so i just bought an iphone online and the IMEI is not registered to anybody... i have been an ATT&T subscriber for a while, and i have the sim where it still says cingular smartchip.. i want to switch it over using turbo sim, will i be able to?

*Note: i don't want the ATT data/3g plan, because i'm around wi-fi all day.. i just want to keep my existing plan. thanks