US2355207A

US2355207A - Telephone system

Info

Publication number: US2355207A
Application number: US495488A
Authority: US
Inventors: Joseph W Dehn
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1943-07-20
Filing date: 1943-07-20
Publication date: 1944-08-08
Anticipated expiration: 1961-08-08

Description

L/NE FINDER SELECTOR CCT Aug. 8, 1944.

J. W. DEHN TELEPHONE SYSTEM Filed July 20 1943 12 Sheets-Sheet 1 INVEN TOR J W DEHN r A r TOR/v5 1944' J. w. DEHN 2,355,207

7 TELEPHONE SYSTEM I Filed July 20, 1945 12 Sheets-Sheet 2 IIHI' n TRK FDR.

| I H! {.21 car 3; INT ALARM ccr zmvs 05014734710 ccr Aug. 8, 1944. J. w. DEHN I TELEPHONE SYSTEM l2 Sheets-Sheet 3 Filed July 20 1943 Aug. 8, 1944. J. w. DEHN TELEPHONE SYSTEM Filed July 20, 1943 12 Sheets-Sheet 4 m l/EN TOP J W DEHN Aug. 8, 1944. J. w. DEHN TELEPHOIQIE SYSTEM Filed July 20 1943 12 Sheets-Sheet 5 lNl EN TOR By J. W DEHN WW 3 ATTORNEY Aug. 1944. J w, DEHN 2,355,207

TELEPHONE SYSTEM Filed July 20, 1943 12 Sheets-Sheet 6 INVENTOR J. W DE'HN A T TORALEY J. w. DEHN 2,355,207

TELEPHONE SYSTEM Filed July 20 1943' 12 Sheets-Sheet 7 4 FIG 7 r 0 REGISTER l l El N TROL RELAYS INVENTOR J W DEHN A T TOEW J. w. D EHN TELEPHONE SYSTEM 7 Filed July 20} 1943 12 Sheets-Sheet 8 /N VEN TO JWOEHN .4 TZ'ORNE)? 1944.; J. w. DEHN 2,355,207

TELEPHONE SYSTEM Filed July :20 1945 12 Sheets-Sheet 9 //v l/EN TO JW DEHN g- 7 1944 i J. w. DEHN 2,355,207

TELEPHONE SYSTEM Filed July 20 1943 12 Sheets-Sheet 10 By JW DEHN- A 7' TORNEV Aug. 8 1944.

FIG.

J. W. DEHN TELEPHONE SYSTEM I Filed July 20 1943 TO OTHER CROSS BAR SIM TO OTHER ROUTE REL.

12 Sheets-Sheet 11 AS REQUIRED FOR ZONE CHARGE CONTROL 2 u E a o u x. 3 g, Q E b O c: E

INVENTOR J W DEHN A T TOQNE V Aug. 8, 1944. J. w. DEHN TELEPHONE SYSTEM 12 Shets-Sheet 12 Filed July 20, 1943 1N VEN TOR J. W DEHN ATTORNEY Patented Aug. 8, 1944 TELEPHONE srs'rnM;

Joseph W. Dehn, Great Y ,.assignor..to v 1 Bell. Telephone Laboratories, Incorporated, New York,N. Y., a corporation of New York;

Application July 20, 1943, serial No. 495,488 Y 6 Claims. (01. 179- 1'7) This invention relates to telephone systems and particularly to those in which connections are established by automatic switches.

The object of the present invention is to enlarge the scope and improve the operation of small dial responsive telephone ofi'lces;

A feature of this invention consists in a full automatic switching oifice for small dialareas in a telephone exchange system in which all telephone connections are under the control of a sender which is automatically connected to calling subscribers lines responsive to the removal of the receiverin a calling subscribers station, the sender being connected to the line by the opera tion of a line finder having a line-finder trunk permanently connected thereto and a trunk finder having a sender permanently connected thereto, said sender having means to determine whether the calling line is a single party line or a twoparty line and means responsive to its connection to a two-party line to determine which of the two parties is calling, said sender also having means operable in response to its connection to one party, such as the party connected to the tip line conductor, for locking the line finder to the party line, thus providing means to reconnect a sender with said line, after conversation has ceased, to facilitate the test of said line conductors for a false ground, and'means automatically operable under the control of said false ground testing means for causing said sender to transmit pulses to operate a first selector for connecting a party line testing trunk with said calling line, said party line testing trunk taking over the control of said line and releasing said sender.

Another and related feature consists in means in said testing trunk for determining whether a false ground is connected to either conductor of said line as-a check of the line condition in order that the party calling be charged for the call and operate'a signal whenlthe line is not in proper condition for telephone service. 7

Another and related feature consists in means in said testing trunk for holding said line for inspection when a false ground is connected to saidline and for connecting a characteristic tone with sai line.

The foregoing and other features of the invention will be described more fully in the following specification which should be takenin connection with the accompanying drawings and appended claims;

Referring to the drawings:

v Fig. 1 illustrates two message ratesubseribers stations connected to a partyline with the line terminating in terminals of line-finder switches, the line finder being diagrammatically shown. Figs. 1 and 2'illustrate a line-finder selector trunk circuit permanently associated with the line finder;"

Fig. 2.diagrammatically illustrates one of a group of trunk finders, the trunk finder shown being permanently connected to a sender;

' Fig. 3 illustrates a first or dual selector permanently connected with the line-finder selector trunk circuit and line finder. Also shown in Fig. 3 is a party line testing trunk circuit selected by the dual selector-under control of the sender;

' Figs. 4 to 12, inclusive, illustrate the portions of a sender'for describing the invention; and

Fig. 13 illustrates the manner of assembling the drawings. toillu'strate the invention.

