TRANSMISSION CONTROLLING SYSTEM OF SELECTION SIGNAL FOR KEY TELEPHONE DEVICE

摘要

PURPOSE:To control effectively the transmission of a selection signal with a simple constitution, by controlling a sender circuit based on the signal which is transmitted and received between a processor which controls a telephone and a processor which controls a trunk line circuit, etc. and realizing the transmission of the selection signal to a trunk line. CONSTITUTION:A processor 7 scans the state of an extension telephone circuit 6 and detects a change of state of the circuit 6. Then the processor 7 drives the circuit 6 based on a programmed procedure. In case the process does not complete just with the driving of the circuit 6, the signal is fed to a processor 5 through a data bus 8. Receiving this signal, the processor 5 drives a trunk line circuit to hold the loop of the trunk line or drives a call switch 4 to give a connection and disconnection between the circuits 6 and 3. On the contrary, the processor 5 scans the state of the circuit 3 and then detects a change of the incoming to the trunk line, etc. Thus the processor 5 drives the circuit 3 to feed the signal to the processor 7. A processor 2 drives a sender circuit 1 to feed a selection signal to the desired trunk line.