Patent GB-191509396-A (GB)
Title: Improvements in or relating to Telephone Systems.
Filed: 1915-06-26
Abstract: 9396. Automatic Telephone Manufacturing Co., [Assignees of Willis, B. D.]. June 27, 1914, [Convention date]. Automatic exchange systems. - In a system in which one subscriber sets up a connexion with another by means of automatic switches, the response of the called subscriber automatically brings into the connexion an operator, who can break the connexion between the two subscribers and communicate with either subscriber to the exclusion of the other, for the purpose of controlling the collection of toll for trunk calls. If the operator learns that an incorrect connexion has been set up, she may herself establish the correct one. The invention is described as applied to a system in which a calling-subscriber A at one exchange is connected by a line switch C, selector E, and repeater F to a trunk 79, 80 leading to a selector M and connector at a distant exchange. The operator's equipment may be arranged at either exchange, but is shown at a point intermediate the two exchanges. The set of relays I and line switch C<2> controlling the connexion of the operator's speaking set J to the trunk 79, 80 are not influenced during the setting-up of the call, but are controlled by a polarized relay 82, which is energized only when the wanted subscriber replies. The coincollecting device shown at station A, described in Specification 687/12, is of the type in which a polarized magnet 19, responding to the reversal of the line current when the called subscriber replies, short-circuits the microphone and shunts the receiver by a resistance, until a coin is inserted. Line switch and first selector. When the subscriber A removes his receiver, his line switch C, operating as described in Specifications 1419/10 and 27,533/13, extends connexion to a group-selector E, which is set by the first set of impulses, as described in Specifications 10,376/12 and 2543/14, on the terminals of a repeater F forming part of a trunk 79, 80 extending to the wanted exchange. Repeater F, Fig. 1. The line relay 28, energized over the calling line, energizes a slowrelease relay 32, which maintains a holding ground for the switches C, E and supplies current to the right-hand winding of a reversing- relay 29. The relay 28 also bridges an inductance 30 and the left-hand winding of relay 29 across the trunk 79, 80, the windings of relay 29 opposing each other, so, that the relay is not energized at this stage. A slow-release relav 31 short-circuits the inductance 30 and left-hand winding of relay 29 during the transmission of selecting-impulses. Selector M, Fig. 2, and connector. The second set of impulses is repeated by the relay 28 to the line relay 81 of the selector M, which operates in the same manner as the selector E to extend the call to a connector, which selects, tests, and rings the wanted line in known manner. Coin-collecting; connexion of operator's equipment to trunk. When the called subscriber replies, the connector back-bridge relay reverses the current in the trunk 79, 80, 93, 95, thereby energizing the polarized relay 82, which closes circuits through the lamps 119, 120, individual to the trunk, and through the line relay 121 of the line switch C<2>, which connects the trunk to an idle-opera.tor's equipment J. The pulldown winding 125 of the switch C<2> is first energized by the relay 121, and then completes a holding-circuit over springs 128, 145, 123, 122 and ground G<2>. The switch C<2> also connects a relay 143 in parallel with the winding 125, and the relay 143 closes a holding-circuit for itself and the winding 125 over springs 146, 147, which circuit is independent of the relay 82. The relay 143 also breaks the connexion between the calling and the called lines, and connects the latter over the springs of relay 163 and contacts 135, 138 of line switch C<2> to the operator's repeater J. The operator then inquires of the called subscriber his number and tells him to wait, as she has a trunk call for him. She then depresses the key K<2>, closing a circuit through the relays 164, 163, 166; but the resistance of relay 164 is high enough to prevent relay 166 from energizing. The relay 163 bridges the trunk 93, 95 to prevent the connector from releasing, and connects the operator's equipment to the calling line instead of to the called line, and the relay 164 bridges the battery B<1> and inductance 167 across the calling-trunk 79, 80, the direction of this current being such that the reversing- relay 29 in the repeater F is energized and reverses the current in the calling line, so that the magnet 18, 19 short-circuits the calling- subscriber's microphone and shunts his receiver. The calling subscriber, hearing the operated answer, deposits a coin, thus rendering his apparatus operative for talking purposes. The operator then inquires of the calling subscriber his number and that of the subscriber he is calling. The operator may then ticket the call, or may require the calling subscriber to deposit further coins, according to the nature of the call. If only one further coin is required, the operator operates the key K<4>, so as to reverse the current supplied over the inductance 167 to the calling line, thereby returning the armature of the coin-collecting magnet 18 to the position shown in Fig. 1. The operator then depresses .the key K<3>, short-circuiting the relay 164 and increasing the current in the relay 166 sufficiently to energize it. The relay 166 locks up over springs 177, 84, extinguishes the lamp 120, and opens all the circuits of the relays 143, 163 and the switch C<2>. The operator's equipment is thus released, and the calling line again connected to the called line. The current is now in the reversed direction, so that the calling subscriber must deposit a further coin before he can converse. If an operator leaves her position, the relay 178 deenergizes and marks her position busy at the contacts of the master switch N. Contacts 180, controlled by relays 179 at each position, may be connected to form a chain of contacts to operate a supervisory signal to notify a chief operator that all the operators' positions are busy. Wrong connexion made; fresh connexion established by operator. If the calling subscriber has, for any reason, obtained the wrong connexion, the operator may tell him to hold the line, and then release the selector M and connector by depressing key K<1>, and set up the proper connexion by means of her impulsesender S. Release. The release of the connexion takes place in known manner under the control of the calling subscriber. Specifications 19,253/12 and 2543/14 also are referred to.