US1863292A

US1863292A - Telephone system

Info

Publication number: US1863292A
Application number: US505823A
Authority: US
Inventors: Whitney Wiley
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1930-12-31
Filing date: 1930-12-31
Publication date: 1932-06-14
Anticipated expiration: 1949-06-14

Description

June 14, 1932. W` WHn-NEY Lfz l TELEPHONE SYSTEM Filed Dec. 5l, 1930 4 Sheets-Sheet l 4 U-O-lr--OLU D--nv-u SEA/DER f3.5

Q I /NVENTOR W. WH/TNEV l ATTORNEY June 14, 1932. W WHlTNEY 1,863,292

TELEPHONE SYSTEM Filed Deo. 5l. 1930 4 Sheets-Sheff(l 2 /NvE/vrof? W. WH/ TNEV A TTORNEV TELEPHONE SYSTEM Filed Dec. 5l, 1930 4 Sheets-Sheet 3 MARS/NAL A T TORNE y w. WHITNEY 1,863,292

TELEPHONE SYSTEM Filed Dec. s1. 195o 4 sheets-sheet 4 June 14, 1932.

Patented June 14, 1932 UNHTEDSTATSS PATENT OFFICE WILEY vWHITNLEY, OF BLOOMFELD, NEW JERSEY, ASSIG-NOR TO BELL TELEPHONE LABO- RTORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK TELEPHONE sY'rsEi/i Application led December 3l, 1930. Serial No. 505,823.

rThis invention relates to improvements in telephone systems and has particular reference to automatic systems in which a calling line is extended from a special service A eperators `position 'to a toll switchboard position for the establishment thereat of a toll or long,v distance connection.

ln well known systems of this character an automatic subscriber sometimes dials the special et or so-calied Zero operator for the establishment of a toll-call when, in fact, the long distance operator is the one desired. The special service operator, under such circumstances, does not request the calling subscriber to restore his receiver and call to the toll operator by dialing the special longl distance code but, instead, obtains from him the oihce and number of the wanted long distance subscriber. The special service operator t-hen establishes a local connection between the special service and toll position by the use of a local selector which, in cooperation with the dialing equipment available at the special service position, selects a trunk connecting' the two positions. This connection, however, is purely local between. trie two operators involved for the passage thereover of the call extending information and since the local selector provides no supervisory7 facilities to the toll position which can be extended back 'to controlsupervision of the calling,r line, the local selector cannot be used to extend the calling line to the toll position. Under such circumstances it becomes necessary for the special service operator to connect the calling subscribers line t-o a singleended holding cord which terminates on a set of terminals on the banks of the iinal connector. Vhen the special service operator communicates the desired` long distance number to the toll operator she likewise 'transmits the terminal number of the holding cord. When the toll operator has established connection with the called line, it will then be necessary for her to establish a connection to the calling snbscribers line and this is done by extending' a cordless trunk, under the control of appropriate apparatus at the cordless B position, to the terminals of the holding` cord. Through the cordless trunk thus used the connection between the callinfblr and called subscriber is completed and the toll operator has talking and supervisory control over the line.

The foregoing routine of operations takes considerable time and, in toll calls where the time required to establish a connection does not justify instructing` the calling subscriber to restore his receiver, as is customary on long distance connections, it would appear desirable to reduce the time necessary to eX- tend the calling line to the toll position and thereby reduce the subscribers waiting time, expedite the establishment of the connection and increase generally the efficiency of the toll plant.

It is one of the objects of this invention, therefore, to provide improved facilities for the direct extension of a calling line from the special service position to the toll position and to make use of these facilities for the transmission of instructions by the special A operator to the toll operator as well as for use as a part of the established connection between the two subscribers.

It is intended to carry out this broad object of the invention by the use of direct trunks connecting the toll position with the special service position, the trunks in question terminating on the arcs of rotary selectors to the movable brushes of each selector of which are connected single-ended cord circuits which terminate at the special service position.

The design of the cord circuit in particular affords a number of novel features, one of which is the transfer of .supervision over the calling line from the special service operator to the toll operator and vice versa depending Vpon which of the two operators involved is connected to the calling subscribers line, it being the intention to always provide the subscriber with facilities for flashing the supervisory signal at either one of the two boards.

A further feature of the invention lies in ay new and novel arrangement whereby the selection of a trunk to the toll position by a cord taken into use is controlled over a conductor which, after the trunk is selected and-connection is established tliereover to the toll position, is also used to control the supernext inpreference without first making an individual test of each .busy trunk in the previous trunk selector.

Still another feature of the invention lies in the use of a selector switch associated with the cord whereby access is obtained to difierent groups of trunks over the saine selector switch. 'The' selector switch employed is preferably a rotary switch with two sets of brushes and correspond-"ing bank contacts. This arrangement enables two or more groups of trunks to be used on the same switch and a connection may be extended over one group or another dependingupon the set of brushes to which the cord conductors and associated circuits are connected.

, In accordance with the invention, therefore, one specific embodiment of which is disclosed herein by way of illustration, the objects and features abovestated are accomplished in theV following improved manner. A- group of'switch-ended cords, each having a supervisory lamp, is provided at the Vspecial service position and tothe arcs of the switch of each cord terminatethe groups of V trunks which extend to the toll `operators, position. Each of these cords contains one key for each trunk group terminating on the arcs of the selector; there being different groups of trunks for different classes of service such as, for example, trunks over which coin collect and refund operations have to be controlled from the toll position and other trunkgroups where no Vsuch .facilities are required. 'If any calling line is extended to the special operators position,.therefore, and the operator learns that a longl distance connection is required, she'depresses the key of that cord taken into usewhicli designates the group of trunks over one of which the connection is to be extended to the toll position and the depression of that key causes the trunk hunting testing circuit to be connected Vover the third conductor of the cord to the particular hunting arc of the two positions exceeds the capacity of a selec-- tor switch, then a plurality of switches are used and the cord is arranged to hunt in every selector in a definite preference, with means for automatically skipping any selector all of -Whose trunks are busy at the time the cord circuit is hunting for an idle trunk.

When a trunk is found, the trunk hunting testing circuit is disconnected from the third conductor of the cord and another circuit is connected thereto which is responsive to sleeve supervisory operations in the selected trunk and controls the lighting of the superposition, the special service operator transmits to the toll operator the necessaryinformation for establishing the toll call. The cord may be inserted into the jack of the trunk line over which the calling subscribers line was extended to the special service position either i before or after the selection of the trunk to the toll position: the calling line extension having been first made free by the removal of the special service cord with which the subscribers line was first answered since, at that time, the special service operator did not know whether the calling subscriber wanted assistance in establishing a purely local connection or whether he wanted a toll call.

Thereafter the calling subscribers line is extended to the toll position by the use of the cord and trunk contemplated-in this invention, thereby obviating the necessity of the toll operator calling the. subscriber over a i* cordless trunk. `The calling subscribers line is placed under the immediate supervision of the toll operator so that as long'as the special service operators telephone circuit is not connected to the cord the calling line is under n supervisory control atthe toll position.

