Closed User Group (CUG) servers and a CUG control database for push-to-talk (PTT) radio communications

摘要

A radio communications system comprises communication terminal devices 1, 2..., N for performing push-to-talk (PTT) communication, a server 100 for processing radio communication between the terminal devices, Closed User Group (CUG) servers 200-1..., 200-N storing group information relating to a particular group of the PTT communication terminal devices 1, 2..., N, and a CUG control database 300 for controlling the CUG servers 200-1 ..., 200-N. Each CUG server registers group information in the CUG control database so that, when a communication terminal device acquires group information from a CUG server and transmits, to the server, a request for an audio information notification to be sent to a second communication terminal device in the acquired group, the server can determine whether or not information of the communication terminal device is registered in the CUG control database, based upon CUG identification in the group information sent with the request. Then, in accordance with the determination result, the server establishes radio communication with the terminal devices in the acquired group and transmits the audio information to the second terminal device.