| 摘要 |
PURPOSE:To transmit/receive a call signal, a howler tone signal or a reference signal for lighting up a message waiting lamp only by one relay incorporated in a subscriber's circuit by switching these signals in a switching circuit with time division. CONSTITUTION:A reference signal switching circuit 21 switches a reference signal 22 for a call signal, a reference signal 23 for a howler tone signal and a reference signal 24 for lighting up the message waiting lamp with time division and the selected signal is sent to a subscriber's circuit through a power supply circuit 20. Synchronously with the switching of the switching circuit 21, the subscriber's circuit actuates relays 210, 21n. Said signals can be sent to the subscriber's circuit only by one relay incorporated in the subscriber's circuit, so that the titled circuit can be constituted comparatively economically. |