The line fin'der'and the trunk selector which are diagrammatically shown herein and the sender which is partly disclosed herein are completely disclosed in detail in my copending application, Serial No. 495,487, filed July 20, 1943. It is believed that the invention may be adequately disclosed and described without the incumbrance of the'larger disclosure and description? i v GENERAL DESCRIPTION The 'telephonebfiice' illustrated herein uses step-by-step switches of a type in general use for finder equipment selectors and connectors. An exception'to this resides in the cross bar switches for the sender register which may be of'the'type disclosed in Patent 2,021,329 of November 19, 1935, to Reynolds. The telephone oflice operates as an automatically operable switching system which may be used as an attended orunattended ofiice in small dial areas adjacent tolarger dial olfice areas. This oflice will, therefore, be knownherein as a fringe office in order to distinguish it from step-by-step offic'es to which connections are made over outgoing trunksf Trunk connections are also made from this fringe 'ofiice'to panel and cross bar oilices.

' Theofiice mechanism isorg aniZed for rapid operation with the mechanism in groups which normally serve particular lines. The line finder, line-finder selector trunk circuit and the dual selector circuit are permanently connected to, gether. A trunk finder circuit is permanently connected to the sender and other trunk finders are permanently connected to other senders. The removal of the receiver in a calling station actuatesaline finder which immediately establishes ergization of the equipment in the lineefinder selector trunk circuit. Dial tone is transmitted to the calling subscribers station iby'the sender and in response the subscriber dialsthe oode'o'f the ofiice in which the called line is located. The office mechanism may therefore bedescribed as divided into units, each unit having a group of line finders and associated equipment for a group of lines which they serve. This group of equipment has a trunk finder circuit-and'a sender .normally associated therewith energized in'response to all calls from this'groupof lines :at all times unless the sender is busy when the call is initiated. If the sender is busy a different trunk .finder associated with a different :sender is used for "association with the callingjline :and the unit of equipment associated therewith. T'Ih'is is :also true of .the line-finderequipment in'order-"that the mechanism of the .ofiice-may be operated in arflexible manner.

In response to the :removal of a receiver a subScri-bers station alinerelay is energized which actuates a line-finder group relay. This energizes a relay in an associatedline finderto establish a start circuit ,for this'line finder and a start circuit for the trunk-finder circuit shown diagrammatically in Fig. 2. The line. finder, .Fig. l, hunts for thecallingline andatqthe same time the trunk finder hunts for the line-finder selector trunk circuit shown in :Figs. 1 and 2 which is connected to theline finder hunting for" the line. Thus, a connection between the calling subscribers line and the senderisestablishedin a very short interval of time. One of the relays in the line finder and relay I02 of the line-finder selector trunk and a're'lay of the trunk-finder circuit are operated;thus connecting the calling "subscriberfsline with a sender'relay "which follows the dial pulses transmitted by-the calling subscriber. Circuits :are immediately established by the sender for'recording the class of service to which the calling subscriber is entitled. For this purpose the mechanism shown in Fig. .4'is

connected to classdesignatingrmechanism of :the

- means, is operated under the controlof the-sender registering equipment for selecting one of two methodsor means for operating the dual selector circuit. Ifthe call isrfor asubscriber in the fringe office, termed herein a local.subscriber,the sender causes therelease of relay -IUZin the line-finder selector trunk circuit as .soon as the code d sit have been completely dialed, thus connecting the dual selector pulse responsive mechanism to the calling subscribers line and dial over the tip and ring conductors. The A relay of the first or dual selector follows the dial pulses of the next digit after the last code digit dialed by the calling subscriber. This connects the brushes of the dual selector with a second selector for extending the call to a local subscriber. As soon'as the mechanism is energized in the sender responsive to registration of the local code digits which cause the connection of the calling subscriber directly to gthefirst selector, other mechanism in the sender is energized to cause the immediate release of the trunk finder may, therefore, be seized by another calling subscriber for completing another switching connection.

When the ofiice code dialed by a calling subscriber and registered by the sender indicates that the ofiice connection desired is over an outgoing trunk to another ofiice, the sender remains connected to the calling subscribers line until all of the digits have been dialed. As soon as the office code has been registeredythe sender controls the operation of relays in the line-finder selector trunk circuit, Figs. 1 and 2, so that the first or dual selector is connected through the contacts of these relays .to the sender; pulsing mechanism instead-of being connected to the calling subscribers line as above described. When sufiicient digits have been recorded by the sender, pulses are transmitted by the sender pulsing mechanism through the relay contacts of the line-finder selector trunk circuit for positioning the first or dual selector. The first digits transmitted by the sender position the dual selector for the selection of a trunk to the wanted ofiice according to the coderegistered in the sender by the calling subscriber. Thus, the sender automatically determines what pulsing means should be used for operating the first selector under control of the sender registers responsive to the dialing of the code .digits.

If the code dialed by the calling subscriber is that .of a distant step-by-step ofiice, the sender transmits v.a maximum of three digits to cause thedual selector and subsequent selectors to find a trunk to the desired step-by-step ofiice. The thousands, hundreds, tens and units digits dialed by the calling subscriber are registered in the sender and subsequently are transmitted by the sender as four. numerical digits as soon as the outgoing trunk has been found. These digits actuate two selectors and .a connector at the distant step-by-step ofiice.

