A radio communications system is disclosed. The system includes a subscriber information management apparatus, and a subscriber authentication module mounted in a mobile terminal connectable to a mobile communications network to which the subscriber information management apparatus is connected. The subscriber authentication module includes a connecting information setting determining unit; a connecting information generating unit; and a connecting information setting unit which sets the connecting information included in a response received from the mobile terminal. The mobile terminal includes a connecting information transmitting unit; a connecting information response receiving unit; and a connecting information transmitting unit. The subscriber information management apparatus includes a temporary connecting information determining unit; a connecting information selecting unit; and a connecting information transmitting unit.