US2402700A - Telephone system - Google Patents

Description

June 25, 1946.

s. B. WILLIAMS 2,402,700

TELEPHONE SYSTEM 7 Sheets-Sheet 2 Filed ,May 22, 1940 CONTROL CIRCUIT //V|/EN TOP 5. B. WILL/A M5 ATTORNEY June 25,1946. 5. B. WILLIAMS TELEPHONE SYSTEM 7 Sheets-Shet s Fild May 22, 1940 at v IN l/EN 70/? s. B. WILLIAMS GAQM A 7'7'ORNEY June 25,- 1946. s. B. WILLIAMS TELEPHONE SYSTEM Filed May 22, 1940 7 Sheets-Sheet 4 lNVE/VTOP 5.5. WILLIAMS A 7' TORNEV June 25, 1946. sQB. WILLIAMS TELEPHONE SYSTEM Filed ma 22. 1940 7 Sheets-Sheet 5 l/Vl/E/V TOP 5 a. WILLIAMS 5? (2 -6. maL

A TTOR/VFY June 5, 19 s. B. WILLIAMS 2,402,700

TELEPHONE SYSTEM Filed-May 22. 1940 7 Sheets-Sheet 6 TO.-'OTI-IER TO OTHER RELAYS 60/ RELAYS 608 //v VEN 70/? S. B. WILLIAMS June 25, 1946. s. H. WILLIAMS 2,402,700

. TELEPHONE SYSTEM File d May 22, 1940 7 Sheets-Sheet //vv/v.ro/? S B. WILL IA MS A TTORNE V Patented June 25, 1946 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM Samuel B. Williams, Brooklyn, N. .Y., assignor to Bell Telephone Laboratories, Incorporated,

New York, N. Y., a corporation of New York Application May 22, 1940, Serial No. 336,494

'28 Claims. 1

This invention relate to measured service telephone systems in which a permanent record is made of the calling line identification and the charge units assessed for a connection between a calling line and a called line and in which the chargeunits ,are designated by one, or. more impulses depending upon the destination of the completed connection or the number of time intervals consumed after the connection is established. The object of 'the'invention i to improve such systems by providing a recording mechanism available to said lines by which the number or otherdesignation of the calling line and the numberofcharge units to assessed for a call there'- irom rare permanen-tlyirecorded. I'm-has been ,iound desirable, {for instance, and particularly in multiofilce and suburban telephone systems. to provide two or more classes of service. ,In such systems the subscribers stations maybe classified asresidence stations and busi- .ness stations and the area itself divided into a plurality ofzones. With such a classification, the residence subscribers will be v iven unlimited flat rate service for calls to stations within the same zone-and will be charged one or more charge units ,Ior each call to stations in any of the other zones. The business, subscribers, on the other hand, will be charged a rate of ,one charge unit for .each call to stations within the same zone but, in addition, will also be charged additional charge units for each call to stations in the other zones. Again, in certain types of telephone systems and particu larly in the local area of such systems, it is cu tomary to assess charges for calls in terms of standard time units consumed during the conversation interval as, for instance, in so-called telechron charging systems wherein calling subscribers are charged a flat rate for each telechr-on unit consumed once the connection is established. In such systems, ,as well as in the multizone system above mentioned, it is believed to be more economical and eflicient to eliminate individual station meters and institute in lieu thereof a central recording system which is adapted to produce apermanent recordior each call which comprises the identity of the calling line and the number of charge units to be assessed for an established connection. g

According to one embodiment of the present invention, the. subscribers lines of a telephone system are divided into a plurality of zones all of which, in establishing connections, have access to line finder switches capable of discriminating between one or more classes of lines, and furnished "with a switch responsive to impulses that designate themumberof charge units-for a .call. These impulses may, of course, be transmitted from a distant repeater which is adapted to produce a number of impulses indicative of a connection established thereover, or from a first selector adapted to produce a single impulse for ,a local call routed therethrough, or ,from a selector in a switching train wherein the call is metered purely on a time basis. The line finder switches have access, in turn, to common recording facilities that are adapted to produce a permanent .identificationof the calling line terminal number or the directory number, whichever is desired, and of the number of charges registered y the line finder register switch. Each aof these records may be produced on a tape or other continuous impressible media by perforators, light valve ap- ,paratus or similar devices well known to the art.

One feature of .the'invention, therefore, isca line finder switch that'inc'ludes a register switch responsive to impulses from a trunk in the switching train, the circuit of said register switch including responsive means that indicate which of two parties of a two-party line is calling. Another feature of the invention is a recordin circuit accessible to all line finder groups which is provided with a novel means Lfor identifying the calling line.

Yet another feature of the invention is a register in said recording circuit which is used in common by the line identifiyng'means of the recording circuit and by the registering switch of the line finder to temporarily register. in succession, each of the digits of which the calling line numberis composed and of the digit that designates the number of charge'units registered in the stepping switch of the line finder taken into use, each ing therewith that translates the marked ter minal into the directory number of the calling line.

A further feature of the invention lies in a guard circuit that keeps a line finder out of serv ice after use in a connection until a charge for the call registered in the switch associated therewith is properly recorded by the recording circuit against the calling line notwithstanding the fact that said, calling line may have restored and released the line finder before a record of the charge has been made.

A telephone system arranged in accordance with this invention is shown schematically in the drawings which form a part of this specification and in which:

Fig. 1 shows two subscribers stations A and B, lines LI and L-Illfl, line circuits LC! and LC-I00, two sets of brushes and two sets of terminals of the bank of each of two line finder switches LFI and LF| l and the brushes and a set of terminals of each of two connector switches Cl and C2;

Fig. 2 shows the vertical commutators 231 and the commutator brushes 238 of the line finders LF[ and LF-l I, resistors 22! to 225, inclusive (a set for each of the line finders) and a line fiinder control unit LFC-B;

Fig. 3 shows the circuit of the line finder switch LFI including the charging register 330;

Fig. 4 shows a line finder control unit LFC-A;

Fig. 5 shows a first selector switch S permanently associated with the line finder LF-I of Fig. 3, a timing circuit TC, a repeater R, two other selectors S2 and S3 shown in schematic fashion, two connectors C4 and C3 accessible, respectively, from selectors S2 and S3; subscribers stations AS! and AS2, a part of the recording circuit and parts of the line finder switch LF| Fig. 6 shows the line identifying portion of the recorder circuit;

Fig. 7 shows the common register and perforator of the recorder circuit; while Fig. 8 shows the manner in which Figs. 1 to '7,

inclusive, are to be arranged with respect to each other in order to show the invention completely.

The subscribers stations are of the usual type employed in common battery automatic telephone systems and each includes a dial or other impulse sending device for controlling the numerical switches through which connections with other subscribers lines are established. The line circuit LC-l comprises a combined line and cutoff relay Ill and a permanent signal lock-out relay I M. The line circuit LC--l comprises similar relays Ill and ll4'.

The line finder switches LF-| and LF-H, selector switches S, S2 and S3, and connectors Cl, C2, C3 and C4 are of the well-known twomotion' step-b-y-step type. A clear and complete description of the structure of such switches is to be found in Automatic Telephony by Smith and Campbell, 2nd edition, pages 53 to 67., inclusive. The bank of each of the line finder switches is represented in the drawing by two sets of terminals and the banks of the selector and connector switches are each represented by a single set of terminals, The line finder LF-l and selector S are shown but the line finder LFH, selector switches S2 and S3, and connector switches CI to C4, inclusive, are represented by the brushes and the one or two sets of terminals.

The distribution of lines on the terminal banks of the line finder switches and the detailed operation of the control circuit shown in Fig. 4 are to be found in Patent 2,210,068 granted to T. L. Dimond on Aug. 6, 1940. Only such parts of these circuits are described in detail herein which are necessary to a complete understanding of the present invention, reference being made to the above-mentioned patent for a more detailed description thereof.

The line finder circuit, as

said before, com.-

prises a line finder switch of known structure which is adapted to step its brushes vertically and horizontally when seeking the terminals of a calling line. The brush shaft (not shown) of this switch is equipped with a pair of normal post springs 324 which can be adjusted to operate when the shaft has stepped vertically to any one of the ten horizontal levels of terminals reserved to the subscriber lines. By means of these springs, as it will be shown, discrimination may be made, say, between a group of lines which is entitled to fiat rate service and another group entitled to individual message rate service. The trunk (that is, the combination of the line finder and first selector S) comprises a pair of charging relays 305 and 306 controlled by the polarized relay 30'! by relay 304 and by a charging switch 330 so that when the line current is reversed, relays 305 and 306 will operate to record the charges on said switch. The operation of the relays 305 and 306 when relay 304 is not operated, is controlled from the interrupter circuit 325 and results in the count of one on the charging switch 330.