If the distant ofiice is .a panel or cross bar .ofiice, the senderv does not immediately transmit the digit pulses as it does to a step-by-step office but waits for a-signalfrom the trunk circuit at the distant office indicating that the trunk has been attached by means of a link to the subscriber's sender in the distant ofiice. This is accomplished by a reversal of current over the trunk fromthe .distant office to the sender equipment in the fringe office. After this signal has been received by the fringe .ofiice sender, it transmits .digits covering the office code and numerical digits andalso station digits if they are required. These are registered by the sender in the distant panel or cross bar oifice. After the completion of registrations by the sender of a panel or cross -bar-ofiice, a signal is transmitted to the fringe Office sender which causes the disconnection of the fringe ofl'ice sender which may now restore to normal. At this time the fringe office sender operates a relay in the line-finder selector trunk circuit causing the connection of the calling subscribed to the mechanism of the distant office which connects the calling subscriber with the called subscriber as registered by the fringe ofiice sender and the distant ofiice sender.

The class of service to which the calling subscriber is entitled is determined by leads connected from the calling line mechanism to marginal and non-marginal relays of Fig.4. This mechanism also designates to thesender whether the line is a single partly line or a twoparty message rate line. The lines arevariously equipped for indicating the class of service to which they are entitled and whether they are individual or'two-party message rate lines. For example, this line mechanism may be a high resistance connected to ground which causesthe equipment of Fig. 4 to operate in a manner as to indicate to the sender that a coin line is calling. Other classifications are transmitted to the mechanism of Fig. 4 which are not particularly of interest in the disclosure of this invention but each class of service indication serves to guide the sender in its functions. When the calling subscriber is connected to a two-party line. a two-party identification testis necessary. Other devices are operated to indicate what routesthe line is permitted to call and to indicate what charge should be made for the call which is made.

If the call is from a two-party'message rate subscribers line, the sender makes a party line test to identify which party is calling. This test is madeat the completion of the first digit and the result of the test is employed by the sender for controlling the energization of mechanism in the line-finder selector trunk circuit and for energizing zone registration circuit equipment. The two-party message rate line as shown in the left portion of Fig. 1 has difierently wired subscribers station sets connected to theconductors of the line, one being termed herein the tip party station and the other the ring party station for identification purposes. During the dialing of the first digit by one of these parties, the sender, upon recognizing that a two-party message rate line is connected thereto, prepares to connect the party line identification mechanism with the line.

As soon as the first digit has been dialed, this mechanism is connected to the line so that an identification test can be made between the dialing of the first and second digits to determine which party is calling. The identifying mechanism is then disconnected from the line before the second digit is dialed.

l The tip subscribers station has ground extending through a winding of the ringer tothe tip line conductor when the receiver is removedfrom the switchhook. This provides an identification of this party by the sender mechanism. The absence of ground is used by the sender mechanism to identify the ring party but a false-ground connected to the tip or ring conductor would be extended over the line loop to the sender identifying mechanism and might cause the tip party to be charged for a call when the ring party is calling. When the sender receives the indication that the tip party is the one making the telephone call, it causes a circuit to be established for operating relay I04 in the line-finder selector trunk circuit which locks and later functions to hold the line finder connected with the line after the connection between the subscribers is released.

As previously describeithe code dialed by the calling subscriber determines whether the first selector will be operated from pulses dialed by the calling subscriber or from pulses dialed by the sender. In one case the telephone switching connection is established between the calling subscriber and a called subscriber in the fringe ofilce and in the secondcase between thecalling subscriber and a subscriber in a distant oflice', the connection to a subscriber in the distant office being under control of the pulsing mechanism in the fringe ofiice sender. For the latter telephone connection the mechanism of the sender is progressively operated as the digits are dialedfor operating, the sender register switches, the select magnetsand hold magnets of the register switches being progressively operated responsiveto each digit dialed. Responsive to the dialing of the code digits for. a call to a distant oflice, a route relay is operated and pulses are transmitted by the sender for controlling the first selector to select an outgoing trunk to the distant ofiice as governed by the route relay operated. This route relay is arranged to controlthe number of digits dialed for selecting the outgoing'trunk and the number of pulses in each digit and also controls the speed of pulsing depending upon the character of ofiice to which the connection is extended.

The release of atelephone connection initiated by the tip party causes the. operation of mechanism in the line-finder selectorltrunk circuit underthe. control of relay I04 which operates a trunk finder permanently connected with. a sender to again connect a sender to the line-finder selector trunk circuit. It will be remembered that relay I04 holds theline finder connected with the calling line. Relay. I04 connects signal sources to thesender which automatically arranges the sender for testing the tip and ring conductors of the calling line after the receiver has been replaced on the switchhook. If the sender finds a ground on the line at this time, it is automatically connected to the dual selector by its own devices and the devices of the line'- finder selector trunk circuit. This mechanism now automatically operates a special c rcuit arrangement in the second sender associated with the line connection to cause pulses to be transmitted by the sender pulsing mechanism to control the dual selector. The brushesof the dual selector "are thus connected with a'party line testing trunk as shown in Fig.4. The-sender is then released and the line-finder selector trunk circuit is responsive for connecting the party line testing trunk with the calling line. The calling line will at this time have thereceivers on the switchhooks unless another call has been immediately started. Antest of the line is made by the party line testing trunk and if no ground is found connected to the lineythe connection is released and the tip party is correctly charged for the call. It is apparent that with 'both receivers on their respective switchhooks ground would not be connected to eithergline conductor unless it were a false ground from a source other than through the windingof theringer in the tip party station. When ground is found connected with the line a busy tone is connected to the line, the line is heldby the party line testing trunk f o r. inspection and an alarm is sounded to attractthe attention of amaintenance man in the fringe office if it is an attended oflice or in a supervising 'ofiice iffthe fringe oifi'ce is unattended. 1

