US2304220A - Telephone system - Google Patents

Description

Dec. 8, 1942. R WALLER TELEPHONE SYSTEM Filed Sept. 10, 1940 lNl/E/V TOR LR. WALLER- QR N at A T TORA/EV Patented Dec. 8, 1942 TELEPHONE SYSTEM Lee R. Waller, Montreal, Quebec, Canada, assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application September 10, 1940, Serial No; 356,144 (or. 179 27) 13 Claims.

established by the operation of a selecting bar,

followed by the operation of a holding bar, the connection being established through contacts at the intersecting point of said bars. In such systems connections may be established automatically between a calling subscribers line and a called subscribers line by the aid of links or between calling lines or called lines to or from a trunk, or connections may be established between lines by the aid of a link over a cross-bar switch that is manually manipulated by an operator.

t is a feature of the present invention to provide means whereby a cross-bar switch may be operated automatically by the aid of an operators equipment to establish a connection between a calling subscribers line and 2. called subscribers;

line over a link, between a trunk and a calling line, between a trunk and a called line and between a calling line and a plurality of called lines over a link in a conference connection.

Another feature is an arrangement of keys;

and a sequence circuit whereby when a connec-- tion between a calling line and a called line is desired, a key for the calling line and a key for the called line are operated in succession by the operator and whereby the connection is then.

effected by the aid of the sequence circuit when the called line key is operated.

Another feature is an arrangement whereby when a call between a trunk and a called line is desired a key for the trunk and a key of the:

called line are operated in succession and whereby the connection is eflected by the aid of the sequence circuit when the called line key is operated, and when a connection between a calling line and a trunk is desired a key for the calling line and a key for an idle trunk are operated in succession and whereby the connection is effected by the :aid of the sequence circuit when the trunk key is operated.

Another feature is an arrangement whereby when a conference connection is desired a special key is operated followed by the operation of the callingline key and the called line keys and the release of the special key in succession and whereby the connection is effected by the aid of the sequence circuit when the special key is released. 1 g

The invention has been illustrated in the accompanying drawing in which:

' Fig. 1 shows a schematic representation of a system embodying the applicants invention; and

Fig. 2 shows the detailed circuit of a system in accordance with the plan shown in Fig. 1 for establishing connections in accordance with the applicants invention;

Referring now to the drawing and particularly to Fig. 1, a cross-bar switch ll] of any well-known type may be employed having selecting bars and holding bars for establishing the connection. The subscribers lines may terminate in the switch in vertical rows. Two of these lines have been indicated at II and I2, and these lines may be connected to links represented by horizontal lines; two links l3 and [4 have been indicated with their incoming and outgoing branches, and connections between subscribers lines and trunks may be established by trunks indicated by horizontal lines, two of these trunks being shown and numbered l5 and I6. An operators equipment has been indicated at 20 and the link controlling circuits have been indicated at 2| for the links l3 and M. In general, the operation of this equipment may be outlined as follows: If the subscriber of line ll desires a connection to the subscriber of line l2 the calling subscriber will, on seizing his line, operate a line lamp 22 in the operators equipment. The operator will then actuate a key 23 to an answering position thereby connecting her telephone set to the calling line and receives from the calling subscriber the number of the desired subscribers line. The operator then operates the key 24 of line 12 to a calling position and thereby causes the link control circuit 2| to operate to establish a connection over an idle link from the calling subscribers line ll through the switch at the cross-point 25 of the link l3 if this link is idle to the incoming branch of this link and through the switch at the cross-point 26 to the outgoing branch of this link to the called subscribers line !2. The operator then releases the keys 23 and 24 to disconnect her telephone set from the connection, ringing current being transmitted to the called line and when the called subscriber answers the connection is completed over line l3 between the calling subscribers line H and the called subscribers line I2. When the calling subscriber hangs up his receiver the connection through the cross-bar switch is released.

In case a connection is desired from a calling subscribers line to a trunk, a connection is established, forexample, from subscriber of line H, by the operation of key 23 to the answering position and a trunk key, for example 29, of an idle trunk l to a calling position and thus a connection is established through the cross-bar switch I!) from the calling line H through crosspoint 30 over trunk l5 to the distant office. I The trunk busy lamp 32 may be lighted to indicate that this trunk is in useand lamp- 22 for the calling subscriber is lighted to indicate that this line is engaged. If a connection is desired from a trunk to a line, the trunk busy lamp 32, if the call is incoming over trunk I5, is flashed to indicate that a connection is desired. The operator will then operate'the key 29 to an answering position and connect her telephone set to the trunk to receive the'desired subscribers numher and she will then operate the 'key 23-to the calling position if a connection is desired to the subscriber of line H, and a connection will then be established between the trunk l5 and line I at the cross-point 36.

