el ewhere so that it has no effect on. the polarized at the substations.

The nest closure of the contact of intcrrupter 317 completes a circuit Irom grounded conductor 320, middle front Contact of relay 313, Contact of interrupter 31?, lower tcontact of elay 311, back contact of relay 321, lower back contact of relay 322,

winding of relay 318 to battery. Relay 318 operates and loclzs through the winding of relay 322 and the lower front contact of relay 318 to grounded conductor 320 but relay 322 d esnot operate until interrupter 317 opens its contact. lVhcn ground was connected to conductor 320 a circuit was also closed over the lower back contact of relay 318 to the winding of relay 326 and battery. Therefore, the operation of relay 318 extends the tip conductor of the subscribers line over the front contact of relay 311, front contact of relay 318, back contact of relay 322, to the upper winding of relay 323 and battery and in parallel through resistance 341 and the inner upper front contact of relay 326 to bat- It also extends the ring conductor over the middle -front contact of relay 311, inner upper front contact of relay 318, inner upper back contact of relay 322, through the lower winding of relay 323, to battery through lamp 324 and in parallel with the winding; of relay 323, through resistance 3 1-2 and the up per front contact of relay 326. Battery 325 the usual coin battery and has a value of approximately 110 volts while the battery connected to the upper winding of relay 323 approximately 50 volts. The net result of the use of these two batteries is the same as though one 50 to 60 volt battery were con nected to the side of the line to which the coin battery is connected. The purpose served by using the two batteries will be apparent hereinafter. The operation of relay 318 opens the circuit of relay 326 which is slow to release and, therefore, after a short interval opens the shunts closed through its contacts around the windings of relay This, therefore, permits the polarized. relay in the substation to operate, if it is going to, before relay 323 becomes effective. In the present case polarized relay 221 operates since it is so connected and polarized as to respond to negative battery applied to th ringconductor. When relay 221 operates it connects ground over the auxiliary switchhook contact, front contact of relay 221, through retard coil 222, upper winding" of relay 221, contact 226, trmismit-ter 225, dial contact 224: to the ring; conductor. It also connects ground over the switchboard contact, front contacts of relay 221, retardation coil. 222, both windings of polarized relay 221, winding of repeating coil 227 to the tip conductor. Therefore, when relay 32o relcases opening the shunts around the windings of relay this ground imbalances the circuit of differential relay 323 so that the relay opcrates and closes a circuit from ground, over its front contact, inner back contact of relay 308, innermost lower front contact of re 1y 108, winding of relay 109 to battery. Relay 109 operates and locks over sequence switch cam 110 to ground. It is to be noted that the windings of relay 323 are so proportioned that the current flowing through them from 110 volt battery 325, over a loop at the subscribers substation, to central oflice battery connected to the upper winding of relay 323 maintains the relay unoperated whereas with ground connected. to the circuit at the-sub station, the current through one winding is reversed and results in the operation of the relayf The same holds true of relay 327;

At the same time that relay 326 was operateda circuit was closed from battery, through the winding of relay 328, inner lower back contact of relay 322 to grounded conductor 320. Therefore, when relay 322 operates following the openin of the contact of interrupter 317, the tip conductor of the calling line is extended over the-outer upper front contacts of relays 311, 318 and 322,'the upper winding of relay 327, and in parallel therewith through resistance 3 13 and the upper front contact of relay 323,,through lamp 324 to 110 volt battery 325. The ring conductor is extended over the inner upper contacts of relays 311,318 and 322 to central ofiice battery through the lower winding of relay 327 and in parallel therewith through resistance 34 1 and the inner front contact of relay 327 to central ofiice battery. As in the case. of relay 323 relay 327 cannot operate with its windings shunted in this manner-Q The operation-of relay 322 opens the circuit of relay 328 and when thisrelay releases after an interval the w ndin s of relay.;327 are con nected 'dlrectly to the line. Since the polarized-relay221 responds only to battery over A the ring conductor, it does not operate at this time-and, therefore, does not connect ground 2 to the line,'leaving relay 327 unoperated.