DETAIL DESCRIPTION Incoming calls T For this description it may be'assumed that an incoming. call is initiated by one of the two parties I50jort60-shown in Fig. 1 connected to the line ,entering the. fringe ofiice, either of which energizes ,theline relay I92 which causes the Operation of a line..finder associated with the group of lines served by the line-finder group. It .was previously indicatedin thegeneralclescription, that .a line finder, -a line-finder selector trunkcircuit and a dualselector are permanently connected together .as shownin Figs. 1, 2. and 3. Only, sufiicient mechanism is shown in the line finder and the dual selector for establishing circuits'forthis invention since the'line finder and dual selector arecompletely shown in my .copending application Serial No. 495,487, filed July 20, I943.v The sender has atrunk-finder circuit permanently connected thereto as diagrammaticallyshown in Fig. 2 and Figs. 4 to 1.1 of the sender. The trunk-finder circuit is shown diagrammatically to save description since this trunk finder is alsodisclosed. in detailin my ccpencling, application Serial No. 495,487, filed July .20, 1943, and reference may behad to this patent application for a complete description of these finders and the selector. The cnergization of the line relay I92, when the receiver is removed from the switchhook, energizes a line-finder group control relay for selecting a line. finder to serve the calling line. The operation of the line-finder group relay connects a start ground shown as start ground I80 through contacts 3 of relay Lil, winding of relay H5 to battery energizing relay H'B. Relay H6 establishes circuits in the line finder, one of which actuates the vertical magnet which starts the line finder in search of the calling line. Relay I I6 also establishes a start circuit for the trunk finder 200 which is one of a group similar to the group of line finders and includes a similar start relay as will be apparent by reference to my copending patent application, SerialNo. 495,487, filed July 20, 1943. The start circuit for the trunk finder may be traced from ground on contact 3 of relay H6, thence over the sleeve lead I40, contact 9 of relay I09,'contact B ot relay I I0, contact I of relay 2I5, winding of relay 2 I 'I to battery. Relay 2I'I operates to establish a cirl cuit for the start relay in the trunk finder 200.

This circuit may be'traced from ground through contact 2 of relay 2I5, contact 3 of relay 2H, conductor 260 to the group start relay in the trunk finder 200. Various mechanisms in the trunk finder are thus operatedso that the trunk finder 200' starts to hunt for the line-finderselector trunk circuit, Figs. 1 and 2, connected to the line. finder that is hunting for the calling line. The vertical magnet of the line finder steps the brushes in an upward movement and the rotary magnet steps the shaft and brushes until one of the sleeve wipersreaches the terminal Whichis connected to the calling line and thereforeto battery through the Winding-of the cutofi relay I9I in the line circuit. Acircuit 'for relay I I4 is thus-established from battery through the winding of the cut-off relay, sleeve brush I43, upper winding of relay H4, contact 2 of relay I I1, upper winding of relay I25 to ground'on contact 3 of relay H6. Relay H4 is sufiicientlyoperated to close its contact 4,.thus establishing a circuit from battery through its lower winding, over dotted lines through contact Iof the rotary magnet, not shown, contact of relay I25, not shown,

to: ground oncontact 2 of relay, H6. This completely operates relay H4 to close the leads from the line circuit to the line-finder selector trunk circuit and establishes a circuit for operating relay -II'I. The circuit for relay HT may be traced, from battery through its upper winding, contact 5-oi relay H4 to the vertical ofi-normal ground. The operation of relay HI' connects sleeve lead I40 and ground from contact 3 of relay H6 through its contact 2 to the line circuit and also establishes a locking circuit for relay H4. The circuit for relay H6 is also open but the latter relay is made slow to release in order to hold the ground on the sleeve lead during the timeyrequired by the ,dual selector to connect ground to this sleeve lead. The original locking .circuit for relay H4 may be traced from battery through its lower winding and contact 4, contact .I of: relay II! to ground on contact 30f ay The energization of relay I I 4, as originally stated, connects theline conductors to the tip and ring leads I4! and I42 which extend through polarized relay I00, contacts I and I0 of relay I02,

contacts

2 and 3 of relay I03 to battery and ground through the windings of the A relay 302 inthe dual selector circuit operating the latter relay. The A relay in the dual selector circuit establishes .a circuit for the B relay 303 which remains operated over diiferent circuit paths under varying conditions of the switching connection. This control is established by the sender for bothlocaland trunk connections as hereinafter described. The B relay connects ground through its contact 3 to sleeve lead 355 before relay H6 is released. This may be traced over lead 355, contact 8 of relay I I I, contact lof relay I04 to the sleeve conductor I40. With this-ground established and relay H'I operated, the locking circuit for relay H4 remains established and a circuit connection also remains established for continuing the operation of the line cut-off relay. The locking circuit forrelay H1 extends to the ctr-normal ground through .contact5 of relay H4.

Trunk finder As previously stated, the trunk finder 200 is energized by relay I I6 to cause the simultaneous hunting of this trunk finder and the line finder. The vertical and rotary magnets of the trunk finder 20.0 are energized for connecting the brushes 220 to .22! with terminals 20I to 208. The brushes 220 to 221 are arrested in their rotary motion when battery is found on the sleeve terminal 203 connected to lead 25L A- circuit is thus established for cut-.oiT relay 2I5 from battery through its'winding, contact I of relayiI'I, conductor ZBI, terminal 203, brush 222, through the winding of a cut-in. relay in trunk finder 200 ,to ground on the contact of a trunk-finder relay. Relay 2 I 5 is operated and the trunk finder cut-in relay is operated in series with relay 2I5 which causes the connection leads shown from the linefinder selector trunk circuit to the-sender. Relay 2I5 in operating releases relay 2 I1 and establishes a locking circuit for itself from battery through its winding, continuity contact I of relay 2, contact I of relay 2I5, contact -6 of relay H0, contact 9 of relay I09, contact 8 of relay III to ground-on sleeve conductor 355.

