COMMUNICATION SYSTEM

PROBLEM TO BE SOLVED: To provide a communication system in which the control delay time to call start is minimized, and the processing during telephone conversation can be simplified by performing the processing to request a call and the processing of actually starting a call substantially simultaneously.SOLUTION: Even if the bandwidth of uplink is insufficient because other terminals 1-3 are in data communication, at a moment in time when a terminal 4 starts communication, the terminal 4 notifies the start of communication to a base station by using a spare frame which is secured in the uplink frame periodically. The base station assigns a frame required for call to the terminal 4 immediately, and makes a transition to a communication system where call and data communication coexist.