You'd probably have to go with your DSL provider's info. Like if Qwest is the CO, only they'll have the DB of their service areas. Not every CO is DSL capable.
I've never done anything like what you want to do, but I do have DSL and know that I was told by my ISP that I could get DSL but when I moved in I found out their facility didn't support it at the time. Although, the Cyber-cafe across the street has DSL.
So it's a tough one from what I can gather. Half the time the phone company doesn't even know.