You can't get them to change your phone line. In reality you have fiber to a device in your neighborhood which changes the signal to copper.
Fiber optic uses light instead of electricty so it potentially faster.
The problem is that their is the phone companies have not installed the equipment to allow for high speed access over these lines. IFTL is a new technology which explains why you might not find anything on the website. ISDN and T-1 are both very expensive in equipment and service charges. Your best bet if you don't have cable in your area is patience eventually they will upgrade the fiber equipment to allow for high speed access. You can call BellSouth americast if you don't get any response from the dsl guys.