The wireless communication system of the present invention has a first communication mode in which a center module preferentially allocates a slot to communication data of a calling sub station according to a priority of the calling sub station, and a second communication mode in which the center module allocates the slot to the communication data received from the calling sub station irrespective of the priority of the calling sub station. The center module determines which sub station can make a call to which sub station, each sub station transmits identification information to the center module, and the center module identifies the transmitting sub station based on the identification information, determines which sub station the identified sub station can make a call to, and allocates the slot to communication between the sub station determined to be capable of making a call and the transmitting sub station.