Patent GB-208509-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1923-07-30
Abstract: 208,509. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Schwartz, M.). Dec. 16, 1922, [Convention date]. Addition to 193,694. Automatic exchange systems. - Relates to a system of the kind described in the parent Specification, in which the first letters of the name of the wanted exchange are dialled to a registercontroller, which translates them into the series of digits necessary for routing the call to that exchange. According to the present invention, "switching line switches" C<4>, Fig. 6, provided with two wiper sets one set having access to the first exchange selectors E<1> and the other set having access to local third selectors E<6>, are inserted between the trunk equipment D and the first selectors. When a local call is made, as soon as the registercontroller RC has recorded the initial letters of the name of the originating exchange, the registercontroller is released and rendered available for other connections, and the switching line switch C' releases the first exchange selector E' and selects an idle local selector E<6>. For the purpose of simplicity the invention is described as applied to a network having a maximum capacity of 100 exchanges. Registercontroller selectors are therefore unnecessary, an idle register-controller being selected by a line switch C<3> associated with the trunk equipment D. Selection of an idle registar-controller and an idle first exchange selector E<1>. Assuming first that the subscriber A, Fig. 6, in BRyant exchange desires to establish connection with a subscriber in another exchange. On removing the receiver the calling line is extended in known manner to a trunk relay equipment D over primary and secondary line switches C, C<2>. The line relay 23, Fig. 1, in the trunk equipment D is energized over the calling loop and at armature 25 closes a circuit for the slow-acting line relay 150 of the register - controller selecting line switch C<3>, which seizes an idle register-controller in known manner. On the response of the switching relay 157, a circuit is closed over the normally - earthed conductor 174 for a relay 2'7 in the trunk equipment D, which relay energizes the line relay 61 of the switching line switch C<4>. The relay 61 closes a series circuit for the switching relay 57 and the stepping magnet 68, and connects the test wiper 76 of the upper wiper set 75 - - 77 to a point in this circuit between the relay 57 and the magnet 68. The switch C<4> now operates in well-known manner to extend connection to an idle first exchange selector E<1>. Operation of register-controller. The registercontroller is arranged and operates in a similar manner to the register-controller described in Specification 194,580, the code impulses being transmitted by the relay 27, Fig. 1, the circuit of which (over the conductor 174) is interrupted by the register-controller impulse relay 507, Fig. 3. When the last numerical digit has been transmitted and the sequence switch S', Fig. 5, has moved to its ninth position, the relay 512, Fig. 3, locks energized, and energizes relay 19, Fig. 1, which switches the talking circuit through and disconnects relay 23. The circuits are so arranged that this operation shall be silent to the calling subscriber. The relapse of relay 23 de-energizes in turn the relays 150, 157 of the switch C<3>, and the register-controller is restored as described in the above-mentioned Specification. Operation when a local call is made. Assuming the subscriber A, Fig. 6, in the BRyant exchange desires connection with a local subscriber A<2>, on removing his receiver a register-controller is selected and the calling line is extended to a first exchange selector E<1> as previously described. The calling party now dials the first two letters BR which are registered by the exchange register J, Fig. 4, in known manner. The terminals of the register J now engaged by the wipers are all disconnected at the left-hand side of the distributing frame I.D.F. with the exception of the bottom terminal, which is jumpered to a bus-bar SW on the right-hand side of the frame. When the digit controlling switch M, Fig. 2, is moved to its third position when the second letter has been dialled, the conductor 400 is grounded and a circuit is completed, over the sequence switch arm 404, the conductor 411, the bus-bar SW, and the conductor 564, for the relay 512, Fig. 3, which locks up and at armature 537 extends ground from the conductor 564 to the conductor 175, thereby energizing the stepping magnet 68 of the switching line switch C<4>. The energization of the magnet 68 does not, however, advance the wipers, which are stepped by retractions of this magnet, The switching relay 57 is deenergized at armature 67, causing the response of the line relay 61 and of the relay 62, the latter relay locking up over its armature 65, and connecting the trunk conductors to the lower wiper set 117 - - 119. The line relay 61, (1) interrupts the circuit of the stepping magnet 68 which advances the wipers a step, (2) closes at armatures 59, 60 a series circuit for the switching relay 57 and the stepping magnet 62, and (3) at armature 64 connects the lower test wiper 118 to a point in the lastnamed circuit between the relay 57 and the stepping magnet 62. The switch now operates in known manner to select an idle local selector E<6> over the wipers 117 - - 119. On the energization of the switching relay 57, the trunk conductors are extended to the engaged local selector E<6>. The response of the relay 62 also de-energizes the line relay 107 of the first exchange selector E<1>, which is rendered available for other connections. Meanwhile the energization of the relay 512, Fig. 3, has completed a circuit for the switching relay 19 of the trunk equipment D, Fig. 1, which switches through the calling line and releases the register in the usual manner. The numerical impulses are now dialled and the local switching apparatus extends the connection as in general practice.