US1970337A

US1970337A - Telephone system

Info

Publication number: US1970337A
Application number: US642031A
Authority: US
Inventors: John G Pope
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1932-11-10
Filing date: 1932-11-10
Publication date: 1934-08-14
Anticipated expiration: 1951-08-14

Description

Aug. 14, 1934. J. G. POPE TELEPHONE SYSTEM 2 Sheets-Sheet l Filed Nov. l0. 1952 /N VEA/TOR' J. G. POPE ATTORNEY Aug. 14, 1934. 1G, Pope 1,970,337

v TELEPHONE SYSTEM Filed Nov. 1o. 1932 z'vshets-shee; 2

/N VEN Ton J. G. POPE 4 from/Ey Patented Aug. 14, 1934 unirse STA TELEPHONE SYSTEM John G. Pope, Montreal, Quebec, Canada, assignor to, Western Electric Company,Y incorporated, New York, NLY.,

York a corporation ci New Application November; 1 0, 1932,. SerialNo. 6421,03-1

c claims. (o1. ris-1r) f i This invention relates to telephone systems and particularly to improvements iii-automatic telephone systems. lts object is to simplify, con-` centrate and increase the utility of the equipment used in establishing automatic connection in such systems.

Hereto-fore, systems have been provided inv which common registers or senders have been provided for receiving impulses to control theA 'rsetting of the switches `for establishing connections between subscriliers and various other functions incident to the control of a connection.

lt is a feature of this invention to concentrate in a register, corni-non to a plurality of links each comprising a line nder and a selector used for the establishing of connections between subscribers lines, means responsive to impulses received from a calling line for transmitting corresponding impulses to control Vselections in the selector and switches beyond, means responding to impulses received from the calling line to select diierent ringing code signals to be transmitted to thegcalled party when the connection has been established, and means for releasing a seized link r" and the register a certain interval after seizure if no further action is taken by the calling subscriber towards the establishing of a connection or if the calling subscriber fails to dial or complete the dialing before the end of this interval or in case oi a revertive call This invention is illustrated in the accompany- Y ing drawings in which:

Fig. l yshows in diagrammatic form an auto-matic telephone system arranged.; in accordance with 7 this invention, while Figs. 2` to 3 show the detail circuits of such a system embodying the features of this invention. Figs. 2 and 3 include a calling subscribers line,r a link circuit comprising a line finder and a selector, a register common to said linlns, a connector and called subscribers line and trunks of various types.

Referring now particularly to Fig. l, which shows in diagrammatic form the general outline of a system embodyingY this invention, if the subscriber l calls, an idle line finder LF is opl erated to connect the associated link 2 with his line and to associate aV common idle register R with this seized link. When the operator dials the nrst digit the selector S associated with the link 2 is operated in its primary movement to select a Igroup or connectors and to hunt for an idle connector C. The second and third series oilirnpulses sent out by the operator will then actuate the connector C in its primary and secondary movements to select the desired Single line 4, or a party lfinc 1, ora group of manual trunks leading to an operators position O or a group of trunks leading to a distant'step-bystep oiiice SS. The connector C then hunts for an idle manual trunk line in the selected group or hunts for an idle trunk outgoing to oce SS and terminating' ina connector such as C-2 which is then operated by succeeding digits to select a desired subscribers line' 6. Ita local subscribers, line 41 or a party line l is selected the nextseries of impulses will operate the ringingV code switch RC in the regis-ter E to select the proper ringing code signal. It the operatorie position O is con nected with, then the code switch is also operated but in this case the usuall line lamp mayv be actuated at the operators position over the selected trunk by theselected code signal.y I'he code switch is similarly operated; when a stepby-stepy cnice isselected after the desiredl subscribers line has been reached.

