GB1276707A - Improvements relating to telephone exchanges - Google Patents

Abstract

1276707 Automatic exchange systems PLESSEY CO Ltd 30 Nov 1970 [24 Dec. 1969] 62827/69 Heading H4K In a telephone exchange abbreviated dialling codes are translated into full directory numbers which are entered into a store and applied digit by digit to a register, for each digit registered the contents are tested for a complete routing code and a counter is incremented, when a routing code is recognized an appropriate junctor is selected and digits still in the store are read out in parallel to a sender associated with the selected junctor, the counter masking the transmission of digits applied to the register prior to recognition of the routing code. As described, routing codes may have up to four digits and the counter is a three-stage counter operating a relay for each stage. The relays operate contacts in the outlet paths of the store. The translations may be in dial pulse or 2 out of 5 code form. As shown, when a call is originated from a subscriber's line 1 a path is set up to an assigned supervisory device 3 via a network 2. The subscriber commences to dial digits into a register 4 and for each digit a router 5 attempts to translate into a routing code. During each attempt in which a routing code is not recognized a counter 15 is incremented by one. During a normal call the router recognizes a code after say four digits and generates a signal RF which selects an appropriate junctor 6 and a sender 7. A path 8, 9 is set up between the supervisory set 3 and junctor 6 and subsequently dialled digits are transmitted over this path and the outgoing junctor. If the router 5 recognizes the first group of digits as a short code, this short code SC is forwarded to a gating array 11 which also receives at 10 the identity of the calling subscriber. A gate responds reading out the corresponding directory number from a location in a short code translation store 12 into a buffer store 13. The directory number is transmitted one digit at a time to a register 4. When a routing code is detected a junctor 6 and a sender 7 are selected and a gating arrangement 14 operated under control of the counter to transmit the digits in store 13 but not already sent to register 4 in parallel to the sender 7, and the translator 12 is released.