US2247477A - Signaling system - Google Patents

Description

July 1, 1941. K. I .BURGENER 23475477 SIGNALING SYSTEM Filed March 1,' 1949 8' Sinister-Sheet 1 July 1, 1941. m L. auRGENr-:R

SIGNALING SYSTEM Filed arch 1, 1940 muoo EN ENQ Emu Q l o July 1, 1941. K l. auRGi-:NER

SIGNALING SYSTEM Filed Harsh l, 1940 8 Shasta-Sheet 3 www? @mmv mm3 vm@ x Sm k wt INVENTOR KARL L. BURGENER M if' ATTORNEYS,

July 1, 1941. K. l. BURGENER SIGNALING SYSTEM Filed March l, 1940 8 Sheets-Shale?. 4

INVENTOR KARL L'. BURGENER ATTORN EY5 July 1, 1941. K. L suRGENl-:R

S IGNALING SYSTEM Filed March 1, 1940 8 Sheets-l-Shet 5 @om s mm RS KARL L. BURGENER ATTORNEYS,

Patented Juiy l, 194i i mi SHGNG SYSTEEM application March l, llifit, Serial No. 321,66@

V(lLi. 179-5) 3l Claims.

'lhe present invention relates to signaling systems and, more particularly, to improvements in telephone systems for use in police dispatching systems.

A conventional police dispatching system comprises a dispatcher position at' which calls on telephone lines extending to telephone stations disposed in police boxes are answered, and from which calls are extended over trunk lines to different destinations. In a system of this type the dispatcher at the dispatcher position iirst operates apparatus to answer a call and subsequently operates apparatus to extend the call to the required destination; andin the event a message is to be broadcast in response to the call answered, the dispatcher at the dispatcher position either extends the call to an announcer position at an associated radio station or initiates a new call which is extended to the announcer position. lin any event the actual message is broadcast by the announcer at the announcer position in the radio station.

While a dispatching system ofy the type described is reasonably satisfactory in service, considerably more time is required in handling calls at the dispatcher position than is desirable.

Accordingly, it is an object of the present invention to provide in a dispatching system including a dispatcher position, improved circuit apparatus which is so connected and arranged that the handling oi calls at the dispatcher po sition is rendered exceedingly fast.

Jituiotlrer object oi this invention is to provide in a telephone system including an operator position provided with apparatus for answering calls on associated telephone lines and apparatus for extending calls over associated trunk lines, a control arrangement responsive to the operation of the call-answering apparatus for operatlng, at least partially, the call-extending apparatos.'

Another object of the invention is to provide in a telephone exchange including an operator position provided with apparatus for answering calls on associated telephone lines, improved. switching apparatus for extending the calls which is governed jointly by automatic means and manual means under the control of the operator at the operator position.

A further object of the invention is to provide in a signaling system comprising an operator position and a radio broadcasting station including a radio transmitter, improved switching apparatus controllable from the operator position for answering calls on associated telephone lines and for completing direct connections to the radio transmitter.

A further object of the invention is to provide in a telephone system comprising a number of operator positions, each including apparatus for answering calls on associated telephone lines and apparatus for completing connections over associated links, improved apparatus controllable from each operator'position to identify a. telephone line including in a connection completed over any one of the associated links.

The features of the present invention are illustrated as being incorporated in a signaling system comprising a dispatcher exchange oi? the combination manual and. automatic type including a number of dispatcher positions and termihating a plurality of manual telephone lines, a private exchange of the automatic type includingan automatic switch trainand terminating a plurality of automatic telephone lines, and a radio broadcasting station of conventional type including a radio transmitter.

In accordance with one feature of the invention the system comprises a plurality of lines, a plurality of links, a plurality of trunks individually associated with the lines, an operator position, means selectively controllable from the operator position for connecting the operator position to any one oi the lines, thereby to answer a call on the one line, means controlled when the operator position is connected to one ol' the lines for connecting the one line to an idle one or the links, an impulse sender controllable from the operator position, means controlled when the one line is connected to 'the one linlk for connecting the impulse sender to 'the one of the trunks associated with the one link, impulse responsive switching apparatus associated with the one trunk, and means for connecting the one link to the one trunk.

In accordance with another feature oi the invention, the operator position is disposed in a dispatcher exchange and the automatic switch train associated with the trunks is disposed in a private exchange, the operator position being provided with a plurality of line keys individually associated with the lines and a plurality of linktrunk keys individually associated with the links and the trunks. More particularly, each of the line keys is operable to connect the operator position to the associated line; and each of the link-trunk keys is operable to connect the operator position to the associated' link and trunk. Also an arrangement comprising a link distributor is provided for assigning idle ones of the In accordance with another feature of the invention the system comprises a plurality of police telephone stations, telephone :lines individually extending between the police telephone stations and a dispatcher exchange, a radio broadcasting station including a radio transmitter, and a trunk extending between the dispatcher exchange and the radio transmitter. Means is provided at each of the police telephone stations for initiating a call on the associated telephone lines; and means is provided in the dispatcher exchange which is controlled from the dispatcher position for connecting position equipment provided thereat to the trunk, the position equipment including a telephone instrument. Finally means is provided in the system which is controlled when the position equipment is connected to the trunk for rendering the radio transmitter operative for broadcast purposes.

In accordance with a further feature of the lnvention, the system comprising a plurality of operator positions, a plurality of groups of links individually associated with the operator positions, a plurality of groups of trunks individually associated with the groups of links, whereby the individual trunks in a given group of trunks are individually associated with the links in the corresponding group of links, means selectively controllable from any one of the operator positions for connecting the operator position to any one of the lines, means controllable when one of the operator positions is connected to one of the lines for connecting the one line to an idle one of the links in the associated one of the groups of links, an impulse sender controllable from the one operator position, means controlled when the one line is connected to the one link in the one group of links for connecting the impulse sender to the associated one of the trunks in the one group oi trunks, impulse responsive switching apparatus associated with the one trunk in the one group oi trunks, and means for connecting the one link in the one group of links to the one trunk in the one group oi trunks.

in accordance with a further feature of the inevention, the system comprises a plurality of automatic switches individually associated with. the

"lines, means controlled when a cali on one of the lines is answered at one of the operator positions for marking an idle one of the links in the associated one of the groups of links and for initiating operation of the assiated one of the switches, means controlled when the one switch seizes the marked link. for removing the marking from the last-mentioned link and for arresting operation of the one switch, thereby to complete a connection between the one line and the one linie in the one group of links, means controlled when one of the switches is operating for preventing operation of the other of the switches, and means controlled when a link: in one oi the groups of links is marked for preventing marking of a link in any other of the groups of links.

ln accordance with a further feature oi the invention, the system comprises a plurality of lines, a plurality of operator positions, a plurality of groups of links individually associated with the operator positions, means at each operator position for extending a number of different connections from the lines over the diiferent links'in the associated group of links, a plurality ot identity apparatus individually corresponding to the operator positions, each identity apparatus vbeing operative selectively to identify the particular lines included in the different connections extended over the links in the group of links associated with the corresponding operator position, normally effective means at each operator position for selectively operating the corresponding identity apparatus, and means including an identity distributor controlled by the operation of one of the identity apparatus for preventing operation of the other of the identity apparatus. More particularly, the identity distributor is connected and arranged to prevent simultaneous operations of two of the identity apparatus in spite of the fact that the two identity'apparatus are seized substantially simultaneously at the two corresponding operator positions.

Further features of the invention pertain to the particular arrangement of the circuit elements thereof, whereby the above-outlined and additional operating features are attained.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings in which Figure 1 illustrates the general arrangement of a signaling system including a central oice, a private branch exchange or P. B, X, a dispatcher exchange, a private automatic exchange or P. A. X and two radio stations and embodying the present invention; Figs. 2 to 8, inclusive, taken together, illustrate the details of a signaling system having incorporated therein the features of the invention, as briefly outlined above; and Fig. 9 illustrates the mode of combining Figs. 2 to 3, inclusive, oi the drawings to form a unified system.

