Abstract: A radio network controller connected to multiple exchanges in a mobile communication system includes an exchange side interface configured to communicate with the multiple exchanges, a mobile station side interface configured to receive a call connection signal from a mobile station via a radio base station, a management unit configured to manage congestion levels indicative of congestion states of the respective exchanges and a control unit. The exchange side interface acquires the congestion levels from the respective exchanges, and the control unit determines to transfer a predefined ratio of call connection signals destined for an exchange having a higher congestion level to an exchange having a lower congestion level, the ratio being predefined corresponding to the congestion level.

Abstract: A radio network control device in a mobile communication network includes a first communication unit communicating with a packet switching device in a packet switched domain; a second communication unit communicating with a circuit switching device in a circuit switched domain; and a management unit transmitting information to the packet switching device, the information indicating whether the radio network control device can correctly communicate with the circuit switching device. The management unit transmits the information when transmitting a signal to the packet switching device via the first communication unit, the signal indicating whether the radio network control device can correctly communicate with the packet switching device, or when transmitting an attach request signal to the packet switching device via the first communication unit, the attach request signal being transmitted from a mobile station.

Abstract: A radio network controller connected to multiple exchanges in a mobile communication system includes an exchange side interface configured to communicate with the multiple exchanges, a mobile station side interface configured to receive a call connection signal from a mobile station via a radio base station, a management unit configured to manage congestion levels indicative of congestion states of the respective exchanges and a control unit. The exchange side interface acquires the congestion levels from the respective exchanges, and the control unit determines to transfer a predefined ratio of call connection signals destined for an exchange having a higher congestion level to an exchange having a lower congestion level, the ratio being predefined corresponding to the congestion level.