I'm considering purchasing an unlocked iPhone for use with my current T-Mobile plan which does not have a data plan on it. If I use the iPhone, is it possible to turn of EDGE or whatever may cause extraneous costs on my T-Mobile bill? This may be a dumb question but if I run the iPhone on another provider will it result in any other charges or should everything be fine just like with my current cell? I will still be able to use Wi-Fi and other features free of charge as long as EDGE is turned off, correct?