Description of the apparatus incorporated in the signaling system Referring new more particulariy to Fig. l of the drawings the signaling system there iilustrated comprises a central oice iii, a l?. E. Iii. a dispatcher eachange a P. El two radio stations 5@ and The central office iti may be of any well-known type; the P. E. 2 i223 is of the manual type; the dispatcher exchange is of the combination manual and automatic type; the P. 2 is of the automatic type; and tbe radio stations and are ci conventional type. Tae Ts. X Z@ comprises op ior position at which group of twoK way Eines, including the trunk line extend g betale n tne central office t@ and the P. ted.

including the first dispatch second. dispatcher position S rione line having a line circuit individu'l associated therewith extends to each telepnone station in the dispatcher exchange Sil. telephone line Ztii extends to the telephone station Ti and has the line circuit Zilli individually associated therewith. Each of the telephone stations in the dispatcher exchange 3ft is located in a police box and comprises the usual telephone station equipment including a telephone instrument and a ringer.

.also a group of two-Way trunk lines entends r1 tele aesmvv change 30 has a trunk circuit individually assoelated therewith, the trunk circuit be@ being 1ndividually associated with the trunk line hib. Further a group of one-way trunk lines extends from each dispatcher position in the dispatcher exchange til to the P. A. X til. For example, the v group oi' trunk lines extending from the rst dispatcher position 600 in the dispatcher exchange 30 to the P. A. X t0 includes the trunk line Tit.`

Each trunk line extending from a dispatcher position in the dispatcher exchange t@ to the P. A. X du terminates in a selector switch in theA P. A. X im, the trunk line 110 terminating in the selector switch 82d in the P. A. X lid. Also a first group of one-way trunk lines, including the trunk line 2id, and a second group of one-way trunk lines, including the trunk line tilt, extend between the P. A. X di! and the dispatcher exchange te. Each of the trunk lines in the first group is provided wth an individual line circuit in the dispatcher exchange til. the line circuit 2lb being individual to the trunk line 210; while each oi' the trunk lines in the second group is directly connected to a `corresponding one of the telephone lines in the dispatcher exchange 3d, the trunk line Mii being directly connected by way of the cable ttt to the telephone line 2M extending to the telephone station Ti. Finally the dispatcher exchange 3d and the radio stations it and til are interconnected by the trunk lines itt and liti, .the trunk line 'ltd extending from each dispatcher `position in the dispatcher ex change il@ to the radio station and the trunk line 'ltd extending from each dispatcher posi tion in the dispatcher exchange 3B to the radio station 6d.

The P. A. X du serves a number of subscriber substations, including the subscriber substation Tt, and comprises an automatic switch train including a number of finder-selector links, a number oi connector switches and 4a. number of groups of selector switches respectively terminating the groups oi trunk lines extending from the various dispatcher positions in. the dispatcher exchange t@ to the P. A. X im. More particularly, the switch train comprises the lnder-selector linlrv tte, including the finder switch dit and the selector switch e327, the connector switch @2i and y the selector switch dit. Finally it is noted that a telephone line dtd extends to the subscriber substation T2. The finder switch dit has access to each telephone line in the P. A. X dii; while theA selector switch d2? has access to each trunk line in the first group ci trunk lines extending between the P. A. X it and the dispatcher exchange :iii and to each connector switch in the P. A. X dd. The connector switch cti has access to each telephone line in the P. A. X il@ and to each trunk line in the second group of trunk lines extending between the P. A. X it and the dispatcher exchange dit. Finally the selector switch d2@ has access to each connector switch in the P. A. X titi. Each subscriber substation in the P. A. X it is number oilv groups of links individually associated with the various dispatcher positions, the rst link 30D and the second link dit being included in a group of links individually associated with the rst dispatcher position tdt. Also it is noted that the line circuits terminating the telephone lines in Ithe dispatcher exchange til and the line circuits terminating the trunk lines in the iirst group of .trunk lines extending from the P. A. X lil to the dispatcher exchange 3d comprise finder switches having access to the links in each group of links. For example, the line cir= cuit 2do comprises a finder switch Sie@ and the line circuit M5 comprises a iincierA switch Smid, the nder switches S23@ and Std@ having access to the first link Bilt and the second link ,Slt in the group of links individually associated with the first dispatcher position ddii in the dispatcher exchange iii.

Finally the dispatcher exchange d@ comprises a link distributor im@ and an identity distributor unit btt commonly associated with the various dispatcher positions, which are utilizedV for purposes more fully explained hereinafter. In order to facilitate communication between the dispatcher positions in the dispatcher exchange 39, order trunks are provided therebetween, the order trunk 6d@ extending between the iirst dispatcher position itil@ and the second dispatcher position ttt. Each dispatcher position in the dispatcher exchange til has a sender control circuit and a sending key set individually associated therewith, the sender control circuit @te and the sending key set Kbit being individually associated with the first dispatcher position dtd.

he sender control circuit dit@ comprises a nder switch Sutil having access to each trunk line in the group of trunk lines extending from the iirst dispatcher position ttt in the dispatcher exprovided with the usual substation equipment in- Y cluding a telephone instrument, a dial and a ringer.

Also the dispatcher exchange di? comprises a change Zit to the P. A. X t@ and a under switch Sti@ having access to a group of digit registers, including the digit register ttt, provided in the dispatcher exchange fit.

The operator position i335 in the P. B. X 2d, shown. in Fig. 8, comprises conventional apparatus including a telephone instrument and equipment for answering and for completing connections between the central oilce it, the various telephone lines in the P. B. X 2d and the dispatcher exchange d. Preferably, the switches included in the switch train in the l?. A. X shown in Fig. il, and including the finder switch ttt, the selector switch the connector switch dit and the selector switch `are oi the usual Strowger type. Preferably, the apparatus in the two radio stations ti@ and shown in Fig. d, Yare identical, the apparatus respectively comprising the radio broadcast transmitters ddii and @titi of conventional connection and arrangement.

Preferably, each of the line circuits terminating a telephone line in the dispatcher exchange 3@ and each of the line circuits terminating a trunk line in the iirst group of trunk lines extending from the P, A. X it to the dispatcher ex-V the rotary switch S23@ is provided with a rotary mag-net M231 for moving the wipers noted in the rotary direction. Further the line circuit Zili comprises a number of relays including a line relay Riti?, a cuto'i relay R205 and a switching links individually associated with the dispatcher positions in the dispatcher exchange 30 is identical to the first link 300 in the group of links associated with the first dispatcher position 600, shown in Fig. 3. The first link 300 comprises :a repeater 305 operatively interconnecting a rst branch of the rst link 30K! including the trunk 750, and a second branch of the first link 300 including the cable 380. Further the first link 30D comprises a number of relays including a start relay R3iil, a stop relay R320, a control relay R330, a hold relay R325, a line relay R340, a supervisory relay R350 and a cut-in relay R360 connected and arranged in a manner more fully described subsequently.

The link distributor 400, shown in Fig. 4, com.- prises four cutoi relays R410, R420, R430 and R446 individually associated with the four dispatcher positions in the dispatcher exchange 30 and four hold relays R405, R4l5, R425 and R435 individually associated with the four dispatcher positions in the dispatcher exchange 30. The particular connection and arrangement of the cutoi and hold relays mentioned are described more fully subsequently.

The identity distributor unit 500, shown in Fig. 5, comprises four cutoff relays R520, R530, Rist@ and R individually associated with the four dispatcher positions in the dispatcher exchange 3@ and four identity relays Riil and R566, the reference character `Rl indicating three of the identity relays, individually associated with the four dispatcher positions in the dispatcher exchange 3u. The particular connection and arrangement of the cutoff and identity relays mentioned are described more fully subsequently.

Freierably, the trunk circuit associated with each of the trunk lines extending between the .lf2 @tand the various dispatcher positions in the dispatcher exchange 3@ are identical to the trunk circuit shown in Fig. 5, individually associated with the trunk line @i5 extending between the X 5i@ and the first dispatcher position i il in the dispatcher exchange Pill. rl'he trunk circuit comprises a ring-up relay totf relay Reli? connected and arranged in e. i er more fully described subsequently.