A clearer conception of the scope and purposeof the invention will be obtained from la consideration of the following description taken in connection with the attached drawings in which, Y n

Fig. 1 shows a part of the cord circuit which is the subject of this invention together with a subscribers'exte-nded connection to the spe-A cial service position and a simplified open ators telephone circ-uit thereat Y Fig. 2 shows the cord trunk selector; Fig'. 3 shows the part of a representative trunk which extends to the toll position;

Fig. 4 showsA the remaining part of the trunk which terminates at the toll position together with a schematic representation of a completed toll connection; and

Fig. 5 shows the manner in wh.ichthe above drawings are to be arranged with respect to Iwie ate.

the long distance area can thereafter each other in orde-r to completely disclose the invention. Y

l/Vhen the calling subscriber 100 initiates call through the medium ci line linder 133, the switching selecto-r 134 and the central otice sender 135, the line is extendedto the trunk terminating in ack 151 at the s1 eeial s rvice position. A typical manner in which this may be accomplished disclosed in Patent No. 1,589,402 to O. H. Kopp, granted June 22, 1926, and hence neither shown .in detail nor made a part ot this description. By closure vof a circuit loop through the sender and the switching selector 13-1 as describedinthe above identified patent, relay 11l8 is caused to oper- Relay. 118 connects resistance ground over its top contact to the trunk terminal on the selector' bank to mark it busy to testing selectors and, on its loiver contacts, closes an obvious circuit for lamp 1:50 which lights and indicates that a call is Waiting. r1the operator answers the call with a special service cord, which is not shown, and upon learning that a long distance connection desired, makes out the usual ticket covering the details ot the call and proceeds thereafter to establish a connection betwee' the calling subscr'ber and the toll position from iv u the connection to be completed in the Well known manner.

are associated. with the cord. The particu1 key depressed depends upon the character of the service to be rendered to the calling subscriber, which fact is known to the operator by the character of the trunk group over which the calling line was extended to the special service position. For example, it the subscriber initiates the call from a coin box station, then the sender associated with the line finder 133 would direct the switching selector 134i to select a coin group of trunk, 'i which the trunk terminating in jack i Would be one and this tact would be known to the operator either by the color of "li lamp LMC or by the segregation ot the various truuk groups to various parts ot jack shell' positions or by any other suitable means. l iices Vfor the purposes ot this disclosure that thespecial service operator will extend the calling line to the toll position over a trunk line designed for the same character i fr ice that over which the calling line .v extended to the special service position. ln this description it is assumed that the subscriber is calling from a non-coin line and that key 136 designates the non-coin truuk group. Accordingly, the operator depresses key 136 of any one ot the idle cords which she takes into use for this connection The opera tion of key 136 closes a circuit Alor relay 108 from battery, Winding ot relay 108, lower contacts of key 136, top outer back contacts of relay 115, normal contacts of relay 102, top contacts of relay 109 to ground. Relay 108 operates and locks over its top outer make contacts to the operating ground on the back contacts of relay 109. Relay 108 closes a circuit from ground over its bottom inner make contacts, top outer normally made contacts oi relay 106, ufinding of relay 105, conductor 139, top outer contacts of relay 119, resistance 138 to battery, operating relay 105. Relay 105, by the closure of its bottom contacts, connects ground to the Winding of relay 111 and resistance 140 thereby keeping relay 111 short cireuited. Relay 103 also closes a path from ground over its top inner contacts, bottom back contact of relay 116, bottom outer back contacts of relay 107 to one terminal ot the Winding of relay 107, This last closure is for the purpose of preventing the operation of relay 107 when relay 106 operates as is described hereinafter.

Relay 108, over its bottom middle contacts, closes a path from ground through both Windin gs in series of relay 116, top inner back contacts of relay 107, bottom middle contacts of relay 108, conductor 126, top middle back contacts of relay 200, to brush 213 and corresponding terminal of selector TKl. It, at this time, the trunk extending to the toll position an d With Which the

brushes

211, 212 and 213 of switch TKl are in contact, is idle, then relay 116 will operate over a circuit from ground through both windings of relay 116 in series, over the circuit path j ust traced to brush 213 and its corresponding contact, conductor i218, bottom contacts of relay 307, bottom normally made contacts of relay 305, resistance 314 in parallel with the upper Winding ot relay 303 to battery. Relay 1,16 operates in the above circuit, short circuits its own bottom high resistance Winding by the closure ot its bottom contacts and connects the upper low resistance wi n ding to the trunk selector multiple bank terminals to make the selected trunk test busy to relays 116 o'f other cords. Relay 116, by its operation, also removes the ground from one side of the Wind ing of relay 107 since, as is described hereinafter, if relay 106 operates at this time the operation of' relay 107 can take place. Relay 303 likewise operates in the above circuit and locks over its bottom Winding and contacts to conductor 218. Relay 303 closes an obvious circuit for relay 308 which operates. Relay 308 removes ground 'from its back contact to conductor 217 thereby removing one of the parallel grounds to this conductor. The further function ot' relay 303 is described hereinafter.

lt, on the other hand, the trunk With Whose terminals on switch 'lKl the selector brushes 211, 212 and 213 are connected is busy at the time that the circuit of relay 116 is closed through, then the grounded low resistance inner contacts ot relay 108 to ground.

Winding of another relay 116 ot the cord which is making the trunk `busy is connected to the corresponding terminal offbrush 213 and the operation of relay 116 of the cordv under consideration yis prevented; Under such circumstances, the hunting circuit of trunk selector TKl will or will not be closed depending upon whether or not the operators telephone circuit is connected tothe cord whose trunk group key has `been operated.

The present embodiment of the invention isdisclosed in connection withan operators telephone circuit provided with the wellV depression of key 136 or 137 automatically connected the operators telephone circuit to the cord under consideration. This is accomplished when relay 105 operated in the manner described ri`he operation of relay 105 closed a circuit :tor relay 106 from battery through the winding ot relay 106, bottom inner normally made contacts ot relay 106, top contacts .of relay 105, bottom middp parallel circuit is likewise closed to the winding of relay 11e which likewise operates and connects'conductors 140 and 141, respectively, to the keys in the operators position Y for future use in iiashing the toll operator or .releasing the trunk connection as more fully described hereinafter. Relay 106 operates, locks over its bottom inner contacts to tli-e said ground at relay 108 and, by opening-its top outer normally made contacts, removes the short circuiting ground over the bottom contacts of relay 105 to the Winding of relay 111 and resistance 140. Relay 111 now operates in series with the winding of rela-y 105 to battery on the top outer contacts of relay 119 and by the closure of its top contacts vconnects the operators telephone circuit to the cord conductors 142 and 143.

