Pensioner Concession Card and Healthcare Card holders are entitled to free clinically necessary ambulance transport. If you are not eligible for a concession and want to be covered, you can purchase insurance from a private health insurer or take out a subscription with the state ambulance service (https://www.ambulance.vic.gov.au/membership).
For further information about this policy see: http://www.bupa.com.au/health-insurance/cover/ambulance