If a conference connection is desired between a calling subscriber and a number of other subscribers, the operator, after she has ascertained this fact from the calling subscriber, will operate the ringing keys, such as for example, 33, of the line I2, and other similar keys to call this line and other subscribers lines and all of these lines will then be connected simultaneously to the cross-bar switch of the calling line by the operation of the special key 34 and other keys as will be described hereinafter,

Detailed descriptions will now be made of these various types of calls in connection with Fig. 2. In this figure a cross-bar switch 50 has been shown for two subscribers lines 5| and 52 terminating in vertical rows in the switch, and one link circuit with an incoming branch 53 and an outgoing branch 54, and one trunk circuit 58 terminating in a horizontal row of the switch. The usual select magnet 55 for the incoming branch of the link and the select magnet 56 forthe outgoing branch 54 of'the link and the select magnet 51 for the trunk 58 have been shown with the holding magnet 59 for line 5| and the holding magnet 60 for line 52. eration of a select magnet and a holding magnet causes a connection to be established throughthe switch which may be constructed in any well known manner in which selecting bars and holding bars are used for establishing the connections at the cross-points. If it is assumed that the subscriber of line 5| calls, the removal of the receiver by the subscriber of this line causes a connection to be established for the operation of the line relay 62 from battery and ground through the windings of this relay, contacts of the cut-off relay 63, contacts of the ringing key 64 and the tip and ring conductors through the subscribers loop. Line relay 62 in operating closes a flashing circuit for the line lamp 66 from battery through this lamp, contacts of the answering key 61 and calling key 68 associated with this subscribers line, contacts of cut-off relay63, armature and front contact of line relay 62, interrupter 69 to ground. The operator seeing the flashing of this, lamp 66 will now connect her telephone set to the calling line by desired subscriber.

the operation of the answering key 61, this connection extending over leads [2, contacts'of key 61, contacts of cut-off relay 63, contacts of ringing key 64 to the line 5|. The operation of the answering key 61 opens the flashing circuit for the line lamp 66. The subscriber of line 5| now informs the operator of the number of the The operator then operates the calling key 13 of the subscribers line 52 if the corresponding subscriber is desired. This starts operations to establish a connection between the calling subscriber and the called subline 5|.