Associated with each line finder switch LFl are two stepping switches of known structure, namely, switches 520 and 530. As the line finder brushes are raised vertically and turned horizontally, the switch 520 is operated each time the vertical magnet 343 of the line finder is operated and switch 530 is operated each time the horizontal magnet 344 is operated. It will be noted that the operation is synchronized by the back contacts of stepping magnets 532 and 533 of switches 520 and 530, respectively, which are in parallel with the back contacts of the vertical and rotary magnets 343 and 344, respectively, of the line finder, The number of vertical steps taken by the line finder is registered on switch 520, the number of rotary steps taken is registered on switch 530 and the particular set of terminals belonging to the calling line is determined by the operation or non-operation of'relay 342 and registered on relay 3l2 of the trunk.

The identification circuit shown in Fig. 6 and the recording circuit shown in Fig. 7 are adapted to be connected to a calling line finder when ground is connected by said finder to conductor 3 l8. A relay SM is provided for each trunk and this, together with relay 602, provides for noninterference in case two trunks are calling for the recording circuit at the same time. A relay 603 is provided for each group of trunks serving the same line finder group. These relays 603 together with relay S04 provide for non-interference between line finder groups. Thus the common identification and recording circuit can be connected to one trunk at a time. When so connected, one of the relays 605, 606 or 601 is operated depending upon whether or not relay 3li2 in the line finder is operated, to distinguish between the upper and lower terminal sets at the brushes of the line finder switch.

The positions assumed by the switches 520 and 530, respectively, indicate the terminal identity of the calling line on the line finder terminal bank, and circuits completed over the terminal arc of each of these switches result in the opera tion of a vertical and horizontal magnet of the cross-bar switch 650 which is effective in closing a cross-point on the switch that includes a grounded conductor that marks the calling line. The cross-bar switch shown is assumed to be a six-wire switch, thus providing for six hundred terminals, one for each line of three line finder groups of two hundred lines each. The vertical rows on the switch represent line finder level positions while the horizontal rows represent the line finder terminal positions. The cross-bar switch 650 is of the type disclosed in Patent 2,021,329, issued to J. N. Reynolds on November 19, 1935, and reference is made thereto for a complete disclosure of its construction and operation. The marking conductors from the various cross-points of the switch 650 which indicate the terminal numbers of the lines on the banks of the line finder frame, extend to the distributing frame 550 where, by cross-connection to the line terminal frame 560,. the line finder terminal number may be translated into a line directory number through the operation of a translating circuit which consists of four relays 52452'I and a relay 62I per group of twenty-five lines, and a group of twenty-five relays 625-4549 for the entire office. The contacts on relay 62! and the relays 625-549 provide for the tens and units digit designations while other contacts on relay 62I alone provide for the thousands and hundreds digit designations as will be subsequently set forth.

The recording circuit shown in Fig. 7 includes a perforator III! which comprises a punching magnet H8 and five recording magnets I5, six pairs of progress-relays lIlII02 'II3'II4, and a register comprising ten relays BO-J39 and relay I4I. Each pair of progress relays is operated for the registration of a particular digit of the directory number and, also, for the digit which represents the number of charge units for the call. When so operated, the lower of the two progress relays connects the register with a group of ten conductors extending between each of the first four pairs of progress relays IIlI--Ill8 and the line translating circuit. One conductor in each group is grounded to indicate the digits involved, thereby causing the operation of one of the register relays. The perforator is then tied in with the operated register relay to punch the digit registered. These operations are repeated for each digit of the calling line number and each pair of progress relays is, in turn, operated and released.

When making the record of the number of charge units, the progress relays I09 and III connect the register relays with the group of conductors which extend to the terminals of the charging switch 330, and the particular conductor grounded by the brush 3I3 will cause the operation of a register relay whose connection with the perforator will result in the punching of the digit that corresponds to the terminal to which brush 3| 3 is engaged.

The repeater R to which the selector S may have access is of a conventional design W811 known to the telephone art and comprises a group of relays which, upon response of the called subscriber ASE, operate to produce a number of pulses which are transmitted over conductor 3I'I to effect the operation of the magnet 3 I U of charging switch 330. The number of pulses produced by the repeater indicates the number of charge units to be assessed for a call routed thereover and it iseasily seen that the number of impulses may be different with groups of repeaters that give access to different zones for which the charges are different. Provision is made to cancel one of the charge units in the repeater on signal from the line finder normal post springs 324 that the call is from a line entitled to flat rate service, in which event, since the. subscriber is entitled to one charge unit for the call, the same must be subtracted from the total charge units assesse for a call routed through the repeater.

The selector S has access, of course, to second selectors such as S2, for example, in which no impulse producing facilities are required. This selector gives access to a'local zone where one charge is provided upon the reversal of the loop on the response of the called line. There are other selectors to which selector S has access which are designed to time the call for charging on a telechron unit basis. These types of selectors as well as the manner of charge control exercised thereby are so well known in the art that their conventional representation as shown in Fig. 5 is thought to be sufiicient to indicate that the scope of the invention is intended to cover all known types of telephone switching facilities adapted, upon battery reversal in response to the answer of the called line, to produce one or more charging impulses for a completed connection, irre-' spective of whether such charges are for the area to which a calling line is extended or for the number of units'of conversation time orboth. To more completely describe the operation of the system shown, assume that the subscriber at station A removes the receiver to originate a call, thereby closing a circuit for operating line relay I I I which extends from battery through the midcile and right windings of said relay, No. 4 contacts of said relay, over line L--I and through station A, through the No. 3 contacts and left winding of relay I II to ground. The right winding of relay I I I has a high resistance and, therefore, said relay is only partially energized by the current in this circuit. Relay III closes its No. 6 contacts thereby connecting ground to conductor finders of both subgroups. (Ground is permanently connected to the top commutator segment of each line finder so that a finder will always stop on the top level, if notbefore.) The ground connected to conductor H2 is further extended through resistor 22I (which is common to the twenty lines connected to the first level of the finders in subgroup A) to start conductor 220. c

As long as there is an idle finder in subgroup A, relay 451 is held operatedv in a circuit which includes the No. 1 contacts of relay 459, left contact of make-busy key 459, upper contacts of the make-busy key MB of each finder in subgroup A, upper back contact of the vertical off-normal springs 345 of each idle finder in the subgroup, thence over conductors 346, through the No. 2 back contacts of relay 5IlI, back contacts of relay 500, and No. Shack contacts of relay 502 of each associated idle first selector, to ground, Assuming that there is anidle finder in subgroup A so that relay 451 is operated, the connection of ground to conductor 220 causes the operation of start relay 450 over the No. 2 front contacts of relay 451, winding of relay 450 to battery.

- Relay 450, in operating, connects ground over its No. 2 contacts'to' conductor 454 to start the ringing interrupter 463, and connects ground over its No. 1 contacts to conductor 462 leading to the alarm circuit 460 for the purpose of effectingan alarm in case relay 450 remains unduly operated. Relay 450 further closes a circuit for operating relay 45I which extends from battery through the winding of relay 45!, No. 4 contacts of relay 454, No. 5 contacts of relay 453, No. 4 contacts of relay 450, to ground at No. 4 back contacts of relay 459; Relay 45I look through its N0, 6 contacts under the control of relays 454 and 459 and closes a. circuit for operating. the-line relay of the selector associated with the allotted line finder.

As shown in the drawings; the brushes 4' to 416 of the line finder allotter switch are in engagement with the first set of terminals, which terminals are connected to the line finder whose circuit isshown in Fig. 3. The circuit closed by relay 45! for operating the line relay 500 of the associated selector S of Fig. 5 is traced from ground through resistor 458, No. 4 contacts of relay 45l, No. 6 contacts of relay 454, through brush 415 and terminal I, conductors 348 and 333, No. 3 back contacts of relay 5132 of selector S, through the upper winding of relay 500 to battery. In operating, relay 500 closes a circuit for operating the slow-to-release relay 50L Rela 5M connects the lower winding of relay 533 through its No. l contactsto conductor 534 which extends to ground in the permanent signal timing circuit TC and connects ground through its No, 4 contacts to the winding of relay 502 and the No. 1

.normal contacts of relay 503 to conductor 300.

Relay 503 operates, locks through its'upper winding and the No. 3 contacts of relay 5M, and connects conductor 300 to conductor 505 via its No. 1 contacts to ground in the timing circuit TC.

The connection of ground to conductor 30!], due to operations consequent to the operation of relay 500, is in preparation for the finding of the calling line as hereinafter described. Relay 45! connects ground through its No. 1 contacts to hold relay 451 operated during the operation of the allotted finder to find the calling line in case this line finder is the only available one in the group. Relay 45l also closes a circuit for operating the stepping relay 452 which extends from battery through the lower winding of said relay, No. 3 contactsof relay 45!, brush. and terminal! of bank 414 of the allotter switch, back contact of the 11th rotary step springs 322, No. 2 back contacts of relay 342, No. 2 back contact of relay 34] the back. contacts of the vertical stepping magnet 343 and the rotary stepping magnet 344 to ground. The stepping relay 452v operates and closesa cire cuit from ground at the No, 3 back contacts of relay 454, front contacts of relay 452,.No. 1 back contacts of relay 453, brush andv terminal i of bank 413 of the allotter switch through the winding of the vertical stepping magnet 343 to battery. Magnet 343 operates, stepping the brushes of the finder up to the first level. The vertical oilnormalsprings 345 are actuated when the shaft on which the brushes are mounted moves out of normal position. The operationv of magnet 343- opens the operating circuit of relay 452, but if the calling line is connected to terminals in the first level of the line finder bank, relay 452 is held operated to prevent reoperation of magnet 343. The circuit for holding relay 452 operated is trace from battery through the lower winding of said relay, No. 3 and No. 2 contacts of relay 45|,. upper winding and No. 3 contacts of relay 453, No. 1 contacts of relay 454, brush 412 and terminal I of the allotter switch, conductor 439,

V commutator brush 238 and first segment of come mutator 231, through conductor I I2 to ground in the line circuit LCI. If, however, the calling line is connected to terminals in some other level of the bank, relay 453 does not operate when brush 238 engages the first commutator segment and, inthis case, relay 452 releases when magnet 343 operates. The release of. relay 452 causes the releaseof magnet 343, and the'release of magnet 343 again closes the circuit for operating relay.