Fre aly, each of the dispatcher positions in r fcher exchange is identical, to the rst spatcher position shown in Figs.

repeater f5 it, impedance element ano. e. number or" lys including the control rela-y and two and connected .and

ore fully described sub- .r circuit at the rst dis comprises number o' line keys individually assoc" ted with the telephone lines in the dispatcher' nange the line key being individually associated with the telephone line lill extending to the telephone station Ti; number of trunk keys, not shown, indi vidually associated with the trunk lines in the first group of trunk lines extending from the F. A. l@ to the dispatcher exchange 3d; a number oi link keys individually associated with the links in the associated group of links, the link key Kit@ being `individually associated with the rst link til@ in the associated group of linlm; and a number of link identity keys individually relays Rf G, which comprises trunk. circuit including associated with the links in the associated group of links, the link identity key K160- being individually associated with the rst link 300 in the associated group of links. Further the trunk circuit at the first dispatcher position B00 comprises a number of P. B. X keys individually associated with the trunk lines in the group of trunk lines extending between the rst dispatcher position @tu and the P. B. X 20, the P. B. X key Kl I0 being individually associated with the trunk line 5l@ included in the group of trunk lines extending between the first dispatcher position 6120 and the P. B. X 20; a radio station key K12!! commonly associated with the trunk lines '|80 and T85 extending between the dispatcher exchange 30 and the radio stations 50 and 80, respectively; and a number of order keys individually associated with the order trunks extending between' the first dispatcher position B00 and the other dispatcher positions, the order key K640 being individually associated with the order trunk 680 extending between-the first dispatcher position 600 and the second dispatcher position 800. Finally the trunk circuit at the rst dispatcher position @lill comprises a common ring key X625 which is operative to ring over a connection associated with the-'rear end of the trunk circuit, and a common split key K146i which is operative to split in either direction a connection associated with the front end of the trunk circuit.

Also associated with the r'st dispatcher posi-Y tion E06 are various groups of signal lamps which are provided in order to facilitate the supervision of the various connections. For example, the identity signal lamp L63?, the lbusy signal lamp Liilt and the line signal lamp L53@ are individually associated with the cable 250 extending to the line circuit 2li@ individually associated with the telephone line EN extending to the telephone station Tl; the call signal lamp Litt, the answer signal lamp L'lil and the busy signal lamp Lll .are individually associated with the cable titi@ extending to the rst link Stu; the signal lamp L'ttis individually associated with the trunk circuit still which is individually associated with the trunk line 575 extending between the first dispatcher position tu@ in the dispatcher exchange and the P. B. X 2t; and the signal lamps and Lit@ are individually associated with the respective trunks iti@ and extending from. the first dispatcher position the dispatcher exchange to the radio stations il@ and respectively.

The sending key set K365i, the sender control circuit and the digit register are connected and arranged in a conventional manner;

in view of the fact that the particular connection and arrangement of this apparatus forms no part of the present invention, the details thereoi have not been illustrated in the interest of brevity. However, for reference purpose, a sending key set, a sender controi circuit and a digit register or the general character of the sending key set the sender control circuit and the digit register respectively, are disclosed respectively in Fig. i6, Figs. l5 and i6,

and Figs. l? to 2l, inclusive, of Thomas F. Crocker Patent lilo. Zl'i'jlil, issued August l, 1939.

A better understanding of the connection and arrangement of the apparatus incorporated in the signaling system will be facilitated from a consideration of the detailed operation of the various pieces o. apparatus incorporated therein incident to the completion and the handling of the various' connections at the first dispatcher asentar position tot in the dispatcher exchanger to and at the operator position. dit in the P. B. X iii,

as will appear hereinafter.

General operation of the signaling system Considering now the general operation oi the signaling system with reference to Fig. 1 of the drawings, it is noted that a call initiated at any one oi.' the telephone stations in the dispatcher exchange tt, such, for example, as the telephone station Ti, causes a signal to be transmitted to each of the dispatcher positions in the dispatcher exchange tt and may be answered at any one of the dispatcher positions, such, for example, as the rst dispatcher position tdt. In order to answer the call from the telephone station 'I'il on the telephone line itl, the dispatcher at the iirst dispatcher position dii@ operates the line key in his trunk circuit individually associated with the telephone line Edi thereby to cause the nder switch Siti@ lin the line circuit ddii individually associated with the telephone line Edil to operate and iind an idle one of the links in the group ci links individually associated with the first dispatcher position ttt, such, for example, as the iirst link tdt. Immediately the dispatcher at the nrst dispatcher position tilt operates the line lrey in his trunk circuit corresponding to the telephone line tdi extending to the telephone station Ti, a connection is. completed between the irst dispatcher position tti? and the telephone station Tl; and immediately the :lnder switch Sit@ in the line circuit ttt individually associated with the telephone line tdi seizes the rst link tot, operation or the sender control circuit ttt/individually associated with the iirst dispatcher position ttt is initiated. More particularly, the iinder switch Sttii of the sender control circuit tdt iinds the trunk dit connected to the iirst link 3d@ and to the trunk line il@ extending from the first dispatcher position tilt in `the dispatcher exchange t@ to the P. A. X dii. Also the finder switch Sdi@ of the sender control circuit tot iinds an idle one of the digit registers, such, for example, as the digit register dtd. Accordingly, at this time, the apparatus at the first dispatcher position ttt is automatically conditioned to extend the call therefrom by way of the trunk line il@ to any subscriber substation in the P. A. X lit, in the event this service is desired.

In the event the call is to be extended from the first dispatcher position ttt in the dispatcher exchange t@ to a Isubscriber substation, such, for example, as the subscriber substation TZ in the P. A. X dd, the dispatcher in the rst dispatcher position tilt operates the sending key set Kdiiii, thereby to cause appropriate digits to be registered in the digit register dtd, whereupon the digit register tilt governs the sender control circuit tilt in order to cause the digits to be transmitted over the trunk line llt to the P. A. X til. The digits transmitted over the trunk line il@ to the P. A. X du control the automatic switch train therein in order to cause the call to be extended to the subscriber substation T2 in a. Well-known manner, thereby to establish. a connection between the telephone station Ti in the dispatcher exchange t@ and the subscriber substation T2 in the P. A. X it The dispatcher at the first dispatcher position Gilt may then operate the link key in his trunk 'circuit individually associated with the first link 3mi and then return the line key in his trunk circuit individually associated with the telephone iii line tdi to its normal position, thereby to caus a three-way communication connection to be completed including the telephone station Ti, the trunk. circuit at the rst dispatcher position ttt. and the subscriber substation Ti. Further it is noted that, 'when the line key in the trunlr circuit at the nrst dispatcher position tilt in#l dividually associated with the telephone line iti is operated inA order to answer the call on the telephone line titi, the lint: distributor ddii opcrates in order to loch out the other dispatcher positions, thereby to prevent the call on the telephone line tti from being answered at the other dispatcher positions. i,

After the connection has been established ben tween the telephone station 'lli in the dispatcher exchange t@ and the subscriber substation 'It in the P. A. X dit, the dispatcher at the iirst dise patcher position tot may tree the trunls circuit at his position by returning the link hey in his trunk circuit individually associated with the first link tt@ to its normal position. Further it is noted that the dispatcher in the first dispatcher position dell may monitor or split in either direction the established connection between the telephone station Il in the dispatcher exchange td and the subscriber substation Ti in the P. A. X di?. Finally it is noted that the release of the established connection between the telephone station 'Ii in the dispatcher exchange titi and the subscriber substation Ti in the P. A. 2 dit is under the control oi the dispatcher at the nrst dispatcher position ddii; and that the dispatcher at the rst dispatcher position tilt may control the identity distributor unit ddii by operating a link identity key in his trunk circuit individually associated with the firstY link tot, thereby to cause the particular telephone station included in the established connection, routed by way of the first link tilt, to be identified. 'I'he identity distributor unit tdt is so connected and arranged that, when it is taken for use by the dispatcher at the first dispatcher position tilt to identify a telephone station, it is locked against use bythe dispatchers at the other dispatcher positions.