scriber by the operation of the link control circuit indicated in Fig. 1 by numeral 2| and consisting of a number of relays as will be described. The first eifect will be the operation of the first relay 14 of the series of sequence relays l4, I5, 16' and Tl. The circuit for relay 14 extends from battery through the winding of the holding magnet60 of the called line, contacts of keys l3 and H23, winding of relay 14 to ground. The resistance of the winding of relay I4 is such that the holding magnet 60 will not operate at this time. If now the link shown is idle the select magnet for the incoming branch 53 of this link'will be operated from battery through the winding of magnet 55, contacts of link relay 18, contacts of the calling key 19 of the trunk 58 as shown, this connection to key 19, however, extending through corresponding contacts of similar keys for other trunks to open this circuit when any of the trunks is taken. for use and from there through the answering key 80 of the trunk shown, contacts of relays 14 and 16 to ground. Relay 14 also closes an obvious circuit for the operation of relay 15 which is slow in operating, to permit the select magnet 55 time to operate before this relay operates. Relay 15 in operating closes a circuit for the holding magnet 59 of the calling subscribers line from battery through thewinding of this magnet, contacts of answering key 61 and contacts of relay 75 to ground, thus establishing a connection at the cross-point 82 between the outgoing branch 53 of the link shown for the calling subscribers Magnet 59 in operating closes a circuit from ground over the circuit as traced at contacts of relay 15 through the winding of the cutoff relay 63 to battery causing the operation of this relay to connect the calling line 5| to' the cross-point 82 and the incoming branch 53 of The opcuit for line relay 62 which now releases and disconnects the operators set HI from the calling line. Relay 15 also closes a circuit for the operation of relay '76, this relay being slow in operating to permit the operation of the abovementioned magnet 59 and relay 63. Relay 16 in operating opens the circuit for the select magnet 55 which now releases, and also closes a circuit for the select magnet 56 of the outgoing branch 54 of the link shown, from battery, winding of this magnet, contacts of relays 18 and 16 to ground. Relay 16 also closes an obvious circuit for the operation of relay 11 which is slow in operating to permit the operation of the select magnet 56. When relay 11 operates a circuit to ground is established at the outer righthand armature and front contact of this relay to shunt relay (4 and to operate the holding magnet 60 of thecalled line 52 from battery, winding of this magnet, contacts of key 13 to ground at relay Tl. Relay 14 is consequently released and causes the release in succession of relays 15, 16 and TI. The operation of the holding magnet 69 now establishes a connectionat the cross-point 84 for the calling line 52' and the outgoing branch 54 of the link shown. The holding magnet 69 in operating closes a circuit for the cut-off relay 85 from battery, winding of this relay, contacts of magnet 69 to ground at relay 11. In the meantime as a result of the operation of the cut-01f relay 63 the circuit established from the calling subscribers line 5| through the cross-point 82 to the incoming branch of the link will operate relay 86 from battery and ground over the loop to the calling subscriber. This relay in turn closes an obvious circuit for relay 8'! and this relay in operating closes a locking circuit to ground for the holding magnets 59 and 69 and cut-off relays 83 and 85 over contacts at the cross-point 82 for holding magnet 59 and cut-off relay 63 and over the contacts at cross-point 84 for the holding magnet 69 and the cut-off relay 85. As noted the cut-off relay 85 connects the called line at its contacts through cross-point 84 to contacts of relay 89. Relay 89 will now'operate'on the operation of relay 81 from battery, winding of relay 89, contacts of relay 99 to ground at the contacts of relay 81. Relay 89 in operating connects the ringing circuit from ground and a ringing source connected at 9| over the tip and ring conductors over the cross-point 84, contacts of relay 85, ringing key 92 of the called line over the tip and ring conductors of this line to the called subscriber to ring his bell. As hereinbefore de scribed, on the release of relay "l4 relays 15, 19 and 11 released and on the release of relay I6 prior to the release of relay 11 it will be noted that a circuit will be completed momentarily for the operation of relay 18 from battery through make-before-break contacts of this relay, contacts of relay 11 when operated and contacts of relay '16 when released to ground. Relay 1.8 inoperating closes a locking circuit for itself from battery winding and contacts of relay 81 to ground. Relay 18 transfers the operating leads for the select magnets 55 and 56 to contacts of relay 93 which correspond to relay 18 and is associated with the next link, so that on the next call the next succeeding link will be seized and relay 18 will also close an obvious circuit for the link lamp 94.

When now the called subscriber of line 52 ,9

of relay 89 when it releases between ringing-impulses as the circuit for this relay is controlled through an interrupter 95, windings of relay 96 to battery and ground. Relay 96 in operating closes an obvious circuit forthe operation of relay 99 which opens the circuit forrelay 89 which is then permanently released and this relay 99 is looked over its own contacts to ground at relay 8'|.- The conversation between the calling subscriber of line 5| and the called subscriber of line 52 may now take place across the condensers 9B, talking battery being supplied for the calling subscriber through the windings of relay 86 and for the called subscriber through the windings of relay 96. The operator may now restore the keys 51 and I3. conversation when the calling subscriber of line 5|, for example, hangs up, relays 86 and 81 will release causing the release of the holding magnets 59 and 69, cut-off relay 6 3 and 85, and relay I8 which extinguishes the link-busy lamp 94,