It is also possible that the operator-s telephone circuit may have been left connected to another cord by virtue of a previous operating connection therewith and-left in that position `after service was ended without the operator listening' out. Under such circumstances relays 111 and 105 ot that cord are locked in Vseries to (battery on the top outer contacts of relay 119 in the same manner as relays 111 and 105 of the cord under description.v However, when a key such asA 136 or 137 is depressed and relay 105 operates, the grounded 10W resistance Winding of this relay is connected to conductor 139 and has the eilect of shunting relay 105 in the other cord which relay then releases and opens the circuit 0I" relay 111 thereby disconnecting the operators telephone circuit from the said other cord. Relay 111 of the cord under description then operates in the manner described and connects the operators telephone circuit thereto. It the operator is connected to no cord, that is, is listened-out by having operated key 120, then relay 1 19 is operated over an obvious circuit and battery through resistance 138 would not be available to operate relay 105 until rrelay 119 'is released, that is, until the operator had released the listen-out key 120.

' Relay 106 completes the operating circuit of relay 107 from battery through resistance 117`v winding of relayv 107 to ground on the bottom outer contacts of relay 106, and also closes the circuit ot relay 202 from battery through the winding` of relay 202, interrupter contacts of selector magnet 203, interrupter contacts of selector magnet 204;, bottom inner back contacts of relay 200, conductor 128, bottom inner normally made contacts of relay 113, top inner contacts of relay 106, top outer back contacts of relay 107 to ground on the top outer back contacts of relay '116. It will be not-ed that, although the circuit of rel-ay 107 was completed by theoperation of relay 106, yet relay 107 does not operate so long as relay 116 remains unoperated since, under these conditions, the groundshort circuitingr resistance 117 is still eii'ective. That is to say, the above traced circuit for relay 202 is effective only if trunk selector TK1 is standing on the terminals ot a busy trunk. Under such circumstances, the above traced circuit of relay 202 is effective andl this relayvoperates. Relay 202 closes the circuit of selector magnet 204C from ground on the top contacts of'relay 116, top out-er contacts of relayr107, top inner contacts of relay 106, bottom inner back contacts o'f relay 113, conductor 128, bottom 'inner contacts of relay 200, top contacts of relay 202, bottom back contacts yoit relay201, winding of selector magnet 204 vto battery. Selector magnet 204i operates, breaks its interrupter contacts` and opens the circuit of relay 202 which releases. The release of relay 202 releasesselector magnet 204Y which now advances its brushes'to the next terminal in the well known manner and reoperates relay 202 over the previously traced circuit. This cycle of operations is repeated until the

brushesY

211, 212 and 213 of selector TKl i reach the terminals of an idle trunk, at which time the shunt to both windings of relay 116 `is removed and a previously traced operating circuit is then effectiveto operate relay 116. The operation of relay 116v opens the circuit of relay 202which releases and the release of relay 202 opens the circuit of the selector magnet 204:, thus stopping the described cycle of operations and leaving the selector brushes resting on the terminals of the selected trunk. The operation of relay 116' removes the short circuit from the winding of relay 107 which now operates and relay 116 further short circuits its own high resiste ance winding in the manner previously described thereby making the trunk test busy to all other limiting cord circuits.

If it should come to pass that the number of trunks of a particular class as, for example, non-coin trunks, available to the cord exceeds the capacity of one switch, that is, three banks of the switch and the corresponding terminals, while the remaining three banks are already used for a groupl of trunks rendering a different grade of service, an additional selector switch, such as T K2, may be furnished which, according' to the present embodiment of the invention is capable of accommodating two addition al groups of trunks; one group on three terminal banks and another group on the remaining three other terminal banks.

. rthese two groups may be combined to convrE35..

stitute one larger group if the traffic justifies it, separate and distinct from, though rendering the same character of service as the trunk group on the three upper terminal banks of switch TKl. 0r they may be two separate groups of trunks for rendering two separate classes of servi c- In the present embodiment of the invention, as disclosed in Fig. 2, switch TX2, is used for one large group of trunks similar to the group on the three upper banks of selector switch TK1.

Each group of trunks is provided with a relay whose vinding is connected to conductor 21'( which is multipled to the back contacts of all relays 308 of the trunk group.

'Since the armature cont-acts of all relays 308 are grounded, an operating circuit eXists for relay 222 so long as one or more trunks of the group are idle. As each trunk of the group is taken into use and its associated relay 308 operated, the parallel grounds to the winding of relay 222 are successively removed so that, when all of the trunks in the group have been taken into use, the circuit of relay 222 is opened and relay 222 releases. If relay 222 is associated with the group of trunks terminating on the three contact banks of switch Tll, above described, and all the trunks terminating therein are busy, relay v222 is released and when the operator depresses key 136 and the circuits of the associated cord are operated to connect the said cord with an idle trunk, the fact that the trunks terminating on switch TK1 are all busy and av 222 released will serve to close a circuit for relay 200 from battery on the contacts of relay 222, upper winding of relay 200, conductor 127, bottom outer contacts of relay 108 to ground on the bottom middle back contacts of relay 107, thereby operating relay 200. Relay 200 locks over its lower winding and bottom outer contacts, conductor 125 to ground on the bottom middle inner contacts of relay 108 and this locking ground is then ext-ended by way of the bottoni back contacts of relay 202 to the winding` of relay 201 which now operates and locks over its top inner contacts to the said ground on conductor elay 200, on operating, transfers the talking

conductors

131 and 145 of the cord from the brushes 211 and 212 of selector r1K1 to the corresponding

brushes

210 and 209 of switch TK2, which brushes are multipled to the staggered brushes 214, and 215 respectively of the other three terininal banks of the switch, so that only one of the two sets of brushes will engage a set of trunk terminals at a time, Brush 20S is similarly multipled to the staggered brush 219. Relay 200, by operating, also disconA nects the windings of relay 116 from brush 21S-l of switch Tll, and relay 201, by operating, connects the windings of relay 116 over coi d ictor 126, oyer its top outer contacts to

brushes

208 and 210 of switch TK2. The circuit of relay 202 is now closed from battery, through the winding of relay 202, interrupt'er contacts of selector magnet 20?) of selector TK2, interrupter contacts of selector magnet 201 of switch TKl, bottom inner contacts of relay 201, conductor 128 and thence to a previously traced ground on relay 11G. Relay 201 also' disconnects the winding of selector magnet 204 of switch TK1 from the contacts of relay 202 and connects the winding of selector magnet 203 to the above-mentioned contacts of relay 202. Hunting will now take place in trunk selector TK2 until an idle trunk is found either by the set of three

brushes

208, 209 and 210 having access to the upper half of the trunk group or by the sot of

brushes

219, 215 and 214 having access to the lower half.

Consideration so far has been given to a description of the extension of a calling subscribers line to the toll position over a noncoin trunk. if the call originates at a station having a coin box, the switching selector and sender shown in Fig. 1 cause the connection to be extended over a coin trunk line and the operator must, accordingly, extend the connection to the toll operators position over a trunk provided with coin collectand coin refund supervisory facilities. When a connection is extended from a coin box substation, therefore, the operator takes up the connection in the usual way with a special servi ce cord, writes out the ticket and refunds the deposited coin to the subscriber. The operator then proceeds to extend the sub scribers line to the toll operator-s position by using the cord under description except that instead of depressing key 136, which designates a non-coin group of trunks, she depresses key 137 which designates a coin group of trunks. A circuit is thereby closed `forv relay 115 from battery through the winding of relay 115, bottom contactsfot rey 137, top outer back contacts of relay 103, normally made contactsot relay 102 to ground on the contacts of relay 109. Relay 115 operates 116'to conductor 123 and thence to theV test wiper 20501: switch TKl. The 'conductors of this group of trunks terminate on terminal banks ofselector-Tll which cooperate with

brushes

205, 206 and 207, respectively.