452'. The described cycle of operations between relay 452 and magnet 343 is repeated to raise the brushes step by step until the brushes of the finder reach the level of th terminals of the calling line, at which time relay 452 is held in the circuit through commutator brush 238 as already described.

In parallel with the winding of vertical magnet 343 is the winding of magnet 532 of rotary stepping switch 520 whose terminal arc comprises ten terminals and a normal terminal N with which the brush 52I of the switch is in normal engagement. The ten terminals are multipled to conductors which extend to the windings of the ten select magnets 6|06l3 of thercross-bar switch 650. in the same order as the numerical designation of each of the terminals, that is, the conductor connected with terminal 0 being connected to the conductor which extends-to the winding of select magnet BIO and so on up to and including the conductor connected with terminal 9 which extends to select magnet 6 l9.

When the circuit is completed for the vertical magnet 343 asab-ove described, a parallel circuit is completed to the winding of magnet 532 and the two magnetsoperating together, cause the brush shaft of the line finder (no-t shown) and the brush 52i of'the switch 525 to step in synchronism so that when vertical. stepping is completed, the brush. 53l will be engaged to a terminal of its are that corresponds to the terminal level to. which the line finder brushes have been raised. The off-normal springs 5|"! of the switch 520 are closed on the first step, the lower contacts connecting ground to conductor 5l9 and the upper connectingthe winding of release magnet 534 to conductor 32!.

In the present embodiment of the invention, it is assumed that lines entitled to two different classes of service will terminate on terminal banks accessible to the same group of line finders of which, say, line finder LF| is representative. Thus it may be assumed that lines entitled to fiat rate service will appear on certain upper terminal levels and lines entitled to individual message rates will appear on lower terminal levels. To discriminate between the two classes of service, therefore, normal postsprings 324 are provided in each line finder, which springs may be adjusted to close at the first terminal level in which the flat rate lines are located, it being further assumed that the individual message rate lines appear below this level and that the normal post springs are not closed therefor. Hence; under the above assumption, if line A is a fiat rate line then, when the vertical magnet 343 has raised the brush shaft to the terminal level in which line A is located, normal post spring 324 operate to perform functions noted hereinafter. One the other hand, if the line A should bean individual message rate line, then the normal post springs will not operate and these subsequently to be described functions will not be performed.

Relay 453 is partially operated by the energize.- tion of its upper winding in the circuit above described to close its No. 6 contacts and thereby operatively energize its lower, locking winding under control of the No. 5 contacts of relay 45L The complete operation of relay 453, due to the energization of its locking winding, opens the circuit through its upper Winding, opens the operating circuit of vertical stepping magnet 343 and closes the circuit for operating the rotary stepping magnet 344. Relay 453 is slow in operating so that the brushes of the line finder will stop vibrating before the circuit is closed foropcrating the rotary stepping magnet. The circuit for operating the rotary stepping magnet 344 is traced from battery through its winding, terminal I and brush 416 of the alotter switch, No. 1 front contacts of relay 453, contacts of relay 452 to ground at the No. 4 back contacts of relay 454. The operation of magnet 344 steps the brushes of the line finder switch into engagement with the first set of terminal in the level to which the brushes were advanced by the operation of magnet 343, and its operation opens the operating circuit through the lower winding of relay 452, causing its release unless the calling line is connected to the terminals engaged by the upper set of brushes I3I, I32 and I33 or to the terminals engaged by the lower set of brushes I34, I35 and I36. If neither of the lines connected to the terminals engaged by the brushes of the line finder is a calling line awaiting connection to a first selector, relay 452 releases when the circuit through its lower winding is opened bythe operation of magnet 344. The release of relay 452 causes the release of rotary magnet 344 and the release of said magnet again closes the operating circuit for relay 452. Relay 452 and rotary magnet 344 are thus alternately operated andreleased to advance the brushes of the line finder step by step until the one or the other of the two sets of brushes engages the terminals of the calling line, whereupon relay 452 is held operated and one or the other of relays 34I or 342 is operated as hereinafter described.

In parallel with the winding of rotary magnet 344 is the winding of magnet 533 of rotary stepping switch 530 whose terminal arc comprises ten terminals and a normal terminal N with which the brush 523 of the switch is in normal engagement. The ten terminals are multipled to conductors which extend to the windings of the ten hold magnets 660-669 of the cross-bar switch 650 in the same order as the numerical designation of each of the terminals; that is, the conductor connected with terminal being connected to the conductor which extends to the winding of hold magnet 660 and so on up to and including the conductor connected with terminal 9 which extends to hold magnet 669.

When the circuit is completed for the rotary magnet 344 as above described, a parallel circuit iscompleted to the Winding of magnet 533 and the two magnets, operating together, cause the brush shaft of the finder and brush 523 of the. switch 530 to step in synchronism so that when rotary stepping is complete and the brushes of the finder are engaging the terminals of the calling line, brush 523 will be engaged to a terminal of its are which corresponds to the numerical designation of the line terminal in the horizontal level in which it is located. The offnormal springs I8 of the switch 530 are closed on the first step, the lower contacts connecting ground to conductor SH and the upper connecting the winding of release magnet 535 to conductor 32I.

If the calling line is found by brushes I3I, I32 and I33, a circuit is closed for holding the stepping relay 452 operated and for operatin relay 34I. This circuit is traced from ground through the upper winding of relay 452, No. 2 front contacts of relay 453, No. 1 contacts of relay 454, brush 412 and terminal I of the allotter switch, conductor 439, N0. 5 contacts of relay 342, lower winding of relay 34I, contacts of release magnet 349, test brush I 33 and terminal II9, conductor II6, No. 6 contacts of relay II4, No. 1 contacts of relay III, No. 1 contacts of relay H4, through the middle winding of relay III to battery. The non-inductive resistor 461 connected across the upper winding of relay 452 makes this relay somewhat slow in releasing so as to prevent its release if the brushes are momentarily advanced beyond the terminals of the calling line; it also prevents the release of relay 452 while the current is building up in the circuit through the test brush and terminal of the calling line. In addition to holding relay 452 operated, the current in this circuit is effective to complete the operation of relay III and to energize the lower winding of relay 34I and thereby partially operating said relay to the extent of closing its No. 3 contacts and completing a circuit from battery through said upper winding and No. 3 contacts, No. '7 contacts of relay 342, to ground on conductor 300 as already traced thereto. With relay 34I completely operated by its upper winding, the line L-I is connected through brushes I3I and I32, the Nos. 1 and 7 contacts, respectively, of relay 34I, upper and lower windings of polarized relay 30l, conductors 302 and 303, Nos. 2 and 3 back contacts of relay 502, to the windings of the line relay 500 of selector S. The complete operation of relays 34I also disconnects the lower winding of relay 342 from conductor 439, disconnects the release magnet 349 from conductor 346, disconnects the lower winding of relay 452 from the contacts of magnets 343 and 344, and closes a circuit for holding relay 452 and operating relay 454. This circuit is traced from battery through the lower windin of relay 452, No. 3 contacts of relay 45I, brush 414 and terminal I, back contact of the 11th rotary step springs 322, No. 2 back contacts of relay 342, No. 2 front contact of relay 34I, conductor 340, upper winding of relay 454 to ground. With relay 34I operated, the complete operation of the line and cutoff relay III through its middle winding is assured by its connection through conductor H6, terminal H9, brush I33, contacts of magnet 349, Nos. 4 and 3 contacts of relay 34I, No. 7 back contact of relay 342, conductor 300 to holding ground potential already connected to this conductor as above described.

