PURPOSE: To improve the efficiency of line utilization in case of forgotten hook- on, by detecting a busy tone and a howler tone by a connector of cordless telephone to bring the line to an idle line state.

CONSTITUTION: A line relay 13 contacts only during calling, a signal from a terminal is inputted to a transmission section 16 and a tone detecting circuit 17 via the relay 13 and a hybrid circuit 14, and the signal inputted to the transmission section 16 becomes a transmission modulating wave and is outputted to a receiving section 32 from an antenna 20. When the busy tone or the howler tone of a telephone exchange is detected at the circuit 17, the detecting signal (a) controls the relay 13 to interrupt the connection to bring the line to an idle line state, and a detecting signal (b) controls the transmission section 16 to interrupt the output to prevent useless power consumption, thereby bringing the line to the idle state, that is, using effectively the assigned transmission and reception frequency.