AT&T won't unlock your Samsung Captivate before the contract is over. If you wish to cancel the contract after 2 years and unlock your phone, You should pay the contract cancellation fee and unlock fee to AT&T which would be very costly to you. Instead, You can simply get the unlock code for your Samsung Captivate from any trusted private source. For example, You can visit simpleunlocking.com and get the unlock code at affordable cost with easy unlocking guide too. Good luck mate.