Subject to user's setting in PoC group communication, the user address of that user is set to non notification against other users. In case of starting PoC group communication, a PoC subscriber selects non notification subjects and transmits a PoC session commencement request. At that time, the caller sets his own address and/or address/addresses of all or a part of users to non notification. On a user designated as a non notification subject due to the caller's setting, PoC terminal apparatuses in receipt of a PoC session commencement request or PoC communication service controlling apparatuses undergo non notification setting processing. On a called party not selected as non notification subject users, if he/she sets his/her own user address to non notification in advance, likewise non notification processing is implemented. Even after a PoC session is established, each user can set his/her own user address to non notification and non notification service complying with user's intention is providable.