Itis thus seen that a trunk `selector may be madeto accommodate two separate and dis 5 tinct groups of trunks rendering-a diilerent character of service and theV selection oi a trunk in either group is accomplished simply by connecting the vtrunk hunting test circuit to the test brush of'one group or the other, and although the brushes ot the entire switch are rotating together and make contact simultaneouslyL with trunks ot both groups, yet only those associ atedwith the trunk group in which a trunk selectionisto be made will be effective, the other brushes being inactive at this time.

If, at the time the circuit of relay 116 is closed `though the selector brush 205 is contacting with the test termi nal of an idle trunk,

. relay 116 willv operateas already described and if it is contacting with the'test terminal of a busy trunk, relay 116-will be shunted, relay 107 will notoperate and a circuit will be closed for relay 202 from battery through the winding of relay 202, Ainterrupter contacts of

trunk selector magnets

203 and 204, bottom yinner back contacts of relay 200, conductor Y 128.I bottom inn-er make contacts oifrelayV 113,

top inner make contacts of relay 106, top outj er contacts of relay 107 to ground on the top contacts of relay 116, operating relay 202 and causing the operation of trunk selector TKl to select an idle trunk in the same man-Y Y ner already described for the operation of thesame trunk selector for `the selection cfa trunk in the non-coin trunk group terminating on terminal banks cooperating with brushes 211,212 and 213. Y

V"When the trunkselector has been brought to rest on the terminals of an idle trunk, lit matters not from which group, relay 116 `opfV crates in series with relay 303 over apreviously described circuit. vRelay 107 likewise operates in the manner described. The operation of relay 107 opens the operating path Re-v ' otrelays202 and .116, disconnects relay 116V from

conductor

126 or 123 and connects the conductor involved of the two said conductors over its top inner front contacts to the winding of relay 101, and closes a circuitfor relay 112 from battery through the winding ot relay 112, bottom outer front contacts of relay 107, bottoni back contacts of relay 116 to ground on the top inner'contacts of relay 1.08 or relay 115, thereby operating relay 112. Relay 101 is know connected to the test terminal of the selected trunk and the windingo'r' this relay is designed topossess the same electrical characteristics as the upper winding ot relay 116 in order to maintain the identicalv busy condition on the trunk test terminal. Relay 116 releases and relay 101 is now connected in a circuit path from ground through Y the winding of relay 101, top inner front contacts of relay 107, bottom middle contacts of relay .108 it this relay is operated, or bottom outer 'contacts ofy relayv 115 if this latter relay is operated, conductor 126 in the former case or conductor 123 in the latter, top middle back Vbottom outer contacts of relay 307, bottom normally madecontacts of relay 305, upper winding lof relay 303 in parallel with resistance 314 to battery. Relay 101 operates. in` this circuit while relayV 303 Vwas operated in the same circuit when relay 116 was in circuit in place of relay 101 and now holds in the same circuit in series with relay 101. The operation of relay 101 connects battery to low resistance 141 and shunts any circuit for lamp 146 thereby keeping the said lamp extinguished. Relay 112 closes the talking conductors 142 and 143 of the cord to the selected trunk and connects ground over its bottom inner contacts'to resistance 144. A connec- Y tien of ground to resistance 144 completes the circuit to lamp 146 vbut since battery is connected to resistance 141 from the contacts of relay 101, lamp 146-remains shunted. Y

lll/Then relay -112'operates, a circuitis closed from battery; through resistance 316'oll the selected trunk, upper vwinding of [relay 302, winding 317 ot the repeating coil, top outer back contacts of relay 300, conductor 223,

brush 211Aand corresponding terminal, top outer back' contacts of relay 200,conductor 131, top outer .back contacts orn

relay

1,13, top

outer front contactsofrelay 112, conductor .and 305 all operate.

Lacasse outer back contacts of relay 113, conductor 145, top inner back contacts of relay 200, brush 212 and corresponding terminal, conductor 216, bottom back contacts of relay 300, repeating coil Winding 318, lower Winding of relay 302, resistance 315 to ground. Relay 103 in the cord and relay 302 in the trunk operate in this circuit. Relay 103 performs no function at this time.

Relay 302 operates and connects ground to the following three parallel paths: one to the Winding of relay 306, another by Way of the bottom outer normally made contacts oi relay 312 to the Winding of relay 30T and another over the same contacts of' relay 312, toi) inner normally made contacts of relay co the Winding of relay 305.

Relays

306, 307 Relay 306 connects ground over its top outer contacts, top normally made contacts ot relay 309, winding oit relay 309 to battery. Relay 309 operates and locks to thev top make contact of relay 303. Relay 307, on operating, closes one pair of contacts of the talking circuit, opens its bottom outer back contacts, thereby opening the original operating circuit of relay 303 and, over its bottom inner contacts short circuits the lower Winding of relay 303. Since relay 303 is held over conductor 218 in series with marginal relay 101 as above described, the operation of

relays

307 and 305 merely transfers the short circuit control to the bottoni operated contacts of relay 305. Relay 101 remains operated, therefore, and maintains battery connected to resistance 141 and keeps lamp 146 extinguished. Relay 309 on operating, closes a circuit from battery through the top Winding` oi relay 310, top inner contacts of relay 309, resistance 319, top inner iront contacts of relay 306, repeating coil Winding 321, conductor 313, top back contacts of relay 400, repeating coil Winding 407, both uf'indiiigs in series of polarized relay 405, repeating coil Winding 408, bottom back contacts of relay 400, conductor 314, repeating coil Winding 322, bottom 'ront contacts of relay 306, resistance 320, bottom contacts of relay 309, bottom Winding of relay 310 to ground. Relay 405 operates in this circuit but relay 310 being marginal does not. Relay 405 closes a circuit for relay 403 from ground at its front contacts, bottom contacts of relay 404, Winding of relay 403 to battery. Relay 403 operates and closes an obvious circuit for lamp 402 Which lights and thereby indicates at the toll position that a call is waiting on the associated trunk.

Should the toll operator delay in taking up the connection the special operator may call the attention of the toll operator by intermittenti-y operating key 121 and cause the flashing of the trunk lamp 402. The operation of key 121 closes an obvious circuit for relay 104. Relay 104, on operating, opens the loop circuit including both windings ci'

relays

103 and 302. Relay 302 releases and in turn releases relay 306. Relay 306, in releasing, reverses the direction of the current ioWing over the circuit previously described and including

relays

310 and 405. polarized and the reversal in the direction oE the current flowing through its yindings causes its release. relay 403 follows the release of relay 405 and opens the circuit of trunk lamp 402. As the operator alternately operates and releases key 121, lamp 402 is alternately extinguished and lighted.

