US1696275A

US1696275A - Lewis h

Info

Publication number: US1696275A
Authority: US
Publication date: 1928-12-25
Anticipated expiration: 1945-12-25

Description

Dec. 25, 1928.

L. H. JOHNSON 'ET AL CALL CHARGING TELEPHONE EXCHANGE SYSTEM 8 SheetsSheet 1 .Lw/5 hf Jo/wsalv Z ALF/7E0 E HAGUE Arron/Er Filed Oct. 20, 1927 1,696,275 L. H. JOHNSON ET AL CALL CHARGING TELEPHONE EXCHANGE SYSTEM 8 Sheets-Sheet Dec. 25, 1928.

LEW/s hf. JOHNSON WVENTMS' ALF/7E0 E. HAGUE Arm/mm D.2s,192s. 1,696,275 I L. H. JQHNSON ET AL CALL CHARGING TELEPHONE EXCHANGE SYSTEM F4" 1;.2o,1927 8 ts-Shee s IIHI MRG/NAL LEW/.5 H Jofl/vs a/v b N I 7' ALFRED f. HAGUE Arm/awn Dec. 25, 1928.

WM. aw

Arm/m0 Dec. 25, 192a L. H. JOHNSON ET AL QALL CHARGING TELEPHONE EXCHANGE SYSTEM 8 Sheets-Sheet 5 Filed Oct. 20, 1927 LEW/5 hf JOHNSON //VVNTO/?5. ALFRED 5 HAGUE 5y Arm/Mfr Dec. 25, 1928.

8 Sheets-Sheet 6 Filed Oct, 20; 1927 wad Arron/v5) Dec. 25,1'92a L. H. JOHNSON ET AL CALL CHARGING TELEPHONE EXCHANGE SYSTEM Filed 00$. 20, 1927 7 Mw a w e 13% g H A & 0H w N 5 w 0 h 8 LA min.

Dec. 25, 1928;

v LEW/s H JOHNSON ALFRED f. HAGUE Arron/var 5 8 7 2 w m 00 r 1 t 9 6 M E T 8 s Y S E L G A m 7 n w 2 X N N E E 0 o N 2 s m N F .t H m m 0 E d J T e m n a H H F R L A H C m lull UP A. KKSQWRQ mm ll U D C III U III U) wuEkQ (323% Ill h D II U 7 f ll hu Ill U) L) U) MW m t Patented Dec. 25, 1928.

UNITED s'rMEs mm PATENT oFr cr.."-f

LEWIS H..JOHNSON, or MADISON, Am) ALEBED E. HAGUE, or wns'r ORANGEQNEW JERSEY, ASSIGNORS T BELL TELEPHONE LABORATORIES, INCORPORATED, OF'NEW YORK, Y., ACORPOR-ATION OF NEW YORK. i r

CALL-CHARGING TELEPHONETEXCHJANGE SYSTEM.

Application filed October'20, 1927. Serial No. 227,396.

'Ihisinvention' relates to a telephone exchange system and more particularly-to a system in which a charge is automatically made for a completed call. The object; of

6 the invention is the. provision of means for controlling the call charging, which will charge the calling subscriber in such a manner 'as to more equitably recompense the operating telephone company for the use of exchange equipment. I

In hirge exchange areas having several ollices, some of which may be located at vary-v ing distant points in the area. it is desirable that means be provided whereby calling subscribers may be charged differently-"for calls to ollices which are most remotely located from the otlice in which the calling line terurinates, than for calls to oflices which are not. i

so remotely located, since remotely located ofiices must be reached over long interoll'ice trunks which are expensive to install and maintain and it is not equitable to the operating company to provide service to all points in the exchange area at the same basic rate.

Of course, where callsare handled on a man- 'ual basis the rate of charge may be very.

40 crating company that for a basic charge a $lllhtl'lllil' shall be enabled to hold an 95- tablishcd connection indefinitely. Inn1anual systems. of course. the operator is able to assess the charge in accordance with the versation is continued on any call. \Vhere, however. calls are extended by means of machine switching devices, operator supervision I is not desirable and from astandpoint of economy the supervision of elapsed time should be attained by automatic means.

Both automatic charging in accordance with the none of the exchange. area into which number of unit periods during whichcom' a call is extended and in accordance with, the

elapsed conversational period has heretofore been accomplished. In accordance with the present invention, however, one specificem- I bodiment of which is disclosed herein by way of illustration, this-is accomplished in the following improved manner:

A timing switch is provided which is started upon the response' of the called subscriber and under the control of a timing interrupter-t completes its cycle once during each unit period of conversatiomthe unit period having cording switch to a position which is indi cat-ive of the number of such periods lapsing during the conversation, the number of steps taken by the recording switch duringveach cycle of the timing switch or during each unit period of conversation, being determined by thezone into which the call has been extended. The number of steps whicht-he recording switch shall take for each unit-period is controlled by the sequence switch of the district selector with which the charge .con-

trolling equipmentis associated and by the sender, the sequence switch assumingdifi'erent positions dependent on 4 the zone into which the call is extended by the district selector. Upon the termination of the call the timing switch is set into a position which is complementary to that assumed by there-- cording switch and is then restored, sending impulses for operating the subscribersmes sage register to charge the call. Registra,

tion is thus effected in accordance with both the elapsed time for the terminated convert-.1

sat-ion and in accordance with the zone of the exchange into which the call was extended.

,VVhere subscribers linesare used having two-party substations thereon, it is desirable to prevent a subscriber on the line from interfering with the registration of a'call through the initiation of a new call. For this purpose provision is made for shunting the line relay during the operation of one of the two message registers associated ,with the line.

A clearer eonception of the scope and purpose of the invention will be obtained from a consideration of the following description. taken in connection with the attached drawings, in which:

Fig. 1 shows a calling subscribers line having two substations thereon, together with certain relays for preventing interference between callinglinesy Fig. 2 shows astart circuit and a portion of two link circuits;

Fig. 3 shows a line finder;

Fig. 4 shows a link circuit for associating the sender of Fig; 5 with the district selectorofFig.7;

Fig. 5 shows a portion of a register sender; r

Fig. 6 shows a call charging control circuit;

Fig. 7" shows a district selector;

Fig. 8 shows in s'ehematio form selectors I for completing connections to an automatic subscriber, to a manual office or to an operator; and

Fig. 9 shows the manner in which Figs. 1

p to 8 should be arranged.

The invention hasbeen embodied in a disclosure which .is substantially like that of Patent 1,567,072 to H. Matthies, granted December 29, 1925. Both thepresent disclosure and that of the Matthies patent show a skeletonized sender substantially identical with that employed in the more complete disclosure of Patent 1,589,402, to 0.11. Kopp,

granted June 22, 1926. Reference to the Kopp patent is made for operations not completely described herein.

