US2208924A

US2208924A - Telephone system

Info

Publication number: US2208924A
Application number: US248433A
Authority: US
Inventors: Jr John Davidson
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1937-07-17
Filing date: 1938-12-30
Publication date: 1940-07-23
Anticipated expiration: 1957-07-23
Also published as: US2209513A

Description

y 1940-v I J. DAVIDSON, JR

TELEPHONE SYSTEM 4 Sheets-Sheet 1 Filed Dec. 30, 1938 INVENTOR BY JDAV/DSON JR.

A T TORNE Y y 0- J. DAVIDSON, J-R

TELEPHONE SYSTEM 4 Sheets-Sheet 2 Filed Dec. 30, 1938 MON IN VE N TOR B y .4011 V/DSON JR.

ATTORNE V July 23, 1940. bAvmsoN, JR

TELEPHONE SYSTEM Filed Dec. 30, 1938 4 Sheets-Sheet 3 IIHI- //v l/EN TOR J. DAVIDSON JR.

JILII o2 m bPi A T TORNE July 23, 1940..

J. DAVIDSON, JR

TELEPHONE SYSTEM Filed Dec. so, 1938 4 Shae ts-Sheet 4 lNl/ENTOR By J. DAVIDSON JR.

{L Gov A T TORNE V Patented July 23, 1940 UNITED STATES TELEPHONE SYSTEM John Davidson, Jr., Montclair, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York JAN 6 Application December so, 1938, Serial No. 248,433

9 Claims.

This invention relates to telephone systems and particularly to special service systems such as intercepting equipments in telephone systems.

An object of the invention is to provide an improved economically arranged ringing, signaling and tripping arrangement for intercepting equipment.

Heretofore, automatic telephone systems have been provided in which when a subscribers line 10 is changed or disconnected, calls therefor are extended to terminals connectedto an intercepting trunk leading to intercepting apparatus for supervision by an operator. In such systems in case of an intercepting trunk circuit, for example, extending to a distant omce, the ringing is usually tripped by the application of a ground potential on one of the conductors to operate the usual tripping relay. In my copending application, Serial No. 154,231 of July 17, 1937, special tripping arrangements have been shown including cold cathode tubes applied to a single party subscribers line system. With this cathode tube arrangement a relay in the automatic system is operated to trip the ringing as soon as the con-, nection is established to the terminals of the intercepting trunk circuit.

It is a feature of the present invention to provide a circuit arrangement for intercepting calls intended for subscribers on party lines, and means is provided whereby when a party line is seized and the ringing code ofthe party on said line, calls for whom are to be intercepted, is transmitted to said line, ringing is discontinued and an intercepting trunk which is associated with said line is connected for recepton of the call. Cold cathode tubes are employed which are responsive to particular ringing signals transmitted to the party line representing the call for the party, calls for whom are to be intercepted.

A special feature is a delay means whereby the ringing is discontinued before the trunk is me pared for the signaling of an intercepting op erator to answer the call.

The invention has been illustrated in accompanying drawings in which:

Fig. 1 shows a calling subscriber's line, an intermediate switch in diagrammatic form and a connector and associated terminals of an automatic .step-by-step telephone system arranged for applying ringing to a. ten-party line;

' Fig. 2 shows an intercepting trunk connected to said terminals and selectable by the connector shown in Fig. l for intercepting calls for'any at particular party, calls for whom are to be intercepted, in accordance with the applicants invention;

REISSUED Fig. 3 shows a connector and associated ter minals of an automatic step-by-step system arranged ior ringing eight or four-party lines; Fig. 4 shows an intercepting trunk arrangement for intercepting a call for any one of the parties on a four or eight party line, calls for whom are to be intercepted; and I Fig. 5 shows a modified portion of an intercepting trunk according to Fig. 2'or 4 with the special relay means omitted.

Referring now to the drawings and particularly to Figs. 1 and 2, terminals I00 which are selectable by a connector C shown in Fig. l and normally extend to a ten-party line have also been extended to an intercepting trunk shown in Fig. 2 so that calls for a particular one of the ten parties on this line will be intercepted by an operator. This intercepting trunk in Fig. 2 terminates in a jack 200 in front of an operator's position who intercepts calls directed over this trunk.

