I have no idea how it works. My wife is on medicare with a Humana PPO supplement. She travels quite a bit, with her home base in Florida and periods of time in Philadelphia and New Orleans. In Philly she has sought medical care for an injured shoulder. I called around to see what hospitals accept Humana, none would accept it. Using a relative who works for one of the hospitals, one agreed to accepting the Humana plan. Orthopedist recommended physical therapy, found one PT that would accept Humana. Among those who would not accept Humana, the response was "we take medicare patients, but not Humana". What the heck does that mean?