" The next closure of the. contact of interrupter 317 completes a circuit from conductor 32-0, front contact of relay 313, contact of interrupter 317, innermost front contact of relay 311, back contact of relay 321, lower most front'contact of relay- 322, winding of relay 31 6-to bat-tery. Relay 316 operates and locks to conductor 320. Italso connects ground from conductor 320, over its innermost lower contact to the winding of relay of relay 316 to grounded conduct-or 320. The operation of relay 312 opens the locking circuit'of relay 315 and the operation of relay 316 connects resistance 329 in parallel with the operating winding of relay 315, thus releasing relay 315. The release of relay 315 opens the circuit of relay 105 and that relay releases restoring the talking circuit to its "normal condition. The release ofrelay 315 also opens the circuit of relay'314. The reclosure of the talking circuit shunts the winding of relay 312-which now releases. A circuitis-now closed frombattery, through resistance'lll, winding of relay 112, lowermost front. contact ofrelay 106, upper back contact of relay 309, unoer back contact of relay 315, innermost front contact of relay 313, back contact of relay 312 to grounded conductor 320. Relay 112 looks over its inner upper front contact to ground over cam 110. The operation of relay 112 opens the locking circuit of relay 103 and that relay releases in turn releasing relays 106 and 107, followed by relay 304. The release of'relay 304 disconnects ground from conductor 320, thus releasing relays 313, 316, 318, 322 and 301.

hen the called subscriber answers polar- 'zed relay 113 operates in the well known manner. A circuit is thereupon completed from ground, over cams 11 1 and 115, front contact of relay 113, cam 116, left contact of interrupter 117, winding of relay 118 to battery. Relay 118 operates and locks over cams 119 and 116, front contact of relay 113, cams 115 and 1141 to ground. When interrupter 117 closes its right-hand contact a circuit is closed from ground as previously traced, over the inner upper front contact of relay 118, cam 120, winding of relay 121 to battery. Relay 121 locks over its upper front contact and cams 115 and 114 to ground. I

At the conclusion of the conversation relay 113 releases in turn releasing relay 118, thus intitiating the restoration of the line finder and district selector.

In the meantime with relays 121'a-nd 112 operated a circuit is closed from battery, over the lower front contact of relay 121, inner lower front contact ofrelay 112, upper winding of-relay 122, winding of relay 250, back contact of relay 251, back contact of relay 252 to ground, assuming that the meter con trol circuit is idle. Relay 250 operates momentarily, but relay 122 looks through its lower windin and front contact to the winding'of relay 252 which operates opening the energizing circuit for allrelays such as relay 122 and releasing relay250. Relay 252 also closes a circuit from ground, through its front contact, winding of relay 251 to battery. Relay 251 operates and closes a circuit from ground at the front contact of relay 252. inner left front contact of relay 251, middle upper front contact of relay 122, alternate contact of relay 109, since relay 109 was operated as above described, lowermost back contact of relays 123 and 124, winding of relay 253 to battery. Relay253 is one'of four party relays each 'ofwhich is individual to one of the four parties connected to. a party line. For example, relay 253 is individual to the secondparty and relay 237 is individual to the third party. The line finder and district selector of Fig. 1 is arranged to serve a maximum offour hundred lines. As will appear hereinafter theselines may be either individual lines or party lines; Ifall of the lines served by'this line finder are party lines, it is necessary that each party relay prepare cirlines appear on the same line finder frame with party lines, the corresponding contacts of the multi-contact relays need not be equipped. The operation of relay 253, therefore, by operating the multi-contact relays 25-1, 255, etc, prepares circuits for all of the second party meters belonging to the party lines served by the district selector of F 1. The operation of relays 255 and 25% closes a circuit from ground, over their right front contacts, right back contact of relay 256, right back contact of relay 257, winding of relay 258 to battery. Relay 255 also prepares a circuit from ground through the winding of message register 223, outer left front contact of relay 255, back contact of line relay 100 (which is now deenergized having been released by the operation of cut-off relay 125 when the line was found in the well known manner), to the metering terminal 126 of the calling line. The circuit may be further traced over the line finder brush, uppermost front contact of relay 122, inner right front contact of relay 258, Winding of relay 259 to battery. Relay 259 operates for a purpose which will be described hereinafter. The operation of relay 258 also closes a circuit from battery, through the winning of relay 260, middle front contact of relay 258, left contact of interrupter 261. When interrupter 261 closes this circuit relay 260 perates, locking over its inner front contact to ground at the front contact of relay 252. When interrupter 261 closes its right contact it completes a circuit from ground, over the outer front contact of relay 260, innermost upper front contact of relay 122, resistance 111 and battery. This shunts the winding of relay 112 and that relay releases opening the circuit of relay 122 in turn releasing relay 252, and restoring the meter control circuit to normal. Since the operating circuit of relay 112 was closed through the contact of relay 106, which is now released, it is i1npossible to make a second charge irrespective of the length of the conversation, although it is obvious that there is nothing in the present inventive idea which would prevent its adaptation to repeated charging under the control of the proper equipment.