As 1n the case of the above mentioned patents, a'plurality of link circuits are arranged to serve a group of calling lines and are taken into service in rotation. When a link circuit completes its function it hunts for and main in a sub-allotted condition until the next link in the series has been put into service. The link circuit is then put into an allotted condition, from which it will be advanced by the-initiation ofa call and the action of the start circuit of Fig. 2. The trip circuit of Fig. 1 and the start circuit of Fig. 2 are so arranged that only one line may be served at a time and so that there may be cooperation between two groups of lines, to each of which a group of link circuits is individual. The details of these functions are described in the above mentioned Matthies patent and since the form no part of the present invention wil be omitted from the following description.

Establishment of connection.

. the switehhook .to initiate a call, thereby closing a circuit from battery through the winding of line relay 101. inner left contact of relay 102 over the subscribers line to ground at the outer leftcontact of relay 102. Relay 101 in operating closes a circuit from battery through resistance 104, winding of relay 103 to ground at the outer front contact of relay I 101. It also prepares a circuit frombat-tery through resistance 111 and the right winding lay 109.

Relay 108 operates in this circuit and closes a locking circuit for itself from battery through the right winding of relay 201, conductor 129 over back contacts of relays simi lar to relay 108 individual to other groups of lines appearing before the same line finder, inner left front contact and left windin of relay 108 to ground at the right contact 0 relay 109. Relay 108 prepares a circuit from ground at its outer right contact through the winding of trip magnet 303 of the line finder to battery in preparation for tripping the proper set of brushes when the line finder is operated. Relay 201 operates in the locking circuit of relay 108 and in combination therewith closes a circuit from ground over its outer right contact, conductor 128, inner right contact of relay 108, winding of relay 110 to battery. Relay 110 locks over its inner right contact to ground at the left contact of relay 109. Relay 110 closes a circuit for starting the allotted line finder. Assuming that the link and line finder shown are the ones to be used next,se uence switch 400 will be. standing in position, 1 and sequence switch 700 in position 2. The operation of relay 110 will therefore close a circuit from ground at its outer contact, outer left contact of relay 108, inner left contact of relay 103-, conductor 131, left back contact of relay 202, inner left back contact of relay 203, conductor 206, upper-left and lower right contacts I of cam 403, brush 402 and termin'al401, conductor 701, left contacts of cam 702, conductor 703, brush 602 and normal .bank terminal of recording switch 600, outer right back contact of relay 607, conductor 608, winding of relay 302 to battery.

Relay 302 in operating closes a circuit from battery through the winding of. up-drive magnet 304 of the line finder, outer left contact of relay 302, lower right contact of cam 704. outer right front contact of relay 302, upper left contact. of cam 705 to ground. The line finder moves upward under the con trol of magnet 304 and since the trip magnet 303 is operated the proper set of brushes is tripped. As soon as the line finder moves upward a locking circuit is provided for relay 302 extending over its inner left contact, lower contacts ofcam 706, right back contact of relay 320, commutator strip 321. brush 322 3o 322. This ,reduces the resistance in series tracedatthe upper left contact cam 705.

to ground',-'which holds relay 302 operated ini dependentof. the start circuit. At its inner right front contact relay 302 establishes a circuit for relay'300, extending from battery through the-left winding of relay 300, inner right contact of relay 302, lower right con-..

tact of cam'704 to ground,as reviously Assoon as-commutator brush 307 engages segment 305, a circuit is closed from ground,

over brush 30.7 and segment 305, the innermost left contact of relay 300, conductor 404, contact 230 of key 204, inner right front contact of relay ,201 to conductor 129 and theright winding of relay 201. This circuit shunts the winding of relay 108 and causes that relay to release, in turn releasing the trip magnet 303.- When brush 307 leaves opened and that relay also releases.

segment '305,'the circuit of relay 201 is When line finder brush 381 makes contact" with terminal 380, which is connectedto'

conductor

1,14 and therefore to battery, a circuit is completed from this battery through the winding of relay 320, inner left-back contactof relay 707, upper right and lower left contacts of cam 708 to ground; Relay 320 operates in this circuit and closes a shunt around its winding through resistance 319 to ground over commutator strip 32l.and brush with the Winding of marginal relay- 109 sufliciently to cause that relay to operate and to open the locking circuit of relay 110, whichv in turn opens the energizing circuit of relay 302. The operation of relay 320 also opens the locking circuit of relay 302, causing that relay to release. The release of 'relay 302 opens the circuit of the up-drive magnet 304 to arrest the hunting movement of. the line finder and opens the circuit of relay 300,

which a so releases. The release of relay 300 closes a circuit from ground through the winding'of cut-off relay 102, conductor 112, terminal 327, brush 326, innermost lower back contact of relay 317, right contacts of can 709, right back contact ofrelay 300 resistance 323 to battery, The operation of cut-off relay 102 opens the circuit of line relay .101, removing battery from conductor 114, thus releasing

relays

109 and 320.

; At thetime relay 300 operates it closes a cii",cuit from ground at its middle. left'con .tactover the inner right back contact of relay. .301, conductor .379, terminal 407 and brush 406 of the link district finder 410, lower right contact of cam 40 8, winding of relay 409, resistance '411-to battery. Re-

- lay 409 operates and closes acircuit from bat position 2 a circuit is closed from-battery through the winding of relay=413, upper con-' tacts of cam 414, right back contact of relay 415 to ground at the left contact of cam'416.

Relay .413 operates, closing a circuit from'bat tery througlrthe left winding of relayf417, I

left front contact of relay 413 to ground at the left back contact of relay 415. Relay'j- 417 upon operatingcloses a circuit'from-battery throughthe windin of -up.-drive magnet 418 of the sender finder 420, left contact ...of cam 47 9, outer right contact ofrelay 417 to groundat the left back contact of relay; 409. The} sender finder moves upward u'n der control ofi magnet4l8r in search of 'an idlesender. Relay 413 also closes a circuit from bat tery through theright winding of;

relay

415, 7 upper cont-actsfof cam 421, middle winding of relay 4-15 to ground at the right contact of-relay 413. The current in this circuit,

however, "is not sufiicient. to operate relay 415, but does create a flux in-the windings of that relay so that it be'comes quick to operate when the .test circuit is closed. The

"to test circuit extends fronibrush 422 over the lower gcontactsfljofli'cam 419, right back "contact of relay: 409,left windingof relay 415,

lower. right and-{upper left contacts of cam 421, middle windingof-'rel ay 415 ;to"ground at the right contact of.

relay

413,2 .Anidle sender is characterized by {battery connected to conductor 502; '.Wl1'en',',.. therefore,- brush.