If the calling line is connected to the set of terminals engaged by the brushes I34, I35 and I36, a circuit is closed from ground through the upper winding of relay 452, No. 2 contacts of relay 453, No. 1 contacts of relay 454, brush 412 and No. 1 terminal, conductor 439, No. 6 back contacts of relay 34I, the lower winding of relay 342, brush I36, to the winding of, the line relay of the calling line (not shown). Relay 452 is held operated by its upper winding and relay 342 is partially operated by its lower winding. Relay 342 closes its No. 4 front contact thereby completing a circuit through its upper winding to ground on conductor 300. Relay 342 is thereby completely operated, connecting the calling line to selector S. Relay 342 also disconnects the lower winding of relay 34I from conductor 439 and disconnects the locking contact of relay 34I from conductor 300 so that, if relay 34I ha also operated due to brushe I3I, I32 and I33 engaging the terminals of a calling line, relay 34I will release and the line engaged by brushes I34, I35 and I36 will be the only one connected to selector S. Relay 342 also disconnects the winding of release magnet 349 from conductor 346, discon- 11 nects the lower winding of relay 452 from the contacts of magnets 343 and 344, and closes a circuit for holding rela 452' and for operating relay 454. This circuit i traced from battery through the lower winding of relay 452, No. 3 contacts of relay 45l, brush 414, and terminal I, normally closed contact of the 11th rotary step springs 322, No. 2 front contacts of relay 342, conductor 340, the upper winding of relay 454 to ground. Relay 342 also connects the test brush I36 directly to conductor 300 to insure the com plete operation of the line and cut-oil relay of the calling line and completes an obvious circuit for relay 3l2 which operates and locks to ground on conductor 5H3.

It is particularly to be noted that further ro tary stepping of the line finder is prevented due to stepping relay 452 holding energized through its upper windin in the circuit for operating the switching relay 341 or 342 of said line finder and Completing the operation of the line and cutoff relay of the subscribers line circuit. It is also to be particularly noted that the switching relays 34! and 342 do not need to be fast operating to prevent advance beyond the terminals of a calling: line because the stepping relay 452 is held operated. Relay 452, being held to prevent further stepping, no further action can take place until the lower operating winding of relay 34 i or 342 has become sufficiently energized to close the locking circuit through its upper winding.

With relay 454 operated, due either to the operation of relay 34| or to the operation of relay 342, a. circuit is closed through the lower winding and No. 5 front contacts of relay 454, through brush 41! of the allotter switch, lower back contact of the make-busy key MB, to ground at the lower front oontact'of the vertical off-normal springs 345. In operating, relay 454 disconnects ground from the contact of the stepping relay 452 to prevent further operation of the rotary stepping magnet 344; opens the circuit path through brush 415 and conductor 348 to the upper winding of the line relay 500 of selector S; opens the circuit through the upper winding of relay 452 and brush 412- of the allotter switch, and causes the release of relay 45!. The release of relay 451 opens the circuit through the lower winding of relay 452, brush 414 and the upper winding of relay 454, thereby causing the release of relay 452. The release of relay 451 also opens the circuit for holding relay 451 operated which, however, will not release if there is an idle line finder supplying ground over conductor 346 through the left contacts of key 469, and causes the release of relay 453. In releasing, relay 453 closes a circuit for operating the stepping magnet 410 of the allotter switch that extends from battery through the winding and interrupter contact of said stepping magnet, No. 2 contacts of relay 454, No. 4 contacts of relay 453 to ground on the No. 1 front contacts of relay 451. The operation and release of magnet 410 steps the brushes of the allotter switch to the next set of terminals.

'If the line finder connected to this set of termimale is busy, relay 454 is held operated by its lower winding in a circuit through brush 41! of the allotter switch to ground at the vertical oil?- normal springs 345 of the busy finder. Since brush 411 makes contact with each terminal be- 'fore it breaks contact with the circuit for the preceding terminal, relay 454 is held operated and the stepping magnet 410 is alternately operated and released to advance the brushes of the allotter switch step by step until brush 4 encounters a terminal connected to an idle line finder. When an idle finder i encountered'relay 454 releases and stops'the allotter. The control circuit'LFCA is then ready tooperate in response to another call.

Returning now, to the selector S, the extension of the calling line through conductors 30 2 and 303 to the winding of relay 500 is effective in operating said relay. Relay 500 completes a circuit for relay 50! extending from battery through the winding ofsaid relay, front contacts of relay 500, No. 5 contacts of relay 502 to ground. Relay 50-I operates and, among other functions; applies ground to its No. '4 contacts which, through the No. 1 normally made contacts of relay 503, is applied to conductor 300. If, now, the normal post springs 324 of the line finder switch are operated, due to the fact that the call comes from a line entitled to fiat rateservice, said ground will complete a circuit through the upper winding of relay 304 via the normal post springs, causing said relay to operate and causing ground to be applied to conductor 311 via the No. 4 back contacts of relay 306. The function of relay 306 and the significance of the ground on conductor 3l1 will be taken up in their respective sequence in the operation of the circuit.

Dial tone is transmitted to the calling subscriber in the usual, manner and, when the subscriber dials the first digit of the called subscribers number, relay 500 is alternately released and reoperated by each of the impulses in the train. Therelease of relay 500, in response to the impulse, closes a circuit from battery through the winding of the vertical stepping magnet 506, winding of change-over relay 509, No. 2 front contacts of relay 50I, through back contacts of relay 500, No. 5 back contacts of relay 502 to ground. The operation of magnet 506 raises the brushes 5, 5l2, 5l3 and 5M to the first level of the bank. As soon as the shaft and brushes 0f the switch are moved out of normal position, the vertical off-normal springs 515 are actuated, closing thereby a circuit for operating relay 5"]. This circuit includes the upper set of contacts of springs 5l5, the front contact of relay 509 and the No. 4 contacts of relay 50L Relay 5l0 locks in a circuit which includes the contacts of the rotary stepping magnet 501, the N0. 2 contacts of relay M0, the No. 5 contacts of relay 502 to ground. When relay 500 reoperates at the end of the first impulse, the vertical stepping magnet 506 releases. Relay 50I is slow in releasing and remains operated while relay 500 is responding to dial impulses. Relay 509 is also slow in releasing and remains operated until all of the impulses in the series have been received by relay 500. The vertical stepping magnet 506 is reoperated by the release of relay 500 in response to each ofthe succeeding impulses of the train, thereby stepping the brushes up to the level corresponding-to the digit dialed.

The first digit dialed by the subscriber may act to discriminate between an unlimited service area and one in which the charge for the call is a function of its destination. For this purpose, a set of normal post springs 529 is provided in the first selector which may be adjusted to close at any desired level. If, for instance, multiple charging is reserved. for trunk outlets located on the fifth level and over the terminal banks accessible to brushes 5| l5l4 of the switch, springs 529 are adjusted to close when the brush shaft'is raised five steps in response to the five impulses of the first digit. When these springs close, an obvious circuit is completed for relay 304 overits lower. winding, causing said relay to operate andperform functions noted hereinafter. For all trunk levels below the fifth, that is, for all outlets provided by digits 1..to 4 inclusive, springs 529 do not close, relay 304 is not operated and selector S moves vertically to engage a second selector S2 which is adapted to reverse the direction of current flow over the talking circuit upon the response of the called subscriber ASI but is not adapted to transmit pulses to operate the charging equipment more than once.

When relay 509 releases after the last impulse of the train has been received (assuming that the switch S has been advanced to the fifth or higher terminal level), it closes a circuit from battery through the winding of the rotary stepping magnet 501, No. 1 contacts of relay 510, back contacts of relay 509 to ground at the No. 4 contacts of relay 501. The operation of magnet 501 advances the brushes into engagement with the first set of the terminals in the selected level and it also causes the release of relay 510 which, in turn, causes the release of magnet 501. If the repeater R, connected to the first set of terminals is busy, the test brush 513 encounters a ground potential thereon which is effective to cause the reoperation of relay 510 over a path that extends from battery to the winding of said relay, the upper contacts of springs 515, contacts of magnet 501, lower back contact of the 11th rotary step springs 516, the No. 4 back contacts of relay 502, brush 513 to the ground potential (not shown) on the sleeve terminal of the busy repeater. Relay 510 recloses the circuit for operating the rotary stepping magnet 501 and the brushes are thereby advanced to the next set of terminals. Relay 510 and magnet 501, in operating and releasin in the manner described, thus cooperate to advance the brushes of the selector step by step until an idle set of terminals is encountered as determined by the absence of ground on the test terminal of the set engaged by brush 513, whereupon relay 502 is operated in a circuit traced from battery through the winding of relay 510, upper set of contacts of springs 515, contacts of magnet 501, lower back contacts of the 11th rotary step springs 516, winding of relay 502 to ground on the No. 4 contacts of relay 501. Relay 502 operates in this circuit but relay 510, being marginal, does not. Relay 502 operates and disconnects the windings of relay 500 from conductors 302 and 303 and connects these conductors through its Nos. 2 and 3 front contacts, respectively, and brushes 511 and 512, respectively, to the terminals of the selected repeater. The release of relay 500 causes, in turn, the release of relay 501 which, in turn, causes the release of relay 503. Ground is momentarily extended from the No. 4 contacts of relay 501 through the No. 4 front contacts of relay 502 and brush 513 to the test terminal of the selected set of terminals to mark the trunk connected thereto busy until holding ground potential is connected to the test ter minal thereof in the usual manner.