If it is assumed that the last three digits of a called subscribers number which is the number of one of the parties on a ten-partyline and calls for whom are to be intercepted, causes the brushes of connector C to land on the terminals I00, and the connector to transmit the desired code signals, the operations of the connector may be as follows: The first two of these three last digits locate the brushes of this connector on the terminals I00 and the third or last digit selects and transmits the desired code. The connector may be seized by brushes IOI of a selector by connecting with the terminals of this connector when a call comes in from a calling subscriber such as I02 as is well known in the art. This causes the relay I03 to operate over a circuit from battery and ground through the windings of this relay, contact of relay I 04, terminals of the connector andthe brushes of selector IOI through the calling subscriber's loop. The operation of "relay I03 closes an obvious circuit for the operation of relay I05 which is slow in releasing and remains operated during the pulses constituting succeeding digits. The operation of relay I05 closes a circuit for a relay I06 from battery, lower winding of this relay, the vertical oiT-normal contacts I0I, contacts of relay I05 to ground. The first releaseof the pulsing relay I03 when the calling subscriber dials the first of these three digits now closes a circuit for the vertical magnet I08 from battery, winding of this magnet, contacts of relays I 06 I09, I05 and I 03 to ground. This causes the connector to take one vertical step and open the vertical off-normal contacts I01. This opens the above-mentioned circuit for relay I06 but this relay remains operated as it is slow in releasing and holds over a circuit from battery through its upper Winding and upper armature and front contact through the above-mentioned pulsing circuit and is consequently maintained operated during the pulsing of the digit. When this digit has been sent, the final operation of the pulsing relay I03 opens the holding circuit for relay I06 which now releases. On the first release of the pulsing relay I03 in response to the second digit, a circuit is closed for the rotary magnet H0 and the relay III. The circuit for magnet H0 extends from battery through the winding of this magnet, contacts of relays H2, I06, I09, I05 and I03 to ground and the circuit for relay III extends from battery through the winding of this relay over the same pulsing circuit. Relay III is slow in releasing and is held operated by a holding circuit over its lower armature and front contact through the pulsing circuit-during the pulsing of this digit. At the end of this second series of impulses, the brushes of the connector have been advanced to and connected with the terminals I00 of the desired party line.

Relay III then releases if,the party line is idle. However, if this party line is busy, relay III remains operated long enough to permit the operation of relay I09 over a circuit from battery through the winding of this relay, contacts of relay I II to ground'on the sleeve terminals at I00 and'when relay III is released, relay [I09 is locked over make-before-breakcontacts of relay III to ground over its lower inner armature and,

front contact and contacts of relay I05. A busy tone is thereby transmitted to the calling subscriber indicating that the line is busy. This tone circuit is extended from the busy tone source at I I4, a condenser I I5, contacts of relays II2 andl09, a condenser I I6 over the tip conductor to the calling subscriber's telephone. If, however, the called party line is ,idle relay H2 is operated when relay III releases over a circuit from battery through a resistance and contacts of relay 20I in Fig. 2 over the sleeve terminal and brush of the connector, contacts of relay I I I, upper winding of relay H2, contacts of relays I 09 and I05 to ground. Relay H2 locks through a circuit from battery, its lower winding and second lower armature and front contact to ground at contacts of relay I 05. Relay H2 also closes a circuit for the operation of" the rotary magnet I I8 for the operation of the code selecting rotary type step-by-step switch I20. The first release of the pulse relay I03 in response to the third digit now closes a circuit for the operation of this magnet as follows: From battery through the winding of magnet H8, contacts of relays H2, I06, I09, I05 and I03. It should be noted that relay III is also operated in'this circuit as hereinbefore traced. Relay III remains operated during the sending of the pulses of this last digit. The rotary magnet II 8 advances the brushes I2I and I22 over the associated contact banks of the switch I20 to select the desired ringing code. The impulses for selecting a ringing code may, as this is a ten-party selective code ringing system, consist of from one to ten impulses. The brushes of this switch therefore will land on any one of the ten terminals as shown in the drawings and connect any one of the five generators indicated I to!) to the corresponding over the tip conductor.