The toll operator answers the call by in sorting the plug ot a toll cord .into the answering jack 411, which cord is shown diagrammati cally in Fig. 4, causi. thereby the operation or relay 404 over a circuit troni. a battery potential in the sleeve o1' the toll cord, trunk jack sleeve 410, upper high resistance Winding ci? relay 404 to ground. The resistance of the upper Winding oi relay 404 is such that the relay device in the toll cord which controls the supervisory lamp 412 is not operated on the current flowing through the said circuit and lamp 412, therefore, will not light. Relay 404 operates and opens the circuit ot relay 403 which releases and eX- tinguishes trunk lamp 402. Relay 404 also operates relay 406 which, on operating, short circuits the upper high resistance Winding of relay 405. The quantity of current noiv flowing through the previously described circuit, including

relays

405 and 310, is increased and is suliicient to cause the operation of relay 310. vWhen this relay operates it operates relay 311 and relay 311, over its top contacts, closes a circuit for operating relay 312, which over i Y bottom inner front contacts locks to ground on the top maize conn tacs ot relay 303. Relay 312, over its 'to itacts, completes the talking loop of the ink. Relay 311 also connects thc same ground to the top outer contacts of relay 305 and thence to the normal contact of relay 303 to hold relays 30S and 312 'from releasing should rel y 303.,` for any reason, release. Re lay 311 also closes a holding circuit for relay 307 trom battery through the Winding of relay 307, bottom outer liront contacts of relay 312 to ground on the top contacts of relay 311. elay 304 is also conne/iced across the talking

conductors

310 and 314 by the closure oi the bottom contacts oif relay 311.

The talking circuit is now established between the telephone circuit ot' the special service operator and that ot the toll operator wherein the telephone circuit C. C. of the toll operator is operatively connected to the toll cord in a manner Well known to the art and hence not shown in the drawings. The special service operator transmits to the toll operator the necessary information for completing the call and will then listen out by operating the position listen-out key or by listening in on another circuit. This op- Relay 405 is iii) eration causes the alterna-te release and operation of relay 404 which, in turn, causes the corresponding response of relay 406 and this relay, by opening and closing its bottom contacts varies, in the manner described, the quantity of current flowing through the trunk circuit, above traced, and including marginal relay 310. Relay 310, therefore. alternately releases and reoperates. rllhis, in

Uturn, alternately releases and operates relay Athe contacts of relay 308.

307 which follows relay 311. The release and reoperation of relay 307 alternately removes and restores the short circuit around the lower winding of relay 303, since, as already described, relayv 305 is held operated from This causes an alternate high and low resist-ance condition on conductor l213 which permits relay' 101 to release and reoperate. The release and reoperationV of this relay'alternately removes and reconnect-s battery over its top contacts to resistance 141 thereby flashing lamp 146.

Y As already indicated, the special service operator may answer the origina-l connection with aspecial service cord, which type of cord is well known to the art, and all of the above described operations take place Independent of whether or not the cord plug 154 in inserted into trunk jack 151 and only as the resultof operating a trunk group key, such as key 136 or 137; Vhen, however, the operator does remove the special service cord from the subscriber connection and substitutes therefor the cord taken for extending said connection tothe toll position, relay 132 operates over a circuit from battery through the winding` of relay 132, sleeve conductor 147, winding of relay 149 to ground.

Relays

132 and 149 operate. Relay 149 opens the trunk conductors to relay 148 which releases and over itsbottom outer contacts closes an obvious circuit for relay 152 which operates and maintains the trunk busy test condition on the selector' bank multiple. Relay 132, over its bottom outer contact, connects ground l to resfstance 144, which ground is in multiple tothe ground from the contacts of relay 112. If, at this time, the cord connection has already been extended to the toll position, re-

y lay 101 will be operated, as already described,

andthe battery from the top contacts of relay 101 will be connected to low resistance 141 and the lamp 146 will be shunted and f extinguished. On the other hand, if the cord connection has not been extended'to the toll positionwhen the cord plug 154 is inserted into jack 151 neither relay 112 nor 101 will be oper ted the operation of relay 132 as abovedescribed closes the aforementioned circuit to light lamp 146.Y Relay 132 also closes obvious circuits for relays 102 and both of which operate, Relay 110 is provided with a locking circuit over its bottom contacts to ground at the bottom inner contacts of relay 107 when this relay operates as described and, over Ats top contacts, closes a pair of c ntacts of the circuit. of relay 104. lllhen' the operator listens out from the cord, relay 111 is released as already described, and the circuit path for relay 104 iscompleted to ground on the bottom contacts ot` relay 111. Relay 104, by operating, removes from its `transfer contacts the bridge composed of both windings of relay 103 from across the talking conductors 131 and145,

or and 129, and if the connection has been extended to the toll position by this ti meand relay 112 operated vin consequence, relay 302 is placed across the subscribers loop Vin a. circuit including relay 302, conductor .142,

'tip of the cord, upper conductor of trunk and line iinderenension, subscribers loop, lower conductor of line finder and trunk, conductor 143 and thence over a previously traced path toboth windings of relay 302. Thus as soon as the subscribers line is connected to the cord taken into use and the cord has been extended to a trunk connecting with the toll position, the circuit for calling subscriber supervision is immediately transferred to the toll position. It is apparent, however, that subscriber supervision at the toll position is dependent upon whether or not the special service operator listens in on the cord. For,

if ,the operator listensin, relay 111 will be operated inthe manner described and relay 104fwill be released. Under such circumstances the subscribers loop Ycircuit above described isV in parallel with the bridge across

conductors

131 and 145 formed by relay 103 and relay 302. Should the subscriber flash, the path through both windings of relay 103 will hold relay 302 operated. Relay 302 holds relay 306 which, in turn, preserves undisturbed the

circuit including relays

310 and 405, previously described, and the toll cord lamp 412 will not flash.V VVThe special service operator, however, has her telephone circuit bridged across the 'cord vand is, therefore, in aV position to challenge if the subscriber should move his switchhook up and down.

1f the cord under consideration is substituted forV the special service cord prior to the described operations for extending the connection to the toll position by the operation of either key 136 or 137, relay 132 will operate as before. Relay 132 will close the above described circuit for the supervisorylamp 146 light-ing it thereby and closing previously tor 143,. over the loop including the trunk switching stage, line finder and calling subscribers line, top outer backcontacts of relay 112, upper winding of relay 103 to ground on the bottom front contacts of relay 104.

.y Relay 103 operates over this circuit and closes battery from the top inner back contacts of relay 112, contacts of relay 103, resistance .141 to lamp 146 thereby shunting lamp 146. If, now, the calling subscriber flashes or disconnects, relay 103 will follow the ilashes and, in turn, flash or light lamp 146. If, in response to a disconnect signal, the cord is disconnected yfrom the multiple at this time, relay132 will release, in turn, releasing

relays

110, 102 and 104and restorev thereby the circuit to normal.

