US1315440A - willis - Google Patents

Description

B. D. WILLIS. AUTOMATIC TELEPHONE SYSTEM.

' APPucATloN man MAR. l. me.

B. D. WILLIS.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION mw MAR. 1. 191e.

1,315,440. Patent-ed Sept. 9, 1919;

2 SHEETS-SHEET '2.

ily-@wg JW HUD!" gay UNITED STATES PATENT OFFICE.

BERNARD D. WILLIS, OF CHICAGO, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY, OF'CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

Original application iled May 2, 1914, Serial No. 835,817.

Patent No. 1,280,609, dated October 1, 1918. Divided and this application filed March 1, 1916.

To all whom-it may concern:

Be it known that I, BERNARD D. VVILLI's, a citizen of the United States oi America, and resident of Chicago, Cook county, Illia nois, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

My invention relates to improvements in automatic telephone systems-that is, systems in which one or more switches are employed for establishingl connection between subscribers lines.

One of the Jfeatures of my invention is the provision oit an improved connector for use especially in connection with a toll operators board, which connector, when it is op erated to connect with a busyl line, locks on said line without establishing` a talking conneciion therewith, and as soon as the dcsired line is again idle a signal is given to the toll operator and the talking connection is completed with the desired line. In this manner the establishment of a connection is greatly expedited, as the toll connection is established as soon as the desired line becomes idle and without the necessity o1 the toll operator again setting up the connection.

This and other objects of my invention will be more clearly understood by reference to the accompanying drawings, in which I have illustrated my invention in connection with automatic switches of well-known types, together with a certain well-known form oi manual apparatus. My invention is, however, equally as well adapted for use with other forms of automatic switches and cord circuits, and the present system is merely for the purpose of illustrating one specific embodiment of m i invention.

Figure 1 shows the terminal conductors of a toll line ending in a jack ,7'2 at a toll board, an operators cord circuit C and a selector switch circuit 'for use with the operators cord circuit.

Fig, 2 shows diagrammatically a connector for completing the toll connection to an automatic substation.

Although reference has been made to automatic apparatus and to a manual apparatus, it is to be understood that this does not mean that the manual part of the system is necessarily a separate and distant exchange Specification of Letters Patent.

` board.

AUTOMATIC TELEII-IONE SYSTEM.

Patented Sept. 9, 1919.

Renewed February 23, 1918, Serial No. 218,898. Serial in itself. It may be simply a manual switchboard, which is usually installed in automatic exchanges for the purpose of handling long distance or toll calls.

In Fig. 1 I have shown a trunk line 53-5-1 which terminates in the usual answering jack jg and multiple jacks at the toll This trunk line is provided with the usual line relay controlling the line lamp 57 and cut-off relay 56.

The operators cord circuit O resembles the usual cord circuit in manual systems in that it comprises an answering plug p2, a calling plug p, calling` and answering supervisory lamps 59 and 60 and suitable relays fer controlling the circuits thereof. The cord circuit is also provided with a calling device (which is herein represented by a pair of impulse springs), a busy supervisory lamp 61 (which will be hereinafter more fully explained), a ringing current generator R and the necessary keys for controlling the operations of the said cord circuit.

The trunk lines which lead from the manual switch-board to the selector F terminate in multiple jacks j* on the manual switchboard. The sleeve conductors of the jacks y" are connected to battery through a relay 62 which controls the circuit of a visual busy signal 63 associated with each multiple jack.

The toll selector F is of the general type of selector switch shown in U. S. Letters Patent No. 815,321, granted March 13, 1906 to Keitli,Eiickson and Erickson, except that the so-called side switch is omitted and the circuits modified tov adapt it to operate in a system in which it is controlled by impulses delivered over two sides of the line in series, as shown in British Patent No. 10,376 or' 1912, and with the addition of a set of springs 158, 176 and 180 that are operated upon the eleventh rotary step of the rotary magnet, the function of which is to give the calling operator a busy signal if all the trunks on any one level of the selector banks are busy and to prevent the said selector switch from further operation.

