What does an ambulance medical biller do?

Ambulance service is just that; a service. Usually a private company, providing a service (showing up and quickly getting you to a hospital when you call 911). They don't get paid by the hospital or the "ambulance fairy", so generally when you are transported by ambulance, you get a bill from them as you would any other business. Many times insurance covers the cost, and if someone has no insurance, you get a bill for the cost of the driver, the medical staff, insurance etc... the costs of emergency transportation. Think of it as a "super-qualifed medical taxi".