Further it is noted that a call may be extended from any one of the dispatcher positions in the dispatcher exchange til to anyone of the telephone stations in the dispatcher exchange 33t or to the operator position 835i in the l?. B. X 2d and from the operator position dit in the P. B. X 2d to any one of the dispatcher positions in the dispatcher exchange dd, in a manner more fully explained hereinafter. Further, calls may be set up in either direction between the central ofiice i@ and the P. B. X 2d and then routed to any one of the dispatcher positions in the dispatcher exchange 3d. vThe dispatcher at any one of the dispatcher positions in the dispatcher exchange t@ may route a call from his position to either one of the radio stations 5t or tl), thereby to 'broadcast directly irom the dispatcher position therein, in a manner more fully explainedhereinafter.

Initiation of a coll ci o telephone station in the dispatcher exchange A call may be initiated at a telephone station in the dispatcher exchange t0, such, for example, as the telephone station Tl, by removing the receiver of the telephone instrument thereat from its associated switchhooi. When the receiver oi the telephone instrument at the telephone station Ti is removed from its associated switchhoolr, a bridge path is completed thereat between the line conductors C262 and C203 of the telephone line 20| extending to the telephone station Tl. 'When this bridge path is completed between the line conductors of the telephone line till a circuit is completed for energizing the winding or the line relay R2i6. This circuit extends from ground by way oi the contacts 206, C262, the bridge path between the line conductors C262 and Cd of the telephone line 2M at the telephone station Ti, C203, the contacts 207| and the winding of B2i@ to battery. When thus energized the line relay Rill@ operates to complete, at the contacts 2li, an obvious path for applying ground potential to the control conductor C266 of the telephone line 20|. IThis application of ground potential to the control conductor C300 o the telephone line Edi completes a path extending by way oi the control conductor C26? in the cable 266" for applying ground potential to the control conductor of the trunk line 610 exten from the P. A. X l0 to the dispatcher exchange 60 in order to mark the trunk line liti and consequently the telephone line 20| as busy to the connector switches in the P. A. X 60. Further the line relay B2i@ completes, at the contacts tit, an obvious path for applying ground potential to the control conductor C266 in the cable 260, thereby to complete an obvious circuit for illuminating the line signal lamp H566 at the iirst dispatcher position 600 and the corresponding line signal lamps at the other dispatcher positions.

The illumination of the line signal lamps at the various dispatcher positions indicates to the dispatchers thereat that a call is waiting to bef answered on the telephone line 20| extemslingl to the telephone station TI. In order to answer the call on the telephone line 20| the dispatcher at one of the dispatcher positions operates the line key in his trunk circuit individually corresponding to the telephone line 20|. Assuming that the call on the telephone line 20| is answered at the rst dispatcher position 600, the dispatcher thereat operates the line key K630i in the trunk circuit at the rst dispatcher position 600 away from its normal position, thereby to complete, at the contacts 633 and 636 thereof, obvious connections between the line conductors C610 and C61! of the trunk circuit at the rst dispatcher position 600 and the respective line conductors C202 and C206 of the telephone line 20|. Also when the line key X630 is thus operated there is completed, at the contacts 635 thereof, an obvious path for applying ground potential to the control conductor C612, thereby to complete an obvious circuit for energizing the upper winding of the control relay R655. When thus energized, the control relay R656 operates to complete, at the contacts 651, an obvious circuit, including the grounded control conductor C612, for energizing the winding of the switching relay R660. When thus energized, the switching relay R660 operates shortly thereafter, this relay being of the slow-to-operate type, to complete,

at the contacts 666, an obvious holding circuit including the grounded control conductor C612 for energizing the winding thereof. Further the switching relay R660 interrupts, at the contacts 665, the previously mentioned circuit for energizing the upper winding of the control relay R655, thereby to cause the control relay R655 to restore shortly thereafter, the latter relay being of the slow-to-release type.

Also, upon operating, the switching relay R660 completes, at the contacts 66d and 663, a connection between the repeater 6116 and the line conductors C202 and C206 of the telephone line ,i 20|, this connection extending from the line conductor C202 of the telephone line 20| by way of the contacts 666 of the line key X630, C616, the contacts 627 of the ring key H625, C613, the contacts 66|, the condenser 6M, the windings tii and 6i2 of the repeater 6i0, the contacts 666, C616, the contacts 6% oi the ring key X626, C670 and the contacts 666 oi the line key X660 to the line conductor C203 oi the telephone line 20B. Accordingly, at this time, the telephone instrument at the telephone station Ti is operatvely connected by way of Vthe previously traced circuit to the repeater 6|0 at the iirst dispatcher position 600. Further the switching relay R660 completes, at the contacts 662, a circuit for supplying operating current to the transmitter 60|, assuming that the plugs P606 and P665 occupy their inserted positions into the jacks .1606 and J 606, respectively, at this time. This circuit extends from ground by way of the winding 613 of the repeater 6|0, the jack .1606, the plug P603, the transmitter 60|, the plug P605, the jack J 606, the contacts 662 and the retarder coil 601 to battery. Further it is noted that a signal current path is completed which extends from ground by way of the winding 6|3 of the repeater 6|0, the jack J606, the plug P603, the transmitter 60|, the plug P605, the Jack J606 and the condenser 606 to ground. The above-traced signal current path by-passes the previously traced cir'- cuit for supplying current to the transmitter 60 I. Also the receiver 602 is operatively associated with the winding 6| 2 of the repeater 6i0 by way of a circuit extending from one terminal of the receiver 602 over the plug P603, the Jack J60l, the condenser 6|5, the winding 6I2 of the repeater 6l0, the jack J606 and the plug P605 to the other terminal of the receiver 602. Accordingly, at this time. the transmitter 60| and the receiver 602 are operatively connected to the repeater 6I0. Hence, a two-way communication connection is completed at this time between the telephone station Ti and the iirst dispatcher position 600.

At this point it is noted that, upon operating, the control relay R656 completes, at the contacts 656, a path for short-circuiting the receiver 602, which path is interrupted at the contacts-656 incident to the restoration of the control relay R655. 'I'his path is completed and subsequently interrupted in order to prevent disagreeable clicks from being produced in the receiver 602 incident to the operation of the switching relay R660. The path for short-circuiting the receiver 602 extends, when completed, from one terminal of the receiver 602 by way of the plug P603, the jack J606, the contacts 656, the jack J606 and the plug P605 to the other terminal of the receiver 602. Further it is noted that the impedance element I6|6 is connected across the line conductors C613 and C616 of the trunk circuit at the first dispatcher position 600, this connection extending from ground by way oi the upper winding or mit to the line conductor Ctlt and'irom battery by way oi the lower winding of Itlt to the line conductor Ctllfi. Accordingly, battery is supplied by way of the impedance element Itid to the telephone instrument at the telephone station Tl at this e.

Also 'when the line key Kilt@ is thus operated there is completed, at the contacts titl thereoi, an obvious path for applying ground potential to the control conductor Citi in the cable itil, thereby to complete an obvious circuit for energizing the winding of the cutoil relay Rllll. When thus energized the cutod relay Ritt operates Ato com plete, at the contacts tilt, an obvious path ior applying ground potential to the control conductor Citt in the cable litt, thereby to coinplete an obvious circuit for illuminating the busy signal lamp lidad at the mst-dispatcher position ttt and the corresponding busy signal lamps at the other dispatcher positions. The illumination of the busy signal lamps at the various dispatcher positions indicates to the dispatchers thereat that the telephone line Ztl is now busy. Further the cutod relay Ritt interrupts, at the contacts ttt, a circuit traced hereinafter for energizing the rotary magnet Miti of the iinder switch Sit@ and interrupts, at the contacts ttt and till, the previously traced oircuit for energizing the winding of the line relay Rl lil, thereby to cause the latter relay to restore shortly thereafter, the latter relay being of the slow-to-release type, and to clearl the telephone line tbl of impedance elements. Upon restoring, the line relay Rt it interrupts, at the contacts it Il il, the previously mentioned circuit for illuminating the line signal lamp Litt at the iirst dispatcher position ttt and the corresponding line signal lamps at the other dispatcher positions, thereby to indicate to the dispatchers at the various dispatcher positions that the call on the telephone C26! and Ctiil in the cable ttt, thereby to retain i the application of ground potential upon the control conductor of the trunk line bill extending from the P. A. X tu to the dispatcher exchange it.

