| 摘要 |
PURPOSE:To make the subscriber circuits small and to make a system economical by providing plural numbers of subscriber circuits with the change-over means for switching call signal to and from howler signal in common. CONSTITUTION:In order to transmit a call (r) signal to a subscriber 4, a line processor 5 periodically energizes an SG relay 14 of a subscriber circuit 1 corresponding to a subscriber 4 and transmits the call signal (r) supplied from a common circuit 8 via a contact switch 16 to the subscriber 4 via a trip circuit 9 and a resistor 10. When the subscriber 4 takes upward a handset, the trip circuit 9 detects it and sends the signal to the processor 5. On the other hand, when a howler signal (h) is sent to the subscriber 4 where the handset remains unhooked, the processor 5 makes sure all the subscriber circuits 1 that a common circuit 8 is used in common do not transmit the call signal, energizes the SW relay 15 installed in the common circuit 8, and supplied the howler signal to subscriber circuit 1. |