terminals and brushes to leads connected to contacts of relay I25, the purpose of which will be described hereinafter. III, when the code selecting digit has been sent, the original energizing circuit for relay H2 is opened, but this relay H2 remains locked as described. When relay H2 was operated and while relay III remained operated, a circuit was completed for the operation of relay I09 from battery through the winding of this relay, contacts of relays III and H2- to ground. This ground also serves to make the line busy as it is connected to the sleeve lead. On the release of relay III, relay I09 locks-over the make-beforebreak contact of relay III to a ground at relay I05. Relay III in releasing closes a circuit for relay I25 from battery, winding of this relay, contacts of relay I21, make-before-break contacts of relay I25, contacts of relays III, I09 and I I2 to ground. The connector is now ready for the transmission of the selected code to the intercepting trunk as shown in Fig. 2.

It should be noted that the trunk in Fig. 2 is provided with a key 202. This may be operated to connect a cold cathode tube 203 to the tip or the ring conductor of this intercepting trunk, depending on whether or not the called party, calls for whom are to be intercepted, is to be rung on the tip or the ring conductor by a code. If it isassumed that the key 202 is operatedto connect tube 203 to the tip conductor, the call for the intercepted party is assumed to be transmitted It should also be noted that lead 204 may be connected to any one of the group of five leads 205 which are connected On the release of relay to five generators not shown but identified by legends generator I to generator 5 and to the first five terminals of the twobanks. of switch I20. The lead 204 is therefore connected to one of these five leads depending on the code of the party for whom calls are to be intercepted and if it is assumed that it is connected to the first conductor which extends to the generator No. I and the first contact onthe banks the number dialed by the calling subscriber would be 1. The brushes I2I and I22 of the switch I20 would therefore be connected to the first terminals of their respective banks. On the operation of relay I25,-the generator I will therefore now transmit codeNo. 1 over the first terminal of the upper bank through the brush to the lead connected to the second upper armature and front contact of relay I25, upper armature and back contact of relay I2'I, upper inner armature and front contact of relay II2 over the tip conductor through key 202 through the tube I03 to ground. This causes the firing of the tube 203 and a circuit is completed over the main anode of this tube from ground through the winding of relay 206, back over the tip conductor to the generator I. This causes the operation of relay 206 which now closes a circuit through the upper armature and front contact from the generator I over the tip connection through the upper electrode 201 of the tube 208 and establishes acertain potential on this electrode. It should be noted also that the same potential from the same generator I is supplied on the lower electrode 209 of the tube 208 by the operation of relay 206 from generator I over the first conductor of the group 205, conductor 204, second lower armature and front contact of relay 206 to the electrode 209. Consequently, tube 200 will not become active as these potentials are of the same value. This matching of the applied potentials on the two electrodes of the tube 200 identities the code ringing for the party, calls for whom areto be intercepted, so that the trunk will be prepared ior the intercepting of this call as will be further explained as the description proceeds. Associated with the generators I to is a pick-up interrupter I which operates to connect ground to the pick-up lead I 3|, once between each transmission of the code by said generators so that when a code has been transmitted as described to the tube 208 and is completed, ground will be connected to conductor Iti' from the pick-up interrupter I20 for theoperation of relay 2I0. Relay 2I0 in operating applies a ground for the operation of the delay circuit comprising the relays 2, ground applied by relay 2I0causes the operation of relay Hi from battery through the winding of this relay and its make-before-break contacts, contacts of relays m, 20.8 and 2I0 to ground. This ground also closes a circuit for the operation of the relay 20I from battery through the winding of this relay and its makebefore-break contacts, contacts of relays 2L5, 206 and 2M] to ground. Relay 2M looks over its middle lower armature and front contact to the ground on the sleeve conductor applied at relay H2 and relay 2II.locks over its armature and conductor.

