Telephone apparatus with call transfer function and with improved arrangement for hand-free operation

摘要

A telephone apparatus is connected to a plurality of telephone lines and has a transfer function for transferring a call among the plurality of telephone lines. The telephone apparatus includes circuit interfaces each of which has a 2-4 line substitution function and conducts an interface function between each of the plurality of telephone lines and a telephone apparatus internal circuit. A first amplifier amplifies a signal from a first telephone line and a second amplifier amplifies a signal from a second telephone line. A control unit compares the levels of the signals from the first and second telephone lines to control the amplification factors of the first and second amplifiers on the basis of a result of the comparison.