`Descriptions will now be made in detail of the establishing of the connection mentioned with special reference tov Figs. ,2V and 3. If Athe calling subscriber at l,` removes his receiver from the switchhook' to4 make aV call a simplex ground is placed on the tip and ring conductors over the line from the callingvpartys telephone causing the operation of relay 8 in the line circuit from battery and ground through the windings of this relay armatures andback` contacts of.' relays 9 and 10 to ground at the subscribers telephone set at 1 Relay 8 operating closes an obvious circuit for the operation of relay l1 which is associated withthe particular group to which the calling line belongs. This relay may be common to ten lines. The operation of relay 8 alsor prepares a circuit at its lowerouterarrnature, and front contact for the operation ofrelayf9 from the sleeve terminal on the line finders having access to this group of lines` Relay llplaces a ground connection Von the line finder commutator 12 onthe terminal representing the level in which the group of linesrare located to which line 1 belongs. As'show'n in the drawing this is the second level; Relay 1l also closes at its left-hand 'armature andI front contact a connection to ground for an interruptorV starting circuit not shown, the interruptorV supplying interrupted ground connection on the lead 13. This relay also prepares a circuit for the operation of relay 14 from battery, winding of this relay, upper inner armature and back contact of relay l5,V righthand outer armature andffront contact of relay ll to ground- Relay 14 in operating connects the 'Y interrupted ground connection on lead 13 to the vertical stepping magnet 17 for the line nder LF. Magnet 17 now steps the line finder in a vertical direction until the commutator wiper nds the ground on its second level when relay 18 is operated from battery through the winding of this relay through the commutator wiper, the terminal on the second level to the ground at relay 11, relay 18 locks at its upper inner armature and front contact to OIT-normal contacts 20 of the line nder LF to ground supplied at the olii-normal contact 21 of the selector switch S. Relay 18 also transfers the pulsing circuit to the rotaryl stepping magnet 22 at the upper middle armature and iront contact and places a ground at its lower middle armature and front contact for a start lead 28 leading to the register R for the association of the register with the link 2. Relay 24 now operates over a circuit from battery through the winding of this relay, armatures and back contact of stepping magnets 25 and 26, second upper armature and back contact of relay 27, start lead 23, second lower armature and front contact of relay 18 to ground at the lower outer armature and back contact of relay'29. The association of the register with the trunk will be described hereinafter.

rIhe rotary stepping magnet 22 now steps the brushes of the line iinder Ll'f over the second level until the ground placed on the sleeve terminal 'of the calling line is found, when a circuit is completed for the operation of relays 30 and 9 from battery through the lower winding of relay 8, winding of relay 9, lower outer armature and front contact of relay 8, sleeve lead and terminal fof the calling line, the sleeve brush ofthe line nder LF, lower winding of relay 30, lower outer armature and back contact of relay 15 to ground at the inner left-hand armature and front contact of relay 14. Relay30 locks from battery through its other winding, upper inner armature and front contact to the ground at relay 14 independent of the connection through the sleeve lead. Relay 30 also connects the tip and ring conductors from the calling line at the second and -third upper armatures and front contacts through the. left-hand windings of the repeating coil 32 and opens the circuit for the rotary stepping magnet 22 at itsupper outer armature and back contact to stop the line finder on the terminals of the calling line. A circuit is also closed for relay l5 from battery through the upper winding of this relay, upper outer armature and front contact and upper inner armature and front contact of relay 30 to ground at relay 14 causing relay 15 to operate. RelayV 15 in operating transfers the start circuit above mentioned to the conductor 33 to the next line finder. yRelay 15 also provides a locking circuit for itself from battery through its lower winding and lower inner armature and front contact to ground at the off-normal contact 20 of the line nder LF'.

Relay 9 operates in the above mentioned circuit in series with relay 30 and remains held up by the ground at relay 14. Relay 9 opens the circuit for the relay 11 to prevent the next nder from operating and removes the relayS fromthe connection to the tip and ring conductors to the callingline. Relay 8 is however held operated by the circuit through its lower winding. Relay 9 closes a connection from ground at its upper outer armature and front contact to the P lead terminating in the banks of connectors. The ground connecting at relay 14 on the sleeve lead serves as a busy indication for the calling line in termin nais of line finders as well as on the sleeve lead leading to connectors which is extended at the lower inner armature and back contact of relay 1). Due to the operation of relays 9 and 30 the simplex ground from the calling subscribers set at l is now extended through the link circuit to cause the operation of relay 34 from battery through the winding of this relay, left-hand 'windings of the repeating coil 32, tip and ring conductors, simplex ground at the calling subscribers set. Relay 34 in operating causes a circuit to be closed for maintaining relay 14 operated.

"This Atransfer to a holding circuit for relay 14 may take place due to the fact that relay 14 is slow in releasing. The new circuit for relay 14 may be traced from battery, winding of this relay, outer right-hand armature and front contact of relayV 34, third lower armature and front contact of relay 15 to ground at the inner lefthand armature and front contact of relay 14.

