GB1363433A - Dual purpose telecommunication system - Google Patents

Abstract

1363433 Automatic exchange equipment STANDARD TELEPHONE & CABLES Ltd 9 Dec 1971 [15 Dec 1970] 59431/70 Heading H4K A dual purpose telecommunications system serves subscribers having both telephone and data facilities and includes a data exchange network and a telephone exchange network with the subscriber connected through a single dual purpose line to a data switching centre. The data centre can distinguish a telephone call and connect it to the telephone network and also has means for connecting calls from the telephone exchange to the subscriber. As shown a telephone network comprises an array of selectors through which telephone subscribers TS1, TS2 can be connected in the normal way. Additional dual purpose subscribers are connected to a switched data network and also through a switch SW1, SW4 to the telephone network. The subscribers equipment is of the type which normally receives and retransmits a network bit stream. Detection equipment which responds to modulation of the bit stream caused by an off-hook condition causes switch SW1 to connect the subscribers line to the telephone exchange and the call is then dialled and set up normally. Calls from the telephone network to a dual purpose subscriber, e.g. DP2, are routed through switch SW4. For a data call DPI and DP2 can be connected through switches SW2, SW3. It is stated that the use of the data centre as overall control even on calls through the telephone network saves time and avoids double connections. It is further stated that different calling signals are desirable so that the called subscriber knows how to respond. The dual purpose lines are allotted a separate different number for each facility provided.