Sender When the trunk finder is connected with the line-finder selector trunk circuit, the mechanism is operated in both the sender and the line-finder selector trunk circuit. A circuit is immediately established for relay I02 in the line-finder selector trunk circuitin order to connect the calling subscribers line with the sender and disconnect the dual selector circuit A relay 302 from any character of pulsing mechanism. The A relay of the dual selector is, however, held operated by a bridge which is established when relay I02 cperates as later described and the A relay maintains the B relay of the dual selector circuit operated. At a later time when the code digits have. been dialed by the calling subscriber the sender will then determine what pulsing means shall be used for operating the dual selector.cir-.

cuit. The circuit for relay I02 may be traced from ground on contact 4 of the B relay 303 in the dual selector circuit, winding of relay I02, upper winding of relay I09, terminal 208 and brush 221, thence over conductor 265 through the mechanism of the trunk-finder circuit, conductor I42, winding of relay I02, resistance 1.03 to battery. Relay I 02 operates in a circuit traced but because of the high resistance I03 in series with the winding of relay 102, relay I09 does not operate at this time. Relay I02 also operates but the result of the operation of the latter relay will be deferred for the moment. The operation of relay I02 establishes a holding bridge for the A relay 302 in the dual selector circuit. The holding bridge for relay 302 may be traced from battery through its lower winding, contact 3 of relay I03, contact I of relay I02, resistance I I2, contact 3 of relay III, contact 2 of relay I03, upper winding of relay 302 to ground. A second bridge in multiple with this bridge may be traced from ground through the upper winding of the A relay, contact I of relay I02, resistance II3, contact 3 of relay [03 to battery through the lower winding of the A relay. Relay I02 connects the tip and ring conductors MI and I42 from the subscribers line to the sender L relay I205. These leads may be traced through contacts 3 and I of relay I02, terminals 20I and 202, brushes 220 and 22I, thence over

conductors

263 and 264 through the mechanism of the trunk-finder circuit 200 over conductors 648 and 649through the party line testing mechanism, Figs. and 6, and the dial tone coil to the L relay I205 as later traced.

A circuit was traced through the winding of relay I02 for operating relays I02 and I02. The

operation of relay I02 establishes locking circuits winding, over sleeve conductor 202 to ground es-' tablished in the trunk finder when the sleeve circuit from the sender is connected to the sleeve circuit of the line-finder selector trunk circuit as described in the aforementioned copending patent application. Relay IOI supplies ground circuits throughout the sender mechanism and provides operating and holding circuits for various relays of the sender. The operation of relays I02 and NI establishes a circuit for relay II! from battery through its winding, contact of relay I02 to ground on contact 4 of relay I.0I. Relay. I I I, in operating, locks to its operating ground through its contact 3. A circuit is also established for out-dialing pulse relays 8J4 and 8I8 at this time which may be traced from battery through resistance 808, contact 4, of relay 802 and resistance 809 which forms apotentiometer,

winding of relay 8I4, winding of relay 8I8, contact 2 of jack 80I, lower winding of relay 800, contact 3 of jack 80I, conductor 842, contact I of relay I001, contact 2 of relay I008, contact I of relay I009, conductor I030, to ground on contact 6 of relay IOI. It will be. noted that ground is also connected'to'conductor I33 which extends to a point 843 in the potentiometer circuit asso ciated with condensers 80 4, 805. These condensers are later used for controlling the operation of the pulsing relay 800. Polarized relays 8I4 to (H8 are operated over the circuit traced since the flow of current is in the correct direction for their operation, but relay'000 is not operated since the current flow is in the opposite direction to the polarization of the latter relay. The functions of these relays will be described after digit pulses have been dialed by the calling subscriber, registered by the sender and the sender is ready to use this mechanism for transmitting digit pulses.

Dial pulsing system As already set forth, relay I02 connects the tip and ring conductors from the subscribers station through theline finder and line-finder selector trunk circuit, contacts 3 and I of relay I02, thence over conductors I45 and I46 to the trunk selector terminals and brushes, through the trunk finder 200 over

