So what is a Medicare Advantage program and how does it really work? Well, a Medicare Advantage replaces traditional Medicare or Medicare Parts A and B. If you do not select a Medicare Advantage and just go with Medicare, than your claims are handled by Medicare. If you have a Medicare Advantage plan than you are working with a traditional Medicare Insurance carrier such as AETNA, Medical Mutual or Blue Cross Blue Shield or one of the many other carriers involved in the Medicare Advantage.