The inder switch for associating a register such as R with the link circuit 2 has been shown as two separate switches FS-l and FS-2 controlled respectively by the stepping magnets 25 and 26. When the ground was placedon the register starting lead 23 as hereinbeiore traced relay 24, operated. A circuit is thereby closed for rotarymagnet 25 from batteryV through the winding of this. magnet, second upper armature and back Contact of relay 27, armature and front contact of relay 24 to ground at the upper outer arma-v ture and back contact of relay 36. When the rotary magnet 25 operates the circuit for relay 24 is opened causingV it to release and thereby releasing the magnet which then closes the circuit for relay 24 so that the magnet and the relay operate and release alternately until a ground on the wiper of terminal bank C when the finder switch FS-l iinds a battery connection on the terminal of the'seized link, which in this case has been shown as the rst of the group, kthe nder switch having a capacity of 22 links. This batteryconnection causes the operation of

relays

27 and 29 over a circuit as follows: Battery, winding of relay 29, lower inner armature and front contact of relay 18, wiper and rst terminal of bank C, lower winding of relay 27, upper armature and back contact of relay 37 to ground. The operation of relay 27 closes a circuit through its upper winding in substitution of the lower winding, the upper winding being of lower resistance. This is to supply a low resistance busy ground at the rst terminal of bank C as a partial shunt to prevent the operation of relays corresponding to relay 27 in other registers which are searching for a seized link. Relay 27 also opens a circuit for the stepping magnet 25 and closes a circuit for the stepping magnet 26 from battery winding of magnet 26, second upper armature and iront contact or relay `27, armature and front Contact of relay 24 to ground at the upper outer armature and back contact of relay 36. Relay V27 also transfers the start lead 23 at the upper outer armature and front Contact to the next register. The stepping magnet 2G now alternately operates and releases withk relay 24 and operates to step the finder switch E1s-2 to the seized link. It should be noted that the terminals of banks B and `G are connected together so that when the R is now fully associated with the link 2.

Referring now to the operation of relay 29 which'operated in series relay 27, this relay pro vides a locking circuit through its lower inner armature and front contact to the ground supplied by relay 37. Relay 29 removes the ground on the start lead for the register at the lower outer armature and back contact and by operating its two upper outer armatures to their iront contacts places the tip and ring conductors of selector S under the control oi the register R. Relay 29 also connects a. dial tone circuit over the tipand ring conductorsback to the calling sube scriber to indicate that dialing may `now take place. tone stored at 41, upper inner armature andfront contact of relay 29, lower outer armature and front contact oi relay 18, oil-normal contact V21 of switch S to the tip conductor of the link, upper right-hand winding of repeating coil 32 to battery at the inner right-hand arma-ture and iront contact of relay 34 and inductively through the lefthand windings of this coil toA the calling` subscribers set. The sleeve conductor oi the switch S is also put under control of the register by congnectingit at the middle lower armature and iront contact to bank H of the finder switch 'FS2.

The link 2 and register R are now in condition for the reception of a first digit to be dialed by the calling. subscriber. This digit will operate lthe vertical stepping magnet 42 of the switch S as follows: The stepping relay 34 operates and releases as the impulses are sent by the calling subscriber. This relay in releasing closes a circuit for magnet 42 as follows: from battery,

r,winding of this magnet, the first terminal and wiper oi bankE, lower inner armature and back contact. of relay 44, second lower armature and back Contact of v'relay 40, lower inner armature and front contact of relay 27, iirst terminal and wiper oi bank D, outer right-hand armature and back contact of relay 34, third lower armature and front contact or" relay 15, to ground at the inner lefthand armature and front contact of relay 14. The succeeding impulse willnow operate the stepping magnet 42 to advance the switch S to the desired level in which connectors, such as C, are connected. The oil-normal contacts 21 of switch S are vopera-ted on the iirst step to remove the dial tone and release relay 18. Relay 14 being slow in releasing does not release during pulsing. The circuit for relay 38 is now alsoV completed in parallel with the circuit to ground established by the release of relay 34 on the reception of the rst impulse, from battery at the second lower armature and front contact of relay 27, upper winding ofrelay 38,. second lower armature and front contact of relay 40 and from thereon to the ground at relay., 14. This relay is slow in releasing so that it will remain operated during the sending of the rst series of impulses. Relay 38 in operating closes an obvious circuit for the operation oi relay 46. At the end of the rst digit relay 38 is released and'closes a circuit kfor-relay 44 from battery,