conductors

263 and 264 to

conductors

648 and 649 in the sender; The tip conductor'649 may" be traced through contact 6 of relay 603, contact 3 of relay 5I0, contact 5 of relay 603, thence over conductor 635 through contact 4 of relay I04, winding I35 of transformer I34 to ground. The ring conductor 648 may be traced through contact 2 of relay B03, contact 4 of relay v.5I0, contact 3 of relay 603 over conductor 636, contact 3 of relay I04, winding I36 of transformer I34, contact 2 of jack II2, lowermost winding of L relay I205, contact I of jack H2 to battery, The L relay I205 is thu held operated over the line loop. The tone coil transformer .134 is energized by the operation of relay II! as previously described, the circuit extending from ground on contact I of relay III, through -winding'.I3I of transformer I34, winding 139 of tone coil 140 to ground. This actuating circuit extends through contacts of other-relays which .when operated cuts off the transmission of tone after the first code digit is dialed. The subscriber, upon hearing the tone, begins to dial the ofiice code. As the dial is manipulated by the subscriber, each open period of the dial. releases the L relay I205 and each closed period of the contact of the dial reoperates. the L relay I205. The pulsing system including the pulse responsive relays is diagrammatically shown since it i the same a shown in detail in my copending application, Serial No. 495,487, filed July 20, 1943. This is also true of the register switch control relays IZOI, the route relays I202 and the register switches I203. Relay I205 and other relays are responsive to the operationfand release of the L relay I205 for energizing the register switch control relays, one relay being operated responsive to each pulse until the digit has been dialed. The digits are successively registered on the registerswitches I203. Relay 109 is shown merely to complete the ,wiring of the. Lrelay I205 and. is used in connection with calls which are delayed by the calling subscriber. Itis a slow release'relay and will release only if the subscriber opens the line for airelatively long interval, thus completing circuits in the-sender'to indicate tothe sender Returning to the point when the path between the calling line and; the sender is first established, class signalsaresent-tothe sender as the first digit is dialed by the calling subscriber. These signals are sent over leads I80, -I8I and I82 and energize the mechanism of Fig. 4 as a matter of information to the sender regarding the character of calls the subscriber is permitted to make without a charge and what calls shall be under the control of a registering device for computing the charge. This mechanism also indicates Whether the'callin'g line is a single party line or a two-party message rate line. The first signal received is over lead" I82. This lead is extended from line terminal I39 through the line finder and line-finder selector trunk circuit to the sender and the signal sent from the line depends upon the mechanism connected to the terminal and if all of the lines in the group are of the single character; Other signals are transmitted over conductors I80 and I8! from the line-finder selector trunk circuit, otherwise the signals over these leads are governed by normal post springs in the line finderserving this line. The circuit established to brush I49 may be direct ground, ground through a high resistance or ground through a low resistance message register or the lead may beopen. In cases where all of the lines of a line-finder level are of the same character, ground. through resistance or direct ground or open maybe connected through the normal post springs of the line finder and thus establish the character of all of the lines 7 of this particular-level, otherwise the indication is individual to each line.

Marginal and non-marginal relays'are shown in the class responsive relays'of Fig. 4. Relays 402 and 40B are operated by the signal received over lead I82 and relays'400, MI, 404 and 405 are operated by signals received over leads I8I and I82. The circuit for

relays

406 and 402 may relay 402 nor 406 operates and a circuit is-established to class terminal 450. The class i'ndica tions are first established and areused later bythe sender when circuits are established between thesender mechanism and the class mechanism. With neither relay 402 nor 406- energized, battery is connected to terminal 450 from the battery 609 shown. in Fig. fithrough resistance 601, contact I of relay 403,: contact I of relay. 401 contact I: of relay 00.0, contact I of relay 402,

contact 3 of. relay..4.06. to. class,iterminal. 450.

which condition islater altered'by the operation of relay 403 to produce the class indication for the sender after certain other mechanisms" have operated. 'When terminal I49 is connected. to-

ground through a high resistance, the marginal relay 402 does not operate but-relay 406 operates in this circuit. The operation of relay 406 establishes a circuit to terminals 455, 456 or 451 depending upon the combination of

other relays

400, 40I, 404 and 405 which are operated over conductors'444 and 445 as will later be described. When brush I49 is connected through a low resistance message register or directly to ground, both

relays

406 and 402 are operated. When both relays are operated a circuit is closed to one of the terminals 440- to 448, inclusive, depending upon the combination of other relays 400, MI, 404 and 405 which are operated.

When relay 406 operates it connects the fundamental tip lead 268- to the marginal relay400 and non-marginal relay 404 as follows: Tracing from the line-finder selector trunk circuit from a resistant or non-resistant condition in the linefinder selector trunk circuit to the sender over fundamental tip lead I30, it is found that this lead extends through contact 5 of relay 401, contact 4 of relay 406, contact 4 of relay 605, contact 2 of relay 600, windingof relay 400, winding of relay 404 to battery. The fundamental ring lead' IBI extends from the line-finder selector trunk circuit or normal post spring through contact 2 of relay 401, contact I of relay 405, contact 2 of relay 605, winding of relay 40I, winding of relay 405 to battery. Each of these leads, the fundamental tip lead I and the fundamental ring lead l8I-, is-connected in the line-finder selector trunk circuit either directly-to ground or ground to a high resistance or left open. If lead I80 or lead- I8I is open, neither the marginal relaynor the non-marginal relay operates; This applies to either the 400, 404 combination or the MM, 405' combination. If either of these leads is connected directly to ground, both relays associated with the lead operate and if either isconnected 4' through a high resistance to ground,

relay

404 or 405 operates depending upon which lead is associated with the high resistance. The marginal relay, relay 400 or 40I, does not operate under this condition. One of terminals 440 to 448, 450 and 455'to. 451 are connected to ground as a result of signals over

leads

262, 261 and 268 according to the following table:

G=direct'gr0und. H. R. G.=high resistance ground.

Terminals'450, 455 to 451. and 440zto 441are cross-connected directly toclass signal? terminals 7 such asv 450 and 46I whichcauses the eventual operation of a class-signalrelay such as relays" 408.and 409.- O'nesuch class signalrel'ayisoper-' ated for each class-of service provided in-the oflice when the

above relays

402, 406; 400-, 401 and 405 have been given an opportunity to oper= relay.

Relay 605 is also a class signal relay operable through the contacts of

relays

402, 406, 400, MI,

404 and 405 for party lines as will be explained.

later.