The toll connector M is of the same general type of connectoi` switch as that dis closed in U. S. Letters Patent No. 815,176 granted March 13, 1906 to Keith, Erickson and Erickson, being modified, however, to adapt the switch to operate in a system in which the central oflice apparatus is controlled by impulses over the two sides of the line in series the circuits being also somewhat modified to adapt the switch to operate in a system embodying the principles of my in vention. This connector is provided with two separate line relays 65 and 66 bridged across the trunk line, which bridge is controlled by the back-bridge relays 67 and 68. The circuit of the relay 66 is likewise controlled by the busy relay 69, the circuit of which is in turn controlled by the slow acting relay 198. This busy relay 69 does not close a locking circuit for itself when energized, as is usually the case in connectors of this type, but its energizing circuit is dependent on the ground on the connector bank contact upon which the private wiper 71 is resting. The operation of this switch is controlled through the medium of the usual vertical and rotary magnets 19A and 203. A ringer relay 73 is likewise provided, which is directly under the control of the operator at the cord circuit O. Likewise, the holding and release circuits of the switches employed in establishing connection with this connector, instead of being controlled from this connector, are controlled directly by the relay 62 at the operators board, one of said relays being associated with each of the selector switches F.'

For the purpose of supplying current for operating the central oice apparatus and for talking purposes there is shown in the drawings a battery B having one terminal grounded at G.

A general description of the apparatus having been given it will now be explained how the operator may extend a connection to the subscriber A whose number is 220. In order to make this explanation clearer assume that the subscriber A has set up a local call through the medium of his line switch C, which is of the general type of individual switch shown in British Patent No. 26,301 of 1906 and of the particular type shown in BritishPatent No. 1419 of 1910, and a selector switch to which his line switch may have access. While this connection remains established a guarding ground will be established on the private conductor 206 from the said selector switch, which will hold the cut-off magnet 122 of the line switch C in energized position in a maniier well known in the art. A toll call coniing into the manual board over the conductors 53 and 54 (Fig. 1) causes the line signal lamp 57 to glow. The operator, upon noticing the line signal lamp 57 glowing, innnediately plugs the plug p2 into the answering jack j2, which immediately causes the cut-olf relay 56 to energize and cut off the line relay 55 and the line signal lamp 57. The energizing circuit for the cut-o' relay 56 extends from ground G15 through the contact of springs 150, springs 151, sleeve of the plug and jack jz and the said cut-off relay 56 to battery B. A further result of the energization of the relay 56 is to close a circuit through the visual busy signals 58 at the different operatois positions that have access to the trunk lines 53 and 54.- The operator now presses the key K4 to connect her head set (not shown, but connected to the conductors 153 and 1511) across the conductors 53 and 5&1. The operator, upon learning that the subscriber at Lsubstation A is desired, inserts the plug p3 into the jack j* and operates the key K5 to bridge the calling device X across the conductors 155 and 156. The insertion of the plug p3 into the jack j* connects the cord circuit O direct with the selector F and closes a circuit through the relay 62. This latter circuit extends from ground G16 through the resistance 157, sleeve of the plug p3, sleeve of the jack y"l and the relay 62 to battery B. The relay 62, upon energizing, closes a circuit through the visual signal relays 63 at the various operators positions, thus showing that the trunk leading to the selector F is in use. The bridging of the calling device K across the conductors 155 and 156 causes the line relay 159 of the selectorI F to energize over the following circuit. From ground G17 through the contact of springs 158 and 17 lower winding of the relay 159, springs 160 and 161, springs 162, ring spring of jack jt, ring of the plug p3, conductor 156, key K5, calling device X, key K5, conductor 155, tip of the plug p3, tip spring of jack j4, springs 163 and 1641 and the upper winding of the relay 159 to battery B. The relay 159, upon energizing, closes a circuit through the slow acting relay 165. The operator now operates her calling device for the first digit 2, in response to which the selector F raises its switch shaft and wipers in the manner described in the selector patent hereinbefore referred to, opposite the second row or level of bank contacts and then operates t0 find an idle trunk line leading to a connector M. As soon as the shaft wipers 167, 168, and 169 corne in contact with the idle bank contacts leading to the connector M, the switching relay 170 operates to disconnect the line relay 159 and extend the connection over the conductors 171 and 172 to the line relays 65 and 66 ofthe connector M. The switching relay 170 is held energized from the cord circuit O rather than from the connector switch ahead, as is usually the case with selectors of this type. The holdinncircuit for the switching relay 170 extends from ground G18 through the contact of springs 173, springs 174i, springs 175, springs 176. springs 177 and 17 8 and the relay 170 to battery B. 1f the selector switch F should find all the contacts in the second level busy, the rotary magnet, upon taking its last rotary step, will open the contact of the springs 176 and the springs 158 and 179 and close the contact of springs 180 and 179. The opening of the springs 176 opens the circuit of the rotary magnet 181 and allows the relay 182 to denergize. The closing of the springs 180 and 179 gives the operator a special busy signal over a path extending from ground G19 through one coil of the busy machine Q2 (only the induction coil of said busy machine being shown), contacts of the springs 180 and 179, lower winding of the relay 159, springs 160 and 161, over the heavy conductor to and through the operators head set (When she restores the key K5), over the heavy return conductor, springs 163 and 164 and the upper winding of the relay 159 to battery B. The operator, upon hearing the busy signal, releases the connection and calls again. Assuming that the selector F obtained connection with the connector M, the relays and 66 immediately energize. The relay 66, upon energizing, closes a circuit extending from ground G20 through the contact of springs 186 and the relay 187 to battery B. The relay 187, upon energizing, prepares a circuit for the vertical magnet by closing the springs188 and 189 and opens the circuit of the release magnet 190 at the springs 189 and 191. A further result of the energization of the relay 187 is to close a locking circuit for itself, which circuit extends from ground G18 at 4the cord circuit O through the contact of springs 173, springs 174, springs 175, wiper 168, conductor 193, springs 192, and the said relay 187 to battery B. The apparatus is now in readiness to receive impulses for the second digit of the called number.