At the end of the normal,

3 returning the'switch so and the link shown to a If a connection is desired from a subscriber to a trunk such as fromthe calling subscriber of line 5| and trunk 58 if idle, the connection may be established as hereinbefore described to connect theoperators telephone 19 to the line 5| and when the calling subscriberindicates that a trunk'connection is desired, thev operator will actuate the calling key 1901? trunk 58 if this trunk is idle. The efiect of the operation of key '19 in this case is that the trunk 58-will be connected 'to the calling line 5| by first causing the operationof the relay M from battery at 99, contacts of key 19, key |93,-winding of relay M to ground. Relay I4 nowin operating closes a circuit for the operation of select magnet 51 of the trunk 58 from battery through'the winding of this magnet, contacts of key 19, contacts of the key 89, contacts ofrrelays 14 and 19 to ground. Relay 14 now operates relay 15 after an interval and this relay closes a connection for'the operation of holding magnet 59 from battery through the winding of this magnet,'contacts of key 61 and contacts of relay 15 to ground. Magnet 59 closes the above-mentioned circuit for the cut-off relay 63 which connects the calling line 5| through contacts of this relay over the cross-point |99tip and'ring conductors ofthe trunk 58' through the winding of relay |9|, contacts of keys 89 and 19 to battery and ground (not shown) atthe operators telephone set 19 to cause the operation of relay |9|. Re-

lay:| 9|' operates relay I92 over an obvious cir- "cuit; This relay closes an obvious circuit for the'trunk-busy lamp I93 which indicates that i this trunk is now in use. Relay I92 also establishes a connection to ground for shunting the battery 99 so that relay 14 will release. It

should, of course, be observed that when relay 16 operates after the operation of relay 15, the circuit for the select magnet '51 is open, while the holding magnet 59 and relay B3 are locked over contacts at cross-point I99 and ground applied at contact of relay |92to maintain the established connection. The operator may now release the key 19 and-connect the trunk 58 through to the calling station through contacts of keys 19 and 89 and as is usual, in circuits of this kind battery and ground will be supplied at the distant endof this trunk to maintain relays |9| and IGZ operated. The circuits may now be prepared in any well-known manner to permit a connection to be established and usual dial tone will be applied so that the calling subscriber of line 5| may now dial the desired number at the distant station. -The operator will alsorelease the key 61 to permit the line lamp 66 to be lighted steadily from ground at contacts of relay 93 to show that this line is engaged, while the trunk-busy lamp I93 indicates that the trunk 58 is busy. If the calling subscribers line is not provided with dialing equipment the operator may dial over the -trunk. In this case the operator will first open the key I93 after she has received theinformation from the calling subscriber that a trunk connection is desired and dial from her set 19 through contacts of key 19 when she operates this key, The opening of key I93 prevents the connection of the calling line to-trunk 58 at the cross-point |99 as described.- When the operator has established a connection at the distant end she will release key I93 so that relay I4 may operate and establish the connection as described at the crossthe calling subscriber of line be a restricted subscriber-who is not entitled to outside calls, theoperator-will, of course, not establish the trunk connection desired. "The releaseof the trunk connection may take place-by the subscriber of line I5| replacing the receiver-thus releasingrelays Inland N12 to release the holding magnet59 and extinguishlamp I62. and release relayj63 to'extinguish'lamp 66.

If a call is incoming over a trunk for a connectionito a desired subscribers line the seizing of the trunk-58 for example at the distant end, causes the operation of -the alternating current relayi|-08 over'thetip and ring-conductors, contacts of keys #9 and BU and-contacts of relay I02, condenser lill'and winding of relay I06. This relay closes an obvious circuit for the operation of relay'IflB which now-locks over its contacts over contacts of keys 8lJ-and- '|9 to ground and closes a-circuitfrom an interrupter I09 over contacts of relay |02,lamp' I03 to battery and ground, causing this lamp to flash to indicate that a call is waiting on this trunk. In answering this call the operator .actuates the key 89 and connects her telephone set to the trunk over contacts of this key. The subscriber at the distant'end of trunk '58-now gives the operator the number of the desired subscribers line and if line 5| is desired theoperator actuatesringing key'6 l to ring the subscriber of line 5| by applyingringing current atthe contacts of this-ringing key. 'When. the operator releases ringing key 64 and the subscriber of line 5| answers relay.62 is operated to cause the line'lamp'BE to flash over a circuit 'as hereinbefore described. When the operator notices the fiashing'of lamp 66 she will operate the key"68 of line 5| and thus close a circuit for the operation of relay 14 from battery through the winding of holding magnet 59, contacts of 'key 68; winding of relay 14 to ground.

