Patent GB-591377-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1945-05-05
Abstract: 591,377. Automatic telephone systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd., and HOPLEY, H. E. May 5, 1945, No. 11488. [Class 40 (iv)] In a telephone system employing routediscriminators, i.e. register controllers which translate the office code into a routing number, but do not control the transmission of the numerical digits, and which also control multifee metering, having translation fields of standard sizes which are arranged in groups accessible to subscribers on both a main exchange and its satellites, the setting up of connections is controlled selectively according to the exchange with which the calling party is associated. Certain calls, e.g. to exchanges outside the multi-fee area in which calls are allowed, are barred to the main exchange subscribers by the absence of appropriate connections in the translation field, the effect of these connections being produced by alternative means where the calls originate from subscribers on the satellite (for whom the wanted exchange is within the multi-fee area) so as to permit the calls to be completed. Access to a route discriminator is obtained through a particular level (8) of the first selectors via an outgoing junction relay set (not shown) and an associated hunting switch. The relay set includes an impulse regenerator which re-transmits the BC digits to set a BC switch in the route discriminator, the remaining digits being stored in the regenerator prior to retransmission to the second selector at a later stage. Main exchange subscriber calling automatic or manual exchange. Relay A operates over the incoming P lead, holds over a loop in the relay set, and brings up Band BA. The regenerator impulse springs take over the holding loop to A as soon as the BC digits are received, and these digits are repeated to set the BC switch in positions 2 and 3 of the switch DD, while in position 4 SS is connected up to start the sending switch S, earth being returned on wire SW to hold up sending from the regenerator. In position 2 of S, RD operates momentarily to earth tags 2-4, 6-0 of the translating field, thus closing a circuit via bank BC1 for advancing DD to position 5, in which earth is extended over BC2 to mark the bank S5 for the first routing digit. Stop relay SZ operates to terminate the outgoing impulses when the marking is picked up, and DD advances to connect up the next wiper of BC. A maximum of 8 routing digits is provided for, and if fewer are required, the later banks of BC are wired to terminal DCO to advance DD automatically to position 13. In this position CO pulls up and SS releases to restart sending from the regenerator. Relay UD operates momentarily as the switch S advances to normal for a reason that will appear later. Metering. On the reply of the called party, earth is applied to the D lead to operate MS which connects SZ to wiper S4 instead of S5 and starts the switch S to control the sending of metering impulses. When wiper S4 reaches position 19 JD operates, whereupon earth is removed from the HD lead to release the route discriminator. Spare code or barred number dialled, or failure to meter. The appropriate contacts on BC 1-9 will not be strapped to tags 1-0 so that during the transmission of the first impulse train SZ will not operate and when S4 reaches position 14 M operates and extends earth to the forced release lead FR, which effects the release of the route discriminator and second selector, and returns NU tone to the calling party. Forced release also takes place if no metering markings are picked up by S4 on a successful call. SZ first operates in position 23 and connects earth to wiper S4 which in position 24 operates M. Main exchange subscriber calling rural exchange (U.A.X.).-Barring irregular calls. Operation is as above up to the end of the transmission of the routing digits, DD in position 13, CO operated, SS released. White UD is up and S is homing, earth is extended via S5 in positions 15, 16, 17 and 18 to tags 5, 6, 7 and 8, one of which is connected in this instance to the BC1 bank contact, and thence to DD5 (position 13), so that DD is stepped to position 14. As the regenerator transmits the first numerical digit, its magnet springs repeat the digit over the SW lead to DDM via DD5. All UAX subscribers' numbers commence with 1, 2 or 3 so that if DD is advanced more than 3 steps, and an irregular excess fee connection is being attempted by first obtaining access to a UAX, earth is applied via DD4 to the FR lead. Main exchange coin-box calls.-The earthing of the SW lead by SS causes the relay set to return earth on the D lead if seized by a main exchange coin-box. CB operates and opens the circuit for RD. The only tags earthed are, therefore, 1 and 5 (in positions 1 and 3 of S2), and if the call is other than a single-fee call or is to a manual exchange (for which tag 9 is used for single-fee calls), the BC1 bank will receive no earth marking, DD will not advance to position 5 and SZ cannot operate via S5. In position 14 of S4, M operates and breaks down the connection. Satellite subscriber calling. A junction relay set taken into use by a satellite exchange subscriber extends earth over the D lead when the route discriminator is seized to operate JD as soon as DD moves off-normal. This relay prepares a local circuit for CB in order to release the discriminator after the routing digits have been sent, since metering is controlled from the satellite exchange, and also prepares a circuit for stepping DD past position 4 independently of the BC1 bank so that a call which is barred to main exchange subscribers can still proceed. In the case of a call to a UAX, the BC1 bank contact is wired to terminal DCO to step DD from position 13 to 14 in order to take the first numerical digit before the discriminator is released and so prevent irregular excess-fee calls as described above. Call barring to ordinary and coin-box subscribers is performed at the satellite exchange.