The. class signal relays are operated in the above manner when the sender is seized, thus indicating the class of the subscriber calling and whether it is a single party line or a two-party message rate line. The signal covering this class of service may be indicated to the sender shortly thereafter. The time of dialing one pulse is al-' lowed for the operation of the class relays to establish the combination circuit paths through the contacts of relays 400 to MI and 404 to 406 and when the calling subscriber dials the second pulse, relay 403 is operated in multiple with the relay which responds to this second pulse. Relay I204 has been indicated to illustrate the circuit for the pulse-2 responsive relay and a circuit is established through contact I2II which is closed by the pulse responsive relay when the second pulse is dialed by the calling subscriber. The circuit for the pulse-2 relay and relay 403 may, therefore, be traced from battery through their windings, contact I2I I, contact I of relay 123 to ground on contact 8 of oif-normal relay I. It will be noted from the pulse responsive relay circuits that relay 123 is operated during the pulses of a digit and released between digits. Relay 403, in operating, looks through its continuity contact 2 to ground on contact 2 of relay 10I and associates ground through its contact I with the class relays. For example, if neither class selecting relay 402 nor 406 is operated, the ground is extended through contact I of relay 403, contact I of relay 401, contact I of relay 600, contact I of relay 402, contact 3 of relay 406 to terminal 450.

Thus, where terminal 450 is cross-connected to a classindicating relay such as 408, a circuit is established for operating the latter relay. If re lay 402 is operated,this ground extends from contact I of relay 403 through contact I of relay 401, contact I of relay 600, contact 2 of relay 402, contact 2 of relay 404, assuming this relay to be normal, contact 3 of relay 405, assuming this relay to be normal, to terminal'440, thus operating a difierentclass indicating relay. Assuming that relays 402, 40I and 405 are operated, this ground is connected from contact I of relay 403 through contact Iof relay 401, contact I of relay 600, con tact 2 of relay 402, contact 2 of relay 404, contact 4hr relay 405, contact 6 of relay 40I to terminal 442. The combinations of these relays are such that after the class registration ,has been made, the ground connected to terminal I of relay 403 may be extended to any one of terminals 440 to 441; inclusive, 450 or 455 to 451, inclusive, to operate any of the different class indicating relays connected to these terminals. I

Relays, such as 408 and 409, are provided for each class of service given to subscribers of the.

oflilce and terminals such as 460 or .46I are connected to any of the terminals 440 to 441, 450 or 455110 456 so that the class indicated by the relays in the upper portion of Fig. 4 will establish a circuit for associating ground from contact I of-relay 403 to the correct terminal for energizing a class relay which will provide circuits inthe sender for certain functions.

In some instances, two-relays are provided for the given class of service, particularly on coin and-non-coin lines w e t e t e s: to t e s medest t on; bu

selected by the difierent route relays to the same destination. V

'For classes other than two-party message rate calls, the terminal 426 is cross-connected to the terminal 428 so that relay 401 isoperated as soon as the class relay is operated. Terminal 426is, however, shown cross-connected to terminal 421 for two-party message rate classes. Thiscauses a two-party identification test to be made as soon as the class relay is operated, and at the conclusion of the two-party identification test, relay 401 is operated as will be described. For this example, it may be assumed that terminal 460 is cross-connected to terminal I and that terminal 4 was grounded by the operation of

relays

405 and 402. It will be remembered that the operation of

relays

402 and 405 connects ground from contact I of relay 403 through contact I.

of relay 401, contact I of relay 600, contact 2 of relay 402,,contact 2 of relay 404, contact 4-of re-.

lay 405, contact 5 of relay 4!, terminal I,

winding of relay 408 to battery. Relay 408-in, operating establishes a locking circuit for itself through this contact 4 to-ground on-contact I of.

relay 403. A circuit is nowestablished for the two-party line test by the operation of relay 600 which may be traced from battery through its winding, terminal 421, terminal 426, contact I of relay 408, to ground on contact I of offnormal relay 10 I.

The party identification test is made as soon as the first digit has been received by the sender and is used by the sender to determine whether. the calling subscriber of thetwo-partymessage.

rate line is the'tip party or the ring party of the line. This test is made only when the operated class signal relay indicates that the calling line This was inis a two-party message rate line. dicated by the operation of relay 408 and the cross-connectionof terminal 426 to terminal 421' through the contacts of this relay. This character'of class signal relay establishes a circuit as traced for operating relay 600. Relay 600 is operated while the first or A digit is being received which prepares the sender for making a test of the calling line between the dialing of the first and second digits. identification test, as will be shown by the circuits traced, relay 5I2 is connected to the tip and 'ring of the calling subscribers line for a' If relay 5I2 is operatedgiven time interval. v at the'end of'this interval between the first and second digit, it indicates that the calling sub-- scriber is a tip party subscriber since this relay 5I2 will operate in a circuit to the ground connected to the lower ringer winding in the tip party ,station of the two-party line shown in Fig. 1. The timing is controlled by condensers and if relay 5I2 is not operated at the endofan accurate time interval between digits, it indicates that the calling party is a'ring party on a two-party message rate line.

