SIDE-TONE ADJUSTING SYSTEM AND METHOD FOR KEY TELEPHONE SYSTEM ESTABLISHING PLURAL KINDS OF SPEAKING PATHS

摘要

SIDE-TONE ADJUSTING SYSTEM AND METHOD FOR KEY TELEPHONE SYSTEM ESTABLISHING A PLUREL KINDS OF SPEAKING PATHS The present invention disclose a switchong system including an exchange coupled to a plurality of central office lines and PBX's telephone lines, and a plurality of telephone sets. Each telephone set includes a side-tone adjusting circuit whitch adjusts a side-tone in response to a balanced impedance to obtain a suitable side-tone. When the exchange receives a speaking path selection request, repesenting one of the lines, from the telephone set, it determines one of a plurality of predetermined impedance information and makes a speaking path between the selected line and the telephone set. The telephone set selects one of the balanced impedances in response to the determined impedance information.