A communications system which performs accounting according to the actual provided communication quality in a QoS authentication service. A radio system has mobile stations, a radio base station, a packet function control apparatus, a node apparatus and an accounting server, performs user accounting according to an actual communication quality. At least one of the wireless base station, packet control function apparatus and node apparatus has a memory unit which stores a granted communication quality, the communication quality which can be provided and accounting data. Further, at least one of the wireless base station, packet control function apparatus and node apparatus has a control unit which measures the communication quality, and transmits a message when the present accounting differs from the accounting for the measured communication quality, and the accounting server has a control unit which performs accounting using the measured communication quality.