The impulses produced by the dialing of the succeeding digits of the called subscribers number effect the operation of the outgoing trunk repeater R associated with an interofiice trunk over which the desired connection may be completed and which determines not only the route of the call but also the number of charges to be madetherefor. Upon extension of the calling line to the repeater R, therefore, the line relay 551 of said repeater is operated, the operating circuit being traced from battery through the upper winding of relay 51!, No. 3 normal contactsof reversing relay 553, through brush 512 of selector S, No. 3 front contacts of relay 502, conductor 303, lower winding of polarized relay 301, No. '7 ,contacts of relay 341, brush 132 and terminal, subscribers loop, brush 131 and terminal, No. 1 contacts of relay 341, upper winding of polarized relay 301, conductor 302, No. 2 front contacts of relay 502, brush 511 and terminal No. 2, normal contacts of relay 553, lower winding of relay 551 to ground. The current in this circuit is not effective to operate the polarized supervisory relay 301. In operating, relay 551 closes a circuit for operating relay 552 and relay 552 connects ground over conductor 510 and to the sleeve terminal of the repeater to:hold the first selector switch S in usual manner and to hold relay 502 operated.

Before proceeding with the description of the manner in which the repeater R produces the number of impulses which designates the charge units for a call established therethrough, it will be recalled that when the line finder LF1 operates to engage theterminals of the calling line, the normal post springs 324 are closed if the calling line happens to be one entitled to flat rate service. Now, when brushes 5| 1-514 of the selector S engage the terminals of the repeater and relay 502 operates in the manner described, ground on conductor 300 is applied through the normal post springs 324, No. 4 back contacts of relay 30G, conductor 311, No. 1 contacts of relay 502, brush 514, No. 2 back contacts of relay 541, winding of relay 542 to battery. Relay 542 operates, locks over its No. 2 contacts to ground on conductor 510 and performs functions noted hereinafter. On the other hand, if the calling line is entitled to individual message rate service, the normal post springs 324 will not be closed upon the operation of the line finder and relay 542 will not operate.

The line relay 551 of'repeater R responds to the impulses produced by the dialing of the second and succeeding digits of the called number to repeat each train of impulses over trunk T, the first repeated train of impulses being effective to control the selective operation of the incoming-selector switch S3 and the last two repeated trains of impulses being effective to control the selective operation of the connector switch C3 to establish connection with the line leading to the called station AS2. The called line is tested and, if idle, ringing current is transmitted thereover to operate the ringer at station AS2, all in the wellknown manner.

The removal of the receiver at station AS2 to answer the call causes th operation of the reversing relay 553 of repeater R in usual manner, thereby reversing the current through the windings of polarized relay 301 and causing said relay to operate and complete a circuit for relay 305 which extends from battery through the winding of said relay, No. 1 normal contacts of relay 306, contacts of relay 301, No. 1 normal contacts of relay 305, No. 2 front contacts of relay 304, conductor 300 to ground. Relay 305 operates and closes a circuit for relay 306 which extends from ground through the No. 4 front contacts of relay 304, No. 3 contacts of relay 305, lower winding of relay 306 to battery. Relay 306 operates, opens the circuit of relay 305 which thereupon releases, locks over its upper winding and No. 2 contacts to ground on conductor 300 and extend con- -15 ductor .3411 over its No. 4 -front contacts, .No. .5 front contacts of relay304, No.2 back contacts of relayv 32.3, winding of polarized :-.relay 301, No. 1 back contacts of relay 323, winding of slow-release relay 309, magnet 3110 of charging switch 330 :to ground. The line finder circuit, over conductor'3 11, is now ready :to receive impulses indicating .intervals of chargeable :elapsed time for the connection or .the initial number .of charges 'for. a conversation depending upon the .zone in whichthe connection is completed or both types of charges depending upon the charging z-rates used in :any' particular telephonesystem. In what follows, the principle of the invention is illustrated-in connection with the charges made for a given Zone, but this is not to .be understood as a limitation of the invention but only as one of the many expressions thereof, it being evident that for local calls in which charges are made strictly in accordance with the number of elapsed time units, said chargeswill .be rendered in the same manner since th chargingimpulses that activate the switch 33.!) (as willbe presently shown) may .beiproduce'd either by:zone charging equipment or by time charging equipment.

Theoperationof .relay 553.also closes .a circuit iromground through the front contacts of relay .552, conductor 51.0, .No. .4 contacts of relay 553, No. 2 normal contacts and winding of relay 536, conductor 561, .through the N o. 1 contacts of relay 539 to battery. Relay 536 operates and looks over conductor 511, .No. 4 contacts of relay 539 to ground on conductor 5.10. From this point on, the operation of the repeater depends upon whether :ornot a signal has been received from the normal post springs 32.4 of the line finder that the calling line is entitled to fiat rate service. If such a signal has been received, then, as already described, relay:542 willhave been operated and locked. If .no signal has been received, indicating thereby that the calling line is entitled to individual message rateservice, then relay 542 will be normal.

Assume, first, that no signal has been received and that relay 542 is normal. Relay 536, in operating, closes .a circuit for operating relay 543 which extends from battery through the No. 2 contacts .of relay 539, conductor 568, the No. 1 contacts of relay 525, No. '1 contacts ofrelay 536, winding of relay 543 to ground. Relay '543, in operating, closes .a' circuit from :battery 558, contacts of relay 543, No. 1 contactsof relay542,'-No. 2 front contacts of relay 541, brush 514 of the selector S, No. 1 contacts ofrelay 5'02, conductor 311 and thence :as traced to ground through the windings of relays 301 and 309 and the winding of magnet 310. This magnet operates-and causes brush 313 to advance one .terminalonits terminal arc. Relay 3119 also operates in the above circuit. When relay 536 operated, it also closed a circuit for operating relay .525 :which extends from groundover conductor510, the No. .4 contacts of relay 539, conductor 5.11:1, the No. 3 contacts of relay 53.6, the .No. 2 normal contacts and winding of relay '525, conductor 561, the No. 1 5

contacts of relay '539 .to battery. Relay 525, in operating, opens the operating circuit for relay 543. Relay 543 accordingly releases, disconnects battery 558 from brush I51 4 and thereby :opens the circuit of magnet 1310 and that of relay 309. The magnet "releases "but relay .3119, being slow release, does not. Relay 525 locks through its No. 2 contact over conductor 511 and, through :the No. 4 contacts of relay 539, to ground on nonductor51'0. Relay 525, inoperating, alsocloses a circuitfor operating relay538 whichextendsirom battery through the No. 1 contacts of 'relay539, con'ductor 56'1, through the winding .and No. :2 normal contacts of relay 538, No.3 contacts of relays (525 and 536, conductor 5'11, No.4 contacts of relay 539,over-conductor 519 to ground. Relay 538, in operating, locks to conductor 5 1 1 and closesa circuit for operating relay .528; this circuit including the No.2 contacts of relay 539, conductor .568, .No. 1 contacts of relay 531, .and the No. 1 contacts of relay 538, winding of relay 528 to ground. Relay 528, in operating, reconnects battery 558 to brush 514 via the No. -2 front-contacts of relay 541 thereby again completing the charging circuit of magnet 310 which now cperates and advances brush 3.I3 another terminal. Relay '538,.in operating, also closes a circuit for operating relay 531; this circuit includes the No. 1 contacts of relay 539, conductor 561, the winding and No. 2 normal contacts of relay 531, the No. 3 contacts of relays 538, 525 and 536, conductor 511, and the No. 4 contacts of relay 539.

Relay 531, in operating, locks through its No. 2

front contacts and opens the operating circuit for relay 528 at its No. 1 contacts which now releases and opens the impulse circuit to magnet 310. Relay 531, in operating, also closes a circuit for operating relay 540 this circuit including conductor 561, the winding and No. 2 normal contacts of relay 546, the No. 3 contacts of relays 531,538, 525 and 536, conductor 511, No. 4 contacts of relay 539 to ground on conductor 510. Relay 540, in operating, locks through its N0. 2 front contacts over conductors 5'11 and 5111, and closes a circuit for again operating relay 528; this circuit including conductor 568 and the No. 1 contacts-of relay 549. Relay 528, in operating, reconnects battery '58 to brush 514 to cause the reoperation of magnet 310 andthe advancement of brush 313 to another terminal. 'Relay549 also closes a circuit for operating relay 539 which is traced from battery through the winding and No. 3 normal contacts of relay 539, No. 3 contacts of relays 540, 53 1, 538, 525 and 536, over conductor I 511, the No. 4 contacts of relay539, to ground on conductor 5'10. Relay 539 operates and locks through its No. 3 'frontcontact to ground on-conductor 510. The locking contacts of relay 539 close "before the operating circuit is opened. The

operation of relay 539 causes the release of relays 528, .525, .536, 53 1, 538 and 540. The release of relay 528 disconnects battery 558 from brush 514 to cause the release of magnet 31!). Each of the relays 525 and 536 to 5411, inclusive, is slow in operating to insure that the operation of relay 5'42 and each operation and release of relay 528 will effect a-corresponding operation and release of the charging switch 330,

The. aforementioned three successive operations of the charging switch 339, effected under the control of the zone relays of repeater 'R, indicate to the line finder that the called 'subscribers station is located in a zone for which three charges are to be made for the call. Assume, now,

that the call was initiated by a line entitled to a flat rate service, in which event and as already noted, the normal post springs 324 will havebeen operated and a ground will have been transmitted over brush 514 to Operate relay 542 which looks under the control of relay 552, Therefore, when -relay15'36 operates to close the circuit of relay 543 which transmits the first charging pulse, the connection of battery 558 to brush 514 isinter- .ruptedat the No. 1 contacts of relay 542 which are openedin consequence of theoperation of this relay. The numberof pulses transmitted to the charging switch 330 in this case is, therefore, one less than the number transmitted when relay 542 is not operated, that is, in the case of a calling line entitled to individual message rate service.