The operator now operates her calling de* vice for the second digit 2, whereby the line relay 65 operates to transmit two impulses through the vertical magnet 194 over a circuit extending from ground G21 through the contact of springs 196 and 197, springs 189 and 188, relay 198, springs 199, the vertical magnet 194 and the side switch wiper 201 to battery B. The vertical magnet 194 receives two impulses over this circuit and operates to raise the switch wipers 70, 71 and 72 to a position opposite the second level of bank contacts. The relay 198, which is included in series with the vertical magnet, remains in its energized position during the entire time that impulses are being sent through it and operates to close the circuit of the private magnet 202. After the last impulse is delivered, the relay 198 opens the circuit of the private magnet 202, which, upon denergizing, permits the side switch to advance from first to second position. The movement of the side switch wiper 201 from first to second position transfers the battery connection from the vertical magnet 194 to the rotary magnet 203. The operator now operates her calling device X for the last digit 0, in response to which the connector line relay 65 operates to transmit ten impulses through the yrotary magnet 203 in series with the relay 198, whereby the shaft wipers are rotated onto the contacts of the desired line. The relay 198, upon denergizing, opens the circuit of the private magnet 202, the private magnet, however, does not denergize and step the side switch to third position at this time because the private wiper 71 is resting upon a grounded contact, which causes the following circuit to be closed as soon as the relay 198 dener gizes: from ground upon the bank contact 223 (upon which the wiper 71 is resting, as it will be recalled that the substation A is in connection with a local selector switch), side switch wiper 208 (in second position), relay 69, springs 209 and 210 and the private magnet 202 to battery B. The magnet 202 is thus held energized, which holds the side switch locked in second position and opens the circuit of the switching relay 211 at the springs 212. The relay 69, upon energizing, opens the circuit of the rotary magnet 203 at the springs 199 to prevent a further rotation of the wipers and opens up one side of the calling line at the springs 214. The engagement of the springs 215 serves to close a circuit for the busy tone from the busy machine Q through the said springs, condenser 218, conductor 172 to and through the operators head set (when she restores the key K5 to normal), return conductor 171, springs 219 and 220 and the relay 65 to battery B. As soon as the operator hears the busy signal she operates the key K6 to connect the special busy supervisory lamp 61 to the spring 220 of the relay 221. The operator may now go ahead and tend to other calls that may come into her position. As soon as the connection of the subscriber A with the other switches is released, the guarding potential will be removed from the bank contact 223 upon which the wiper 71 is resting. The removing of the ground from the bank Contact 223 opens the circuit of the busy relay 69 and the private magnet 202. The private magnet, upon denergizing, allows the side switch to move from second to third position. The relay 69, upon denergizing, removes the busy tone from the conductor 172 and closes a circuit through the relay 221 at the operators cord circuit. This circuit extends from ground Gr23 through the relay 66, contact of springs 214, springs 225, conductor 172 and through the said coil 221return conductor 171, springs 219 and 220 and the relay 65 to battery B. The relay 221, upon energizing, closes a circuit through the supervisory busy lamp 61 over a circuit extending from ground G25 through the contact of springs 226 and 220',

