Patent GB-197487-A (GB)
Title: Improvements in telephone exchange systems
IPC: H04Q1/22
Filed: 1922-03-28
Abstract: 197,487. Western Electric Co., Ltd., (Western Electric Co., Inc.). March 28, 1922. Automatic exchange systems.-In order to supervise the working of an exchange in which calls are established in known manner over numerical selectors under the control of a register-controller set by impulses transmitted by the calling subscriber, a recording-clerk's position is provided to which any one of a predetermined group of lines is automatically connected when a call is initiated on that line. The arrangement is such that the recording equipment, when released from connection with one line, cannot be connected to another line on which a call is already progressing, and, in fact, cannot be connected to any line until no calls exist on any of the other lines of the group. Records are made of the times elapsing between the initiation of a call and the connection of an idle register-controller to the line, and between the initiation of a call and the commencement of the transmission of impulses, a signal being given in the event of the calling subscriber commencing to transmit impulses before an idle register-controller has been connected up. A record may also be made of the character of the impulses transmitted. The transmission of metering current during the release of a connection is indicated by buzzer and lamp signals, whilst, in a coin-freed system, similar signals indicate the transmission of coincollecting or coin-refunding current. Slightly modified arrangements are described according as the calling subscribers are served by call-finders or provided with line-switches. The invention is stated to be also applicable to step-by-step systems, in which case a record is made of the time elapsing between the initiation of a call and the connection to a first group selector ready to receive impulses. General arrangements for a group of subscribers A. Fig. 1, served by call-finders 132. Each subscriber's line of a group of, say, forty lines on which observation is desired, is connected by plugs 122, 123, 124 to a connecting circuit 102 - - 107 terminating in the apparatus shown in the dotted rectangle at the right of Fig. 3, one such connecting circuit being individual to each line, whilst the recording clerk's apparatus shown in Fig. 2 and outside the dotted lines in Fig. 3 is common to all the connecting circuits and is connected to any one when a call is initiated upon the subscriber's line associated therewith. Plugs 122, 123 are connected to the line A by means of a plug 125, the heat coils 126 being removed, whilst plug 124 is connected at the intermediate distributing frame IDF by means of a shoe 127. The completion of the plug-and-jack connection 201 associates the recording-clerk's talking set with the recording equipment and hence with a calling-subscriber's line, whilst the closure of contact 203 grounds the common lead 204 over conductor 231 and key 209. Supervision of establishment of call. When subscriber A removes his receiver, the individual relay 300 energizes in series with line relay 152 which starts the operation of the call-finder 132 in known manner. Relay 300 connects relay 302 to the grounded conductor 204 over a back contact of relay 306 and in series with relay 307 which energizes and completes circuits 211, 214, 216, 218, 313, 221, 219 and 223. 214, 216, 218, 315, 222, 227 for time-registering mechanisms 213, 225 respectively, which are periodically operated by alternating-current controlled by a driving fork 215. Relay 302 locks up over relay 306 and the grounded lead 210, energizing relay 305 and lighting individual calling lamp 301; whilst relay 306 energizes in this circuit, breaking the initial energizing circuit of relay 302 and the circuits of corresponding relays 303 individual to other lines, and so preventing the connection of a second calling line to the recording equipment. Relay 302 also connects the subscriber's loop A over leads 102, 103, and 308, 309 to the recording-clerk's talking set, and completes a circuit over the loop A for relay 322. Relays 324,. 