. winding ofrelay 44, second lower armature and back Contact of relay 34, upper armature and iront Contact of relay 46 to ground. This circuit is possible due to the slow-to-release characteristics or relay 46. Relay 44 locks at its ,upper inner armature and iront contact to the ground This circuit may be traced from the dial supplied by relay 27. Relay 44v now transfers the impulse circuit to the rotary stepping magnet 47 for the switch S which now operates to hunt for an idle connector such as C The operating circuit for this magnet may be traced from battery, winding oi magnet 47, rct terminal and wiper oibank F, upper outer armature and front contact of relay 44, lower outer armature and back contact of relay 48, to the interrupter and ground at 49. The brushes of switch S are now stepped around under control of

relays

44 and 48 until an idle connector C is found. When the brushes are passing over terminals of busy trunks a ground is received over the sleeve terminal and sleeve leads, second lower armature andV iront contact of relay 29, rst terminal and wiper of bank H, upper armature and back contact of relay 48 to shunt the windingoi this relay which is connected to ground to prevent this relay from operating which it would ordinarily do as relay 44 has established a connection to battery for the Ywinding of this relay at the second upper armature and front contact. Relay 48 is thus prevented from operating as long as` the ground is found on the sleeve lead oi switch S thus permitting the rotary magnet 47 to be stepped from one busy connector to another. To prevent relay 48 from operating immediately on the operation of relay 44 it should be noted that rotary oli-normal contacts 5) are closed to ground 105 and on the first step of the rotary stepping magnet 47 these contacts are opened to permit relay 48 to be controlled by the ground on the sleeve leads. When an idle connector is reached this shunt to ground is removed Yallowing relay 48 110 to operate. Relay 48 in operating remains under the control of-relay 44 and transfers the sleeve lead to ground through the upper winding of relay 40 over a circuit through the lower armature. This ground and back Contact of relay 45, upper armature and front contact of relay 36, upper armature andl back contact oi relay 38 and upper armature and front contact of relay 48, through a winding of relay 40, serves as a busy potential for the sleeve ter 120 minal of the selected connector.

1f all ofthe connectors should be busy the switch S rotates to the eleventh position and thereby causes the operation of contacts 51. The operation of these contacts provides a ground 125` for the shunt of relay 27 to cause the release of the connection as will hereinafter be described and sends a busy tone from a source at 5S to the calling subscriber to indicate that there is no available connection to the called party.

vif it is assumed that an idle connection has been found the subscriber will dial the second digit. When this digit is dialed impulses from relay 34 aresupplied to the vertical stepping magnet 54 of the connector C from battery through 135 the winding of this magnet, winding of relay 55, vertical oir-normal `contacts 56, upper armature and back contacts of relay 57, the tip conductor back to the switch S, upper outer armature and front contact of relay 29, first terminal and wiper oi bank K, second upper armature and back contact of relay 40, lower inner armature and front contact of relay 48, lower outer armature and bach contact of relay 59, lower inner armature and front contact of relay 44 and over the pulsing circuit hereinbeiore traced to the ground at relay 14 under control of relay 3,4. The stepping magnet 54 will now operate under control of these im pulses to advance the connector to the desired level in which the called subscribers line may be found. Relay operates in series with thevertical magnet 54 and locks over the vertical oinormal contacts after the first impulse and as it is slow in releasing remains operated during pulsing. When the pulsing ceases relay 38 releases as heretofore and relay 59 operates as at the first step of the vertical magnet, the vertical off-normal contacts 56 supplies battery through a resistance over a circuit through the rotary O- normal contacts 6i), P lead, the rst terminal and wiper of bank L of switch FS--2, upper inner armature and back contact of relay 40, lower armature and front contact of relay 36, third lower armature and back Contact of relay 38, makebefore-break contacts of relay 59, upper winding of this relay to ground. Relay 59 in operating looksthrough its lower inner armature and lower windings from battery to ground supplied at relay 27 and opens the pulsing circuit for the Vertical magnet 54. he operation or relay 59 transfers the pulsing circuit at its lower outer armature and front contact to the ring conductor leading to the connector C so that if now the opera Mtor dials a third digit the impulses will be transmitted through this connection prepared by relay 69 over the upper outer armature and back con-vk tact of relay 40, the first terminal and wiper of bank J of switch FS 2, second upper armature. and front Contact or" relay 29, ring conductor,