Had the subscriber at substation 230 been calling the removal of his receiver would have connected ground over contact 238, back contact of relay 231, retardation coil 232, upper winding of relay 231, switchhook contact 234, transmitter 235, dial contact 236 to the ring conductor and through both windings of relay 231, left winding of the repeating coil to thetip conductor.- When, therefore, relay 319 is connected to the tip and ring conductors as above described this relay operates.

Relay 319 in operating closes a circuit from ground through the winding of relay 321, contact of relay 319, upper back contact of relay 305, innermost contact of relay 107, through the winding of relay 12 1 to battery. Battery through resistance 330 is connected in parallel with relay 124, thus insuring the operation of relay 321. hen relay 12 1 operates and locks over its inner-upper front contact and the bottom contact of cam 110, this locking ground is connected in shunt of resistance 330 and battery, releasing relay lVith relay 321 operated the interrupted ground controlled by interrupter 317 is transferred from the winding of relay 318 to the winding of relay 316 so that if relay 12st does not operate before the next closure of interrupter 317, the identification circuit will be dismissed and no registration willbe set up in the district, resulting in a free call.

If the registration is made correctly the remaining tests are made as above described. Relay 231 is polarized to respond to battery connected to the ring conductor. Therefore, when relay 318 operates connecting battery 325 to the ring conductor, relay 231 operates disconnecting the ground at its back contact from the line. lVnen relay 326 rel ases opening the shunt around the winding of relay 323, the current flow through that relay prevents its operation. hen battery is connected to the tip of the line by the operation of relay 322, relay 231 does not operate and the ground remains connected to the line. Therefore, when the shunts are removed from relay 327, this ground causes the operation of relay 327 closing a circuit from ground, over the f ont contact of relay 327, upper back contac of relay 303, second front contact of relay 107, winding of relay 123 to battery. Relay 123 loci-ts over i s inner upper front contact to the ct of cam 110. lVhen the re 'ation e ui ment functions the meter electing circuit may be traced from grourul, over the outer right front contact of relay 256, inner left front contact of relay 251. middle upper front contact of relay 122, normal contact of relay 109, upper front contacts of relays 123 and 12%, winding of relay 237 to battery. Relay 237 operates and connects the third party meter 233 to the metering terminal of the line ready to receive metering potential as previously described.

In the case of substation 210, relay 211 responds to battery connected to the tip conductor and conneccai ground over front contact to the line operating relay 327 and in turn relay 123. In the case of substation 240 since the operation of the hook switch connects ground. to the line, relay 319 is operated in the manner described for substation 230 in turn operating relay 12 1-. Relay 241 does not respond to heavy battery connected to the ring conductor and, thereregistration relays 124 and 109 operate.

' of interrupter 261.

fore, the ground which remains connected to the line operates relay 323, in turn operating relay 109. Relay 241 does respond to battery connected to the tip'conductor, and removes the normal ground therebyprevent' ing the operation of relay 327.

To summarize i If substation 210 calls, registrat-ion relay 123 operates. lfsubstation 220 calls registration relay-109 operates If substation 230 calls, registration relays '124 and 123 operate. If substation 240 calls.

Relay 109 serves the added purpose of reversing the direction of current flow through the substation so that the ground will be removed from the l1ne during conversation. In the case ofsubstation' 220 it prevents the operation of relay 221, while in the case of substa- 4 ual line will not be provided with a polarized relay, grounded contact and a choke coil such as shown in connection with the party line. Since there is no ground at any point of the test none of relays 109, 123 or 124 is operated. The meter selecting circuit extends from ground over the front contact of relay 252, inner left front contact of relay 251, middle front contact of relay 122, normal contact of relay 109, upper back contact of relay 123, upper winding of relay 127, windings of relay 256 to battery. Relay 256 operates and closes a circuit from battery, through the winding of relay 258, right back contact of relay 257, to ground at the outer right front contact of relay256. It also closes a circuit from batte"y, through the winding of relay 259, in nor front contact of relay 258, uppermost contact of relay 122, to the metering terminal of the individual. line, over the back contact 1 of message register 202 to ground. Relay also prepares a circuit from battery, through the winding of relay 260, middle front contact of relay 258, to the left contact lVhen interrupter 261 closes that contact relay 260 operates and locks to ground at the outer front contact of relay 258. Relay 260 prepares a circuit from ground, over the right contact of inter- 1 rupter 261,outermost contact of relay of 260,

inner front contact of relay 122, to resistance 111 and battery, thus releasing relay 1'12, and terminating the registration in the manner previouslydescribed.