In the event that the repeater R is equipped with overtime registering apparatu wherein overtime intervals for the connection are charged for at the rate of a definite number of charge units, say the same number which is initially charged when the connection is answered by the called subscriber, battery at the winding of relay 539 andthe Nos. 1 and 2 contacts thereof may be placed under the control of said registering apparatus which, operating at the beginning of the overtime interval, opens said battery to cause relay 539 to release. Since relay 552 would still be operated, then, when the battery is reconnected to the winding of relay 539 and the Nos. 1 and 2, contacts thereof by said registering apparatus, the repeater would then operate as before to'produce four charging pulses which are transmitted to the charging switch 330. The locked relay 539 is released again at the beginning of the next overtime interval and the operation is then repeated to produce another set of four pulses. Y

It will be noted that the polarized relay 301 is included in the circuit of the magnet 310 of the charging switch 330. In accordance with wellknown practice, in the event that the invention is utilized in'telephone systems involving two stations per line in which, say, theparty on the tip side of the line connects ground to the tip cbnductor upon initiating a call, the first selector is provided with a relay 323 that,over a circuit (not shown), responds to this ground on the tip conductor and, upon so operating, reverses the 'direc tion of] current through polarized relay 301. Now wh'erithe charge impulses are transmitted from th repeater or from any circuit adapted to transmit charge impulses in accordance with zone calling or in accordance with elapsedtime inter vals, not onl willmagnet 3,10 and relay 309 operate but polarized relay 30'! win operate also, in

18 by completed for relay 306 extending over the No. 4 back contacts of relay 304 No. 3 contacts of relay 305, lower winding of relay 306 to battery. Relay 306 operates, locks over its upper winding and N0. 2 contacts to ground on conductor 300, and completes a charging circuit for relay magnet 310 which extends from battery through the No. 5.contacts of relay 306, No. 2 contacts of relay 305, No.5 back contacts of relay 304, No. 2 back contactsof relay 323, winding of relay 307, No. 1 back contacts of relay 323, winding of relay 309, winding of magnet 310 to ground. Magnet 310 operates to advance brush 313 one terminal to register the onechai'gefor the call.

" When relay306 operates, the locking circuit of relay 305 is transferred to interrupter lead 316 via the No. 1 front contacts of relay 306,- No. 1 contacts of relay 1, No. 3 contacts of relay 305, No. fl back contacts of relay 304, to interrupter ground on conductor 316. When the ground is removed from conductor 316, relay 305 releases and the charging circuit is opened thereby causing the release of magnet 310. Y

The connection of ground to conductor 318 causes the operation of relay 601 in a circuit that extends from ground on said conductor, lower ference in case twoor more trunksare simul which event a path is completed for relay 308 pulse and causing relay 309 to operate and hold between pulses. When charging is completed, relay 309 releases and ground is connected to conductor 313 via ground on conductor 519 from the lower contacts of ofi-normal springs 511, 518 of switches 520 and 530, contacts of relay 309, upper contacts oi'oiT-normal springs 319 of switch 330 'toconductor 318;

In the event that the call is completed througha selector in a local zone for which but one charge is made for the call, relay 304 will not be operated and, upon the operation of relay 301 in response to a currentreversal consequent to the called line answering, relay 305 operates from a ground closure on conductor 315 of the interwinding of.-said relay, back contacts of relay 602' to battery. 7 There is one relay 601 for each trunk and this, together with relay 602which is common to all relays60'1, provides for non-intertaneously calling for the recording circuit shown in Figs. 6 and 7. For, with the operation of relay 601 of anytrunk over a circuit identical to the one above .describedfsaid relay locks over its upper winding and No. 3 front contacts, winding of relay 602 to battery, causing the latter relay to operate and disconnect battery through its back contacts, which battery extends to the lower winding of allrelays 601. Now if another trunk connect ground to its own start conductor 313 and, therefore, to its associated relay 601, the fact that one relay 601 is already locked in series with relay 602 means that operating batteryis disconnected'from the lower (operating) winding of all relays 601 until relay 602 releases This insures that only, one trunk at a time can be connected to'the recording circuit.

A circuit'is now completed for relay603 which extends from battery through the front contacts of relay 602, lower winding of relay 603, back contacts of relay 604 f to ground. Relay 603 operates andlocksover its. upper winding and No. 4 ,front contacts, winding of relay 604 to ground, thereby'causing relay 60 1 to operate in said locking circuit. 7

One relay 603 is provided for each group of trunks that serve the' same line finder group. These relays, together with relay 604 provide for non-interference between line'finder group inasmuch as the operation of relay 604 in the locking circuit of anyone of the relays 603 cuts off the ground required to complete the circuit of any of the'remaining relays 603, thereby effectively locking out all other line iinder groups from access to the recording circuit once any particular trunk in a group is locked in with it; When relay 603 is operated, relay 605 operates in a circuit which is completed from ground rupter circuit 325 which is only shown schematically. Relay 305 operates and locks under the control of the operated contacts of relay 301 and its ownNo. 1 contacts. After an interval, ground through the front, contacts of relay 604, No. 3 con tacts of relay 603, winding of relay 605 to battery. Relay 605 operates to mark the line finder group with which the calling trunk is associated, there being other relays such as, for example, relays .is applied to conductor 316 and a circuit is there- 606 and 601 designating other and separa'tegroups 19 that are connected to the contacts of appropriate relays 603 in said different groups for the purpose.

Upon the operation of relay 605 a circuit is completed for relay 605' which is traced from battery through the winding of said relay, the No. 2 contacts of relay 605, No. 5 contacts of relay 603, No. 4 contacts of relay 60!, conductor 608, to ground on the No. 2 contacts of relay 3|2, which latter relay operates or not depending upon whether or not relay 3 l2 has operated to indicate that the calling line isloc-ated in the lower terminal bank of the line finder frame. In a similar manner, relay 606' or relay 601' will or will not operate in response to the operation of relay 606 or 601, respectively, to indicate that the call has originated in a line located in the lower terminal bank of the appropriate line finder frame.

When relay 605 operates, ground on its No. 1 contacts is applied to conductor B09 and a circuit is thereupon completed over the No. 1 contacts of relay 603, No. 1 contacts of relay 601, conductor 6, brush 52| of switch 520, a conductor 53! depending upon the terminal engaged by the brush 52L Since this brush was stepped in synchronism with the brushes l3l, I32 and I33 in rotary movement when the line finder switch was seeking the vertical level of the calling line, the terminal engaged by brush 52I marks the numerical designation of the particular level of terminals in which the calling line is located. If, for instance, the calling line had been located in the ninth vertical level, causing vertical magnet 343 to take nine steps to reach said level, then brush 521 would be engaging its ninth terminal and grounding conductor 53! as shown. The ground on conductor 53! completes an obvious circuit for vertical select magnet 6 l9 of the crossbar switch 650 which is a structure of the type disclosed in Patent 2,021,329 granted to J. N. Reynolds on November 19, 1935. The operation 'of select magnet 6l9 closes an obvious circuit for relay 62! causing said relay to operate. Now;

depending upon the terminal set in the level of the line finder bank in which the calling line is located and, therefore, the number of rotary steps taken by brushes I31, I32 and I33 to reach the terminal set, will determine the terminal engaged by brush 523 of switch 530 since magnet 533 of this switch operated in unison with rotary magnet 344 at the time said last-mentioned mag net operated to step the line finder brushes rotatively' to the terminal set of calling line. If, for

instance, it is assumed that the calling line is 10- cated in the first terminal set, requiring but one step of rotary magnet 344 to rotate the switch brushes to said terminal set, then brush 523 will have likewise taken one step and engaged terminal zero, in which event the operation of relay 62! causes a circuit to be completed extending from ground on the contacts of said relay, No. 2 contacts of relay 603, No. 2 contacts of relay 601, conductor (2, brush 523 and terminal engaged thereby, conductor 544, winding of hold magnet 860 of crossbar switch 650 to battery. Since select magnet 619 is already operated, th operation of hold magnet 560 is effective in holding closed the cross-point indicated by the dotted box 613 in accordance with the teaching of the above- 7 mentioned patent to J. N. Reynolds.

shows. The cross-bar switch 830 is a six-wire switch which thus provides for six hundred terminals, one for each line of three line finder groups of two hundred lines each, which is the grouping ordinarily used with line finder switches equipped with two sets of terminal banks of one hundred terminals each. The vertical columns of these switches represent, as said before, line finder level positions, while the horizontal rows represent the line finder terminal positions. Each of the six contacts of each cross-point of the switch 639 is reserved for a line whose line finder terminal designation corresponds to the numerical designation of the cross-point, and the distinction, between a line in the upper bank and a corresponding line in the lower bank is made at the cross-point itself by reserving the upper of two consecutive sets of contacts for the line in the upper bank and the lower set to the line in the lower Ibankj Since, for three groups of two hundred lines each, there would thus be two lines in each group having the same line finder terminal designation, one in the upper bank and one in the lower bank of each group, it is ap parent that all the contact pairs in each of the cross-points of the switch will bear identical numeri-cal designations, the lowest cross-point, closed by select magnet 6m and held by hold magnet 686, having all its contact sets identified by the number'til while the highest cross-point closed by select magnet M9 and held by hold magnet'liiiil, having all its contact sets identified by the number 99.