When the cord yhas been extended to the toll position the toll operator thereafter completesthe connection to the wanted subscriber in any well known manner. Supervision of the calling liney is under the control of lamp 412 of the toll cord. Should the subscriber flash, relay 302 releases which, in turn, releases relay 306. The release of relay 306,

. .i reverses the direction of current flowing in the circuit previously traced and including

relays

310 and 405. Relay 405 is polarized and releases as already described. The release of relay 405 connects ground over the back contac-ts of relay 405 tothe low resistance winding of relay 404. The combined parallel circuit of the upper and lower windings of relay y404'increases the current over the sleeve conductor circuit of the cord, previously traced,

, and the increase in current operates the relay device inthe cord which controls the circuit of'lamp 412. Lamp 412 lights and, as the subscriber flashes, the above circuits alternately operate and release to flash the lamp.

When conversation has terminated and the calling subscriber restores, the circuit for relay 302 is opened, relay 302 releases, and, in turn, releases lrelay 306. Relay 306 reverses the trunk conductors to cause the permanent lighting of lamp 412 as an indication that the calling subscriber has restored. Upon receiving the signal, the toll operator disconnects the toll cord from the jack and by so doing releases relay 404. Relay 404 releases relay 406 and thereby opens the short circuit around the high resistance winding of relay 405. Thev increase in current in the circuit including relays 405 and relay 310, previously traced, causes relay 310 to release.

'When relay 310 releases, it in turn, releases relay :311. Relay 311 releases relay 307 and relay 307, in releasing, removes the short circuit around the lower winding of relay 303. The decrease in current through the circuit including both windings of relay 303 and the winding of relay 101 and resistance 314, previously traced, is not suiiicient to maintain relay 101 energized. Relay 101, therefore, releases and removes battery from resistance 141. The removal of shunt battery from resistance 141 causes lamp 146 to light over a previously traced circuit. The lighting of lamp 146 indicates to the special service operator that the toll operator has released the trunk whereupon the special service operator removes the cord plug 154 from trunk jack 151. rlhe disconnection of the cord releases relay 132, thereby releasing

relays

102, 110 and 108 or 115. Relay 102 is slow to release so that

relay

108 or 115 will have time to release before its locking path is closed again through the back contacts of relay 102 to ground on the contacts of relay 109. The release of

relay

108 or 115 releases all operated relays and restores the circuit to normal.

The A operator may also disconnect the connection to the toll operator at any time by listening in and by operating the position disconnect key 122. In order to listen in the operator first depresses key 136 or 137, depending upon the trunk group to which the trunk taken into use belongs, and then depresses key 122. rlhe operation of key 136 closes a previously traced circuit for relay 105 and relay 111 will then remain shunted to ground on the top contacts of key 136 through the bottom contacts of relay 105 until key 136 isreleased whereupon relay 111 operates and locks in series with relay 105 as already described and connects the operators telephone circuit to the talking conductors of the cord. The operation of key 122 closes a circuit for relay 109 from ground through resistance 153, contacts of key 1.22` top contacts of relay 114, upper winding of relay 109 to battery. Relay 109 operates and releases relay 108 or 115. Relay 109 locks over its bottom winding and contacts to ground on the contacts of key 136 or 137. This locking` circuit prevents

relay

108 or 115 from operating and originating a new call should the corresponding trunk group key be accidentally depressed when relay 114 releases and opens the operating circuit of relay 109. The

release oIn relay

108 or 115, in turn, releases relay 113, if it is operated and relays 200 and 201, if these last two relays are operated and also relays 114, 106, 107 and 112. The release of relay 112 operates relay 104 over a previously described circuit and reconnects battery and ground through relay 103 and the back contacts of relay 112 to the 4calling subscribers line, as previously described. Relays 105 and 111 remain operated, however', keeping the operators telephone circuit connected to the cord. 1f now, the

' subscriber from the toll position.

calling subscriber is still on the line, relay 103 operate's'andv extinguishes lamp 146. If, however, the calling subscriber has already restored, relay 103 will not operate, lamp 146 will remain lighted and the A operator is free to disconnect the cord from the multiple. When the cord is disconnected all relays, except 105 and 111 release. Relays 105 and 111 will release when the operator listens in on another cord or when she operates the position y listen-out key y120. The disconnect ysignal to the toll operator is given as previously described. Y Y

If the A operator disconnects the cord from the multi le before receiving the disconnect signal as described above, the release of relay 132 will not release relay 108 or`115 as either of these relays will hold to ground on the bottom contactsl of relay V101 during the interval between the release of relay 132 and the release of relay 102. and thence to ground on the top contacts of relay 109. Relay 110 will remain locked under control of relay 107, thereby keeping relay 104 operated unless the special service operator has listened in on this circuit. Relay 104 being operated under such circumstances keeps relay 103 ofi' the trunk, thereby releasing relay 302 and consequently causing the closure of circuits which light lamp 412 of the toll cord as already described. When the toll operator disconnects, the removal of the short circuit around the lower winding of relay 303 releases relay 101 as already described, and lamp 146 will light, as already described. The special .service operator will then release the connection by listening in'and by operating the position-disconnect key 122. p Although the present embodiment ofthe invention is based on the assumption that. theV calling subscriberrwill not restore the receiver during the interval between giving the toll number and the .establishment of a' talking connection with the wanted subscriber yet it is realized that subscribers often will restore the receiver and must be recalled. Provision is therefore made to ring back the If the subscriber restores, relays 302 Vand 306 are released and lamp-412 will light as already described. When the connection is ready the operator will depress theringing key of the'toll cord, which is not shown, and this operation will connect battery over the tip of thecord and operate relay 400. Relay 400 operates and closes a circuit forrelay i304 from ground on the top outer contact of relay 400, conductor 313` winding 321 of repeating coil, top inner back contact of relay 306. resistance 320, condenser323, winding of relay 304, bottom contacts of relay 311, resistance l319, bottom outer back contacts of relay 306,

winding 3,22 of repeating coil, conductor 314,'bottom front contact of relayv 400, ballast lamp401 to a source ofringing current. 'Relay 304 operates and ,connect-s ground to the` `30'8and' 309 in order to guard' against any possible false release of these relays during the ringing period. fWhen the subscriber answers, relay 302 operates and previously described circuits arey then eifecti'veto extinguish lamp 412.'

