Patent ID: 8130690

Claim:
A communication system in which a press-talk call start request is received from a mobile station in a group and semi-duplex many-to-many multicasting service to other mobile stations as members of press-talk is realized, the communication system comprising: a first press-talk server that sends a first call control signal of multicasting service including a group address as an identifier of the press-talk and an address list of one or more mobile station addresses as members of the press-talk or one or more base station addresses to a second gateway in order to perform call connection to a member of the press-talk belonging to the second gateway different from a first gateway which communicates with a first base station receiving the press-talk call start request, wherein when receiving the first call control signal of the multicasting service, the second gateway extracts all addresses specified as destinations from the address list, (1) where the extracted addresses are mobile station addresses, the second gateway searches, based on a mobile station number for each mobile station address included in the address list included in the first call control signal of the multicasting service, a mobile station location information table storing mobile station numbers of the mobile stations and base station numbers of base stations having the mobile stations under the base stations, when a press-talk call of the press-talk is not set up for the specified second base station, the second gateway sends press-talk call setup indication to the second base station, when receiving the press-talk call setup indication, the second base station performs radio channel configuration to perform press-talk to the one or more mobile stations under the second base station included in the address list, (2) where the extracted destination addresses are base station addresses, when press-talk call is not set for the second base station of each base station address included in the address list included in the first call control signal of the multicasting service, the second gateway sends press-talk call setup indication to the second base station, when receiving the press-talk call setup indication, the second base station performs radio channel configuration to deliver the press-talk, and wherein the gateway realizes the semi-duplex many-to-many multicasting service to both communication of the first call control signal of the multicasting service to the mobile station from the first press-talk server and communication of the first call control signal of the multicasting service to the second base station.