Is it possible to unlock current iPhones?

[asdfTT123]

My old phone appears to be dying on me so I'm in need of a new phone. I'm currently on the T-Mobile network, and I was wondering if it's possible to easily unlock the current iPhones to allow use with my T-Mobile SIM. If so, how? Also, could I encounter any issues if my plan currently does not include a data plan? Is there any way I can turn off data/EDGE to avoid ridiculous charges, while still using the phone function, wifi, and other apps? Thanks.

 

[mingenyx]

if you replace it you are most likely going to get a 1.1.2 if lucky [if u get a1.1.3 ur screwed] but if u get a 1.1.2 u have to buy astealthsim or turbosim on ebay/online to unlkock.