COMMUNICATION SYSTEM AND GATEWAY

PROBLEM TO BE SOLVED: To provide a communication system in which half-duplex many-to-many multicasting communication can be performed to both a mobile station and a base station by using a unified call control protocol such as SIP on an IP network, and can contain mobile stations and base stations of existing wireless facilities. SOLUTION: The communication system in which the half-duplex many-to-many multicasting communication is performed to a plurality of mobile stations 100a, 100b 100c and 110 includes a gateway 104a for converting a first protocol to connect the mobile station 100a, a base station 101a and the gateway 104a, and a second protocol for connecting the gateway 104a, a call control device 105 and a distribution device 106. The gateways 104a, 104b, 104c and 114a perform the protocol conversion for both communication to the mobile station and communication to the base station, so that the half-duplex many-to-many group communication can be achieved. COPYRIGHT: (C)2009,JPO&INPIT