CONTROL SYSTEM OF SUBSCRIBER'S CONTROLLER

摘要

PURPOSE:To secure the function of a telephone set in case of a power failure by providing a by-pass circuit to a device consisting of a digital telephone set and non-telephone equipment which are connected to a digital subscriber line and powered on by the commercial power source. CONSTITUTION:Changeover switches 8 and 8' and a connection control circuit 7 are provided and connected among the digital subscriber line 1, digital telephone set 3, and communication equipment (unshown in the figure) such as facsimile. Further, by-pass circuits 9 and 9' are connected to the changeover switches 8 and 8'. The telephone set and communication equipment use the commercial power source of AC100V as their operating power source. An AC detector 12 operates in case of a power failure and the changeover switches 8 and 8' are operated to connect the telephone set 3 to the subscriber line 1 through the by-pass circuits 9 and 9'. A switching control circuit 13 monitors signals of signals of signal lines 1 and 5 in power recovery and the switches 8 and 8' are reset when there are a small number of signals. Consequently, the function of the telephone is secured even in case of the power failure.