Further when the line key Kbit is operated there is completed, at the contacts @it thereof, a circuit for energizing in series the winding of the cutoff relay Riti@ in the link distributor ftllil and the winding of the start relay included in one oi the links in the group of links individually associated with the first dispatcher position tilt, the particular one of the start relays, the winding of which is energized, depending upon the condition of the chain circuit included in the group oi links mentioned for energizing the windings of these start relays. lin the present example, assuming that the first link ttt in the group of links individually associated with the first dispatcher position but is idle, a circuit `is completed for energizing in series the winding of the cuto relay Rill@ in the link distributor tu@ and the winding of the start relay Rlu in the iirst link tilt. This circuit extends from ground v by way of the contacts its, ist and tra, the

winding of Ritiii, the contacts titl, the control conductor in the cable tt, the contacts 632 of the line key Kbit, the control conductor C255 in the cable ttt, the contacts Slt and ttt and the winding of Ril@ to battery. When thus energized the start relay RMU operates to prepare, at the contacts 3l l, a circuit traced hereinafter for energizing the winding of the stop relay Bildt, to complete, at the contacts tit, an obvious holding circuit for energizing .the winding thereof by way of the grounded control conductor Gibt in the cable ttt and to interrupt, at the contacts Zitti, a point in the previously traced circuit for energizing the winding thereof. Further ,the start relay Rill@ prepares, at the contacts dit, a circuit traced hereinafter for energizing the winding of the hold relay Rtillb in the link distributor ttt. Finally, the start relay Rill@ completes, at the contacts tilt, a circuit for energizing the rotary magnet Miti of the nder switch Slut, this circuit extending from ground by way oi the contacts 335, tt and tit, the control conductor Citi in the cable itil, the contacts ttt oi the line key Klitt, the control conductor Citt in the cable ttt, the contacts tilt and tdt and the rotary magnet M2371 to battery. When' thus energized the rotary magnet M2M operates to interrupt, at the contacts 23d, the previously traced circuit :for energizing the .rotary magnet tutti and to condition the wipers noted of the finder switch Sutil to be driven one step in the clockwise direction. The rotary magnet Milli! then restores in order to drive the wipers noted of the nder switch Still one step in the clockwise direction and to recoxnplete, at the contacts itil, the previously traced circuit for energizing the rotary magnet M2M. Accordingly, the `rotary magnet Mltl'l operates intermittently, thereby to drive the wipers noted ofthe lnder switch Siittl lstep by step in the clockwise direction until the vtrunk tt extending to the ilrst link litt is seized,

in a manner more fully described hereinafter.

When the previously traced series circuit for energizing the winding of the start relay RM@ in the first link tti! and the outoii relay Riti@ in the link distributor tu@ is completed, the cuto relay Rtlt also operates. Upon operating, the cutoil relay Rill@ interrupts, at the contacts til, an obvious path for applying ground potential by way of the contacts dill and the winding of the cutoH relay Rill@ to the control conductor @tti in the cable tu@ and interrupts, at the contacts lit, obvious paths for applying ground potential by way of the contacts dit and the windings o the cutoff relays Riltil and Raitt, respectively, to the control conductors Ctb'l and Ctbd in the cable dell. The control conductors CM2, Citt?! and Cti'it in the cable tt respectively extend to the second, third and fourth dispatcher positions. Accordingly, the operated cutod relay Rulli individually corresponding to the first dispatcher position dll prevents operation of the cuto relays Ratt, Rttb and Ritt@ individually corresponding to the second, third and fourth tor tml individually corresponding to the rstdispatcher position tilt remains in its operated position, it is impossible for the dispatchers at the other dispatcher positions to answer incoming calls to the dispatcher exchange ttl. This arrangement prevents interference between the dispatchers' at the various dispatcher positions and causes a call on a telephone line to be answered at the particular dispatcher position at which the line key individually associated with the telephone line is iirst operated.

Continuing now with the operation of the i'lnder switch S230, when the nder switch S2130 seizes the trunk 250 extending to the iirst link 300 the previously mentioned circuit for energizing the winding of the stop relay R320 in the first link 300 is completed, this circuit extending from ground by way of the wiper 23d and engaged contact in the associated contact bank 2160 of the iinder switch S230, the control conductor C@ of the trunk 250, the contacts 3H and the winding or' R320 to battery. When thus energized the stop relay R320 operates to interrupt, at the contacts 332, the previously traced circuit for energizing the rotary magnet M2M, thereby positively to arrest further operation ci the rotary magnet M201 at this time. Further the stop relay R320 completes, at the contacts 323, an obvious circuit for energizing the windingoi the control relay R330, thereby to cause the control relay R330 to operate shortly thereafter, the latter relay being of the slow-to-operate type. Upon operating, the control relay R330 completes, at the contacts 330, the previously mentioned circuit for energizing the winding oi the hold relay R005 in the link distributor tilt, this circuit extending from ground by way of the contacts 330 and 3h0, the control conductor C-il in the cable 300 and the winding of Ri to battary. vWhen thus energized the hold relay Raitt? operates to complete, at the contacts dit, an alternative holding circuit substantially identical to that previously traced for energizing the winding of the start relay R3l0 and to interrupt, at the contacts 401, the previously traced circuit for energizing the winding of the cutoi relay R690. The cutoff relay R4|0 then restores, therebyto prepare, at the contacts lll and M2, the previously traced paths for applying ground potential to the control conductors C052, C031 and C456 in the cable 450. The application of ground potential to the control conductors C452, C451 and C458 renders the apparatus at the respective second, third and fourth dispatcher positions again operative to answer incoming calls to the dispatcher exchange 30. Accordingly, it will be understood that the cutoff relay RMU remains in its operated position in order to disable the apparatus at the second, third and fourth dispatcher positions only during the brief time interval while the nder switch S230 is hunting for the trunk 250 extending to the rst link 300.

Also. upon operating, the control relay R330 completes, at the contacts 33|, a circuit for energizing the winding of the switching relay R220 in the line circuit 200, this circuit extending from ground by way of the contacts 33|, the control conductor C252 of the trunk 250, the wiper 232 and engaged contact in the associated contact bank 242 of the iinder switch S230 and the winding of R220 to battery. When thus energized the switching relay R220 operates shortly thereafter, this relay being` of the slow-to-operate type, to interrupt, at the contacts 220, a further point in the previously traced circuit for energizing the rotary magnet M231, to complete, at the contacts 223, an obvious holding circuit for energizing the winding of the cutoff relay R205, and to complete, at the contacts 22| and 222, a connection between the telephone line 20| and therepeater 303. The connection between the telephone line 20| and the repeater 305 extends from ground by way of the upper winding of the line relay R340, the winding 306 of the repeater 305, the line conassai?? ductor CESE of the trunk 250, the wiper @0l and engaged contact in the associated contact bank tali oi the finder switch S230 and the contacts tti to the line conductor C202 of the telephone line till; and from battery by way of the lower winding of the line relay R300, the winding 3d? of the repeater 300, the line conductorv Ctt of the trunk 250, the wiper 233 and engaged contact in the associated contact bank 260 of the finder switch S230 and the contacts 222 to the line conductor @Zta of the telephone line zal. When this connection between the telephone line 20 and the repeater 303 is completed the upper and lower windings of the line relay Rel are energized, thereby to cause the latter relay to operate.

