Can i unlock my iphone 4 in contract?

Just bought it online through ATT. Latest updates on it. Wanting to unlock say f the contract n go to diff carrier with it.

Http://attiphoneunlocker.com/

We can unlock any iPhone, from the first generation, the iPhone 3G, 3GS, 4 and the 4S. Our unique unlock supports All bootloaders, basebands, and firmwares as we do not unlock using software, we unlock using Apple's IMEI database.

It can be unlocked only via factory unlocked. Most iphone 4 models are either baseband 4.11 or 4.12, which can be only factory unlocked. You can use gevey sim to unlock this if it is 4.10 and lower.