In order to discriminate between a lack of registration because the line tested is an individual line and one due 'to faulty opera tion of the identification equipment, the winding of relay 127 is introduced in the circult of relay 256 as above described. ff -the the line relay (not shown) and the wind-' line is an individual line the message register will be connected directly to the meteringtermin'al and relay 259 will operate in series therewith. If the lack of registration is due to faulty functioning relay 259 cannot operate. Therefore, when relay 260 operates, battery is connected over-the back contact of relay'259, middle front contact of relay 260, in shunt of the high resistancewinding of relay 256, thus reducing the resistance in series with relay 127. Relay 127 is marginal-and cannot ope ate as long as the high resistance winding of relay 256 is in its circuit. lVith this winding shunted relay 12'? operates and closes a circuit over its lowermost contact, lowermost contact of relay 112, to the meter 123. A record is, therefore, set up ofthe number of imes that the equipment fails to register. This meter is common to the district selectors served by the identification equipment. If the number of failures recorded appears excessive, key 129 may be operated, locking relay 127 and flashing lamp 130 so that the identity of the district selector may be determined. Relay 127 also opens the circuit of down-drive magnet 131 of the line finder, preventing its restoration to normal and thus indicating the line with which the trouble arose.

Relay 106 is'individual .to the district selector and a similar relay such as relay 132, etc., is provided. for each district selector of th group served by the identification circuits of Figs. 3 and 4. These relays are arranged in sequence and the locking circuit of any relay extends over the back contacts of the relays following it in the sequence. Therefore, if two relays operate at the same time only the lower relay in the sequence can lock and the other district selector must await the release of the identification circuit. If, for any reason, this chain locking circuit is broken so that relay 106, for example, cannot lock. the operation of relay 303 in the energizing circuit of relay 106 prepares a circuit from ground, over the front contact of relays 303. right contact of interrupter 331, winding of relay 332 to battery. Relay 332 looks over its upper f ont contact to the front contact'of relay 303. Relay 303' also closes a circuit from' ground, over its front contact,rlower contact of relay 313, winding of relay 314 to battery. If relay 106 looks through the winding of relay 304 the circuit of relay 303 isopened at once and relay 332 cannot operate. Vi ith relays 332 and 314 both operated the closure of the left contact of interrupter 331 completes a circuit from ground at the front contact of relay 303, left contact of interrupter 331., lower front contact of relay 332, front contact of relay 314, winding of relay 333 to battery. Relay 333 locks through its lower winding and lower front contact, key 334, winding of relay 335 to ground, thus operating an alarm which can only be silenced by the operation of key 33 1-. It also lights lamp 336 to indicate which identification circuit failed. Relay 333 also connects ground over its front contact, uppermost back contact of relay 309, lowermost contact of relay 100, which is operatedbut not locked, winding of relay 112, resistance 111 to battery. Relay 112 releases relays 103, 100 and 303. Since no registration was set up the call will proceedasa free call. If relay 106 locks, relay 30% operates in the locking circuit, opening the circuit of relay 303. However, relay 30 1 substitutes ground at its lower front contact for the ground at the front contact of relay 303. Therefore, if the line is open so that relay 312 cannot operate, and in turn relay 313 does not operate, relay 31% remains operated and the alarm operates as above described.

According to the present disclosure three identification circuits are provided to serve a large group of district selectors and each of these normally'serves a particular part of the group. Means has been provided, however, so that if one identification circuit fails to function, one of the other identifica tion circuits may be used. If the identification does not take place within a predetermined time relay 332 is operated under the control of interrupter 331 and looks as above described. The operation of relay 313 releases relay 314- so that the subsequent closure of the left contact of interrupter 331 extends ground over the front contact of relay 332, back contact of relay 314, to lamp 337 and winding of relay 300 and battery. Relay 300 extends its operating ground over the back contact of similar relays 100 and 450 of the other identification circuits, through the winding of relay 338, key 339, right winding of relay 340 to battery. Relays 338 and 3&0 operate, relay 3 10 sounding an alarm and locking to the alarm circuit. The op eration of relay 333 connects ground over its front contact to the armature of relay 300, thus holding relay 300 operated When interrupter 331 opens its contact. Relay 300 also closes a circuit for relay 302. Relay 302 opens the circuit of relay 3041 at its upper back contact and when relay 301 releases completes a circuit over the upper front contact of relay 302, back contact of relay 301, through the windings of relays 305, 306, 307, 308 and 309 in parallel to battery. Relays to 309 in operating transfer the circuits which connect the district selector with this identification circuit to the identification circuit shown at the left of Fig. 4. Since both identification circuits indicated on Fig. 4 are identically the same as that shown in Fig. 3, only the transfer and switching relays have been shown.

