GB1298269A - Improvements in and relating to telephone systems - Google Patents

Abstract

1298269 Automatic exchange systems STANDARD TELEPHONES & CABLES Ltd 28 April 1971 [23 June 1970] 30327/70 Heading H4K In a multiexchange system including one exchange equipped with a data processor which is accessible over order wires from the other exchanges, a call originated in one of the latter seizes a register which determines from the initial digit(s) whether an own exchange call is involved and if it is not requests routing data from the processor. The system simplifies the numbering scheme for non-director exchanges which are effectively converted to common control working by the addition of a register/sender having access to a processor in a group switching centre. As shown, a calling line causes its line selector LS to hunt for a register controlled RC which on being found actuates the K relay in the caller's line circuit and starts register connector RCS in its quest for a free register REG. The latter discriminates the first digit such that if it is other than "O" the digits are merely repeated to the group and final selectors for setting thereof in the usual way (relay CON having been brought up by the register). If the first digit is "O" however the register stores further digits and seizes the data terminal attached to the order wire extending to the processor and transmits some or all of the digits thereto. Routing instructions are returned by the processor to the register which, at the conelusion of dialling, operates relay CON and outpulses the routing digits to the group selector followed by the numerical digits of the wanted party's number to the next exchange. Special services may be provided, these being discriminated by the initial, digit. Reception of such a digit causes the register to seize a calling line identifier CLI which checks the caller's class of service before the requested service is actually provided. Key-dialling subscribers are connected via the register and hunter RH to a special bank of receivers for reception of their dialling signals. The registers may be provided on a one per group selector basis or on a one per limited number of group selectors basis so that in the latter case a lockout circuit rather than a register connector may be utilized.