springs of key K6 and the lamp 61 to battery B. The side switch wiper 208 passing to third position, closes a circuit through the bridge-cut-otf coil 122 of the line switch C. This circuit extends from ground G2G, side switch wiper 208, private wiper 71, Contact 223 over the conductor` 123 and the winding 122 to battery B. A further result of the side switch wiper 208 passing to thirdposition is the closing of a circuit through the relay 211, which, upon energizing, completes the connection through to the substation A.

The operator, upon noticing the lamp 61 glowing, restores the key KG to normal and presses the key K9. As soon as the key K9 is depressed, the circuit through the line relay 65 is maintained, but the circuit through the line relay 66 is broken at the springs 243 and 2441 of the key K9. The denergization of the relay 66 closes a circuit through the ringing relay 73. This circuit extends from ground G21 through the contact of springs 196 and 195, springs 227, relay 73 and the side switch wiper 201 (in third position) to battery B. The relay 73, upon energizing, disconnects the callingline from the called line and bridges the ringing current generator R2 vacross the called line. The operator now restores the key K" to normal, thus bridging the coil 221 again across the line conductors 155 and 156, which causes the said relay to energize and close a circuit through the supervisory lamp 59. As soon as the called subscriber answers, the back-bridge relays 67 and 68 are energized. The said relays, upon energizing, disconnect the line relays 65 and 66 from the conductors 171 and 172 and connect the calling line with the called line inductively through the windings of the repeating coil S. The disconnecting of the relays 65 and 66 from the conductors 171 and 172 allows the relay 221 of the cord circuit to denergize, which, upon denergizing, opens the circuit of the supervisory lamp 59. The keys K7 and KS of the cord circuit O are so arranged that the operator may connect her head set with either the calling or the called end of the cord circuit without connecting it with both ends at the same time.

