In Australia there are several different companies that provide medical transport services. Hospital and Medivac are used to indicate the status/priority of flight.
In Western Australia there is the Royal Flying Doctor Service (Fly-Doc) and the RAC Rescue Helicopters (Rescue). Other states have Air Ambulance services by different operators (Ambulance VIC/NSW, Careflight). For all emergency services aircraft 3 numbers are issued, the first number indicating the state the aircraft is based/contracted to (I believe these are correct but stand to be corrected: 1 - ACT/National Aerial Firefighting Centre, 2 - NSW, 3 - VIC, 4 - QLD, 5 - SA/NT, 6 - WA).