If the second identification circuit should fail to complete its function in the proper time the same operations will take place and the circuits further extended to the third identification circuit. In case all three fail, the operation of relay 450 of the third identification cir uit opens the circuit of relay 338 and releases relays 300, 400 and 450. Calls may also be rerouted from the second identification circuit to the third and first and from the third identification circuit to the first and second in the same way as they were advanced from the first to the third as above described.

If at the completion of the identification tests, relay 312 fails to reoperate and consequently relay 315 does not release, a circuit is closed for relay 31 1, over the lower front contact of relay 315, outer lower front con tact of relay 316 to grounded conductor 320, thus operating relay 338 and bringing in an alarm through the operation of relay 335. Relay 333 operates relay 112 as before.

It is to be noted that where the failure to make registration is the result of trouble on the part of the line or the district selector, relay 112 is operated and the identification circuit merely dismissed. lVhere the difficulty is due to the identification circuit an attempt is made to complete the identification by associating the district selector with other identification circuits.

lVhat is claimed is:

1. In a telephone exchange system, telephone lines, a plurality of substations on said lines, a plurality of selectors, means for extending a. connection from one of said lines over any one of said selectors under the control of one of said substations, and means common to said selectors and said lines for identifying said substation.

2. In a telephone exchange system, a telephone line, a plurality of substations on said line, a plurality of selectors, means for extending a connection from said line over any one of said selectors under the control of one of said substations, an identification circuit common to said selectors, means to associate said identification circuit individual ly with a selector, and means in said identification circuit to set up a record in the selector of the identity of said substation.

3. In a telephone exchange system, a telephone line, a plurality of substations on said line, a plurality of selectors, means for extending a connection from said line over any one of said selectors under the control of one of said substations, an identification circuit common to said selectors, means to a."- sociate said identification circuit individnah ly with a selector, means in said identification circuit to set up a record of said substation in said selector, and means in said selector responsive to the completion of identification to disconnect said identiii tion circuit from said selector.

4. In a telephone exchange system, a telephone line, a plurality of substations on said to setup a record in the selector of said substation, and means in said identification cir cuit eli'ective if said selector is not in condition to receive the identification to disconnect saididenttication circuit from said selector.

5. In a telephone exchange system, tel phone lines having a pluralityo-t subscribers substations, a plurality of groups of selector switches for extendin connections from said lines, an identfication circuitcommon to each group of selector switches, means in each identification circuit to identify a calling substation and to set up a record of the substation inv a selector, and means effective if an identification circuit does not function pro perly to associate the identification circuit of another group with said selector.

6. In a telephone exchange system, telephone line, a plurality of substations on said lines, certain of said substations being connected to ground, a plurality of selectors, means for extending a connection from said line over any one of said selectors under the control of one of said substations, an identifi cation circuit common to said selectors, means in said identification circuit to determine whether the calling partys substation is con nected with ground and to record that fact in said selector, and means effective if said record is not established to disconnect said identification circuit from said selector.

7. In a telephone exchange systenna line having a plurality of substations thereon, a plurality of selectors for extending connections over said line under the control of any one of said substations, means to test said line to determine the substation controlling the extension of the particular connection, a network common to said selectors, means to insert said network-in the circuit of said line before testing said line, and means responsive to the completion of the test to'remove said network from said line. 1

8. In a telephone exchange system, a line having a plurality of substations thereon, a plurality of selectors for extending connections over said line under the control of any one of said substations, means to test said line to determine the substation controlling the extension of the particular connection, a net work common to said selectors, means to connect said network in parallel with a portion of the circuit of said line, means responsive to the establishment of said parallel connection to open said line intermediate the terminals of said parallel connection, means thereafter efiective to initiate said test, and means responsive to the completion ot-said test to reclose said line and thereafter disconnect said network from said line. 7

9. In a telephone exchange systenn'telephone lines having a plurality of subscribers substations located thereon, a plurality of selector switches for extending said lines, an identification circuit common to said selector switches, means responsive to the establishmentof a connection over one of said selectors switches to set up a talking circuit through said selector, means also responsive to the establishment of a connection to i361 porarily

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