As soon as the conversation is completed, the called subscriber, upon replacing his receiver upon the switch-hook, allows the backbridge relays 68 and 67 to denergize and again bridge the relays 65 and 66 across the conductors 171 and 17 2, thus causing the supervisory relay 221 to energize and close a circuit through the supervisory lamp 59. As soon as the calling subscriber transmits a disconnect signal over the conductors 53 and 54, the relay 228 breaks the circuit of the cut-oli' relay 56 at the springs 150. However, the relay 56 does not denergize, for at the instant that the springs 150 separate, the shunt around the relay 229 is removed and the said relay 229 is cut in series with the relay 56. The relay 229, upon energizing, closes a circuit through the front supervisory lamp 60 and permanently opens the shunt around itself at the springs 151. The operator, receiving the disconnect sig nal, immediately removes the plug p2 from the jack t7'2 and the plug p3 from the jack jt Removing the plug p2 from the jack 7'2 opens the circuit of the relays 229 and 56. The relay 56 immediately denergizes and opens the circuit of the visual busy signals 58 at the springs 230 and 231. Removing the plug p3 from the jack j4 opens the circuit of the relay 62, which, upon denergizing, opens the circuit of the visual busy signals 63 at the springs 132 and also opens the circuit of the relays 170 and 187 of the selector F and the connector M, respectively, at the springs 173. The relay 170, upon deenergizing, closes a circuit through the release magnet 233. The said circuit extends from ground G30 through the contact of the springs 235 and 236, springs 237, springs 238 and 239, off-normal springs 234 and the release magnet 233 t0 battery B. The release magnet, upon energizing, releases the selector F in the same manner as described in the selector patent referred to. The relay 187 of the connector M, upon deenergizing, closes a circuit through the release magnet 190. The said circuit extends from ground G21 through the contact of springs 196 and 197, springs 189 and 191, off-normal springs 240 and the release magnet l190 to battery B. The magnet, upon energizing, restores the switch shaft and side switch wipers to normal position and its own circuit is broken at the springs 240 when the shaft reaches its lowest position.

It will thus be seen that I have provided a very eticient system and one in which the connector locks upon a busy line, and as soon as this line becomes idle, the side switch is tripped so as to cut the connection through to the desired line and at the same time a signal is fiashed at the operators board, advising the operator of the fact that the connection has been established with the called line, so that the operator can then supply ringing current to the line to signal the subscriber. It will furthermore be seen that the connector, instead of being provided with the usual condensers in the talking conductors in order to divide the same into calling and called branches, is provided with a repeating coil, and, furthermore, that the front-bridge relays of the connector are disconnected from the talking circuit when the called subscriber answers by the operation of the back bridge relays, and in this manner the amount of leakage across the line is greatly reduced.

lVhile I have thus illustrated and de scribed my invention in connection with one particular' type of automatic system and in connection with automatic switches and toll apparatus of a particular character, it will, of course, be understood that I do not wish to be limited to the exact construction shown and described, but that various changes and modifications will readily suggest themselves to those skilled in the art and come within the spirit of my invention.

What I claim as my invention is:

l. In a telephone system, a manual switchboard, a subscribers line, an automatic connector switch controllable from said switchboard to connect with said line, a side switch in said connector movable to successive positions in the operation of the same, means controlled by said side switch in one of its positions adapted to complete said connection, and means operated if said connection is attempted when the said line is busy to lock said side switch in an intermediate position to render said connecting means inoperative, said locking means rendered ineffective when the said line becomes idle, whereby the said side switch is permitted to move to another position to render said connecting means operative to complete said connection.

2. In a telephone system, a manual switchboard, a subscribers line, an automatic connector switch controllable from said switchboard to connect with said line, a side switch in said connector movable to successive positions in the operation of the same,4 means controlled by said side switch in one of its positions adapted to complete said connection, means operated if said connection is attempted when the said line is busy to lock said side switch in an intermediate position to render said connecting means inoperative,

said locking means rendered ineffective when the said line becomes idle, whereby the said side switch is permitted to move to another position to render said connecting means operative to complete said connection, anda signal at the switchboard for indicating when said connection is completed.

3. In a telephone system, a manual switchboard, an operators head set at said board, a subscribers line, an automatic connector switch controllable from said switchboard to connect with said line, means in said switch for automatically preventing the completion of such connection while the said line is busy and for giving the operator a busy signal,

means for` automatically completing such connection when the said line becomes idle, and another signal at the switchboard for indicating when said connection is completed.

4;. In a telephone system, a manual switchboard, an operators head set at said board, a subscribers line, a trunk line extending from said switchboard to an automatic connector switch, said switch controllable over said trunk to connect with said' line,- contacts in said switch and means for closing them after the said line has been found to complete connection thereto, means for preventing the closure of said contacts when the said line is busy and until it becomes idle and for giving the operator a busy signal, and another signal at the switchboard for indicating when said connection is completed.