front contact, contacts of relay 20I to ground on the sleeve at relay I I2. Relay H2 is prevented from operating at this time as long as the ground is supplied from the contacts of relay 2I0 as it is short-circuited by this ground at its upper outer armature and back contact. However, as soon as relay 2I0 releases relay 2I2 is operated over a circuit from battery winding of relay2i2, contacts of relays 2II, 2M, II2 to ground over the sleeve. The tripping of the ringing code is accomplished as soon as relay 2M is operated as the tip and ring conductors are connected through the contacts of this relay to the two electrodes oi, the cold cathode tube 223 which therefore shunts the tip and ring conductorsand causes the operation of relay I21 over a circuit extending from battery through the upper winding of relay I21, contacts of this relay, contacts of relay I25, the first contacts on the lower bank, brush I2I and contacts of relays I25, I27, H2 over the ring conductor, contacts of relay 20I, through tube 223, contacts of relay 20I over the ,tip conductor, contacts of relays H2, I21, I25,

reverses the battery and ground through the I windings of relay I03 for supervision. Then when the pick-up ground is again extended from pick-up interrupter I30 over lead I3I relay 2I3 operates from battery winding of relay 2I3 and its make-before-break contacts, contacts of relay 2I2, conductor I3I, pick-up interrupter I30 .to ground. Relay 2I3 looks over its upper armature and front contacts through contacts of relays 20I and H2 to ground over the sleeve Relay 2I3 in operating closes a circuit for relay 2I8, and this relay in turn closes an obvious circuit for lighting of lamp-220 to indicate to the operator that a call has been intercepted on this trunk. The purpose of this delay 2l2 and 2I3. At this time, thiscircuit is therefore to permit the tripping of the ringing before the lamp 220 is operated and the operator has a chance toinsert the plug 22I into jack 200. When the operator answers the call by inserting plug 22I into Jack 200, relay 222 operates and extinguishes lamp 220. Transmission battery for talking is now supplied for the calling subscriber through the winding of relay I03 and for the operator through the winding of relay I 04. Conversation between the subscriber and operator may now begin.

If the calling subscriber disconnects first, relay the connector switch and the release magnet II for the ringing code selecting switch I20. The circuit for the release magnet I40 may extend from battery through the winding of this magnet, the vertical oilE-nonnal contacts I02, contacts of relays I05 and I04 to ground and the circuit for the release magnet I M for switch I20 exends from battery through the winding of this magnet, off-normal contacts I43 of the switch I20, contacts of relays I05 and I00 to ground. When these two switches are returned to normal, the circuit for the two release magnets are opened. The release of relay II2 disconnects the ground on the sleeve causing the release of relays 20L 2, M2, 2I3 and tilt. In case the operator. disconnects first, the relay I00 releases and reverses the battery over the tip 'and ring conductors to the preceding switches and when the calling subscriber disconnects, relay I03'is released causing the release of relays I 09, I21

and II2 and the release of the switches as described.

300 of afour-party or eight-party line for the interception of calls incoming to any one of the parties of these two types of lines; The connector CI is similar to the connector C in Fig. l and operates practically in the identical manner as far as selecting a party line is concerned. The operations of this connector as far as the functions thereof in making the selection of a party line are concerned need not therefore be described in detail. It may consequently be assumed that the connector functions have progressed to the point where relay 30I has been operated. This relay corresponds to relay I 25 in connector C and the description may therefore begin with the transmission of the third or ringing codeselecting digit. It should be noted that in Fig. 4, a key 400 may be operated to connect either the tip or the ring to the tube 402 for the reception of the code signal over the tip or the ring conductor. Ringing code selecting switch 303 is in; case of a four-party line, of