422 engages terminal 423, corresponding; to the sender of Fig;I5".which i'sfas'sumed to be idle, the test -circuit above. traced is "completed overterminalto battery, and arelay 415-v opera-tesiqilickly-f .Therela-y 415 upon operating. clqs'es;;a-. locking circuit for itself frombattery through its right -winding, upper-'contactsiof canzr'42l to ground at its left front"contact; ,It alsoyopensthe I circuit of "relay; 417', which releases, in turn releasing magnet 418 andbringing the send,

er finder to'restionthe terminals of the idle sender. The releaseof relay,417 int-urnreleases relay 413.1,,'When relay 413 'releases with relay415 operated, a circuit is closed I from battery through the winding ofse-x quence switch magnet f400,lower left con-, tact of cam -'47o contact-427" of jack 428,

left back mama oflrelay 413, right front contact of; relay-415 to ground at the left contact of cam2 416,*-'advancing sequence switch 400 to position" 3.

'When sequence switch 400 rcaches' pottion 3,- Jcircuitis. closed from ground: 1. through the left and middle" windings of" relay 503,. leftiba-ck contacts-"of

relays

504 and 505, conductor 506,- terminal 430. brush 431,right,contact of cam 4 34, brush 432 and terminal 433, conductor 315; contacts of cam 710 (assuming that the} district selector has been advanced-'toposition .3, as here 7 inafter described) through t e loivcr wind-r I I ing of 351 in para-llel to battery. Relay 317 is mardoes not operate, but relay 351' ela a circuitfor'relay' 509. 'Relay 509 closes a v circuit for relayf510.

As soon" as sequence switch: 400 arrived in pos1t1on2 it prepared the pulsing circuit for receiving dial pulsesJ This circuit may be traced from battery through the left wlnding of relay 500, conductor 537, terminal 440, brush 441. lower contact of cam 429,

, brush 47 8', terminal 47 7, conductor 37 5, lower rightcontact of cam 711, upper back contact of relay'317, --upper-back contact of relay 306, brush 334, terminal 333,"con'ductor' 117 through the subscribers substation, conductor 11 6,"terminal; 332, brush 331, lower back contact of relay 306,-lower back contact of relay 317, windingof relay'330, upper right contact of'cam 712,-c'onducto'r 382, terminal 442, brush 443, upper fright' and' lower left contacts of foam 403; brush 1444: and terminal 445,-u ground at the'back contact of relay 513.5 .Relay 500 operates, inaturn operating relay 518; in the wellknown manner, relay 518 operating'relay519;2A circuit'is'thereuponrClojsed from the source .of tone 516,

through the'right winding of relay 500, regand remains in this position throughout the ister steering switch brush 520 in its normal posit1on,-front contact of re1a'y'519, contact of cam 514 to ground .at the outer right front contact of. relay 509. This toneis transmitted to the calling subscriber to inform him that the sender is ready to receive impulses which he may then send out by manipulating his fdi'al.' When relay- 510 operated itremoved' battery from conductor 502, releasing. relay 415. When relay 415.,

releases, a' circuit] isclosed from battery throughthe winding of sequence switch magnet 400, upper leftcont'act of cam 476, right back contactof relay 415 tofground at the left contact of cam 416. Sequence switch 400 advances to position 5 over this circuit further operation of the sender. Y 1

The calling subscriber .now proceeds to dial the desired llne number for setting the registers and translator (not shown) of the sender in the well known manner. 'After the dialing of the fir'st digit the register steering switch. one wiper of which is shown at 520, advances from normal, closing. a circuit for relay 517,jcxtending from battery through the winding of relay 517, terminals and brush 52 0, contact of relay 519, contact of cam 514 to ground at the outer right contact of relay 509. Relay 517 closes an obvious circuit for relay 521'. f a

As soon as the code registers of the sender have" been set in accordance With the first two dialed by the calling subscriber,

closes an obvinumber of a subscriber located in a zone of the exchange for which an additional charge must be made on the callingsubscribers message register, thence through the winding of relay 536 to battery. Relay 536 energizesand locks over its left front contact, the contact of cam 514 to ground at the outer right front contact of relay 509, and extends lockin ground through its left front contact to the winding of relay 538, causing the operation of the latterrelay. Relay 538 upon operating establishes a circuit from ground at the outer-"right contact of relay 509, the contact of cam 514, the contact of rela 538 to battery through thewinding of relay 535. Relay 535 operates. opening the initial energizing circuit of relay 536 and connecting the translator are 534 over the .cable 539 to the class switch 540 which is diagrammatically indicated in the upper right portion of Fig. 5. The class switch is thereupon set from the are 534 of the translator in the ,well known manner. Relay 536 upon energizing preparesa circuit extending from ground over its right-contact, the contacts of

vcams

571 and 542, closed during the brush selec tion controlling positions of the sequence switches associated with the sender, conductor 543, terminal 439, brush 438, right Eon- ,tacts of cam 405, brush 406, terminal 407, con- 770. This circuit is completed as will be de'- scribed, hereinafter through the winding of relay 611 of the registration controlling circuit forindicating at the. registration controlling circuit thefact that the subscriber has initiated the establishment of a connection into a zone of the exchange area for which he should be assessed anadditional charge;

When the link circuit advances into position 2 for hunting for an idle sender, a circuit is closed for rela 714 extending from battery through the 11a winding of relay 714, lower right contact of cam 715, upper left contact of cam 716, conductor 375. terminal 477 and brush 478 of district finder 410 to ground at the right contact of cam 429. When relay 302 releases and relay 714 Y relay 302 to ground at-the upper left. contact of cam 705. As the sequence switch 700 ad vances from position 2 to 3, relay 714 releases. When sequence switch 700 is in position 3 a circuit is closed to test the responsive con dition of relay 308. This circuit extends from battery through the winding of relay 308, the right winding of relay 309 to ground through the left contacts of cam 708. The current flow through the winding of relay 308 at this time is the least upon which this relay should operate. If relay 308 operates,

as it should, a circuit is closed for relay 310, extending from battery through the winding of relay 310, outer left back cOntact of relay 311 to ground at thecontact of relay 308. Relay 310 locks over its inner right front contact to ground at the lower left contact of cam 727 and prepares a circuit for advancing sequence switch 700 into position 4. With sequence switch 700 in position 3, relay 714 is again ener ized over a circuit extending from battery t rough its left winding, the lower right contact of cam 715, the lower left contact of cam 716, conductor 7 01, terminal 401 and brush 402 of district finder 410, the lower right and upper left contacts of cam 435, brush 436 and terminal 437 of sender finder 420, conductor 532, the front contact of relay 521, the right back contact of relay 504, the left'contact of cam 526, winding of sender stepping relay 522, winding of overflow relay 523, left contact of cam 527, resistance 530 to ground.