Magnet 59 does not operate in this circuit. Relay 14 in operating closes'a circuit? for the operation of select'magnet 51 from battery through the winding of this magnet, contacts of key 80, contacts of'relays l4 and 16 to ground. When relay operates due to the operation of relay 14 a circuit is completed'for the operationof holding magnet59 from battery'through the winding of this magnet, contact of keys 68 and 60 an'dcon- F 'tacts of relay 15 to ground. It should be noted that this circuit'to ground on contacts of relay l5 shunts the winding of relay M which now releases. Magnet 59 now establishes a connection between the called subscribers line 5| and the trunk 58 at the cross-point 109 and causes the operation-of the cut-off relay 63 which releases line relay 62 and'connects the line 5| to the trunk'58 at its contacts. This connection causes the operationof relay |il| over the tip and ring conductors of the subscribers loop through contacts'of key 80 to battery and ground at the operators telephone set. Relay |ll| operates relay I02 which'lightsthe trunk-busy lamp Hi3 with a steady light to indicate that the trunk is busy. 'The operator then releases the" keys 8!] and B8 and the line 5| is connected to the trunk 58 through contacts of keys 80 and 19.

In case a conference connection is desired between a number of subscribers, the answering key, for example 61, of line 5|, is operated if the call is incoming over line 5| and the calling subscriber of line 5| will then inform the operator that a conference connection is desired between his line and a number of other'lines. The oper- 1point 00 and then release keys 6! and 19." Should =-ator then proceeds to ring these other lines by operating-their ringing keys, such for example key 92 of line 52. After shehas rung the numbers of such subscribers she 'willoperate their calling keys,'such as 13 for example of line 52, after firsthaving opened the connection through key: N33 to prevent the establishing of any connections until all the calling keys have beenoperated. 'After such keyshave been operated the operator will restore key Hi3 and thereby cause the operation of relay" to startthe operation of-the circuits to establish a conference connection. It will be noted that in this case the procedure will bethe-same as in a line-tolineconnection except that as keys, such as H9 of' the called subscribers lines are operated, all holding magnets'corresponding to holding magnet .60 for line 32 willbe operated through con- .tacts-of'keyssuch as |0'of the corresponding lines .to ground at relay 15 when this relayoperates. Thusit will be seen that when relay 11 operates, holding magnet-59 will be operated to establish a. connection between the'calling line 5| at the'cross-point 82 of link which is the one that was seized and the holding'magnets corresponding to holding magnet fifi of all the called lines will be operated as mentioned from battery throughthe windings of these magnets and their corresponding keys, such as H0 for line 52 andcontacts of relay '15 when this relay operates, and thereby cause the connection to be established at cross-points, such as 84, for the outgoing branch of the link as-shown, and the calling subscribersline-5l will therefore be connected to 'all' the other called lines throughthe link, the calling line being connected at crosspoint'82 to the incoming-branch and the called lines to the outgoing branch at cross-point 84 and other similar points for'the other lines. The operator may thenrelease all the keys actuated and conversation between the conference lines may take place in the same manner as described in connection with line-to-line calls.

What is claimed is:

1. In a telephone system, a switch, lines and links terminated therein, magnets in said switch for actuating it'to connect lines in said switch through a link, a key for each line, means controlled by the actuation of the key for a calling line andthe key for a called line for actuating magnets in said switch'to establish a connection between the calling line and the called line through an idle link over said switch said means being so arranged that the calling line and the called line are connected to said link after the key for the called line is actuated.

2. In a telephone system, a cross-bar switch, lines and links terminating in said switch, magnets in said switch for actuating it to connect linesin said switch through a link, a key for each line, means controlled by the operation of the key for a calling line and the key for a called line for actuating said magnets to first establish a connection between the calling line and an idle link through-said switch and then establish a connection between the called line and said link through said switch, said means being operative to actuate said magnets only after the key for the called line has been actuated.

3.'In a telephone system, a switch, lines and links terminating in said switch, magnets in said switch for actuating it to connect the lines in said switch through an idle link, a'key for each line, a series of relays, circuit means for operating said relays ina certain sequence, means controlled by the operation of the key for a calling line followed by the operation ofthe key for a called line for starting the operation of said relays in sequence after the key for the called line has been operated and circuit means controlled by said keys and said relays when operated in sequence for actuating said magnets in a certain sequence to establish a connection between said calling line and said called line through an idle link over said switch.

