The central point of the entire system is a signalling board capable of incorporating 36 or 100 transmitters. It is located in rooms of patient care personnel (nurses rooms, first-aid rooms, etc.). The board receives radio calls from remote controllers or transmitters located near patient’s beds. A received call is confirmed by acoustic and optic signalling. The device is powered with lowered voltage (using a 230/12VAC power adapter). Continuity of power supply is ensured by the use of built-in battery, which supplies the signalling board in case of mains power supply shortage.