5. In a telephone system, a manual switchboard, a subscribers line, an automatic connector switch controllable from said switchboard to connect with said line, a side switch in said connector movable to successive positions in the operation of the same, means controlled by said side switch in one of its positions adapted to complete said connection, means operated if said connection is attempted when the said line is busy to lock said side switch in an intermediate position to render said connecting means inoperative, said locking means ineffective when the said line becomes idle, whereby the said switch is permitted to move to another position to rendersaid connecting means operative to complete said connect1ona signal at said switchboard, and a relay for operating said signal upon the completion of said connection.

6. In a telephone system, a manual switchboard, a subscribers line, an automatic connector switch controllable from said switchboard to connect with said line, means in said switch Jfor automatically preventing the completion of such connection while the said line is busy, means for automatically completing such connection when the said line becomes idle, a `signal at said switchboard, and a relay for operating said signal upon the completion of said connection.

7 In a telephone system, a manual switchboard, a subscribers line, a trunk line eX- tending from said switchboard to an automatic connector switch, said switch controllable over said trunk to. connect with said line, contact-sv in said switch and means for closing them after the said line has been found to complete connection thereto, means for preventing the closure of said contacts when the said line, is busy and until it 4becomes idle, a signal at said switchboard,

and a relay operated over said` trunkv line to operate said signal upon the completion of said connection.

8. In a telephone system, a manual switchboard, a subscribers line, a trunk `line eX- tending from said switchboard to an automatic connector switch, a cord circuit at said switchboard having access to said trunk line, means in said cord circuit for operating said connector switch to connect with said line, means in said switch for. automatically preventing the com letion of such connection, while the said ine is busy, and means in said switch for automatically completing such connection when the said line becomes idle, and a visual signal at said switchboard 'for indicating a completion of said connection.

9. In a telephone system, a manual switchboard, a subscribers line, a trunk line extending from said switchboard to an automatic connector switch, a cord circuit at said switchboard having access to said trunk line, an operators head set at said cord circuit, means in said cord circuit for operating said connector switch to connect with said line, means in said switch for automatically preventing the completion of such connection while the said line is busy and for giving the operator a busy signal, means in said switch for automatically completing such connection when the said line becomes idle, and another signal in said cord circuit for indicating when said connection is completed.

10. In a telephone system, a manual switchboard, a subscribers line, a trunk line extending from said switchboard to an automatic connector switch, a cord circuit at said switchboard having access to said trunk line, means in said cord circuit tor operating said connector switch to connect with said line, means in said switch for automatically preventing the completion of such connection while the said line is busy, means in said switch for automatically completing such connection when the said line becomes idle, a signal in said cord circuit. and a relay operated over said trunk line to operate said signal upon the completion of said connection.

11. In a telephone system, a manual switchboard, a subscribers line, a trunk line extending `from said switchboard to an automatic connector switch, a cord circuit at said switchboard having access to said trunk line, means in said cord circuit for operating said connector switch to connect with said line, means in said switch for automatically preventing the completion of such connection while the said line is busy, and means in said switch for automatically completing such connection when the said line becomes idle, a pair of signals in said cord circuit, one signal for indicating when said connection is completed and the other signal for indicating the response of a subscriber on said line.

12. In a telephone system, a manual switchboard, a subscribers line, a trunk line extending from said switchboard to an automatic connector switch, a cord circuit at said switchboard having accessto said trunk line, means in said cord circuit for operating said connector switch to connect with said line, means in said switch for automatically preventing the completion of such connec tion while the said line is busy, meansin said switch for automatically completing suchy connection when the saidline becomes idle, a pair of signals in said cord circuit, one signal for indicating when said connection is completed and the other signal for indicating the response of a subscriber on said line, and a common controlling relay :tor said signals operated over said trunk line.