Also, upon operating. the control -relay interrupts, at the contacts 330, a further point in the previously traced original circuit for energizing the winding of the start relay Raid and prepares, at the contacts 333, a point in a circuit traced hereinafter for energizing the winding of the start relay, not shown, included in the second link 315. Further the control relay R330 completes, at the contacts 332, an obvious path for applying ground potential to the control conductor C301 in the cable 330, thereby to complete an obvious circuit for illuminating the busy signal lamp Lil@ at the rst dispatcher position 50d. The illumination of the busy signal lamp Lille indicates to the dispatcher at the rst dispatcher position 000 that the nder switch S230 in the line circuit 200 has seized the first link 300 in the group of links individually associated with the rst dispatcher position 600 and, in the event the call on the telephone line 20| is to be extended to the P. A. X 40, that the rst link 300 will be utilized. Finally, the control relay R330 interrupts, at the contacts 335, an obvious path for applying ground potential to the control conductor C308 in the cable 380. When ground potential is removed from the control conductor C38Bin the cable 380, operation of the sender control circuit 806 is'initiated. More particularly, the nder switch S8|0 of the sender control circuit B operates automatically to nd a trunk extending to an idle one of the digit registers, such, for example, as the trunk 801 extending to the digit register 308. When the nder switch S8l0 seizes the trunk 801 extending to the digit register 808, further operation of the nder switch S3l0 is arrested and the digit register 808 is conditioned to register digits transmitted thereto. Also the finder switch S800 of the sender control circuit 806 is operated to search for the trunk 340 marked as a calling trunk by the absence of ground potential upon the control conductor C380 thereof. When the nder switch S809 seizes the trunk 0|0, further operation thereof is arrested and the sender control circuit 806 is conditioned to be operative further in accordance with the operation of the sending key set K305i in the event the call is to be extended from the first dispatcher position 600 to the P. A. X 40. At this time, a bridge path is completed in the sender control circuit 806 by way of the finder switch S30Q between the line conductors C0|| and CBIZ of the trunk 3&0 and, consequently, between the line conductors C11| and C112 of the trunk line H0 extending from the rst dispatcher position 5230 in the dispatcher exchange. 30 tojthe P. A. X t0. When this bridge path is completed between the line conductors ofthe trunk line 11.0 the selectorvswitch 820 in the P. A. X 40 is conditioned to be operative in response to impulses transminted thereto. also atA this time. the une conductors 011i and C112 of the trunk line 113 are respectively connected by way of the contacts H33 and 156 of the link key X153 to the line conduc tors C335 and 033i in the cable 333 extending to the iirst link 303, the link key R150 in the trunk circuit at the iirst dispatcher position 330 being individual to the first link 303. However, it is noted that the line conductors`C33i and C333 in the cable 383 are not operatively connected to the repeater 303 in the iirst link 303 at this time, due to the restored position of the cut-in relay R330.

Upon operating, the line relay R333 completes, at the contacts 331|, an obvious circuit for energizing the Winding of the hold relay R325, thereby to cause the latter relay to operate. Also the line relay R340 interrupts, at the contacts 333, a point in a path traced hereinafter for applying ground potential to the control conductor C333 in the cable 330, for a purpose morefully explained subsequently. Upon operating, the hold relay R323 prepares, at the contacts 323, a further point in the previously mentioned path for applying ground potential to the control conductor C333 in the cable 333 and completes, at the contacts 321, an obvious holding circuit for energizing the winding of the control relay R330.

At this time, the call from the telephone station Ti on the telephone line 23E has been answered by the dispatcher at the rst dispatcher position 333 and the apparatus in the trunk circuit at the rst dispatcher position 333 is conditioned to extend the call on the telephone line 33t by way of the iirst link 330, the cable 333 and the trunk line 333 to the P. A. X 33 in the event this service is desired by the person at the telephone station Tl. Also, at this time, the telephone instrument at the telephone station Tl is operatively connected by way of the telephone line 33i and the cable 233 to the transmitter 33t and the receiver 302 at the rst dispatcher position 333. Accordingly, theperson at the telephone station Tl and the dispatcher at the first dispatcher position 333 communicate with each other and the dispatcher at the iirst dispatcher position 4330 is advised concerning the extension of the call in the event this service is desired.

i'tensz'on of a call from the dispatcher exchange to the'P. A. X

in the event a call from a telephone station to a dispatcher position, such, for example, as the call from the telephone station Ti to the iirst dispatcher position 333 routed by way of the telephone line 233, the cable 233 and the rst link 333 is to vbe extended to a subscriber substation in the P. A. X |33, such, for example, as the `subscriber substation T3, the dispatcher at the first dispatcher position 333 initiates the extension of the call by operating the sending key set R333 in accordance with the appropriate series of digits. When the sending key set K303 mitted over the trunk line 110 and operates to select an idle connector switch in a corresponding group of connector switches, such, for example, as the connector switch 33E. The connector switch 32| then responds to the following two digits to seize the telephone line 333 extending to the subscriber substation `'llz in the usual manner. The subsequent operationof the connector switch 32! depends upon the idle or busy condition of the subscriber substation T2 in accordance with conventional practice.

After the sender control circuit 306 has transmitted the last digit registered, it operates to cause ground potential to be applied by way of the finder switch S333 to the control conductor C332 oi the trunk 303. The application of ground potential to the control conductor C332 Iof the trunk 3i@ completes an obvious path, in-

cluding the control conductor C332 in the cable 333, for energizing the winding of the cut-in relay R363, thereby to cause the cut-inrelay R333 to operate shortly thereafter, the latter relay being of .the slow-to-operate type. The sending key set 303, the sender control circuit 333 and the digit register 303 are then automatically released. Upon operating, the cut-in relay R333 completes, at the contacts 33l, a holding circuit :for energizing the winding thereof, this circuit extending from ground by way of the resistor 33t, the contacts 15|! of the link key K133 in the trunk circuit at the iirst dispatcher position 303, the control conductor C333 in the cable 333, the contacts 33E and the winding of R333 to battery. Also the cut-in relay R333 completes, at the contacts 333, a loop circuit between the upper winding of the supervisory relay R333 and the repeater 335 in the nrst link circuit 303 in the dispatcher exchange 33 and the connector switch 3M in the P. A. X 33, 'this circuit extending from the line conductor C'ill of the trunk line 113 byi way of the contacts 333 of the link key K133, the line conductor C333 in the cable 333, the contacts 333, the winding 333 of the repeater 305, the upper winding of R333, the resistor 302, the winding 333 ofy the repeater 303, the line conductorC33l in the cable 333 and the contacts 'E53 of the link key K333i to the line conductor C332 of the trunk line 333, the line conductors Cili and C312 being connected together in the connector switch 321i by way of the selector switch 330 in the P. A. X 33. When the upper winding of the supervisory relay R333 is thus energized this relay does not operate as is thus operated the digit register 333 previously selected by the finder switch S3i3 of the sender control circuit 303 is governed by way of the sender control circuit 303 to register the digits set up by the dispatcher at the iirst dispatcher position 333 on the sending key set K305. The digit register 333 then controls the sender control circuit 333, thereby to cause the digits registered in the digit register 303 to be transmitted by the sender control circuit 303 over the nder switch S339, the trunk Bi0 and the trunk line to the P. A. X 30. The selector switch 323 in the P. A. X 40 responds to the first digit trans-e it is of the differential type, an obvious circuit being completed at this time for energizing the iower winding thereof, at the contacts 333, incident to the operation of the cut-in relay R333.

Further the cut-in relay 'R333 prepares, at the contacts 333, an alternative path traced hereinafter for applying ground potential to the control conductor C333 in the cable 333, completes, at the contacts 333, an obvious alternative holding circuit for energizing the Winding of the control relay R333, andI completes, at the contacts 333, an obvious path for applying ground potential to the control conductor C333 in the cable 333 and consequently to the control conductor C333 of the trunk BH3. The application of ground potential to the control conductor C333 marks the trunk 3i3 as busy to the iinder switch S803 of the sender control circuit 333, thereby to prevent seizure of the trunk 3l3 by the finder switch S803 when operation of the sender control circuit 333 is again initiated incident to the extension of another call to the P. A. X 30.

Finally, the cut-in relay R360 completes, at the contacts 362, ank obvious path for applying ground potential .to the control conductor C304 in the cable 380, thereby to com .plete an obvious circuit for illuminating the call signal lamp L'l3A at therst dispatcher position 600. The illumination of the call signal lamp L'I13 indicates to the dispatcher at the iirst dispatcher position 600 that the sender control circuit 806 has completed its operation and that the connection has been extended from the first link 300 to the P. A. X 40.