That is claimed is: f

1. In a telephone system, allink circuit, a selector switch in which said link circuit terminates, a plurality of trunk circuits to which said switch has access, means controlled over the test brush of said switch for controlling the hunting movement thereof to cause said switch to connect said link with an idle trunk, a supervisory signal 'in said link circuit and means for controlling said signal over'said test brush.l c

2. In a telephone system, a link circuit, a selector switch in which said vlinkcircuit terminates, the said switch having a plurality of sets of contact banks and a corresponding plurality of sets of cooperating brushes, a plurality of groups oftrunk circuits, each of said groups being connected to a separate set of contact banks of said switch, means con-` said sets of cooperating brushes for controlling thezhu'nting movement of saidswitch in the `corresponding banksto cause said switch toV connect said link circuit with an idle trunk, av supervisory signalin said link i circuit and ineansfor controlling said signal over said testfbrush. A s v 3'. 'In a telephone system, a link circuit, a plurality of selector switches, a group of trunk circuits terminatingin each of lsaid selector switches, means for` connectingisiaid link circuit toeacli ofsaid selector switches in a deinite'order or preference, means'controlledV over the testbrush ofthe selector switch to which saidlink circuithas first preference for controlling the hunting movement thereof, means responsive to an allbusy condition of the trunk group terminating in any selector switch for connecting said link Y.

circuit to the next selector switch iii the order of preference without testing the busy trunks terminating in the previoussele'ctor switch, means controlled overthe test brush of the selector switch to which said link circuit has been' connected for controlling the hunting 'movement thereof to cause said switch to vcon'- nect said linkwith an -i'dle'ltrunlg a superi visory signal in said link circuit andrjmeans for controlling said signal over said test brush,

4. In a telephone system, an operators position,a cord circuit at said operators position, a selector switch in which said cord circuit terminates, a plurality of trunk circuits to which said switch has access, means controlled over the test brush of said switch for controlling the hunting movement thereof to cause said switch to connect said cord circuit with an idle trunk, a supervisory signal in said cord circuit and means for controlling said signal over said test brush.

5. In a telephone system, an operators position, a cord circuit at said operators position, a selector switch in which said cord circuit terminates, the said switch having a plurality of separate sets of contact banks and a corresponding plurality of separate sets of cooperating brushes, a plurality of groups of trunk circuits, e-ach of said groups being connected to a separate set of contact banks of said switch, means controlled over the test brush of any set of said sets of cooperating brushes for controlling the hunting movement of said switch in the corresponding bank to cause said switch to connect said cord circuitwith an idle trunk, a supervisory signal in said cord circuit and means for controlling said signal over said brush.

6. In a telephone system, an operators position, a cord circuit at said operators position, a plurality off selector switches, means for connecting said cord circuit to each of said selector switches in a definite order or preference, a plurality of groups of trunks terminating in the contact banks of said switches, means controlled over the test brush of the selector switch to which the said cord circuit has first preference for controlling the hunting movement thereof, means responsive to an all-busy condition of the trunk group terminating in any selector switch for connecting said cord circuit to the next selector switch in the order of preference without testing the busy trunks terminating in the previous selector switch, means controlled over the test brush of the selector switch to which said cord circuit has been connected for controlling the hunting movement thereof to cause said switch to connect said cord circuit with an idle trunk, a supervisory signal in said cord circuit and means for controlling said signal over said trunk.

7. In a telephone system, a calling line, a first .and second operators position, a cord circuit at said first operators position, a selector switch in which said cord circuit terminates, a plurality of trunk circuits extending to said second operators position and to which said selector switch has access, means controlled over the test brush of said switch for controlling the hunting movement thereof to cause said switch to connect said cord circuit with an idle trunk, means including said cord circuit for extending said calling line to said selected trunk, a supervisory signal in said cord circuit, and means responsive to an operation over said selected trunk at said second operators position for controlling said signal over said test brush.

8. In a telephone system, a cord circuit, a selector switch in which said cord circuit terminates, said selector switch having a plurality of terminal ban is and cooperating brushes, a supervisory signal in said cord circuit, a plurality of groups of trunks connected to the said plurality of banks, each of said trunks being provided with a signal, an operators telephone circuit, means controlled over one of said brushes for controlling the hunting movement thereof to cause said switch to connect said cord circuit with an idle trunk in one of said plurality of groups of trunks, means for operatively connecting said operators telephone circuit, to said cord circuit means responsive to the connection of said operators telephone circuit to said cord circuit for operating said trunk signal of said selected trunk, means for controlling said supervisory signal over said test brush and means for keeping' said trunk signal operated when said operators telephone circuit is disconnected from said cord circuit.

9. In a telephone system, a calling line, a. cord circuit, a selector switch in which said cord circuit terminates, said switch having a plurality of terminal banks and cooperating brushes, a supervisory signal in said cord circuit, a plurality of groups of trunks connected to said plurality of banks, a signal for each of said trunks, an operators telephone circuit operably associable with said cord circuit, means controlled over one of said brushes for controlling the limiting movement thereof to cause said switch to connect said cord circuit with an idle trunk in one of said plurality of groups of trunks, means responsive to said connection of said operators telephone circuit to said cord circuit for operating said trunk signal of said selected trunk, means including said cord circuit for extending said calling line to said selected trunk, means in said selected trunk for controlling the said cord circuit supervisory signal over said test brush and means responsive to a disconnection of said operators telephone circuit from said cord circuit for maintaining operated said trunk signal from said calling line.

l0. In a telephone system, an operators position, a cord circuit, a selector switch in which said cord circuit terminates, said switch having a plurality of terminal banks and cooperating brushes, a supervisory signal for said cord circuit, a plurality of groups of trunks connected to said plurality of terminal banks and extending to said operators position, means controlled over one of said brushes for controlling the hunting movement thereofto cause said switch to connect said'cord circuit with an idle trunk in one of said plurality of groups of trunks and means controlled over said test brush and responsive to an operation over saidselected trunk at said operators position tor operating said supervisory signal.

ll.,A Ina telephone system, a cord circuit, a selector switch in which said cord circuit terminates, said switch having a iplurality ot terminal banks and cooperating brushes', a supervisory signal for said cord'circuit,' a pluralityL of groups of trunks connected to said plurality of terminal banks, each ot said trunks being provided with a signal, anV operators telephone circuit, means controlled over one of said brushes for controlling` the hunting movement thereof to cause said switch to connect said cord circuit with an idle trunk in one of said plurality or Vgroups of trunks, means controlled over said test brush for operating said supervisory signal and means responsive to an .operable connection ot said operators telephone circuit to said cord circuit for operating said trunk signal on said selected trunk. Y j

l2. In atelephone system, a calling line, an operator-s position, a cord circuit in said operators position, a selector switch in which Ysaid cord circuit terminates, sain switcn havn ing a plurality of terminal banksand cooperating brushes, a supervisory. signal or'said cord circuit, a plurality of groups ot trunks connected to said plurality of terminal banks, an operators telephone circuit, means for operably connecting said operators telephone circuit to said cord circuit, means controlled. over one ot said brushes for controlling the hunting movement thereof to cause said switch to connectsaid cord circuit with an idle trunk in one of said plurality or" groups of trunks, means controlled over said Ytest brush for o eratin@` said su ervisorv siOnal c J b 7 Y of groups Vof trunks,

means for extending said calling line to said first operators position, means including` said cord circuit tor extending said calling line to said selected trunk, and means responsive to an operative connection orp said operators telephone circuit with said cord circuit'and the disconnection of said selected trunk from said cord circuit for establishing a 'talking connection between said calling line andsaid operators'telephone circuit.

