A radio communication system including a system computer connected to a radio communication device including a radio communication antenna and an audio management system via a data bus. The audio management system is connected to a user communication device. The system computer is arranged to switch between a data communication service and a voice communication service upon receiving a signal from the radio communication device indicating that a carrier on a predetermined fixed frequency has been detected or has ceased to be detected by said radio communication device, or from the audio management system indicating that a request for a predetermined fixed frequency voice communication service has been detected or has ceased to be detected by said audio management system.