lower'armature and back contact of relay 57, winding of the rotary stepping magnet S3 to battery. The operation in this case is the same as in connection with the sending of the preceding digit except that the rotary off-normal contacts :FIGO are open to remove the battery from the P lead. When the desired line is reached at the end of this digit the connection will be established as hereinafter described. A called line may be either a party line, such as 7, or a local line, such Fas 4, or a group of local trunks or outgoing trunks may have been selected. In case the local line i or a party line 7 has been selected and the selected line is busy a ground will be present on the sleeve lead in the usual manner and this will be 'connected through the winding of relay 57, the sleeve lead in the switch'S, the second lower armature andfront Contact of relay 29, iirst terminal and Wiper of bank El, upper armature and iront contact of relay 48, upper armature and back con- "tact of relay 38, upper armature and iront contact of relay 35, lower armature and front contact of relay 46 before it releases after the release of relay 33, upper armature and back contact of relay 39, winding of relay 65 to battery. Relay '65 operates and locks to ground at relay 277. Relay 65 then closes a circuit for the operation of the release magnet 66 of the connector C, from battery, winding of release magnet 66, armature and back contact of relay 55, vertical oit-normal contact 56,l upper armature and back contact of relay 57, tip conductor, upper outer armature and front contact or relay 27, nrst terminal and wiper of bank K, middle upper armature and back contact of relay 40, lower inner armature and iront contact of relay 48, lower outer armature and front contact 'of relay 65 to ground at the lower inner armature and back contact of relay 3S. The connector C releases and restores its oftnormal contact to'normal position. It should be noted that this ground from relay 38 is also applied through the upper armature and front contact of relay 65, over the iirst terminal and wiper of bank M, through `the winding of the release magnet 67 to battery to cause switch S to be released. Relay 65 also closes a circuit for the op-V tone through the repeating coil 32 to-inform the calling party that the called line is busy. The release of the link circuit and the line nder is under control of the calling party. The release of the. line inder ltakes place when the calling party hangs up his receiver as will be described hereinafter in connection with the release of a connection after a call is terminated.

Assuming, however, that the called line is idle, whether party line 7 or single line 4, relayy 40 will operate on the release or" relays 38 .andi to prepare the circuits for dialing for the singing code of the called subscriber. Relay 40 locks over its lower winding to ground at relay 2'7.V

Relay 57 is also operated in series with relay 40 and the cut-off relay in the called subsoribers line Yto cut through the connection over the tip and ring conductors. The code switch RC is operated by ringing code selecting impulses regardless of whether the called party 'is on a single line or on a party line. The number for ringing code selection comprises two digits. The rst digit causes the code switch RC to be stepped either to position l or position l0 depending on the digit dialed. The pulsing circuit for operating the step-by-step magnet 69 of the code switch may be traced from battery, winding of this magnet, the Zero terminal and wiper of the bank B1 of the code switch RC, second lower armature and front Contact of relay 40 to the pulsing circuit to ground at relay 14. Relay 38 is also operated from battery, lower winding of relay 38, to the ground at relay 14 over the pulsing circuit and maintained operated dur# ing pulsing through the circuit closed at its lower outer armature and front contact. The stepping magnet 69 is now actuated either one step orten steps depending as stated upon the digit dialed. When this digit has been dialed the circuits are prepared for the operation of the stepping magnet in accordance with the second digit. The pulsing circuit for the operation of stepping magnet 62 in accordance with the seconddigit is the same as described for the lrst digit. The dialing of this digit places the wipers of the code switch on the desired combination for transmitting the code signals. The wiper D is the one that is placed on the desired code from' ringing interrupter circuit that is connected in any well known manner to the terminals of this bank. The` wiper of bank B of this switch is placed on an open Contact to prevent further stepping in case another digit is dialed. The wiper C prepares a restoring circuit, the wiperA closes pick-up circuits for relays 70 and 71 and wipers E1 and F2 close the start circuit for the interrupter. As soon as the ringing interrupter circuit is in position to begin a code signal, ground is supplied over the connected pick-up lead to operate relays 70 and 71. The

