CONNECTION STATE DETECTING APPARATUS, TELEPHONE SET, PROGRAM FOR TELEPHONE SET AND INFORMATION RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To prevent a telephone set from malfunctioning without the need for an exclusive circuit for detecting the polarity of line terminals. SOLUTION: Transistors T12, T2 are made conductive for connection to a telephone set at power up and a CPU 2 recognizes the connection to the telephone line when a dial tone signal from the telephone line is detected. COPYRIGHT: (C)2005,JPO&NCIPI