PURPOSE: To perform a trunk line terminating connection service superior in extensibility and utility by using a voice synthesizing circuit and a push-button signal receiving circuit to perform terminating connection of a trunk line.

CONSTITUTION: A control circuit 300 connects a trunk line trunk 201 and a voice synthesizing circuit 600 by a channel 700 of a channel network 400 and transmits a voice guidance requesting transmission of a push-button PB signal to the trunk line. Thereafter, the channel is switched to a channel 701, and a PB signal receiving circuit 500 is connected to the trunk line trunk 201. The PB signal which is transmitted from a calling subscriber of the trunk line in accordance with the voice guidance is detected by the circuit 500, and its information is sent to the circuit 300. The circuit 300 performs a line connection processing on a basis of information of the received PB signal.