Patent GB-354858-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04M15/10
Filed: 1930-05-20
Abstract: 354,858. Automatic exchange systems. ASSOCIATED TELEPHONE & TELEGRAPH CO., 1033, West Van Buren Street, Chicago, U.S.A. May 20, 1930, No. 15549. Convention date, June 3, 1929. [Class 40 (iv).] In a system wherein arrangements are provided for metering a call both as regards zone and duration, the meter control equipment and the zone recording equipment are adapted to be associated with the connection over separate hunting switches. Metering in accordance with the called zone is effected by characteristic numbers of impulses, repetition of the signal being effected in accordance with the duration of the call. Arrangements are also provided whereby in the event that no charge is to be made for a call, or that dialled impulses are not transmitted within a predetermined time, the meter control equipment is automatically released. Moreover metering is prevented when a connection is broken down by a toll operator. As shown, selector repeater SR accessible to a line switch LS, Fig. 1, is associated by an individual plunger-type switch P, Fig. 2, with idle zone metering control equipment, Fig. 3, through the intermediary of a master switch MS. The zone metering equipment comprises relays 302, 310, 315, 325 for registering the zone of a called subscriber, which relays mark the wipers of switch SPS to determine the number of metering impulses. A continuously-driven switch TPS common to the exchange operates in conjunction with the switch SPS to effect metering in accordance with the duration of the call. Fig. 4 shows zone register switches ZRS, ZRS<1> which are associated with the control equipment, Fig. 3, by a plunger switch P<1> which is one of a number of such switches each associated with a control equipment. This apparatus also includes a time release switch TR which causes release of the equipment if no impulses are dialled within a predetermined time. Line switch, Fig. 1. Assuming subscriber A desires communication with A<1>, Fig. 2, upon removal of receiver, line relay 104 is energized to initiate operation of line switch LS which hunts until an idle trunk is found when relay 103 operates to mark the release trunk 115, switch the connection through wipers 110,113 and associate the subscriber's meter with the metering lead 116 over wiper 112. Selector repeater SR, Fig. 1. Line relay 121 is operated to energize relays 123, 127 in series, the latter of which connects dial tone to line 114 and earths lead 207 to operate relay 210 of a plunger switch P, Fig. 2, individual to the selector repeater SR. Relay 210 operates plunger magnet 216 and the switch P connects the selector repeater SR to the zone meter control equipment, Fig. 3, over contacts 223 .. 226. Line relay 121 also opens the short-circuit across relay 122 which earths trunk 115 and lead 205 to operate relay 234 over lead 219. Plunger switch P<1> also is operated over 341 to extend the leads 342 .. 345 to the zone registering equipment ZRS, ZRS<1>, and thus energize relay 347 which closes circuit of magnet 391 of switch TR stepping of which is effected by an interrupter 249, Fig. 3. Failure to dial impulses within predetermined time. If the subscriber neglects to dial impulses within the time required for the wipers of switch TR to reach their fourth bank contacts, the meter control equipment is released and the calling subscriber is given a busy signal. When the wipers 355, 356 engage their fourth contacts, the selector repeater SL is raised one step by an impulse sent back to vertical magnet 130 over wiper 355 and relay 275, Fig. 3, is operated over wiper 356 to energize relay 251. Relay 251 operates relay 269 and these relays interact to impulse the rotary magnet 131 of the selector SR and drive it until stopped by cam springs 186, 187 in the 11th position. Springs 186 connect overflow busy tone to the calling line and springs 187 energize relay 129 which causes release of relays 123, 127, 210, 234 and consequent restoration of switches P, P<1>, TR. Upon replacement of the receiver in response to busy signal, the selector SR and line switch LS are released. Dialling within allotted time period. Dialled impulses operate relay 121 which through stepping magnet 130 raises the selector wipers to the desired level. Relay 121 also repeats impulses over leads 206, 221, 342 to vertical magnet 370 of the zone register ZRS, which upon its first step opens the release circuit controlled by switch TR at off-normal springs ON. At the end of the first train transfer of the impulsing circuit to the rotary magnets is effected. The selector SR hunts in the selected level until wiper 191 encounters an idle line, e.g. 202, when the switching relay 129 switches the lines through to selector D, Fig. 2. The rotary magnet 378 of the zone register ZRS, however, is operated by the second digit on to contacts individual to the zone being called. Relay 375 is operated in series with the rotary magnet 378 and at