STAND-ALONE KEYPHONE SYSTEM

摘要

A STAND-ALONE KEYPHONE SYSTEM A stand-alone keyphone system that is designed to be installed at any location where it is desired that a plurality of telephone lines be available to each of many user points. The system operates independently of all other systems and without the need for a KSU or a central control unit. Each system allows a plurality of telephone lines to be connected and operated simultaneously and a plurality of systems may be connected within each installation with minimal loading of telephone lines. The system comprises, within a single housing, a DTMF telephone set and a key adapter set that further comprises all the mechanical and electronic circuits to operate the system including a switching subsystem and hold circuit subsystem. The system incorporates a hold pushbutton for placing any of the telephone lines on hold, a set of four telephone line accessing pushbuttons; and a set of line status LED's that indicate if the corresponding line is idle, ringing, busy or holding.