A radio data communication system includes a router and LAN (Local Area Network) switch connected to an IP (Internet Protocol) network. A private BTS (base station Transceiver Subsystem) exchanges data with a mobile terminal, and a private IP exchange performs switching between mobile terminals. A call manager manages a call, and a private BSC (base Station Controller) provides a mobile subscriber with a complete path and assigns a vocoder in response to a request for an incoming or outgoing call to process the incoming or outgoing call . An Internet interface (Internet interface) connected between a high capacity IPC (Inter-Processor Communication) node board assembly (HINA) in the private BSC and a LAN cable, communicates with the private BTS under the control of the call manager, transmits packet data received from the radio terminal to the IP network, monitors installation or uninstallation and functional errors of the private IP exchange, and transmits the monitoring results to a wire system manager in the call manager through an Ethernet port.