When a call is attempted from a terminal that can transmit/receive data by connecting to different plurality of networks, a radio routing agent that is positioned at a core network selects an optimum wireless route from a plurality of wireless routes and provides the optimum wireless route based on an entire radio resource and a route state. Therefore, when a normal response is received by attempting a call to a call receiving terminal through the optimum wireless route that is selected by the radio routing agent, a call processing apparatus transmits the optimum wireless route to a terminal in which a call is attempted through a base station.