A wireless system includes plural different access networks and terminals (19, 20) having interfaces corresponding to the plural different access networks (3, 5, 9, 13). Each of the access networks includes an access gateway (AGW) performing flow control. Upon receiving a packet transmission stop signal, the AGW determines whether a predetermined message transmitting chance is given. The AGW includes a control unit that transmits a message that requests a handover to another access network to a terminal when the message transmitting chance is given. The terminal includes a unit that performs a handover to another access network, upon receiving the message.