' circuit may be traced from battery, lower arma- .during the transmission of a code. .cuitgfor relay 73 may be tracedfrorn battery,

the pick-up lead connected tovthis brush. The circuit for relay originates from the same battery, winding of relay 70 and its make-beforebreak contacts, the fourth lower armature and front contact of relay 41),wiper of bank C to ground. Relay 70 locks 'at its lower armature and front vcontact to ground at relay 27 and closes a circuit for the operation of relay 72 from battery, winding of this relay, upper inner armature and front contact of relay 7o, wiper of bank D to the ringing interrupter 'circuit over vthe particular terminal selected; Relay/.72 is thus controlled by the ringing interrupter oircuit operated 'and released in accordance-with the code selected. That i's the' ringing interrupter may providea ground on the terminal of bank D interrupted in accordance withydiierent codes. Each time relay 72 operates inv accordance with the code, ringing current is supplied from the ringing current source at overthe line to the called partys bell. This ringingcir- Vcuit may be tra-ced from the ringing current .generator at 75 over the two leads closedv attlie armatures and front contacts of relay A'72,.the upper outer and middle armatures and front contacts of relay 40, iirst terminals and wipers of banks J and K, upper outer and middle armatures and front contacts of relay 29 out over the tip and ring conductors to the called subscribers telephone.

When the called subscriber answers, a sirn- `plex ground vconnection is placed on the line 'causing the operational" relay 73. As soon fas relay 71 releases which takes place at the beginning of a code and as relay 71 is maintained lreleased during the transmission of a code, re-

lay 73 .is operated whenever relay 72 is released The cirwinding ofthis relay, armature and back contact of relay 71, armatures and back contacts of relay 72, to ground at the operators telephone .set. One of the purposes of relay 73 is to absorb the line charges caused by ringing. When relay v'71 is operated between each` code and the `Vcalling subscriber has answered, relay 37 will operate, that is during the so called silent periodto prevent the tripping of, the ringing .durf `ing the transmission of a code. Relay 37 operates over the same lcircuit as relay 73 and in ,operating opens the holding circuit for relay 27 as well as the-circuits for relays 7l and 70` Relay 70 releases and prevents further ringing by A.opening the circuit for relay 72. The release of relay 27 causes the release of the .register circuitas hereinbefore described. During ringing .part of the ringing current was by-passed through'condenser `*76 to 'give the calling' subscriber an audible ring-back tone.` When the register restores to normal relay 29 is also released toclose the tip and ring conductors of `the switch "S through to the repeating coil 32 thus completing the 'transmission circuit and opening theregister start circuit. Relay 29 also places a ground on the sleeve terminal tobusy the called line as well as causing cut-orf relay `in the called 'subscribers line to operate and relay 57 to be maintained operated.

VThe releasefof the connection is underthe ,control ofl the calling party. Whenwtlie calling party hangs up his receiver, relays 34 and -14 are released,`relay 14 closing ral circuit "to vthe rellease'magnet 78 on the line finder vLF and the release magnet 67 'of the switch S to causel the i,"tline finder and switch S to'v release.` Relay 14 in releasing also opens the circuit for the cut-oir" relay of the called subscribers line and for the tne ground applied at 'the inner right hand armature and back contact or relay 14. Magnet 66 locks to ground at the on" normal contacts 56 i the connector C is released. It should be understood Vthat 'the ground for the operation of release magnet 66 is applied before the ground V.for the release magnet 67 by 'the armatures of relay `i4- so asto permit the connector tov release first. yRelay -30 in the switch S is released as i tne'release or relay .lli and relayl is released on the release or the line'iinder by the opening i of the oii-norrnalcontacts 20.

