TELEPHONE DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an optimum detecting method for a DTMF signal and a modem signal sent from an exchange during a telephone call with an opposite side. SOLUTION: When a 1st DTMF signal sent from the exchange through a line during the telephone call with the opposite side through the line is detected, transmission muting is turned on and then when a 2nd DTMF signal from the exchange is detected, reception muting is turned on.