To release a sound simulating a user's living sound through a simple operation for crime prevention at the time of leaving home.

When the user inputs a predetermined telephone number through a telephone set 110 (IP telephone set), its incoming request is received by a sound data delivery server 184 within an Internet service provider 180. The delivery server 184 stores a plurality of kinds of sound data according to various family structures, in which sound data to be supplied to each user are preliminarily set. The sound data preliminarily selected by the user are successively supplied while being converted to voice signal from the server 184 to the telephone set 110.