A conference apparatus has a memory to store information relating to devices and their owners, and determines a device owned by each participant based on the information stored in the memory. The conference apparatus notifies an interface apparatus the devices owned by each participant and the devices upon which the conference apparatus determines whether to allow participants to participate in a conference; the interface apparatus sends a permission to participate in the conference to a device owned by each participant and transfers to the conference apparatus a conference participation request received from each device upon which the conference apparatus determines whether to allow the corresponding participant to participate in the conference.