It's been closed for a couple years now. There's no way to make (or move) a new character on it. A Gold World Pass might work, but I doubt it. The only way to be on Bahamut now is to have a character on it before it was closed.
can't you call and supply your registered name, birthdate, address, and last used credit card? that's the stuff they asked me when i called in. i think if you use the internet acnt reactivation they require a cd-key though...