Abstract: A combined communication, security and alarm radio system for supervising equipment in a plant or installation, in which a base transmitter/receiver (4) is in two way communication with a remote control unit (2). A plurality of portable transmitter/receiver units (12) enables direct communication between operators through the base transmitter/receiver unit (4). An alarm message unit (8) connected to both the control unit (2) and a telephone exchange landline enables pre-recorded messages to be transmitted in sequence to a plurality of subscribers. Each portable transmitter/receiver unit (12) has a push button (27) to activate the alarm message unit (8) through the base transmitter (4) each being recognizable by its own tone. The system also includes a paging transmitter (6) and up to as many paging receivers (14) as there are portable units (12).