PURPOSE: To attain power ON/OFF control for various installations from a visiting place by discriminating whether or not a 1st voice of the voice from a public telephone line is a predetermined password, decoding a voice instruction and turning on/off the power supply circuit connecting to each installation.

CONSTITUTION: Whether or not a 1st voice of the voice from a public telephone line is a predetermined password is discriminated by comparing it with the content of a voice synthesis VLSI 5 and when the voice is the password, a changeover circuit 4 sends a reply signal to a callout telephone set. When an instruction for items desired to be controlled is uttered in voice, an instruction decoding circuit 8 outputs a voice stored in voice synthesis 10 memories 7-18, compares a voice waveform to decode the content of the instruction. The instruction decoding circuit 6 outputs a no-voltage contact signal to the control circuit 11 depending on the decoded instruction content and the control circuit 11 turns on/off the connection for an input line 12 and an output line 13 for the control signal or the power supply or the like. Thus, the power on/off of various terminal equipments or other control installed in a subscriber,s equipment is realized in voice.