PURPOSE: To relieve the load on a radio base station and a network by gathering plural slots in operation into one and applying a packet processing to voice data with the group address of the grouped slots as a destination address.

CONSTITUTION: A frame using one frequency sent from a radio terminal station to a radio base station is divided into 8 slots, and 4 slots each are allocated to transmission and reception respectively. In the case of communication from a terminal station 111 using the slot 201 of a frame 200 to a terminal station 121, from a terminal station 112 using the slot 202 of the frame 200 to a terminal station 131, and from a terminal station 113 using the slot 203 of the frame 200 to a terminal station 141, a base station 110 generates transmission slots 201-203 in which a multiple address communication address is set to a destination address 211 of a transmission packet 210 and a sender address 212 is set to the address of the base station 110 as a data part 213 of the packet 210 and sends the packet to a network 100. Thus the load of the network is relieved by forming voice data divided into plural slots to one packet and sending the packet in the form of multiple address communication.