Relays

522 and 714 operate in this circuit, relay 714 looking over its inner'left front contact and the lower left contact of cam 715, thence over the circuit traced whereby it remains energized as the sequence switch 7 00 advances into position 4. Relay 714 also closes a circuit to advance sequence switch 700 into position '4, extending from battery through magnet 700, upper left contact of cam 718, lower left contact of cam 704, outer right contact of relay 310, outer left front contact of relay 7 .14, right back contact of relay 302 to ground at the upper left contact of cam 705. As soon as sequence switch 700 leaves position 3, relays 308 and 310 release.

When the district sequence switch reaches position 4 for controlling brush selection, the circuit previously prepared at the contact of relay 536 and extending to the upper right contact of earn 770 is completed over the uppfii left contact of cam 770, conductor 741, t

battery through the right winding of relay 611. Relay 611 upon energizing looks over its left winding and left contact, conductor 612 to ground at the upper left contact of cam 727.

The district selector is now controlled by the sender in its brush and group selections and then proceeds to hunt for an idle trunk in the well. known manner. After an idle trunk is selected, a circuit is established in position 9 of the sequence switch 700 for relay 714, extending from battery through the right outer right back contact of relay 609 to winding of this relay, the left'contact of cam 719 to ground at the contact of relay 351, advancing the sequence switch 7 00 into position 10. In position 10 relay 714 remains energized over the circuit just traced. In position 10, which is the selection beyond position of the district circuit, the control of succeeding switches is effected over a fundamental circuit which may be traced in part through the upper right and lower left contacts of cam 768, outer right back contact of relay 301, conductor 701, thence as traced to the sender, through

relays

522 and 523, cam 546, brush 544, compensating resistance 545, left back contact of relay 524, right front contact of relay 507, conductor 543, returning over terminal 439 and brush 438, the right contacts of cam 405, brush 406 and terminal 407, conductor 379, the inner right back contact of relay 301 to the right contacts of cam 770.

As soon as selections are completed and the connection has been set up to the called subscribers line, reversed battery from the incoming selector operates relays 522and 523 in the usual manner. These relays in turn cause the operation of relay 531 and

relays

524 and 504. With these relays operated, the sender is advanced to position 18 for controlling talking selection. Relay 351 is operated in parallel with the winding of relay 317 throughout selections. The operation of relay 504 above mentioned now opens a shunt around the right winding of relay 503, including that winding in the circuit of relays 351 and 317. Relay 351 thereupon releases, in turn opening the circuit of relay 714, which also releases. Upon the release of relay 714 the district sequence switch 7 00 is advanced into position 12 over a circuit extending from battery, winding of magnet 700, lower left contact of cam 713, outer left back contact of relay 714, outer right back contact of relay 302 to ground at the upper left contact of cam 705. As the sequence switch enters position 11, ground is connected to conductor 315 at the lower right contact of cam 720, which is extended over terminal 433, brush 432, upper contacts of cam 446, left winding of relay 415, right back contact of relay 409, left contact of cam 434, brush 431, terminal 430, conductor 506, left back contact of relay 505 to the windings of relay 503. Since these windings are also connected to ground, relay 503 now releases, in turn releasing relay 507. The release of relay 507 does not release relay 509, since that relay is locked to its own front contact. A circuit is therefore closed from ground over the left back contact of relay 507, front contact of relay 509 to the winding of relay 505, which relay looks over its middle left contact to conductor 506 and to ground as above traced. After leaving position 11, relays 351 and 317 are both disconnected from conductor 3.15. After leaving position 10, the subscribers line becomes disconnected from the sender at contacts of cams 711 and 712.

Test for particular calling substation.

In positions 11 and 12 of sequence switch 700 a test of the calling line is made by the relay 308 to determine which party on the line has initiated the call. As the sequence switch passes through positions 10% to 11 a circuit is established for relay 306 extending from battery, lower winding of relay 306, inner left back contact of relay 311, upper contacts of cam 721, commutator segment 312, brush 313 to ground. Relay 306 upon operating extends its own operating ground over its lower front contact to battery through the left Winding of relay 309, energizing the latter relay. Relay 309 upon energizing locks both itself and relay 306 over its inner left front contact, the left normal contacts of relay 314, the left normal contacts of relay 302, the right contacts of cam 706 to ground over commutator segment 312 and brush 313. Relay 309 at its outer right front contact also closes a secondary holding circuit for relay 306 through its upper winding. Relay 309 also connects the winding of relay 308 to brush 331 of the line finder through the inner right contact of relay 309, and to brush 334 over the outer left contact of relay 309. Since the substation 100 has been assumed to be calling, these circuits will be completed to ground over terminal 332, conductor 116, through the ringer at substation 100 and over terminal 333, conductor 117 switchhook contacts thence to ground through the ringer, and relay 308 will energize in turn operating relay 310, the latter relay locking to ground at the lower left contactof cam 7 27 Relay 306 also closes a circuit for relay 722, extending from battery through the right winding of relay 722, the lower contact of interrupter 723, conductor 724, the inner upper front contact of relay 306, conductor 7 25 to ground at the lower right contact of cam 705. Relay 722 locks independently of interrupter 723 over its inner right contact to the circuit above traced. When relay 722 energizes, as soon as interrupter 7 23 makes its upper contact a circuit is closed through the winding of relay 302, the outer right contact of relay 722, the upper contact of interrupter 723, conductor 724, innermost upper front contact of relay 306, conductor 725 to ground at the lower right contact of cam holding circuit of relay 309, which releases, in turn releasing relays 306, 722 and 302. The timing interrupter 723 is so arranged that relays 306, 309 and 722 do not release until relay 308 has had time to operate and to lock relay 310 energized.

The release of relay 306 now connects the left windings of repeating coil 760 to the sub- 05, Relay 302 upon energizing opens the 330 operates .in this circuit and closes a circuit for relay 707, extending from battery through the windin'g of relay 707, contact of relay 330, upper contacts ofcanr 726 to ground at the upper right contactsof cam 727.

Talking selection. With sequence switch 700 in position 12,

relay 714 is energized in a circuit extending to the sender from battery through its left winding, the lower right contact of cam 715, the lower left contact of cam 716, conductor 7 01, terminal 401, brush 402, the lower right and upper left contacts of cam 435, brush 436,,t'ern'iinal 437, conductor 532, the front contact of relay 521, the front contact of relay 504, the right contact of cam 526, the sender sequence switch being in position 18 for talking selection,.the windings of

relays

522 and 523, the'right contact of cam 527 to ground through resistance 530.