in case the calling subscriber fails to com- Lmence dialing or the called party or the called :party does not answer within a predetermined time, or in case of a revertiv'e call the connection rs released. The means for accomplishing this is also located in the register Rf Incase o1" the subscriber failing to dial or of a revertive call, .it will-be noted that `on theoperation ofV relay .27 a circuit is completed for the therrnostaticv element `from batterythrough the winding oi" this element, the lower'outer armatures and back contacts or Vrelays S1 and 44; lower outer armature and iront contact of relay 27 to ground. As the bimetallic therinostatic spring of element 80 heats toa certain' temperature, it bends and gradually moves vtowards the front contact. When making this -front contact relay 8l is operated rorn battery, windingv of this relay/,iront contact or element Soto the ground at relay. 27. Relay '81 operates and vlocks under control of the lower 'armature and' back Contact of relay 44 and the ground at relay 27. Relay 81 in operatingprepares a circuit for relay 10 in the line circuit from battery, winding or this relay, the P terminal and wiper of the line finder, iirst terminal and wiper of bank A, lower inner. ar-

mature and front contact of relay 8l, and since circuit for relay l0 rromrelay 27. Relay 10 operates and locks atfits upper armature and iront `Contact to the simplex ground .on the tip and ring Vconductors for the calling subscribers line. Relay l0 also opens thecircuit for relay 34 causing the release. of the linky and register to normal as hereinbefore described. Y

1 If the 'calling 'subscriber should commence dialing before the element 80 has `fully operated and restored, the operation of relay llllaiter the rst digitis `dialed will open the circuit for the relay so; lThe locking circuit for ,relay e1 will be opened so that this relay will release and prevent thel release circuit from operating.

The release due to delay caused by the called party not answering within a predetermined time operates'as follows: Under this condition relay'70 is operated during ringing, operations and 'closes a circuit forthe element '80 at the upper outer armature and'fronft contact. Relay 8l is then operated by the circuit closed by the spring -of element 80. If the called partyfshould answer during a ringing code, that is when relay "7l is released, relay 73 wil'lfoperate and 'tnus'prevent the release of the connection by maintaining 'the v`element 8'0 in condition to prevent Vit -fror'n cooling off until relay 71 is again operated fore described.

I If instead of callinglines 4 or 7, atrunk group is called leading to an operators position O, when ground on the P terminal causes the operation of relays 39 and 84 from battery through the winding` of these relays in series, make-beforebreak contacts of relay 59, third lower armature and back contact of relay 38, lower armature and front contact of relay 36, upper inner armature and back contacts` or" relays 40, first terminal and wiper of bank H, the P terminals and wipers of switches S and C to ground; relay 39 opens the `-circuit of relay so that this relay will not operate and prevent the release ofy relay 27. Re-

.,lay 84 supplies interrupted ground from source Y 49 at its uppervouter armature and front contact through the lower outer armature and front contact of relay 49, upper outer armature andY back contact of relay`40, first terminal and wiper of bank J, second upper armature and front contact of relay29 over the ring conductor of switch S, lower armature and back contact of relay 57,

A winding of the rotary magnet 63 to ground. This causes the operation of the rotary vmagnet 63 until an idle trunk line has been found. When the idle trunk is reached the circuit for relays 39 and 84 is opened to stop the `stepping of the rotary magnet 63. IIhe operation from this point on is the same asin connection with the .calling of the local connection.

If a subscriber at a distant oflice is desired the third digit will bring nthe terminals of connector C on the first of a group of `trunks leading to this 'cnice and if the rst trunk` is busy the relays 39 .and 84 will operate the same as in hunting for an idle trunk to an operator. When an idle trunk is found this is indicated by aconnection to ground through a resistance on the C lead. When this condition is reached relay 39 remains operated but relay 84 is released due to its marginal characteristics, thus stopping the stepping of magnet 63. The release of relay 84closes a circuit for the operation of relay 37 from battery, winding of this relay, lower armature and back contact of relay 84, lower armature and front contact of relay 39 to ground. vRelay 27 is thereby released and causes the release of the register R. To dial the subscriber at the distant oice the calling subscriber will then dial an additional number to operate the connector C-2. The pulses will in this case be repeatedin simplex .over the tip and ring conductors of the switches Sand C and the selected trunk, as the operation of relay 34 closes such a connection from battery at its inner righthand armatureand front contacts. K

While the'invention has` only been shown and describedin connection with a single disclosure, it should be understood that it could readily be applied to other systems without departing from the spirit thereof. i

What is yclaimed is?,

l. In a telephone system, a calling subscribers line having an impulse transmitter, a plurality of link circuits accessibley to said calling lines, a register common to said links, means responsive to the calling subscriber removing his receiver from the switchhook yfor seizing an idle link circuit and the register, said register being responsive to said impulse transmitter, means in said register l`for releasing said link and register a certain interval after'seizure if the calling subscribervfails to register operative a certain interval after the I( .reception oi impulsesfrom the calling subscribers .to cause the release. of the register as hereinberesponsiveto impulses received from the calling line for selecting` .different ringing code signals, and means in said registerresponsive to impulses from the calling line for transmitting corresponding impulses over the! selected link to control, selections beyond. f