EflChCOIl'EZtCt of each contact pair in the crossbar switch is extended to a terminal in the distributing frame 559 there being, for the switch, six hundred terminals in all and these, inturn, are cross-connected to terminals in the line finder frame 5% in accordance with the directory number of the several lines as shortly to be described. In the event that the cross-point representsa party line, such fact will be known from the operated hold magnet which has a group of additional sets of contacts reserved for this purpose. The armatures of these contacts are connected to block 610 and the contacts of a hold magnet whose cross-points represent the party lines are cross-connected to a relay 565 having two transfer contacts the armatures of which are cross-connected to the appropriate terminals on distributing frame 550 and the back and. front contacts to the appropriate directory numbers on terminal frame 566. The operation of the hold magnet will close an obvious circuit for relay 563 which, upon operating, transfers the ground on the cross-point at terminal on frame 550 to the proper party terminal on frame 530. Hence when the horizontal hold magnet 680 opcrates, ground is applied over its No. 1 contacts. conductor Sit, No. 4 contacts'of relay 605 (or front contact if calling line is in the lower hank) Iback contacts of relay 605 to the vertical contact in cross-point 6i? thence over a conductor to the terminal of the distributing frame and over to a terminal on the line terminal frame 550.

The decoding of the line terminal number into the directory number of the line is accomplished through a group of four relays 524-52l and one relay til for each of twenty-five lines and one group of twenty-five relays 625649 for the whole ofiice which, in the case illustrated, is limited to six hundred lines although the decoding principle is workable for a ten thousand line oifice. Each relay in the group of twenty-five relays 625649 is assigned to one of the numbersfrom zero to twenty-four with relay 625 assigned to zero and relay 649 to twenty-four, the remaining intermediate relays being assigned to corresponding intermediate numbers in consecutive numerical order.

Each relay in each group of four relays 524-521 is equipped with six sets of transfer springs, the back contacts of which are all commoned and connected to the winding of relay 62l associated with one particular group of four relays. The transfer contacts are all connected to individual terminals on the line terminal frame 560, each of said terminals being reserved to one line in the group. Since a group of relays 524-521 and the associated relay 62! are intended to serve a group of twenty-five lines and only twenty-four transfer contacts are provided by the four relays 524-52| of a group, the remaining terminal is provided by the No. 1 continuity set of contacts of the associated group relay 62!, the moving contact of which is wired to the line terminal frame 560. Remembering that the twenty-five relays 625-4549 are to serve all groups of twenty-five lines, since they are common to the office, each of these relays is Wired to a front contact in a corresponding relay in each group of relays 524-521. Thus, if we consider that the relays 524521 and relay 62! shown in Figs. 5 and 6, respectively, are reserved to the first group of twenty-five lines of the office, namely, lines 000 to 024, inclusive, relay 625 is extended, through the No. 1 front contact of relay 62!, to the 000 terminal on frame 560; relay 626 (not shown) to the No. 6 front contact of relay 524 the transfer contact of which is connected to terminal of the frame 5611; relay 62! (not shown) to the No. front contacts of relay 524 the transfer contact of which is connected to terminal 002 on frame 560. In the same manner each of the other relays is connected to one of the remaining front contacts in the order indicated up to and including relay 649 which is connected to the No. 1 front contact of relay 521, the cooperating transfer spring of which is reserved to line No. 024 on line terminal frame 560. The twenty-five relays (625-4549) are, of course, multiplied to corresponding contacts in each of the groups of four relays (ML-521) reserved to each of the other twentyfive line groups in the office whose transfer contacts are wired, in turn, to the line terminal frame 560.

Now in decoding the terminal number of a line into its corresponding directory number, it is necessary to cross-connect the terminal on the distributing frame 550 bearing the line number on the line finder frame with the terminal on the line terminal frame 560 designating the hundreds, tens and units digits of the wanted directory number. Since the present invention is being disclosed with respect to an office limited to six hundred lines, all thousands digits of directory numbers will be zeros and the highest directory number in the office (exclusive of party numbers) will be 0599. Hence when the particular crosspoint on switch 65!! operates and grounds the conductor individual to the calling line from the front or back contacts of relay 605 (or 806 or 601') the cross-connection between the terminal on the distributing frame to which the individual conductor is connected and the terminal on the line terminal frame 560 which designates the desired number for directory listing purposes, the ground on the individual line conductor will be applied to one of the back contacts of one of the relays in the group of relays 524-521 involved which, in turn, will complete the circuit of the associated relay 62!.

If the individual conductor is connected to terminal 000 in the line terminal frame 560, the ground on said conductor is applied to the winding of relay 62! via its own No. 1 continuity contacts, and when relay 62! has operated, said ground is similarly applied to relay 625 via the No. 1 front contacts of relay 62l causing said relay to operate. On the other hand, if the individual conductor is cross-connected to any terminal other than terminal 000 (or its equivalent in groups of twenty-five) on the line terminal frame 560, relay 62! will operate as before described but relay 625 will not operate. When relay 62! operates, however, ground is applied to conductor 652 which extends to the Winding of each of the relays in the group of relays 524-521 associated with the particular relay 621 that operated, causing said relays to operate and close their respective transfer contacts to each of the relays in the group of twenty-five relays 62 5649, except relay 625. Now the relay in this group which will be operated will depend, of course, upon which of the twenty-four terminals on frame 560 the individual line conductor is cross-connected, and the operation of relay 62! in any one group of twentyfive lines combined with the operation of a relay in the group of relays 625-649 will ground four conductors that will operate, in succession, four relays in the group of ten relays -139 in the register of Fig. 'I that will cause the punching of appropriate respective codes for the thousands, hundreds, tens and units designations of the directory number. The manner in which this is achieved through relay 62! and relays 625-64i) is as follows:

Each relay 62! has as many lower contact pairs as will be required to give the thousands, hundreds, and tens and units designation, the last two in accordance with the particular relay in the group of relays 625649 that was operated from frame 560.

The object in decoding is to operate, in succession, one relay in the group of ten relays 130-139 for each of the digits of the number, depending upon the value of the digit itself. The numerical designation of each of said relays lath-I39 is chosen to indicate each one of the ten digits with relay 130 indicating the first or zero digit and relay 139 indicating the last or ninth digit. This group of relays is wired to the contacts of pairs of progress relays in Fig. '7 which, operating and releasing progressively in the manner to be hereinafter described, connect these relays to conductors which extend to the contacts of the relays 62! and/or those of the one relay in the group of relays 625649 which is operated.

In decoding the thousands and hundreds digits, it will be remembered that each relay 62! represents twenty-five numbers. It is obvious, therefore, that each of said relays may be made to mark arbitrarily the particular thousands and hundreds digit which includes the group of twenty-five lines represented by the relay. Each of these digits may, of course, be anything from 0' to 9 for the thousands depending upon the maximum line number capacity. Hence in order to mark the particular thousands digit of the thousands group that includes the twenty-five numbers designated by any relay 62 I, a conductor is extended from one of a pair of contacts on said relay 62! to that terminal on block 142 which connects with the armature of that pair of con- 23; tacts on relay HM, the make contact. of. which extends to the winding of the one relay inithe group of relays 130-738 whose unitsdigitdr'esignation corresponds to the particular: thousands digit to be clesignated. Since it has been. ass sumed that, in the specific embodiment of; the invention herein disclosed; the exchange is limited to six hundred lines andit may. be further. assumed, but not as a limitation, that the directory numbers will be no higher than 0599, it is obvious that all relays 825 must. be wiredtoprovide a O-thousands indication; Accordingly, the lowest make. contact on relay 621' is connected by a conductor 6.52 withterminal zeroon block.