Relays

714 and 522 energize in this circuit, relay 714 closing a circuit extending from battery through sequence switch magnet 700, the lower left con.- tact of cam 717, the outer left front contact of relay 714, the right back contact of relay 309 to ground at theupper right contact of cam 705. Relay 714 upon energizing locks to the fundamental circuit over its inner left front contact and the lower left contact of cam 715. As sequence switch 700 rotates out of position l2-toward position 16 ground is intermittently connected to the fundamental circuit in shunt of sender stepping relay 522 at the lower contacts of cam 708. When the sender is satisfied as to its talking selection setting, the fundamental circuit is opened at the sender through the operation of relay 525, and relay 714 de-energizes, arresting sequence switch 7 00 in its next stopping position. The seguence switch may be arrested 1n any one 0 three positions; position 13 which may be a no charge position, and a charging position for connections to certain zones of the exchange, position 14 which is a charging position for connections to certain other zones of the exchange, and position 15 for connections to an operators position.

At the sender after talking selection is completed, relay 515 operates connecting battery conductor 506 in parallel with the winding of relay 505. The current in this circuit is now suflicient to operate relay 415 which closes a circuit from battery through the left winding of relay 417, left contacts of cam 421, to ground at the left front contact of relay 415. Relay 417 closes a circuit from battery through the winding of sequence switch magnet 400, upper contact of cam 479, outer right front contact of relay 417, left back contact of relay 409 to ground, advancing sequence switch 400 to position 6. In this position, all of the conductors extending to the sender are opened and the sender is completely released. As soon as sequence switch 400 leaves position 5, relay 415 releases andin turn releases relay 417 unless the sender finder 420 is standing on one of its top ten terminals. If the latter is true, relay 417 is held operated in a circuit from battery over its left winding, left front contact, upper left contact of cam 42.4, commutator segment 464, brush 463 to ground. With relay 417 operated atthis time, a circuit is closed from battery through resistance 411, winding of'relay 409, lower contacts of cam 414, inner right front contact of relay 417,.lower left contact of cam416 to ground. Relay 409 locks through-its inner left contacts to ground at the lower contact of cam 467 and also closes a second locking circuit for relay 417. With relay 409 operated, a circuit is closed from battery through the windin of down-drive magnet 465 of the sender nder 420, left contact of cam 412, to

ground at the outer left front contact of relay 409. When the sender finder reaches its low ermost position, a circuit is closed from ground over brush 463, bottom commutator segment 406, upper contact of cam 456 to resistance 411, shunting the winding of relay 409 and causing that relay to release and in turn release relay 417. lrVith relay 417 released in position/,6, a circuit is closed from battery through the winding of sequence switch magnet 400, lower right contact of cam. 476, right back-contact of relay 417, to,

ground at the lower left contact of cam 416, advancing sequence switch 400 to position 7.

When sequence'switch '400 reaches posinew, the link circuit is ready to associate itself with another'district. If another district is standing in position 1 waiting association with alink, a circuit will be closed from ground over the lower left contact of cam 708 and lower right contact of cam 728 of that district, contact 393 of jack 374, conductor 392, contact of jack 448, contact of jack 449, upper contact 'ofcam 416, right back contact ofrelay 415, upper contacts of cam 414, winding of relay 413 to battery. Relay 413 closes a circuit from battery through the left winding of relay 417, left front contact of relay 413. to ground at the left back contact of relay 415. Relay 417, in operating, closes a circuit for up-drive magnet 447 of the district finder 410, lower right contact of cam 479, right front contact of relay 417, left back contact of relay 409, to ground. The district finder moves upward under control of magnet 447 in search of the district which is awaiting a link. Such a district is identified by battery connected over the left contacts of cam 709 of that district, contact 373 of jack 374, to conductor 366. Relay 413, in operating, closes the same circuit through the right and middle windings of relay 415 as it closed'in position 2. At this time the test circuit extends from ground at the right front contact of relay 413, through the middle winding of relay 41.5, upper left and lower right contacts of' cam 421, left winding of relay 415, right back contact of relay 409, lower right and upper left contacts of cam 419, contact of jack 449 to brush 451.

If the district for which the district finder is hunting does not lie between the last position occupied by the finder and the top of its bank, it will continue to move upward until brush 453 engages segment 452, completing a circuit overthe upper right contact of cam 408, winding of relay 409, resistance 411 to battery. The operation of relay 409 opens the test circuit, opens the circuit of up-dri've magnet 447 and closes a circuit from battery through the winding of down-drive magnet 454, lower right contact of cam 412, left front contact of relay 409 to ground. The district finder is restored to its lowermost position under the control of magnet 454, at which time a circuit is closed from ground over brush 453, bottom segment 455 of the district finder commutator, lower right contact of cam 456 to resistance 411, shunting and releasing relay 409 which restores the test circuit and the circuit of up-drive magnet 447. When brush 451 encounters terminal 450 to which conductor 366 extends, the test circuit is completed and relay 415 operates quickly. As -in the previous case, relay 415 locks through its right winding, the upper con tacts of cam 421, to ground at its left front contact, opening the circuit of relay 417 to de-energize magnet 447 and to bring the district finder to rest on the terminals of the district. With relay 415 operated and relay 417 released, a circuit is closed from battery through the winding of sequence switch magnet 400, lower left contact of. cam 476, contact 427 of jack 428, back contact of relay 413, right front contact of relay 415, upper right contact of cam 416. contacts of jacks 449 and 443 to conductor 392. Sequence switch 400 a-dvarces to position 8 in this circuit.

Relay 415 is held operated in position 8 from battery at the district over terminal 450, brush 451, contact of jack 449, upper left and lower right contacts of cam 419, back contact of relay 409. left winding of, relay 415, lower right and upper left contacts of cam 421, to ground at the left front contact of relay 415. With relay 415 operated, a circuit is closed from ground at the left contact of'cam 416, right front contact of relay 415, upper left contact of cam 429, brush 478, terminal 477, conductor 375, upper left contact of cam 716, lower right contact of cam 715, left winding ofrelay 714 to battery. Relay 714 operates and closes a circuit from battery through the winding of sequence switch magnet 700, lower left contact of cam 717, outer left front contact of relay 714, outer right back contact of relay 302, to ground at the upper left contact of cam 705. Se-

uence switch 700 advances to position 2 in t is circuit, releasing relay 714. The advance to position 2 removes ground from conductor 392 and battery from conductor 366. The removal of battery from conductor 366 opens the circuit of relay 415, and that relay releases, closing a circuit from battery through the winding of sequence switch magnet 400, upper left contact of cam 476, right back contact of relay 415, to ground at the lower left contact of cam 416. Sequence switch 400 advances to position 9.

The link circuit remains in this position until the link circuit standing next to it in the series is advanced from position 1 for the purpose of selecting asender. Link circuit 260 occupying that relationship to the link circuit of Fig. 4, a circuit may be traced from ground over the lower contact of cam 261, upper right contact of cam 262, conductor 263, contact 460 of jack 428, upffeir right contacts of cams 461 and 462, winding of sequence switch magnet 400 to battery, advancing the link circuit to position 10 which is the equivalent of position 1, so that the link circuit is ready to operate in response to the next call in the group of lines served thereby.