the termination of the second digit transfers the impulsing circuit to the stepping magnet of a register ZRS<1> which responds to the third digit and determines the zone to which the call is extended if such determination is not completed by the switch ZRS. Operation in event that connection set up is one for which no charge is made. Under these circumstances wipers of switch ZRS engage contacts X which are directly earthed and all the relays 302, 310, 315, 325 are operated over leads 344, 345 to energize relay 275 and open a second holding circuit for the plunger switch P. Moreover when one or more of the relays 302, 310, 315, 325 are operated relay 280 is energized to cause release of switch P<1>, and also registers ZRS, ZRS<1> and time switch TL which are thus rendered available to other switches such as P<1>. When the final digit is transmitted, connector H seizes the called line and irrespective of the busy or free condition of the line opens the loop over relays 123, 124. This causes release of relay 210 and switch P and also the release of all operated relays, Fig. 3. If the line is busy, busy tone is transmitted to the calling subscriber over contact of relay 127 which releases when the loop is opened, but if the line is idle the response of the called subscriber again operates the relay 123 to energize relay 125 which connects lead 208 to the meter lead 116. Since, however, switch P is released no metering can take place. Talking battery is now connected to the calling subscriber over relays 121, 124 and to the called subscriber over relay 123, 124. Metering. According as the zone of the called subscriber is determined by two or three digits, the switch ZRS or both switches ZRS, ZRS<1> are set on to contacts characteristic of the zone. As the zone of subscriber A<1> is determined by three digits relay 302, connected in series with marginal relay 310, Fig. 3, is operated over lead 344, and wipers of switches ZRS, ZRS<1>, the latter of which engages a contact earthed through a resistance. Relay 302 operates relay 280 which releases switch P<1> as previously described and marks wipers 251, 262, 268, &c., of switch SPS in a manner characteristic of the called zone. When the line loop is opened by the connector H in response to the final digit, and relay 210 is de-energized, the meter circuit is prepared at contact 211 and also by operation of relay 231, and when the loop is again closed on response of the called subscriber relay 125 is operated to complete the meter circuit and initiate the operation of switch SPS which steps automatically until earth is picked up by wiper 274 from contact of the time switch TPS engaged by wiper 281 to operate relay 288 which opens the stepping circuit. The banks of the wipers of the switch SPS are slip wired in the manner shown so that after the switch has stopped, successive steps of switch TPS connects earth in turn to the wipers of switch SPS<1>. The time switch TPS is continuously advanced under the control of cam contacts 249 and when it again co-operates with the contact associated with contacts engaged by the switch SPS in the stopped position, a circuit is completed over wiper 293 for relay 295 which energizes relay 250 to operate the time limit switch TL one step. Operation of the switch TL causes energization of relay 126 which transmits a momentary busy tone to the calling subscriber to signify that one talking period is nearing completion. Movement of wiper of switch TPS to next contact extends earth over wiper 274 to relay 269 which actuates the subscriber's meter to record the zone. As the zone of the called subscriber is characterized by energization of relay 302 only, earth is connected by contacts of switch TPS, SPS only over wiper 274 to operate the meter once during a time period, but if one or more of the additional wipers 251, 262, 268, 337 are connected to relay 269 by energization of relays 302, 310, 315, 325 in combinations characteristic of the called zone, corresponding numbers of impulses are transmitted during a cycle of the switch TPS to operate the meter. When the wiper 281 again commences its cycle of operations, relay 250 causes operation of switch TL which effects transmission of busy tone to apprise the subscriber that a third talking period is about to begin. Release. Upon termination of conversation, replacement of the receiver by calling subscriber energizes relay 126 which earths release trunk 115 to maintain the line switch during metering. Relay 256 also is released by operation of relay 243 following release of relay 122, and relay 251 is operated to energize relay 269 to again operate the meter and switch TL, which latter is released upon operation of relay 243. Relay 269 deenergizes relay 251 and these relays continue to inact if not prevented. As the call, however, is in the first zone, cut off relay 277 is operated upon the first step of the switch TL so that only one additional impulse is transmitted to the meter following termination of the call. If the connec-