325, 326 in turn energize, relay 325 preparing a looking circuit for itself over relay 314 which, however, is as yet short-circuited over a front contact of relay 324. Relay 329 also energizes over conductors 327, 311, 310, 204 to prepare a locking circuit for itself over relay 328 which is as yet short-circuited. When the line-finder 132 reaches the calling line, a battery connection to to the third brush of the finder energizes the cutoff relay 151 to disconnect the line relay 152 and to initiate the hunting operation for an idle register-controller, and a circuit is completed over conductors 156, 106, 321, 319 for relay 317 which energizes a relay 304 to open ,the initial energizing circuit of relay 302. Relay 300 also deenergizes at this time, opening the short-circuit around relay 328 which energizes and lifts lamp- 333. When an idle register-controller 135 is connected up, relay 300 energizes in series with the calling line and the impulse relay at the registercontroller and closes a circuit for relay 312 which energizes to light lamp 334, energize relay 335 and open the previously traced circuit for timing- device 213 which thus registers the time interval before an idle register-controller is connected up. Relay 312 also prepares a locking circuit through relay 362 which is as yet short-circuited, and energizes relay 323 to disconnect relay 322 which was de-energized when the impulse relay was. connected to the calling line. Relay 324, however, remains locked up over conductor 364. When the calling subscriber transmits the first impulse. the de-energization of relay 300 opens the locking circuit of relay 324 which de-energizes and opens the short-circuit around relay 314. Relay 314 energizes, opening the circuit of timing-device 225 which thus records the time elapsing before the subscriber commences to transmit impulses. Relay 300 also opens the short-circuit around relay 362 which energizes. A record of the character of the impulses transmitted may be obtained by inserting the plug 207 into jack 206. Relay 233 energizes over a front contact of relay 300, locks up relay 205 to key 209, and repeats the impulses to the magnet 208 which moves a pen into contact with a moving strip 230. Should the calling subscriber commence to transmit impulses before an idle register-controller has been seized,. relays 323, 335 are not operated, so that relay 322 de-energizes in response to the first interruption and with relay 300 also de-energized at this time, relay 324 falls back, relay 314 responds to open the circuit of timing-device 225 as before, whilst relay 336 energizes and lights the lamp 337. Supervision of coin-controlling and metering operations. When, during release, coin-controlling current is applied to the tip conductor, this current is also transmitted over conductors 147, 102, 308 to energize relay 237 in series with a polarized relay 238 which responds to coin-refunding current to light lamp 235 but does not respond to coin-collecting current, so that in this case lamp 236 is lit. In both cases relay 239 operates a buzzer 240. If metering current is applied in known manner over the fourth brush of the finder 132, meter magnet 158 is operated to register one call and relay 228 operates in a parallel circuit over conductors 157, 107, 316 to light lamp 241 and operate buzzer 240. Release of recording-clerk's equipment; prevention of connection to a partially-established call. The whole recording-equipment is released by operating key 209. If, at this time, any relay 300 is energized due to a call existing on a second line of the group, the removal of ground from lead 231 at key 209 causes relay 202 to operate, whilst relay 232 operates over key 209 and disconnects lead 231 from key 209, thereby effectively locking up relay 202 until no call exists on any line. This connection of relav 202 to lead 204 prevents relays 307, 302, 303 from energizing in series therewith, so that neither the line on which a call is in progress or any other line initiating a call can now be connected to the recording equipment. During the interval between the connection of a finder to the second calling line and the seizure of an idle register-controller, the de-energization of relay 300 at a time when no other calls exist in the group unlocks relays 202, 232, but, upon the re-energization of relay 300, the line is still prevented from connection to the recording-equipment since the initial energizing circuit of relay 302 is now opened by relay 304 as described above Modified arrangements for a group of subscribers B, Fig. 1, each provided with a line switch 128. In this case, plugs 112, 113, 114 are all connected at the frame IDF by shoes 116, 117, the straps 165, 166 being removed, whilst the tip of a fourth plug 115 is connected to an off-normal contact 107<1> of the line switch. Manual switch 321 is moved to the left so that relay 304 is energized over contact 107<1> as soon as the line switch moves from normal. The other operations take place in a similar manner to that described above, the energization of relay 328 and the lighting of lamp 333 taking place when an idle first group selector has been seized. Metering current is supplied ever the test wiper of the line switch to operate the meter magnet 154 and over the circuit 155, 107, 316 to operate magnet 228 as before. Specfications 24928/13 and 100,459 are referred to.