A radio network controller connected to a first exchange and a second exchange which manage a same location registration area. The radio network controller includes a manager configured to manage a mobile station under control of the radio network controller, in association with the first exchange or the second exchange; a transfer configured to transfer a signal transmitted from the mobile station to the first exchange or the second exchange which is associated with the mobile station; and a monitor configured to monitor state of the first exchange and the second exchange. The transfer is configured to transfer a signal from the mobile station associated with the first exchange, to the second exchange, when the monitor detects inaccessibility to the first exchange.