M2 which, in turn, extends to the armature of the No. 12 contact set of relay the make of which is connected to the winding. of. relay 730'. For any other thousands digit, of course; said conductor would be connected to the appropriately numbered terminal onblock'l-iiand would hundred lines, audit is obvious that eaehrel'ay,

thus belonging to a particular hundred, may be made to indicate the fact by a-conductorwhih connects through the progressrelay Hi3; one of a pair of contacts on saidrelay 621 with the winding of the particular relay in the group of ten relays l36-l39Whose units digit designation corresponds with the hundreds digit of the hundreds group'in which said relay B21 belongs. Thus if the relay 62! shown in Fig. 6 isone of four such relays which makes up the one hundredsroup, the make contact on the next to the lowest contact pair is connected by conductortfi't to the No. 1 terminal on blockl'26 which terminal, in turn, is connected with the armature of the No. 11 con.- tact set of relay 163., the make of which extends to the winding of relay 535. It will be shownthat when a permanent record is to be made of the hundreds digit, assuming it to be the digit 1' relay 732 will be operated to perform this function;

To decode the tons and units number, further consideration has-to be given to the fact thatthe lines are grouped in units of twenty-five each. If

we assume any group of one hundred numbers and remember that this group of numbers is rep resented by four relayslike relay 62 I; the distribution of the lines among the four relays with respect to their tens and units designation. is as Now when a line calls, it will'cause the-operation of the relay 62! ofv itsown twenty-five line group and one of the twenty-five relays. inv the group of relays t649, and the 'combinationof both of these two operated relays will ground'two conductors, one for the tens digit: and onefor the 75" .of, numbers initiates a call.

430-139 whose units designations correspond with the tens and unitsdigit to be recorded.

The make contacts of thecontact sets 4 to 8,

inclusive, in each of the four relays 625 in each group of one hundredlines are wired to the armatures ofthe relaysBZB-MB in accordance with the above distributionoi numbers and when relay 62! operates, ground isapplied to two of the armatures oi the relay in the group of twenty-five relays 625-649twhich has been operated from the terminal of frame 568.. As an example, consider the wiring of relay MI (1) which is the group relay for the line numbers 06,-24=,- inclusive, that is, operates with the. appropriate relay in the group of relays 625-649 when any line in said group For the first ten numbers (fills-09') theZero tens digit must be designated in the order in which relays 62563 l are operated; Consequently, the make of its No. 6 contact set is connectedjo an upper armature of eachrelay 625-634;.inclusive, thecorresponding makes of which are all wired toth zero terminal on block l2'izwhich, in turn, is connected to the armature of the No. 12 contact set. of relay 705, its makecontact extending to the winding of relay l30. It is obvious, therefore, that when relay. 62H operates, and any one of the relays 525-634 operates which fact indicates that the tens digit. of the calling linenumberiszero, relay 130 will 0perate (through thecontacts of; relay to designate the tens zerov digit. Line numbers from Iii-l 9; inclusive, havea 1 for. the tens digit; hence the make contact of'the No. 7 contact set of relay i2i is connected to corresponding armatures in each of. the relays 635-6Mwhose, make contacts onthe other-hand are all multipled and connected (connecting conductor omitted) to the N0. 1 terminal on block 12.! which, in turn, is connected; to the No.11 armature of relay 105, its make contact extending to the winding of relay 131; Line numbers 26-24, inclusive, have a 2 for the tens digit; hence the-make contact of the No. 8 contactset is connected tocorresponding, armatures in each of the relays 645-549 whose cooperating make contacts are all multipled and connected (connecting conductor not shown in the drawing) to the No. 2 terminal on block 72'! which, in turn, is connected to the No. 10 arrnature (not shown) of relay 105, its make contact extending tothe winding of relay "I32.

The'wiring for the units digits designation is similarly carried'out in accordance withthe above table. It will be observed from said table that relays 625-634 operate consecutively for each of the units digits 0-9, inclusive. Since relay 62| (1) marks the group of lines 06-24, the make contact of the No. 4 contact set of said relay is connected to corresponding armatures in each of the relays 625-63 3, inclusive. In this case, however, andin contrast with the wiring of this w groupof relays; for the designation of the Zero digit, each cooperating make contact on each of said relays is connected to a different terminal on block 128; the cooperating make contact of relay 625 which operates for the line iillbeing connected toterminal 0 and thereby causing the operation of relay ltil'through the No. 12 contacts ofrelay: 1.0T as will be shown; the cooperating. make contact of relay 626which operates for. the. line. 01b, being. connected. to terminal! and; thereby. causing the. operation of; relay. 113i.

through the No. 11 contacts of relay 101 and so on up to and including the cooperating make contact of relay 634 which operates for the line 09 being connected to terminal 9 and thereby causing the operation of relay 139 through the No. 3 contacts of relay 101. Relays 635-644 operate consecutively for each of the units digits 10-19. Since relay 621 (1) marks the group of twenty-five lines including these numbers, the make contact of the No. 4 contact sets is further connected to corresponding armatures of each of said relays 635-644 and the corresponding cooperating make contacts are each connected to terminals -9 respectively on block 128.

The last four relays 645-649 operate consecutively for each of the last four numbers of the group 20-24 involving units digits 0-4 inclusive. Hence the make contact of the No. contact set of relay 621 (1.) is connected to corresponding armatures in each of the relays 645649, inclusive, and their respective cooperating make contacts are each connected to terminals 0-4, inclusive, on block 128, resulting in the operation, aswill be shown, of relays 130-134, inclusive, to designate the respective units digits of the last four line numbers in the group of 00-24 lines.

In the same way, by following the above table, the Nos, 4-8 contact sets of each of the separate relays 621 (2), 6:21 (3) and 621 (4) are connected to the various relays 625-649, inclusive, to ground terminals on blocks 121 and 128 to cause the operation of the appropriate relays 130-139 to indicate the tens and units digits.

When, therefore, relay 621 operates, its No. 1 contacts are closed to extend ground on the No. 1 contacts of hold magnet 6 60 previously traced to a terminal on the line terminal frame 560 to the winding of some relay in the group of relays 625-649 causing said relay to operate. The relay which is operated in the group is the one that marks the tens and units number of the calling line, and since the proper relay 621 is likewise operated to mark the thousands and hundreds, the identity of the calling line is ready for recording the same on tape.

The recording circuit shown in Fig. '1 comprises six pairs of progress relays 101-113, the recording relays 130-139, relay 141, and a perforator 110 of known construction having the five punch magnets I to 5 and a punch magnet 118. It is also provided with a relay 116 in the event that a plurality of recording circuits all use the same perforator. When, therefore, a relay in the group of relays 625-649 is operated, as for instance, relay 625, a circuit is completed for relay 1111 which traces from battery through the winding of said relay, No. 1 contacts of relay 102, No. 1 contacts of relay 625. to ground. Relay 101 operates and connects the windings of relays 130-139 to block 142. Inasmuch as one of the terminals on this block is grounded by conductor 654 extending to the No. 10 contacts of relay 621 of the group of twenty-five lines containing the calling line and, therefore, marks the thousands digit of the line number in the manner already described, a circuit is thereby completed for one of the relays 130-139. Since it has been assumed that the number of lines in the exchange is less than a thousand, conductor 654 will be connected to terminal 0 on block 132 whereupon a circuit is completed for relay 130 extending from ground on said terminal, No. 12 contacts of relay 101, winding of relay 130 to battery. Relay 130 operates to ground conductors which 26 complete circuits to certain of the magnets of the perforator to operate in the combination required to punch the code of the digit 0 according to the following code:

Punch positions The connecting wires to the magnets extend to the right contacts of relay 116 whence they extend to the terminal block 123. There is further provided another block 124 to which are connected the make contacts in each of the ten relays 130-139 that denote, according to the above code, the digit to be indicated by each of said relays. For instance, relay 1311 marks the zero digit and when operated to cause the punch-- ing of said digit upon the tape must, according to the above code, produce the operation of punch magnets 3 and 4, Hence the relay is provided with two sets of contacts that extend to the block 124 from which they are cross-connected to conductors 3 and 4 on block 123 and are grounded when the relay operates. Simi larly, relay 139 which marks the ninth digit should cause the operation of magnets 1 and 5. Hence it is provided with two contact sets, the makes of which extend to the terminals of block :124 from which they are cross-connected to conductors 1 and 5 on terminal block 123 to close partial circuits thereover for punch magnets 1 and 5 when the relay operates. In the same way, each of the intermediate relays is furnished with a number of contact sets appropriate to the respective digital value that each of the relays is to designate.

Now when relay 101 operates, ground is applied over conductor 654, No- 12 contacts of relay 101, winding of relay 130 to battery. Relay 130 operates and closes a circuit for relay 116 extending from ground on the No. 1 contacts of relay 130, right winding of relay 116, contacts of relay 119 to battery. Relay 116 operates and looks over its left winding and No. 4 front contact, winding of relay 119 to battery. Relay 119 operates and disconnects battery from the operating winding of relay 116 and all other relays 116, if any, are

. provided for connecting the perforator with more than one recording circuit. If, however, but one recording circuit is to be used, relays 116 and may be omitted and the conductors extending between the make contacts of the relays 130-139 and 141 and the right armatures of relay 116 may then be directly connected to the armatures of relay 111 and thence to the windings of the perforator magnets.

When relay 116 operates, a circuit is completed for rela 121 which extends from ground on the No. 1 contacts of relay 605, conductor 609, through the Nos. 2 and 5 contacts of relay 102, No. 1 normal contacts of relay 115, No. 1 contacts of relay 116, winding of relay 121 to battery. Relay 121 operates and closes a circuit for slow-to-release relay 120 via the No. 1 back contacts of relay 122, which relay 120 operating, in turn operates relay

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