Patent GB-305158-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q1/20
Filed: 1927-11-01
Abstract: 305,158. Automatic Telephone Manufacturing Co., Ltd., and Ostline, J. E. Nov. 1, 1927. Automatic and semi-automatic exchange systems.-Equipment by which an operator may observe the progress of calls on certain trunks includes means for recording the dialled impulses and, in a system employing register-controllers, the impulses transmitted by the register-controller, and lamps for indicating various stages of progress of the call. In the case of an abnormal condition. the operator can lock up the connection and communicate with the attendant. The observation may be carried out at the originating exchange, or the service of a number of exchanges may be observed from a central office. Arrargement of observation trunks. 50 trunks are provided, each having a switching relay such as 211 and a second relay such as 201 for preventing the operation of the switching relay in certain circumstances. The trunks are arranged in five groups of ten, each group having a pair of relays such as 245, 251. Relay 242 is common to all the trunks and controls the circuits of the relays such as 245, and its circuit includes contacts of all the switching relays such as 211. When the equipment is ready for observation. relay 242 and the relays such as 245 are energized. The observation trunks are connected to selector trunks by means of a terminal board TB, and when a selector is seized, switching relay 211 energizes over the test wire 104, locks and releases relay 242 and the relays such as 245. If another selector is seized while the observation equipment is in use, or if a seleetor is seized before the equipment is prepared for use, relay 201 energizes and locks and prevents the operation of the corresponding switching relay 211, so that such calls have no effect. To deal with simultaneous calls, each switching relay is arranged to open the locking circuit of the switching relays to the right of it. Observation by local operator. The operator connects the jacks J2. J3, energizing relay 300 to disconnect the central observer's equipment, and plugs into the jack J to connect up her listening set. Relay 226 energizes and connects up relay 242. If this relay fails to energize, a circuit is closed for the buzzer B. When a call is connected through to the observation equipment by switching relay 211, relay 242 and the relays such as 245 are released as already described, and relay 201 now pulls up, connecting up group relay 251 and start relay 257. which lock. Group lamp 0 and unit lamp O, Fig. 4, are lighted to indicate the trunk under observation. Pilot lamp 513<1> is lighted as long as conversation continues, being dependent on relay 201, and guard lamp 514<1> is lighted under control of relay 257 until the observation trunk is released by the operator. Dialled impulses are received by a polarized relay 376 in series with a condenser, while impulses from the register-controller are received by a similar polarized relay 376<1>, all the impulses being recorded on a double pen register PFR. Relay 713 is energized over guard wire 732 until the desired connection is complete, and connects the listening set across the out-impulse circuit, so that the Operator hears clicks corresponding to the impulses, and in the case of a busy condition, hears at what stage the busy signal is sent. Pilot lamp 706 lights when metering takes place. The connection may be locked up by means of key K1, which operates relays 280, 275 to shunt condenser 372 by resistance 288, so that there is a loop across the observation trunk when relay 713 falls back. To hold the register-controller, key K6 is pressed, releasing relay 713 and extending ground to switching relay 730, Fig. 2, which energizes, and to guard wire 732. To call the attendant after a connection has been looked up, key E2 is pressed, momentarily disconnecting relay 280 to energize relay 270, which locks in series with line relay 105, Fig. 2. The buzzer B is sounded, ana a tone is given to the operator through induction coil I. The attendant plugs into the jack J1, and by means of key K4 releases relay 270 to disconnect the buzzer B. The attendant may place a tracing tone on the connection by means of key K5, which also controls relay 270, and listen in on the switches by plugging into the individual test jacks. The connection may be locked at the desired point by earthing the test wire, and the trunk can then be released from the observation equipment. Observation from central office, Figs. 6, 7. It is assumed that the system does not employ register-controllers. A four-wire observation trunk extends from the equipment at each exchange to the central office, a switching relay such as 401 being provided for each trunk. A duplicate set of switching relays such as 401' is employed when there are two observing operators, connections being made at a jumper block JB. When the jack J is plugged into, common relay 435 energizes, preparing the circuits of the switching relays such as 401 and connecting up the relays such as 226 at each exchange to prepare the equipment thereat. On a call being connected to the local exchange equipment, switching relay 401 energizes, locks and releases relay 405. A fresh circuit is closed for relay 226, but the similar relays at other exchanges are released The progress of the call is observed substantially as in the case of the local equipment, similar lamps and control keys being provided. When there are two observing operators, the dotted line connections are made at the jumper block JB in place of the full line connections. The common relays 405, 405<1> are arranged to energize in turn so that successive calls are routed alternately to the two observing positions. Indicating the hunk under observation. The exchange lamps such as 1, 10 are controlled by the switching relays such as 401, 410, while impulses are sent from the local exchange to set the switches T1, T2 which control the group and unit lamps. Start relay 257, Fig. 3, connects up magnet 303 of the sending switch SS, Fig. 4, and this then interacts with relay 305. When a terminal marked by group relay 251 is reached by wiper 307, relay 311 pulls up and closes the impulse circuit to relay 530, which repeats the impulses to magnet 515 of the switch T1. After the requisite number of impulses have been sent, relay 311 is short-circuited over wiper 306, and the impulse circuit is opened. A second set of impulses is sent in the same way, a terminal cf wiper 307 being marked by switching relay 211, to operate magnet 532 of the switch T2. changeover relay 517 being energized meanwhile. The release magnets are controlled by the release key K.