GB787031A - Improvements in private automatic exchanges - Google Patents

Abstract

787,031. Automatic exchange systems. TELEPHONE MANUFACTURING CO., Ltd. Jan. 4, 1956 [Dec. 22, 1954], No. 37087/54. Class 40 (4). In a self-complete private automatic exchange each outgoing trunk from a control circuit terminates in a selective electro-mechanical bridge connector with two levels such as is described in Specifications 781,851 and 781,852, one level giving access to the incoming trunks of the self-complete private automatic exchange and the other level giving access to the incoming trunks of another similar exchange. The system is designed for ready expansion without disturbance of existing equipment and makes use of line-growth units LGU and trafficgrowth units TGU as described in the earlier Specifications. When a call is initiated it is extended over a traffic growth unit such as TGU1 to a feed bridge and control circuit such as CON1. A register such as REG1 is taken into use to record the dialled digits and complete a marking circuit. For calls within the exchange one of the outgoing trunks in group A is selected and the connection is completed in the manner described in the earlier Specifications. For calls to exchange B one of switches SW11-SW15 is operated whereby the register selects one of outgoing trunks B. For calls to further exchanges C or D one of switches SW21- SW25 is operated so that the register selects one of outgoing trunks C or D, Fig. 3, in a further set of connections BMX1-BMX5, similar to the connections BMT1-BMT5. Trunking diagrams are shown in Figs. 2 and 4.