A private conversation request is received from a first communication apparatus, and a region of fixed range based on the position of a first user is set as a first conversation-listening area. Based on a position management database, a second communication apparatus positioned inside the first conversation-listening area from among one or a plurality of second communication apparatus is detected as a first evacuation communication apparatus, and an evacuation order causing the first evacuation communication apparatus to be evacuated from the first conversation-listening area is transmitted to the first evacuation communication apparatus.