course, only equipped for four selections by the operation of the switch 303 from oneto four steps, and in the case of an eight-party line equipped as shown for eight selections. The selections of a code as determined by the setting of this. switch will always cause the operation of relay 305 over a circuit from, battery, winding of this relay, contacts of relay 3M and through the brush 300 and any terminal of the associated bank to the corresponding interrupter l M2 to interrupt the operation-of this relay in accordance with the interruptions as determined by interrupter I for the first four steps or in accordance with the interruptions as determined by interrupter 2 for the last four steps to transmit superimposed ringing current over a tip or ring conductor as determined by the operation of relay 301 or 308 or both of these relays or neither of these two relays. If it is assumed that the switch 303 has been set to apply a code for the first party on any type of party line, the brush 310 will land on the first. terminal of the associated bank and thus neither of the relays 301 or 308 will be operated. In this case superimposed negative current will be applied on the tip conductor and interrupted in accordance with the interruptions of relay 305 as determined by the interrupter 1 controlled by the brush 306 of the switch 303. In this case the negative superimposed current will be supplied at a source connected at 312, and the circuit may be traced from this source over contacts of relays 305 and 301, upper winding of relay 315, contacts of re-' lays 301, 308, 315 and 310, the tip conductor, key 400, key 403, the upper electrode of tube 402, the lower electrode of this tube, key 403 to ground. This causes the firing of tube 402 which thereby closes a circuit over its main anode through the upper winding of relay 404 causing this relay to operate and look through its lower winding to ground at contacts of relay 405. When the code has been transmitted once, the usual pick-up interrupter 319 will supply ground on the lead 406 causing relay 405 to operate and this relay in turn applies ground through contacts of

relays

404 and 408, winding of this relay to battery causing relay 408 to operate and look over its middle lower armature and front contact over the sleeve conductor to ground at relay 316. This ground on pick-up conductor 406 also causes the operation of the first delay circuit relay 410 from battery through the winding of this relay and its make-before-break contacts, contacts of relays 404 and 405' to ground. When the ground on the pick-up interrupter 319 is removed, the delay circuit relay 411 will operate from battery.

through the winding of this relay, contacts of relays 410 and 408, over the sleeve conductor to ground at relay 316. When relay 408 operates it connects the tip and ring conductors to the cold cathode tube 413 which then is broken down by the ringing current and closes a circuit for the operation of relay 315 from .the negative tripping battery at 318 through contacts of relay 305 when it is released, contacts of relay 301, upper winding of. relay 315, contacts of relays 301, 308 and 315 over the tip conductor, contacts of relay 408 through tube 413, contacts of relay 408, back over the ring conductor, contacts of relays 316, 315 and 308 to the generator ground at 318. Relay 315 locks through its lower winding from battery, its second lower armature and front contact in the ground at relay 320. Relay 315 opens the circuit for relay 301 which new releases causing the release of relay 305, causing the ringing code to be discontinued. On the next connection of ground through the pick-up interrupter 3| 9 a circuit is completed for the last delay circuit 418 from battery through the winding of this relay, make-before-break contacts of this relay, contact of relay 411 to the ground at the pick-up interrupter 318. Relay 418 closes a circuit for relay 420 which new lights lamp 421 to indicate to the operator that a call is Similarly any other code'may be supplied over the tip or ring conductors by the settings of the code ringing selecting switch 303 and the consequent operations of relays 301 and 308 and various combinations. For example, if the switches select the secon ct'contact on the banks, relay 308 is operated from battery through the lower winding of this relay over the second contact through brush 310, contacts of relay 301 to ground. This closes a circuit for the transmission of superimposed negative ringing current over the ring conductor from the source 312, contacts of relays 305, 301, upper winding of relay 315, contacts of relays 301, 308 and 315 over the ring conductor. If the brushes of the crossselector are advanced to the third contact, relay 301 is operated from battery, through the upper winding of this relay, third contact and brush 3E0 to ground at relay 301. In this case superimposed positive ringing current will be transmitted over the tip conductor from the source at 323, contacts of relays 301, 305, 301, upper winding 01 315, contacts of relays 301, 308, 315 and over the tip conductors. If the fourth contacts are selected, both relays 301 and 308 are operated and superimposed positive ringing current is transmitted over ring conductor. The circuit for relays 301 and,308 may be traced from battery through the lower winding of relay 301, upper winding of relay 308, the fourth contact and brush 310 to ground at contacts of relay 301,

and the circuit for the ringing current may be from the source 323, contacts of relays 301, 305, 301, upper winding of relay 315, contacts of relays 301, 308, 315 over the ring conductor. Similarly if the switch 303 is set to the fifth, sixth, seventh and eighth contacts, the same type 01 ringing current is transmitted from the sources 312 and 323 over the corresponding conductors as for codes 1, 2, 3 and 4. but relay 305 will be interrupted at a different rate as the brush 308 will connect with the interrupter 2 in its various positions 5, 6, 1 and 8. I