13. In a telephone system, a calling line, a iirst cord circuit, a selector' switch in which said cord circuit terminates, said switch having a plurality ot terminal banks andA cooperating brushes, a supervisory signal for said cord circuit, a plurality ot groups of trunks connected to said plurality of terminal banks, means controlled over. one of said brush-es for controlling the hunting movement thereof to cause said switch to connect said cord circuit with an idle trunk in one of said plurality means controlled over said test brush for operating said supervisory signal, an operators position, a second cord circuit at said operators position, said second cord circuit having a supervisory signal, means including said first cord circuit, vsaid selected trunk and said second cord circuit for extending said calling line; to said oper-V ators position and means responsive to a dis connection of said first cord circuit from said calling line to operate said supervisory'signal in said second cord circuit.V Y'

lll. ln a telephone system, a calling'line, a iirst and second operators position', -a cord circuit at said first operators position, a plurality oi selector switches, groups ot trunks terminating in said switches, vmeans Vfor connecting said cord circuit to each of said selector switches in a definite order or preference, means controlled ver the test brush of the selector switch torwhich said cord circuit has first preference for controlling thev limiting movement thereof, means-responsive to an allbusy condition of thetrunkgroup of any selector switch for connecting said cord circuit -to the next selector switch in the'said order ot preference without testing the busy trunks terminating in the previous selector switch, ieans controlled over the testlbru'sh of the selector switch to which said' cordcir- Y t has-been connected 'for controlling Vthe hurting movement thereof 1 to cause said switea to connect said cord circuit with'an idle trunk extending to said second operators position, a supervisory signal in saidV cord circuit, means including said cord for eX tending said calling line to vsaid selected trunk, and means responsive te an operation over' said selected trunk at saidVV second `opcrators position ior controlling said signal over saidtest brush.

l5. In a telephone system, a cord circuit, a plurality or selector switches, groups of trunks terminating in said switches, means for connecting said cordV circuit to each of said selector switches in a definite lorder or preference, means controlled over'- the test brush of the selector switch to which said cord circuit lhas first preference for controlling the hunting movementv` thereof, means vresponsive to an all-busy 'condition Vot the trunk group of any selector switch for connecting'said vcord circuit. to' thenext selector switch in the said order ofpreference without testing the busy trunks'terininatin'g in the previous selector switch,'means controlled over the test brush of the selector switch to which saidA cord circuit has been connected for controlling the hunting movement thereof to cause'said switch to connect said cord circuit with an idle trunk, a'siofnal for :said trunk, a vsupervisory'signalin said cord circuit,f an operatcrs"telephone circuit, means for operatively connecting said operators telephone circuit to said cord circuit, means responsive to the connection of saidoperaioo tors telephone circuit to said cord circuit for operating said trunk signal of said selected trunk, means for controlling said supervisory signal over said test brush, and means for keeping said trunk signal operated when said operators telephone circuit is disconnected from said cord circuit.

16. In a telephone system, a calling line, an operators position, a cord circuit, a plurality of selector switches, groups of trunks terminating in said switches, means for connecting said cord circuit to each of said selector switches in a definite order or preference, means controlled over the test brush of the selector switch to which said cord circuit has first preference for controlling the hunting movement thereof, means responsive to an all-busy condition of the trunk group terminating in any selector switch for connecting said cord to the next selector switch in the said order or preference without testing the busy trunks terminating in the previous selector switch, means controlled over the test brush of the selector switch to which said cord circuit has been connected for controlling the hunting movement thereof to cause said switch to connect said cord circuit with an idle trunk, a signal for said trunk, a supervisory signal in said cord circuit, an operators telephone circuit operably associable with said cord circuit, means responsive to the connection of said operators telephone to said cord circuit for operating said trunk signal of said selected trunk, means including said cord circuit for extending said calling line to said selected trunk, means in said selected trunk for controlling said cord circuit supervisory signal over said test brush, and means responsive to a disconnection of said operators telephone circuit from said cord circuit for maintaining operated said trunk signal over said calling line.

17. In a telephone system, an operators position, a cord circuit, a plurality of selector switches, groups of trunks terminating in said switches, means for connecting said cord circuit to each of said selector switches in a definite order or preference, means controlled over the test brush of the selector switch to which said cord circuit has first preference for controlling the hunting movement thereof, means responsive to an all-busy condition of the trunk group terminating in any selector switch for connecting said cord circuit to the next selector switch in said order of preference without testing the busy trunks terminating in the previous selector switch, means controlled over the test brush of the selector switch to which said cord circuit has been connected for controlling the hunting movement thereof to cause said switch to connect said cord circuit with an idle trunk, a supervisory signal in said cord circuit, means controlled over said test brush for operating said supervisory signal, and means responsive to to an all-busy condition of the trunk group terminating in any selector switch for connecting said cord circuit to the next selector switch in said order of preference without testing the busy trunks terminating in the previous selector switch, means controlled over the test brush of the selector switch to which said cord circuit has been connected for controlling the hunting movement thereof to cause said switch to connect said cord circuit with an idle trunk, a signal for said trunk, a supervisory signal in said cord circuit, an operators telephone circuit, means for connecting said operators telephone circuit to said cord circuit, means controlled over said test brush for operating said supervisory signal, and means responsive to said operable connection of said operators telephone circuit to said cord circuit for operating said trunk signal on said selected trunk.

19. In a telephone system, a calling line, an operators position, a cord circuit in said operators position, a plurality of selector switches, groups of trunks terminating in said switches, means for connecting said cord circuit to each of said selector switches in a definite order or preference, means controlled over the test brush of the selector switch to which said cord circuit has first preference for controlling the limiting movement thereof, means responsive to an all-busy condition of the trunk group terminating in any selector switch for connecting said cord circuit to the next selector switch in said order of preference without testing the busy trunks terminating in the previous selector switch, means controlled over the test brush of the selector switch to which said cord circuit has been connected for controlling the hunting movement thereof to cause said switch to connect said cord circuit with an idle trunk, f

connection of said selected trunk from said cord circuit for establishing a talking connection between said calling line andsaid operators telephone circuit.

l20. In a telephone system, a calling line, a first cord circuit, a plurality ofy selector switches, groups of trunk circuits terminat ing in said switches, means for connecting said first cord circuit to each of said selector switches in a definite order or preference, means controlled over the test brush of the selector switch to which said first cord circuit has first preference for controlling the hunting movement thereof, means responsive to an all-busy condition of the trunk group terminating in any selector switch `for connecting said cord circuit to the next selector switch in said order of preference without testing the busy trunks terminatingin the previous selector switch, means controlled over the test brush of the selector switch to which said first cord circuit has been connected for controlling the limiting movement thereof to cause said switch to connect said cord circuit with an idle trunk, a supervisory signal for said first cord circuit, means controlled over said test brush for operating said supervisory signal, an operators position, a second cord circuit at said operators position, said second cord circuit having a supervisorysignal, means including said first cord circuit said selected trunk and said second cord circuit for extending said calling line to said operators position, and means responsive to a disconnection of said first cord circuit from said calling line to operate said supervisory signal in said second cord circuit, In witness whereof, I hereunto: subscribe my name, this 29th day of December, 1930.

i WILEY VVHI'INEY.