' Charge calls initiated substation 100.

\ It will first be assumed that the call which has been completed is of such a character that a charge should be made for it. For this call to a remote zone of the exchange, therefore, the district sequence switch 700 has been set into position 14. With sequence switch 700 in position 14 a circuit is closed for relay 609 extending from battery, wind ing of relay 609, conductor 610, to ground at the left contact of cam 7 20. When the called subscriber responds a circuit is completed for relay 729 extending from the ti brush 730, over the upper contacts of cam 68, the upper right winding of repeating coil 760,

winding of relay 729, lower right winding of coil 0,lowercontacts of cam 770, to the brush 7 31.- Relay 729 energizes and a circuit is established for relay 722 as soon as interrupter 732 closes its lower contact, from battery, through the left winding of relay 722, the lower contact of interrupter 732, the lower left and upper right contacts of cam 718. the front contact of relay 729, conductor 733, to

ground at the inner right front contact of relay 609. A circuit is closed upon the energization of relay 7 22 extending from battery, winding of stepping magnet 657 and brush 655 and its first terminal of the timing switch 650, conductor 613, outer left contact of relay 7 22, upper contact of charging interrupter 7 32, lower left and upper right contacts of cam 718, front contact of relay 729, conductor 733, to ground at the inner right front contact of relay 609. Under the control of interrupter 7 32 the timing switch is advanced into position 7.

As the timingswitch passes through a position 2, a circuit is closed to advance the recording switch 600 one step. This circuit extends from battery, through the winding of stepping magnet 625, conductor 614, brush 605 and the first terminal of the bank associated therewith, inner left front contact of relay 609, conductor 616, upper contacts of cam 719, closed in position 14, conductor 617, outer left front contact of relay 609, No. 2 terminal and brush 656 of the timing switch 650, outer right back contact ofrelay 615, to ground over the No. 2 terminal and brush 653 of the timing switch. When the timing switch passes through position 3 ground on brush 656 is connected to conductor 336 and thence to battery throughthe winding of charge relay 335 operating this relay. Relay 335 now looks over its inner right front contact to ground at the lower left'contact of cam 720 and at its intermediate right contact extends its locking ground through the winding of relay 311, energizing the latter relay. Relays 311 and 335 perform no other useful functions at this time.

As timing switch 650 passes through position 4, since the relay 611 has been assumed to be operated, ground on brush 656 is extended through the right front contact of relay 611, brush 605 and its No. 2 terminal, to bat- As soon as the timin switch reaches position 7, a circuit is esta lished from battery,

through its stepping magnet 657, brush 655, strapped terminals 7 to 22, conductor 618, outer right contact of relay 707, conductor 734, interrupter 619, conductor 620, upper contacts of cam 726,'to oundat the up er right contact of cam 72 Under the inguence of slow interrupter 619, the timing switch is now advanced around into normal position, the time required for the complete cycle of the timing switch being approximately five minutes. If conversation still continues, the above described operations of

switches

600 and 650 continue throughout the duration of conversation, the recording switch 600 being advanced three steps for each complete cycle of switch 650.

When the calling subscriber hangs up to terminate the call, relay 330 deenergizes, opening the energizing circuit of relay 707. Relay (07 is, however, held energized over its inner right front contact,contact 736 of interrupter735, the upper contacts of cam 726, to ground at the upper right contact of cam 727 until the interrupter opens the contact 736. lVith relay 7 07 released, the disconnect relay 317 energizes as soon as interrupter 735 again makes its contact 737, over a circuit extending fromba-ttery, lower wind ing of relay 317, upper contacts of cam 710, outer left back contact of relay 7 07,

contacts

737 and 736 of interrupter 735, to ground over the upper contacts of cam 726 and the upper right contact of mm 727. The interrupter 735 in conjunction with relay 707 introduces a relay in the operation of relay 317 of approximately 0.25 seconds so that should the calling subscriber accidentally depress the switchhook, the connection will not 'be wiped out. The operation of relay 317 disconnects the tip and ring conductors of the subscrib- 'ers line from the repeating coil 760 and closes a circuit for advancmg sequence switch 700 to position 16. This circuit may be traced from battery, winding of magnet 700, lower contacts of cam 721, innermost u'pper front contact of relay 317, to ground at the upper left contact of cam 727.

A test is now made to determine if the ground placed on the tip and ring conductors of the calling line at the substation 100 has been removed as it should be when the calling subscriber restores his receiver to the switchhook. With sequence switch 7 00 in position 16, a circuit is established from battery, lower windin of relay 306, inner left front contact of re ay 311, lower right contact of ca-m'7 38, to ground at the lower left contact of cam 7 08. Relay 306 energizes extending its operating ground from cam 708 over its inner lower front contact to the left winding of relay 309 which relay operates. At its outer right front contact relay 309 closes an obvious holding circuit through the upper winding of relay 306 and its inner left contact, closes a locking circuit for both itself and relay 309, extending through the left normal contacts of relay 314 and the inner left normal contacts of relay 302, the right contacts of cam 706,to ground over commutator segment 312 and brush 313. Relay 309 closes a circuit for relay 7 07 extending from batter through its winding, the next to outer rig t front contact of rela. 309, the upper contacts of cam 706, to groun over segment 312 and brush 313 as soon as the sequence switch 700 reaches position 16. Re-

lay 309 at its inner left and right contacts also connects the winding of relay 308 to the tipand ring brushes 334 and 331 of the line finder and thence to the tip and ring conductors of the calling line. Relay 308 should not operate at this time.

Relay 306 upon energizing connects ground from the lower right contact of cam 705, conductor 725, inner upper contact of relay 306, conductor 7 24', over the lower contact of interrupter 723, to battery through the right winding of relay 7 22. Relay 722 looks over its inner right contact to ground over the circuit just traced, independently of the contact-of interrupter 7 23, and when the interrupter closes its upper contact extends the ground on conductor 724 over the outer right contact of relay 722 to battery, through the winding of relay 302. Relay 302 energizes opening the locking circuit of

relays

309 and 306 which release in turn releasing relay 7 22. With relay 309 released, a circuit is closed to advance sequence switch 700 to position 17 extending from battery, winding of magnet 7 00, the lower left contact of cam 713, the outer left back contact of relay 714, the inner right back contact of relay 309, to ground at the upper right contact of cam 705. As the sequence switch enters position 16% the holding ground extending to the contact 328 of relay 317 is extended over the lower left contact of cam 742, the outer right front contact of relay .311, the intermediate right front contact of relay 310 to battery through the right winding of relay 300. Relay 300 upon energizing extends this operating ground over its right contact to battery, through the left winding of relay 301, causing relay 301 to energize. At its outer right back contact relay 300 disconnects battery through resistance 323 from the-sleeve conductor 112 of the subscribers line thereby releasing the cut-off relay 102 and at its outer right front contact connects the sleeve multiple of the calling line through the winding of relay 337 to round at the upper left contact of cam 72 so that should affinal selector test the multiples of the calling line at this time, the relay 337 will be operated to open the message registering circuit which, as will hereinafter be explained, extends through the back contacts of this relay. False registration is thus prevented. Relay 102 upon deenergizing connects the message register 105 assigned to the calling substation 100 over the right back contact of relay 102 and the inner right backcontact of relay 101 to conductor 114.