' Control and time of two-party message rrate Zine test n wf b remembered that relays 10I and m1 For the two-party line were operated when the sender is first seized inworderto establish batteryrand ground. supplies to-the relays of the sender. This establishesa current how in the biasing winding of polarized relay 505*and operates relay. 6I4.. The circuit for relay 6M maybe traced: from contact 3 of relay contact 2- of relay 6I3, winding.

ofrelay GM to battery. The circuit through the biasing winding of relay 505 may be :tracedfrom ground on contact I of relay I01, through.

resistances

503 and 504, upper winding of relay 50.5, contact3 of relay II I to battery. Relay BM in operating establishes a circuit for relay 6I5 which is obvious and-need not be traced. Relay 615 establishes a circuit-throught'he lower windlngof relay 505 traced from ground on contact I of relay'l'OI, contact 3 of relay BIB, contact 20f Relay 123 remains operated during the pulse ofa digit. and restores tonormal after the pulses of each digit have been dialed by a calling subscriber. The circuit for'relayl23 may be traced from battery through its winding, contact 'of pulsing relay I206 to ground on contact! of relay IOI.' Relay I206, through which the above circuit 'is traced, follows the operation of the L relay I205 as the contact of the L-relay is connected to the armature during eachpulsing period from the calling subscribers dial. Relay I206 is therefore released during each open pe riod 'of' the dial and operated during each closed period. Relay I23is a slow releasing relay and therefore remains operated-during the pulsing of.

the digit but after the pulses of the digit are dialed, the contact of relay- I206remains open and relay I23 releases. Referring again to the operation of the party line test relays, it will be remembered that relay 600 isoperated and relays 6M and 6I5 are operated. Atthe end of the first digit dialed by the callingsubscriber, the'release of relay I23 thereforeestablishes a circuit for relay6l3. The circuit for relay 6I3 may be traced from-battery through its winding and continuity contact, contact I of relay, 600, contacts 3 and 20f relay I23 to ground on contact 8 of the oif- 4 normal ground. relay 'IOI. Relay 5I3 inoperating looks through its continuity contact to ground. on contact 3 of relay WI and causesthe release of relay 6I4sincethe operated circuit for the latter relay extends through contact. 2 of relay 6'I3. The release of relay 6I4'releases relay 6I5 'which opens the circuit to the condenseritimed relay 505. With relays 6M" and GIS released and relay. 510 operated a circuit is nowejstablished from 110"-volt battery 562 to the tip and ring conductors of the subscribers line connected" to the callin-gsubscribers stati'orrmechanism. This circuit may be traced from the l10-volt battery 562 through contact I of jack 5I3, resistance 518, up-

per winding of relay 5I2i-contact 3 of relay 502,

varistor 657 in multiple with resistance 6I5; contact, I of relay 5I5- to a junction point 641 connected with the tip. and ring conductors of the The connection to the tip con- 7 ductor extends through contact 3- of relay 6M,

subscribers line.

contact 3zof relay 5I0, contact 6 of relay 603, tip conductor 649 which extends to the tip conductor of the line connected with" subscribers stations I50 and IE0 as previously traced. From the junction .point 6M the connections-made to the ring conductor of the subscribers line are through contact 4 of relay 5I0, contact 2 of relay 603, ring conductor 648 which extends over the ring conductor of theline to the subscribers stations I50 and I60, as previously traced. The relay 5I2 is thus held associated with the subscribers line for a period of time between the first and second digit dialed by the calling subscriber. During the time that relay 5I2 is presented to the calling subscribers line the L relay I305 is held operated in a local circuit under control of relays 6M and 5I0 so that a false pulse will. not be sent to the registering mechanism. This circuit may be traced from battery through the upper contact I of jack H2, lowermost winding of the L relay I205, contact 2 of jack H2, coil I30 of transformer I34, contact 3' of relay F04, contact 3 of relay 603, contact 2 of relay 6M, contacts I and 6 of relay 5I0, resistance 509 to ground.

Relay 505 releases in approximately .050 second under the control of condenser 500 and when released connects ground through contact 2 of relay 506 released and. contact 2 of relay 5I0 operated to the armature of relay 5I2. If the calling subscriber is a tip party of the two-party message rate line, relay 5I2 will have been optact 2 of relay H1.

erated when associated with the ground extending through the lower winding of ringer I64 at the tip party station I60. With relay 5I2 operated, ground is connected through the armature and contactof relay. 5-I2, winding of relay 5I4 to battery through resistance lamp 516. If relay 5I4 is thus operated, it establishes a locking circuit for itself to ground through its contacts I and 5, contact 4 of relay 603 to ground on contact 2 of relay 'III. Relay 5M establishes a circuit to reoperate relay 505 and. operate relay 502. The circuit for relay 502 may be traced from bat teryv through its. lower winding, contact 3 of re-v lay 5I0', contact 4 of relay 603- to ground on conbattery through lamp 5I6, contact 4 of relay 5I4, to the tip lead conductor 56I to replace the volt battery supply which is cut oil by the operation of relay 502. It will be remembered that lead 56I extends through varistor BI! and resi'stance 6I6, contact I of relay 6I5, contact 3 of relay 6M, contact 3 of relay. 5I0, contact 6 of relay 603 to tip conductor 649. Relay 502 extends its operating ground through its contact 5 to opcrate relay 5I I. This circuit extends through the upper winding of relay 5 to battery. The operation of relay 502 also shunts resistance 503 which is in series with the biasing winding of relay 505 and opens the'operating circuit for relay 505.

Relay 505, due to the reduction of resistance in series with its upper or biasing winding, releases in approximately .015 second. During this interval the 48-volt battery connected to the subscribers line along with the varistor I2II and resistance I2I6 causes the discharge of the line in such a Way as to prevent'bell tapping at the subscriber's station.

The release of relay 505 and the operation of relay: 506 open the locking circuit previously tracedfor relay 5I0 which now releases. This removes the holding circuit for the L relay I205 and reconnects thetip-ancl-ring line leads through 1 continuity contacts-to the L'relay I205. -The Relay 5M connects 48'-volt.