If Fig. 5 is inserted between the positions A and B as shown in dash-dotted lines in Fig. 2 or. Fig. 4. it is evident from this figure that the delay circuit for operating the signal 220 or 421 is omitted so that when

relay

201 or 408 is operated, the ringing is tripped through thetube 500 and at the same time, relay 501 is operated by the ringing current. This relay is locked to ground on the sleeve circuit. Relay 501 closes an obvious circuit for the operation of relay 218 or 420 which operates thesignal 220 or 421. This arrangement may be used where it is not desired to have any delay in operating the signals.

What is claimed is:

1. In a telephone system, a calling line. a called party line, means for establishing a connection from said calling line to said called line and for transmitting a ringing code to said party line for calling any one of the parties on said line, an intercepting trunk associated with said called party line, and means responsive to a particular ringing code transmitted to said party line and trunk for establishing a talking connection over said trunk.

2. In a telephone system, a calling line, a

called party line, means for establishing a connection from said calling line to said called line and for transmitting ringing code to said party line for calling any one of the parties on said line, an intercepting trunk associated with said called party line, and means responsive to a particular ringing code transmitted to said party line and said trunk for establishing a talking connection over said trunk and for disconnecting said code ringing;

3. In a telephone system, a calling line, a called party line, an intercepting trunk, associated with said called party line, an'operators position, means for establishing a connection from said calling line tosaid called party line and to said intercepting trunk for transmitting ringing codes to said party line and trunk, and

means for establishing a talking connection from said calling line over said intercepting trunk to said operator's position operative if a particular ringing code is transmitted.

4. In a telephone system, a calling line, a called party line, an'operator's position, an. intercepting trunk associated with said called party line, means for establishing a connection from said calling line to said called line and for transmitting a ringing code to said party line for calling any one of the parties on said line, and means in said trunk for discontinuing the transmission of aparticular ringing current to said party line and for establishing a connection over said intercepting trunk to said operators position. I

5. In a telephone system, a calling line, a called party line, an intercepting trunk, associated with said calledparty line, an operators position, means for establishing a connection from the calling line to said called line and said trunk and for transmitting diflerent ringing codes to call corresponding parties on said party lines, means responsive to'the transmission of a particular ringing code for discontinuing said transmission and for establishing a certain interval thereafter a talking connection from the calling line to said operator's position over said trunk.

6. In a telephone system, a calling line, 8.

called party line, an intercepting trunk associated with said called party line andterminating at said operator's position, an operator's position, a signal at said operator's position, means for establishing a connection from the callin line to said called party line and said trunk and 1 for transmitting diflerent ringing codes to call ticular ringing code for discontinuing said transmission and for operating said signal.

,7. In a telephone system, a calling line, 9. called party line, an intercepting trunk, an operators position, a signal, means for establishing a connection from the calling line to said called party line and said trunk and fortransmitting diflerent ringing codes to call corresponding parties on said party lines, and means responsive to the transmission'oi a particular ringing code for discontinuing said transmission and for operating said ,signal a certain time interval thereafter.

8. In a telephone system, a calling line, a called party line, means for establishing a connection from said calling line to said called party line in response to dial pulses, means for selecting a particular "ringing code for ringing a corresponding party on said called party line in response to dial pulses and for transmitting said ringing code at intervals to said called party line, means for producing a signal during the interval between the transmission of said ringing code, an intercepting trunk connected to said called line having a normally opened talking connection, means associated with said intercepting trunk operative in response to the transmission corresponding parties on said party lines and ringing code at intervals to said called party line,

means for producing a signal during the interval between the transmission of said ringing code, an intercepting trunk connected to said called line having. a normally opened talking connection, means associated with said intercepting in'unk operative in response to the transmission oi! said particular ringing code to said called party line and to said intermediate signal for closing said talking connection and for thereafter discontinuing the transmission 0! ringing code and the intermediate signal, a signaling device, means operative in response to said first-mentioned signal tor actuating said signaling device a definite interval after said ringing code has been discontinued.

' JOHN DAVIDSON. Ja.