When the sequence switch 7 00 left position 16, relay 707 released. With relay 301 operated, a circuit is now closed to operaterelay 615 extending from battery, winding of relay 615, conductor 621, left front contact of relay 301, conductor 622, brush 602, conductor 703,

upper contacts of cam 702, upper contacts of cam 710, outer left back contactof relay 707, contacts of interrupter 735, upper contacts of cam 726, to ground at the upper right contact of cam 7 27. Relay 615 upon energizing locks over its outer left front contact and the front contact of relay301 independent of contacts of interrupter (35 and establishes a stepping circuit for magnet 657 of the timing switch extending from battery, winding of magnet 657, inner right back contact of relay 607, terminals and brush 651, interrupter contacts of magnet 657 to' ground at the middle left contact of relay 615. Switch 650 advances until it assumes a position which is complementary to the position intov which the recording switch 600 was advanced during the conversational eriod.

It will be assumed that switch 600 is standing in position 7" having been .advaneed six steps during two cyclesof switch 650 or during a conversation which lasted ten minutes. When therefore, switch 650 reaches position '10 a circuit is closed from battery, through magnet 657, brush 604, in position 7, conductor 626,.brush 654, resistance 630, the inner left back contact of relay 623, to ground at the inner left contact of relay 615. This circuit holds the magnet 657 from further operation. As soon as interrupter 624 closes its contact, brush 654 becomes connected through the right winding of relay 607, outer normal con tacts of relay 623, interrupter contacts'624, outer right front contact of relay'615, to ground at brush 653. Relay 607 energizes in this circuit and at its inner right back contact opens the stepping circuit of switch 650 to arrest the further advance of the switch and at its left contact establishes a lockin circuit for itself extending from batte through the winding of relay 623 the le t winding and contact of relay 607, to'ground at the inner left contact of relay 615. At its inner left front contact, relay 623 closes a circuit for relay 627 extending from battery, through the winding of relay 627, the inner left front contact of relay 623, to ground at the inner left front contact of relay 615.

Relay 623 at its inner right front contact extends the operating circuit of message register 105 from conductor 114, over terminal-380, brush 381, conductor 329, inner right front contact of relay 623, through brush. 652, and at its outer right front contact establishes a ste ping circuit for magnet- 657 extending from attery, through magnet 657, the outer right front contact of relay 623, interrupter 624, outer right front contact of relay 615, to ground at brush 653. Timing switch 650 vnow advances into position 22. As it advances through

positions

11, 13, 15, 17 19 and 21, the operating circuit for message register 105 is completed from brush 652, conductor 628, back contact of relay 337, outer left contact of relay 335, through resistance 339 to battery. Message register 105 is thus operated six times or three times for each five minutes of the previously conducted conversation.

To prevent the subscriber at substation from interfering with the operation of the message register during registration, through the operation of line relay 101, since at this time the cut-off relay. 102 is deenergized, the line relay 101 is shunted down in a circuit extending from battery, through resistance 340, left contact of relay 310, outer left front contact of relay 300, brush 331, terminal 332, conductor 116, thence to the inner left back contact of relay 102. It is thus not possible for the subscriber to operate line relay 101 at this time.

In the meantime relay 607 in conjunction with relay 626 has completed a circuit extending from battery, winding of magnet 625 and its interrupter contacts, brush 601, inner right front contact of relay 627, inner right front contact of relay 607, brush 651, interrupter contacts of magnet 657, to ground at the intermediate left contact of relay 615 for advancing the recording switch 600 into position 21. A circuit is then repared for operating relay 302 extending rorn battery, winding of relay 302, conductor 608, the outer right front contact of relay 607, terminal No. 21 and brush 603, terminal No. 22 and brush 651 of timing switch 650, interrupter contacts of magnet 657, to ground at the intermediate left contact of relay 615 which circuit is completed as soon as switch 650 100 reaches position 22. Relay 302 upon energizing advances sequence. switch 700 into position 18 over a circuit extending from battery, winding of magnet 7 00, upper left contact of ,cam 718, outer right front contact of relay 105 302, to ground at the upper left contact of cam 705. As soon as the sequence switch ad vances out of position 17, relays 609, 615, 300, 301, 310 and 311 release but relays 607, 623

and 627 remain locked to ground atbrush 653 in position 22 of timing switch 650.

With the sequence switch 7 00 in position 18 a circuit is established for the down drive magnet 769 of the district selector extending from battery, through the windingof magnet 769, the upper right and lower left contacts of cam 715, to ground over the lower contacts of cam 708. "When the district selector shaft reaches its normal position, brush 743 engages commutator segment 744 establish- 12 ing'a circuit extending from ground, at the upper right contact of cam 727, brush 743,

segment 44, conductor 745, brush 606 in p6- sit-ion 21, the outer left front contact of relay 627, interrupter contacts and winding of extending from battery, winding of magnet 1 657, brush 603 in position 22, brush 651 in position 22, interrupter contacts of magnet 657, brush 606'in position 22, conductor745,

segment 744 and brush 743, to ground at the upper right contact of cam 727.

As soon as switch 650 leaves position 22 the locking circuits of relays 607, 623 and 627 are opened at brush 653 and these relays release. Relay 627 upon releasing closes a circuit for advancing the rccording'switch 600 to normal extending from battery, wind-y sition complementary to that taken by the rocording switch 600, that it is arrested before reaching position 22. Should it. advance, however, to position 22 and need to hunt further, for example, to assume a position complementary to position 10 of switch 600, the latter switch being assumed in a position for charging for a fifteen minute conversation, then switch 650.will continue advancing to position 22 where a circuit will be established for magnet 657 extending from battery, winding of magnet 657, right back contact of relay 627, brush 603 in position-.10, brush 651 in position 22, interrupter contacts of magnet 657, to ground at the intermediate left con tacts of relay 615, advancing switch 650 into position 1. Switch 650 is then advanced to position 4 which position is complementary to position 10 of recording switch 600 in the manner previously described.