4. In a telephone system, a, cross-bar switch, lines and links terminating in said switch, magnets in said switch for actuating it to connect lines in said switch through a link, a series of relays, a circuit means for operating said relays in a certain sequence, a key for each line, circuit means controlled by the operation of the key of a calling line followed by the operation of the key of a called line for starting the operation of said relays in sequence, and means controlled by said operated keys and said relays for actuating said magnets in a certain sequence to establish a connection between the calling line and the called line through a link over said switch, the starting of the operation of the relays in sequence taking place when the key for the called line is operated.

5, In a telephone system, a cross-bar switch, lines and links terminating in said switch, magnets in said switch for actuating it to connect lines in said switch through a link, a key for each line, a series of relays, circuit means for operating said relays in a certain sequence, means controlled by the operation of the key of a calling line and the key for a called line for starting the operation of said relays in sequence and circuit means controlled by said operated keys and said relays for first operating magnets in said switch for establishing a connection between the calling line and an idle link followed by the operation of magnets in said switch to establish a connection between the called line and said link, operative on the operation of the key for the called line.

6. In a telephone system, a switch, lines, trunks and links terminating in said switch, magnets in said switch for actuating it to connect a line to a link or a line to a trunk, a key for each line, a key for each trunk, means controlled by the operation of the key for a calling line and a key for a called line for actuating said magnets to establish a connection between the calling line and the called line through a link over said switch operative when the key for the called line is actuated, means controlled by the operation of the key for a calling line and a key for a trunk for operating said magnets to establish a connection between said calling line and said trunk and operative when the key for the trunk is actuated.

'7. In a telephone system,ia cross-bar switch, lines, trunks and links terminating in said switch, magnets in said switch for actuating it to interconnect lines through a link and a line to a trunk, a key for each line, a key for each trunk, means controlled by the operation of the key for a calling line and the key for a called line for actuating said magnets to establish a connection between said calling line and said called line through an idle link over said switch operative when the key for the called line is actuated and means controlled by the operation of the key for a trunk and the key fora calling line for establishing connections from said trunk to said called line 75 said magnets to establish a connection over said switch between said calling line and said called lines over a link operative when the separate key is released.

9. In a telephone system, a cross-bar switch, lines, links terminating therein, magnets in said cross-bar switch for actuating the switch to connect lines in said switch through a link, a key for each line, a separate key, means for calling a plurality of said lines, means controlled by the operation of the separate key, the key of a calling line and the keys of the called lines and the release of the separate key for actuating said magnets to establish a connection over said switch between said calling line andrsaid called lines over a link operative when the separate key is released, connections between the calling line and the links preceding the connections between the link and the called lines, said connections between the link and the called lines occurring simultaneously.

10. In a telephone system, across-bar switch, lines and links terminating in said switch, magnets in said switch for actuating it to connect lines in said switches through a link, a key for each line, a special key, means controlled by the operation of said special key followed by the operation of the key of a calling line and the operation of the keys of a plurality of called lines and the subsequent release of the special key for actuating magnets of said switch to establish a connection between the calling line and a link and for actuating magnets in said switch to establish connections between the called lines and said link simultaneously, said operation of all of said magnets in said switch being efiective on the release of the special key.

11. In a telephone system, a switch, lines and links terminating therein, magnets in said switch for actuating it to connect lines in said switch through said links, a key for each line, means for first actuating certain magnets for connecting a calling line to an idle link and then actuating certain other magnets for connecting said called line to said link, said operating means for said magnets being controlled jointly by the operation of the key for a calling line and the key for a called line to actuate said magnets after the key for the called line has been operated.

12. In a telephone system, a switch, lines and links terminating therein, magnets in said switch for actuating it to connect lines in said switch through a link, an operators position, a key for each line, means controlled by theactuation'of the key for a calling line for connecting said operators, position to said calling line, means controlled by said actuation of the key for the calling line and the actuation of the key for a called line, for actuating said magnets to establish a connection between the calling line and the called line through an idle link and for disconnecting said operators position from said called line.

13. In a telephone system, a switch, lines and links terminating therein, magnets in said switch for actuating it to connect lines in said switch through a link, an operators position, a key for each line, means controlledby the actuation of the key for a calling line for connecting said operators position to said calling line, means controlled by said actuation of the key fo the calling line and the actuation of the key for a called line, for actuating said' magnets to establish a connection between the calling lineand the called line through an idle link andfor disconnecting said operators position from said called line, said means being efiecti've when the key for the called line is actuated.

' LEER. WAILER

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