At this time, the dispatcher at the iirst dispatcher position 600 may return the line key K630 in the trunk circuit at his position to its normal position in order tomfree the trunk circuit at the rst dispatcher position 600; on the other hand, the dispatcher at the rst dispatcher position 600 may retain the line key K630A in its operated position until after the subscriber at the called subscriber substation T2 has answered the call extending thereto or -the call has been abandoned, as he desires. As previously noted, the connector switch 82| operates in accordance with conventional practice upon seizing the telephone line 830 extending to the subscriber substation T2 in the P. A. X 40. More particularly, in the event the subscriber substation T2 is busy at this time, busy tone current is returned over the previously traced loop circuit extending between the connector switch 82| in the P. A. X 40 and the repeater 305 in the rst link 300 in the dispatcher exchange 30. On the other. hand, in the event the subscriber substation T2 is idle at this time, ringing current is projected from the connector switch 82! over the telephone line 830 to the subscriber substation T2 in order to operate the ringer thereat; and ring-hack tone current is conducted over the previously traced loop circuit extending between the connector switch 2i in the P. A. X t0 and the repeater 305 'in the iirst link 30@ in the dispatcher exchange Sil. Tone current conducted over the previously traced loop circuit is by-passed around the upper winding of the supervisory relay R355) by way of the condenser 3M and energizes the windings 30u and tilt of the repeater 3535, thereby to cause a similar tone current to be induced in the windings tu@ and illl of the repeater 33:3 which is 'oy-passed around the windings of the line relay Rfit by the condenser tilt. The tone current induced in the windings Silo and tilt of the repeater 3585 is returned over the previously traced loop circuit extending hetween the repeater and the telephone station Ti, and to the trunk circuit at the First dispatcher position tt@ by way ci the telephone line Eii and the cable it@ in the event the Eine key KS3@ occupies its operated position,

lWhen the subscriber at the subscriber substation T2 answers lthe cali by removing the receiver of the telephone instrument thereat from its associated switchhook, the connector switch 821i in the P. A. X t@ switches through, thereby to cause the current traversing the previously traced loop circuit extending between the connector switch mi in the P. A. X t@ and the repeater @t5 of the first link 3Go in the dispatcher exchange 3@ to be reversed, whereupon the upper winding of the supervisory relay R35@ is energized in the reverse direction. When the upper winding of the supervisory relay R35@ is thus energized this relay operates as it is of the diierential type. Upon operating, the supervisory relay R350 interrupts, at the contacts 35i, the previously mentioned path for applying ground potential to the control conductor C384 in the cable 380, thereby to interrupt the previously mentioned circuit for illuminating the call signal lamp L1'I3 at the rst dispatcher position 600. When the call signal lamp L113 is extinguished it indicates to the dispatcher at the first dispatcher position 600 that the call from the telephone station Tl in the dispatcher exchange 30 to the subscriber substation T2 in the P. A. X 40 has been answered.

At this time, the dispatcher at the rst dispatcher position 600 returns the line key K630 in the trunk circuit at his position to its normal position in the event this has not previously been done. When the line key K630 is returned to its normal position the previously traced connection between the line conductors of the telephone line 20| and the trunk circuit at the rst dispatcher position 600 is interrupted at the contacts 633 and 636 thereof. Also, at the contacts 635 of the line key K630, the previously mentioned holding circuit for energizing the winding of the switching relay R660 is interrupted, thereby to cause the latter relay to restore. Upon restoring, the switching relay R660 interrupts, at the contacts 66| and 663, further points in the previously traced connection including the trunk circuit at the rst dispatcher position 600 and interrupts, at the contacts 662, the previously traced circuit for supplying current to the transmitter 604. Further, when the line key X630 is returned to its normal position there is interrupted, at the contacts 636i thereof, a further point in the previously traced circuit for energizing the rotary magnet M231 of the finder switch S230 and, at the contacts 63! thereof, there is interrupted the previously traced original circuit for energizing the winding of the cut-oi relay R205. Finally, at the contacts 32 of the line key X630, there is interrupted the previously traced holding circuit for energizing the winding of the start relay Rl, thereby to cause the latter relay to restore. Upon restoring, the start relay RME! interrupts, at the contacts 39 l, the previously traced circuit for energizing the winding of the stop relay R320, thereby to cause the latter relay to restore. Further the start relay RSG@ interrupts, at the contacts 362, a further point in the previously traced holding circuit for energizing the winding thereof, interrupts, at the contacts tilt, a iurther point in the previously traced path for applyinfr ground potential to the control conductor Citi in the cable 25B, and interrupts, at the contacts tit, the previously traced circuit for energizing the winding of the hold relay in the ,L Fink distributor thereby to cause the latter relay to restore.

Finally, upon restoring, the start relay REIG prepares, at the contacts gt3, the previously traced chain circuit between the rst link 360 and the second link @it for energizing the winding of the start relay, not shown, in the second iink tl'ii. rThis prepared circuit extends from the control conductor in the cable 26@ by way ci' the contacts tit and to lthe control condoctor 03:23 extending to the second link 3'15, battery by way of the winding of the-start relay in the second link SM5-being connected to the control conductor Upon restoring, the

hold relay Rliil prepares, at the contacts ttl', the previously traced path for applying ground potential by way or" the contacts tti and the winding of the cutoi relay Rlii to the control conductor C653 in the cable 56. Accordingly, at this time, it will be understood that the link distributor it is completely released and the order to answer a call on the corresponding telephone line, a circuit substantially identical to that previously traced is completed for energizing in series the windings of the cutoff relay RMI) in the link distributor Mill and the winding of the start relay, not shown, in the second .link 315, this circuit extending from ground by Way of the contacts Ml, 133i and 421the winding of R410, the contactsadm, the controlconductor C453 in the cable 45t, the contacts of the link key mentioned in the trunk circuit at the first dispatcher position Wil, the control conductor in the 'corresponding cable, the control conductor C301, the contacts @it and 333 to the control conductor Chit extending to the second link 31d, battery potential by way of the winding of the start relay, not shown, in the second link 315 being applied to the control conductor CMS. Accordingly, at this time, the .trunk circuit at the first dispatcher position til@ is completely released and the apparatus thereat is in readiness to answer another call on a telephone` line in the dispatcher exchange 3d.

Supervision and release of un established connection between n telephone station in the dispatcher exchange and a subscriber substation in the P. d. X

An established connection between a telephone station in the dispatcher exchange 3@ and a subscribed substation in the P. A. X d@ is supervised by the dispatcher at the particular dispatcher position in the dispatcher exchange at which the connection is set up. For example, the established connection between the calling telephone station Ti in the dispatcher exchange t@ and the called subscriber substation T2 in the P. A. X iii and routed therebetween by way of the telephone line iti, the iirst link 5mt, the trunk line 11ll, the selector switch dit, the connector switch 321 and the telephone line dit@ is supervised by the dispatcher at the hrst dispatcher position tilt. More particularly, the person at the calling telephone station Tl in the dispatcher exchange 3@ has swltchhook supervision and may signal the dispatcher at the rst dispatcher po-f sition Edil by repeatedly operating the .switchhook at the telephone station Ti, thereby intermittently to interrupt the previously traced loop circuit extending between the telephone station Tl and the line relay Riiiill. The line relay RM@ operates and restores intermittently, thereby intermittently to complete, at the contacts ttt, the

previously mentioned circuit for illuminating the answer signal lamp L11d. This circuit extends from. ground by way oiY the contacts @lili and from ground by way of the contacts 32d over the contacts ttt, the control conductor C386 in the cable 38d and the answer signal lamp 1.1115 to battery. The intermittent operation of the line relay Rill@ causes the answer signal lamp L11@ to lash,lthereby to indicate to the dispatcher at the first dispatcher position Et@ that a person at a calling telephone station in the dispatcher exchange Sil desires the dispatchers service. y

Similarly, the subscriber at the called subscriber substation T2 in the P. A. X t0 has' switchhook supervision and may signal the dispatcher at the first dispatcher position B00 by repeatedly operating the switchhook at the subscriber substation T2, thereby to cause the connector switch 82|! to operate intermittently in order intermittently to cause current to be reversed overthe previously traced loop circuit extending between the connector switch t2l in the P. A. X il@ and the repeater 305 in the rst llink 300 in the dispatcher exchange tu. The intermittent reversal of current over the previously traced loop circuit causes the supervisory relay R350 to operate and restore intermittently, thereby to complete intermittently, at the contacts dhthe previously traced circuit forilluminating the call signal lamp L11t, whereupon the call signal lamp L11ii is dashed. The ash ing of the call signal lamp 1.113 indicates to the dispatcher at the ilrst dispatcher position ttt that a subscriber at a subscriber substation in the P. A. X til desires the dispatcher's service.