13. In a telephone system, a manual switchboard, a subscribers line, a trunk line extending from said switchboard to an automatic connector switch', a cord circuit at said switchboard having access to said trunk line, means in said cord circuit for operating said connector switch to connect with said line, means in said switch for automatically preventing the completion of such connection while the said line is busy, means in said switch for automatically completing such connection when the said line becomes idle, a pair of signals in said cord circuit, one signal for indicating when said connection is completed and the other signal for indicating the response of a subscriber on said "line, a common controlling relay for said signals operated over said trunk line, and a manually operated key for shifting the control of said relay tromone signal to the other.

14. In a telephone system, a calling and a called line, an automatic connector switch, a repeating coil associated with said switch for repeating talking current between said lines, means for extending the calling line to said switch, a relay bridge connected across the calling line when so extended, said bridge adapted to control said switch to connect one winding of said repeating coil with the called line, and a relay bridge across the called line when so connected, said last bridge operable upon the response of the called subscriber for disconnecting said first relay bridge and for substituting the other winding of said repeating coil therefor, said other winding of the repeating coil in a continuous metallic bridge across the conductors of the calling line during talking.

15. In a telephone system, a manual switchboard, a subscribers line, a trunk line terminating in a connector "switch, a controlling relay for said switch normally connected to said trunk line, said relay controllable from said switchboard for operating said switch to connect with said subscribers line, a repeating coil for repeating talking current between said lines, a relay bridge across the said subscribers line when so connected, and means controlled by said bridge over said subscribers line :tor disconnecting said controlling relay and for connecting the said trunk line and the said subscribers line by way of said repeating coil, one of the windings of said repeating coil being in a continuous metallic bridge across the conductors ofsaid trunk line.

16. In a telephone system, a manual switchboard, a subscribers line, a trunk line terminating in a connector switch, a controlling relay for said switch normally connected to said trunk line, said relay controllable from said` switchboard for operatingl said switch to connect with said subscribers line, a repeating coil for repeating talking current between said lines, a relay bridge across 'the Said subscribers line when so connected, means controlled by said bridge over said subscribers line for disconnecting said controlling relay and for connecting the said trunk line and the said subscribers line by way of said repeating coil, one of the windings of said repeating coil being in a continuous metallic bridge across the conductors of said trunk line, and means controlled from said switchboard for maintaining said switch in operated )osition after said controlling relay has heen disconnected.

17. In a telephone system, a subscribersV line, an automatic connector switch adapted to establish connection therewith, a trunk line, means for controlling said switch over two sides of said trunk line in series, means for locking said switch on said subscriber-s line when said subscribers line is busy without extending the connection through to said line, and means for automatically completing said connection when said subscribers line is again idle.

18. In a telephone system, a subscribers line, an automatic connector switch adapted to establish connection therewith, a trunk line, means for controlling said switch over two sides of said trunk line in series, means for locking said switch on said subscribers line when said line is busy without eXtending the connection througl'l to said line, means for automatically completing said connection when said subscribers line is again idle, a signal7 and means for operating said signal when connection is completed with the subscribers line.

19. In a telephone system, a subscribers line, an operators board, an operato1"s head set at said board, means including an automatic connector switch for establishing a connection from said board to said line, means for locking said connector switch on said line if the same is busy and for giving the operator a busy signal without establishing a talking connection between said board and said line, means for automatically cutting said connection through when said line is no longer busy, another signal at said board, and means for operating said other signal to inform said operator when said connection is cut through to the line.

20. In a telephone system, a subscribers line, an operators board, means including an automatic switch for establishing connection from said board to said line, a side switch having three operative positions, means for locking said side switch in second position when said connector establishes connection with a busy line, and means for causing said side switch to pass to third position as soon as said line is no longer busy.

21. In a telephone system, a subscribers line, an operators board, means including an automatic switch for establishing connection from said board to said line, a side switch having three operative positions, means for locking said side switch in second position when said connector establishes connection with a busy line, means for causing said side switch to pass to third position as soon as said line is no longer busy, and means i'or signaling said operator when said side switch is tripped to third position.

`Signed by me at Chicago, Cook county, Illinois, this 24th day of Feb., 1916.

BERNARD D. WILLIS.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C.

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