, In passing through 'position 1 relay 627 is operated from battery, through the inner right contact of relay 615, to ground over the No. 1 terminal and brush 653 of the timing switch. If the switch 650 fails to stop, not finding a definite position marked by brush 604 of the recording switch, it will advance into position 22 where tliecircuit previousl traced for advancing it to position 1 wi 1 be opened at the outer right back contact of relay 627. Since the timing switch has not properly set iself, relay 623 has not energized andtherefore a circuit is closed from ground at theupper left contact of cam 705, the outer right back contact of relay 302, the outer left back contact of relay 714, the right contact of cam 713, the outer left back contact of relay 623 to-the selector time alarm circuit thereby causing an alarm to be givenafter a predetermined interval.

If the conversation time is extended beyond the maximum recording capacity of the charging 'circuit of Fig. 6 which may be 50 minutes for a call into zones requiring but one charge for each unit period of conversation, 25 minutes for a call into a more remote zone requiring two charges for each unit period of conversation, or 15 minutes for a call into most remote zones requiring three charges per unit period of conversae tion, the switch 600 will stop in position 11 and the timing switch 650 will continue timing and conversation will proceed without further charge.

Charge calls initiated by substation 150.

Had the party at substation 150 initiated the call, the circuits would havefunctioned in-the manner above described, except that when relay 308 tested, with the sequence switch 700 in positions 10% to 11%,no ground would have been found and relays 308, and

310 would not have operated and after the release of

relays

306, 309 and 722, sequence switch 700 would advance to position 17.

Under this condition, as sequence switch 700 enters positions 16% 'to 17 the locking circuit of relay 317 is extended from battery, through the upper winding of relay 317, the lower left contact of cam 742, the outer right front contact of relay 311, the middle'right back contact of relay 310, to battery through the left winding of relay 301. The cut-off I relay 102 is not released since relay 300 is not operated. Relay 30.1 operates, in turn operating relay 615 to start charging operations. From this point, the charging takes place as previously described except that the charging circuit extends from ground, through message register 106 assigned to the substation 150, the right front contact of relay 102, the inner right back contact, of relay 101, conductor 114, terminal 380, brush 381, conductor 329, the inner right front contact of relay 623, brush 652, conductor 628, the back contact of relay 337, the outer left front contact of relay 335, resistance 339, to battery.

Ulaarge calls to other zones of ezvchang e.

In the foregoing discussion it has been assumed that the connection was established to a remote zone of the exchange area requiring three charges per unit period of conversation. If the connection were established to a less remote zone, then the relay 611 would be operated and locked as previously described,but the se uence switch 700 of the district selector wou d be set into position 13 for talking rather than into position 14. Under these conditions when the timing switch 650 passes for advancing the recording switch 600, extending from ground on brush 656 in posit1on 2, the outer left front contact of relay through position 2 during each of its cycles, the path previously traced 609, conductor 617, the upper contacts of cam 719, conductor 616, the inner left front contactof relay 609, brush 605 and conduc- I vanced only two steps during each cycle of the timing switch and only two charges will be registered on the calling subscriber's message register for each five minutes of conversation.

For still nearer zones of the exchange area, the relay 611 is not operated and the sequence switch of the district is set into position 14. When, therefore, the timing switch 650 passes through position 2 during each of its cycles, the recording switch is advanced one step over the circuit previously traced through the contacts of cam 719. Since relay 611 is not operated, however, the stepping path for switch magnet 625 previously traced over the right contact of relay '611 in

positions

4 and 6 of brush 656 is not closed. Thus, the recording switch 650 is advanced only one step during each cycle of the timing switch and only one charge is registered on the message register of the calling line for each five minutes of conversation.

N 0 charge call.

It may be desirable to give free service to subscribers when they call into certain zones of the exchange area. Forsuch calls, the district sequence switch 700 is set into position 13 for talking and relay 611 is not operated. Under this condition, the advance of the timing switch during-its first cycle will operaterelay 335 and lock it as before but the timing switch is ineffective to advance the recording switch since all of the stepping paths to magnet 625 are open either at cam 719 or at the'right contact of relay 611 and therefore, the recording switch remains in'its normal position 1. The timing switch, however, proceeds as before to rotate through successive cycles until the conversation is terminated. As soon as the conversation ends, the district sequence switch advancesg-into position 16 as previously described and 'is thence timed into position 17 under the control of

relays

306, 309 and 722, and interrupter 7 Since the recording switch is not advanced the circuit for operating relay 302 is now closed immediately over conductor 608, the outer right back contact of relay 607, brush 602 in position 1, conductor 703, the upper contacts of cam 702, the upper contacts of cam 710, the outer left back contact of relay 707, contacts of interrupter 7 35, upper contacts of cam 726, to ground at the upper right contact of cam 727, Relay 302 upon energizing advances the district sequence switch into position 18 as before described where the district and line finder switches restore as hereinbefore described. Relay 615 does not energize since its circuit is not closed at brush 602 of the recording switch. When the sequence switch 700 advances out of position 17, the circuit of relay 609 is opened and with relay 609 deenergized the timing switch is advanced into position 22 over a circuit extending from battery, winding of magnet 657, inner right back contact of relay 607 brush 651, interrupter contacts of magnet 657, brush 601 and normal terminal, to ground at the inner right back contact of relay 609. In position 22 a circuit is closed for advancing switch 650 to normal extending from battery, winding of magnet 657, brush 603 and normal terminal of switch 600, terminal 22 and brush 651 of switch 650, interrupter contacts of magnet 657, brush 601 and normal terminal, to ground at the inner right back contact of relay 609. The restoration of other apparatus employed in the connection proceeds from this point as previously described. Since at no time was relay 623 operated, the charging path to the subscribers message register was not closed and no charge was made.

What is claimed is:

1. In a telephone exchange system, a calling line, a called line, means for extending said calling line to said called line, a call charging device for said calling line, means for measuring the number o;t unit periods of conversation elapsing from the time the called subscriber responds until the calling subscriber hangs up, a recording means operative by said last means, a circuit for operating said charging-device, and means con trolled by said measuring means to close said circuit a number of times in accordance with the record set up on said recording means.

2. In a telephone exchange system, a calling line, called lines of different classes, means for extending said calling line to said called lines, a charging device for said calling line, a recording means, means for advancing said recording means in accordance with the number of unit periods of conversation elapsing from the time the called subscriber responds until the calling subscriber hangs up and in accordance with the class of the called line, and means operative after the calling subscriber hangs up to operate said charging device a varying number of times for each unit period recorded by said recording means in accordance with the class of the called line.

3. In a telephone exchange system, a calling line, called lines of different classes,v

means for extending said calling line to said called lines, a charging devipe for said calling line, means for measuring the number of unit periods of conversation elapsing from the time the called subscriber responds until IOU