Furthermore, the ilashing of ,the call signal lamp 1.113 or the iiashing of the answer signal lamp L11tl indicates to the dispatcher at the first dispatcher position litt that the established connection upon which his service is desired is routed by way of the ilrst link ttt, the signal lamps Llllt and L111 being individual to the iirst link @dit The dispatcher at `the ilrst dispatcher position ttt then operates the link key H15@ to its talk position, thereby to complete, at the contacts 158 thereof, an obvious path for applying ground potential to the control conductor Cats, thereby to complete an obvious circuit for energizing the lower winding of the control relay R655. When thus energized, the control relay R655 operates to complete, at the contacts 558, an obvious circuit for energizing the winding of the switching relay Rt, thereby to cause the switching relay R65@ to operate shortly thereafter, the latter relay being of the slow-tooperate type. Upon operating, the switching relay R650 completes, at thel contacts 653, an obvious holding circuit for energizing the winding thereof including the grounded control conductor C633 and interrupts, at the contacts litt, the previously mentioned circuit for energizing the lower winding of the control relay Ratti, thereby to cause the control relay R655 to restore shortly thereafter, the latter relay being of the slowtorelease type. Also, upon operating, the switching relay R650 completes, at the contacts an obvious connection between the windings t i i and @i2 of the repeater titl and the line conductors C615 and @dit of the trunk circuit at4 the first dispatcher position ttt, and completes, at the contacts dit, an obvious alternative circuit for supplying current to the transmitter till.

Also when the link key Kitt is operated to its talk position the previously traced direct connection between the line conductors C111 and C112 of the trunk line 11@ and the line conductors C385 and Cf'ltl, respectively, in the cable Zitti are interrupted at the contacts 153 and 156, respectively, thereof. Further, at the contacts 15d and 151 of the link key Kit, there is completed a connection between the line conductors 011i and C112 of the trunk line 110 and the repeater di@ in the trunk circuit at the rst dispatcher position ii, this connection extending from the line conductor C11l of the trunk line 11b by way of the contacts 15d of the link key K15I, the line conductor (21M, the contacts 1d? of the split key K1N, the line conductor C615, the contact ttl, the windings lill and tit of the repeater tlt, the line conductor C616, the condenser 192, the line conductor C139, the contacts 145 of the split key K140, the line conductor C165 and the contacts 151 of the link key K150 to the line conductor C112 of the trunk linel 110. Finally, at the contacts 152 and 155 of the link key K150, a connection is completed between the line conductors C385 and 038| in the cable 300 and the repeater 6I0, this connection extending from the line conductor C385 in the cable 380, the contacts 152 of the link key K150, the line conductor C163, the contacts 143 of the split key K140, the line conductor C615, the contacts 65|, the windings 6H and 6I2 of the repeater 6I0, the line conductor C616, the condenser 192, the line conductor C139, the contacts 146 of the split key K140, the line conductor C166 and the contacts 155 of the link key K150 to the line conductor C38I in the cable 380. Accordingly, at this time, the apparatus in the trunk circuit at the rst dispatcher position 600 is operatively connected to both the repeater 305 in'the first link 300 in the dispatcher exchange 30 and the subscriber substation T2 in the P. A. X 40, the telephone station TI in the dispatcher exchange 30 being 'operatively connected to the repeater 305, as previously noted. Hence, a three-way communication connection including the telephoneA station Tl, the subscriber substation T2 and the rst dispatcher position 600 is completed at this time.

With the link key K150 thus operated, the dispatcher at the rst dispatcher position 600 may split the connection in either direction by selectively operating the split key K140i in the trunk circuit at his position. More particularly, in order to split the connection and talk to the person at the calling telephone station Tl in the dispatcher exchange 50 to the exclusion of the subscriber at the called subscriliverY substation T2, the dispatcher at the iii-st dispatcher position G operates the split key K113i! to its front position. When the split key Kllil is operated to its front position the previously traced connection between the repeater 5i@ and the trunk line lll@ extending to the PA.. X ill is interrupted ,at the contacts F52 and 'E55 thereof; and, at the contacts ll of the split key K'li, there is ccmpleted a bridge path between the line conductors Gili and CH2 of the trunk line llt, thereby to retain the connector switch Mi in the l2. X liti in its operated. position. This bridge path extends trom the line conductor C'l'il o the trunk line il@ by way of the contacts *55 o the link key K'lil, the line conductor (1165i, the resistor itil'. the contacts 'it of the split key Kidd, the line conductor 0F65 and the contacts l5? of the link key ll'l to the line conductor Cl'i of the trunk line lid. On the other hand, order to split the connection and talk to the subscriber at the. called subscriber substation. TZ in the P'. A. X til to the exclusion of the person at the calling telephone station Ti in the dispatcher exchange 35, the dispatcher at the iirst dispatcher position 56@ operates the split key Kilt@ to its rear position. When the split key Kid@ is operated to its rear position the previously traced connection between the repeater @iii and the cable 35i@ extending to the repeater 355 in the first link 305 is interrupted at 'the contacts 153 and 1&5 thereof; and, at the contacts 156i of the split key K150, there is cornpleted a bridge path between the line conductors C176 and CH2 of the trunk line 'l, thereby to retain the connector switch B2i in its operated position. This bridge Apath extends from the line conductor C'lll of the trunk line 110 by way of the contacts 154 of the link key K150, the line conductor C164, the resistor 190, the contacts 144 of the split key K148i, the line conductor C165 and the contacts 151 of the link key K150 to the line conductor C112 of the trunk line 110.

After the dispatcher at the first dispatcher position 600 renders the desired service to the person at the calling telephone station TI in the dispatcher exchange 30 or to the subscriber at the called subscriber substation T2 in the P. A. X 40, he returns the link key K150 to its normal position, thereby to recomplete the previously traced direct connection between the telephone station Tl and the subscriber substation T2 and to free the trunk circuit at the first dispatcher position 600. More particularly, when the link key K150 is returned to its normal position there is interrupted, at the contacts 158, the previously mentioned holding circuit for energizing the winding of the switching relay R650, thereby to cause the latter relay to restore. At this time, the apparatus at the rst dispatcher position 600 is completely released.

At any time, the dispatcher at the first dispatcher position 600 may determine the particular telephone station in the dispatcher exchange 30, included in an established connection extending between the dispatcher exchange 30 and l the P. A. X 40 by way of one of the links in the group of links individually associated with the rst dispatcher position 600, by operating the corresponding link identity key in the trunk circuit at the rst dispatcher position 600. For example, in order to verify the telephone station included in the established connection between the telephone station Tl in the dispatcher exchange 3;@ and the subscriber substation T2 in the P. A. X it routed by Way of the first link 3d@ and the trunk line'llil, the dispatcher at the rst dispatcher position '505 operates the link identity key Kllli in the trunk circuit at the first dispatcher position the link identity key K'liill being individual to the rst link 356. V/'hen the link identity key E216@ is thus operated there is completed, at the contacts 'it thereof, a circuit for energizing the winding of the cutoi relay R52@ in the identity distributor unit 5t@ individually corresponding to irst dispatcher position this circuit extending from ground by way of the contacts 55S, 5t@ and 539, the Winding of R520, Ci'l, the contacts liti of the link identity key Kit@ and the resistor 'E35 to battery. When thus energized the cutoi relay R522@ operates to interrupt, at the contacts and. 523, a circuit substantially identical to that previously traced for energizing the windings of the cutoff relays R535, and respectively corresponding to the second, third and fourth dispatcher positions. Accordingly, the operated cutoi relay R52@ individually corresponding to the first dispatcher position @Citi prevents operation oi the cutoi relays R536; R563@ and R555 individually corresponding to the second, third and fourth dispatcher positions. Hence, it will be understood that, when the identity distributor unit 555 is being utilized by the dispatcher at the rst dispatcher position 5G51 to identify a telephone station in the dispatcher exchange 30, the identity distributor unit 555 is locked against use by the dispatchers at the other dispatcher positions.

Also, upon operating, the cutoff relay R520 completes, at the contacts 526i, an obvious cir-

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