2. In a telephone system, a calling subscribers line, a plurality of link circuits including a line finder and a selector, a register common to a plurality of links, means responsive to the calling subscriber removing his receiver from the switchhook for actuating theline finder of an idle link to connect said link to the calling line and to associate the register with'said link, means in said seizure of the idle link for releasing if from the line of no further actions are taken by thecalling subscriber toward the establishing of a connection beyond, means in said register responsive to the line for controlling the selector of the seized link to establish connections beyond, and means in said register thereafter responsive to impulses received .from the calling subscribers line for selecting a ringing code signal for transmission over. the established connection beyond.

3. In a telephone system, a calling subscribers line, a called subscribers line, a plurality of link circuits including a line nnder and a selector, connectors accessible by said selector and having access to called subscribers lines, means responipo :sive to the calling subscriber 4removing his receiver from the switchhook for actuating the line finder of an idle link to connect said link to the calling subscribers line and to associate the register-with said link, means in said register responsiveto the reception of series of impulses from the calling subscribers line for controlling the selector of the seized link to extend the connection from the calling subscribers line to an idle connector and for controlling the seized connector to extend the connection to a desired called subscribers line, means in said register thereafter' responsive `to impulses received from the calling subscribers line for selecting a ringing code signal and for transmitting the selected signal to the connected called subscribers line, and means in said register for releasing a partially established connection to a called subscribers line after a certain time interval provided no further actions are taken toward .1,25 the completion of the connection by the calling subscriber withinA said time interval.

4. vA calling subscribers line, a called line, a plurality of link circuits, a register commonito said links, means operative when the calling 'subscriber removes his receiver from the switchhook for seizing an idle link andthe register, means for extending a connection between the seized link and the called line, means in said register for releasing the seized link and the register acertain interval after the calling subscriber has removed his receiver from the switchhook if no further actions are taken on the part of the calling subscriber toward the extending of the connection, means in said register responsive to current 140 impulses received from the calling subscribers line for controlling the establishing of a connection between the seized link and the called line, means in said register responsive to. the current impulseswfrom the calling subscriber-s line for .1115

fselecting' ringing code signals,- and means in said register responsive on the completion of the selection ofv a ringing code signal for transmitting the selected signal to said calledline.

5. In a telephone system, a calling subscribers-.150

line, a called subscribers line, a plurality oic link circuits, a register common to said link circuits, means responsive to the calling subscriber removing his receiver from the switchhook for seizing an idle link and the register, switches, means in said register responsive to impulses from the calling subscribers line controlling the setting of said switches to extend a connection from the seized link to the called subscribers line, an auxiliary switch in said register responsive to irnpulses received from the calling subscribers line for selecting diiierent types of ringing code signals, means responsive on the completion oi the selection of a ringing code signal for transmitting the selected signal to the called subscribers line and means in said register for releasing said register a certain interval after the calling subscriber removes his receiver from the switchhook operative if no impulses have been received within this interval for controlling the setting of said switches.

6. In a telephone system, a calling subscribers line, a plurality of link circuits accessible to said calling line, single lines, party lines, groups of trunks, a register common to said links, means responsive to the calling subscriber removing his receiver from the switchhook for seizing an idle link and the register, a switch connected to each link, other switches accessible by said first switch and having access to said party lines, individual lines and groups of trunks, means in said register responsive to impulses from the calling line for transmitting corresponding impulses over the selected link to control the associated switch to select an idle one oi said other switches and to thereafter control the said selected second mentioned switch to select a party line, a single line, or a group of trunks, and if a group of trunks has been selected to hunt for an idle trunk in said selected-group of trunks, means in said register thereafter responsive to impulses received from the calling line if an idle trunk has been found for transmitting impulses in simplex over said trunk, means in said register responsive to impulses received fro-rn the calling line for selecting different codes of ringing signals if a single or a party line has been selected, and means in said vregister' for releasing a partially established c0nnection to a single line, a party line or a trunk after a certain interval provided no further actions are-taken by the calling subscriber towards the completion of the connection within said interval.

J. G. POPE.

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