The Apple server are closed ! time is over ! It dose not work any more
What do you need: A jailbroken iPhone that can be activated in iTunes (that is, not officially blacklisted), a computer with the latest iTunes installed and working internet connection. You will also need to know the carrier that your iPhone is locked to.This will unlock all basebands like 4.11.08 , 4.12.01 ,1.0.13 ,1.0.14,2.0.10
Updated with new solution
To unlock your iPhone 4 on iOS 5 with Gevey SIM you MUST update your iPhone 4 to pre-jailbroken custom firmware to preserve the unlockable baseband which are compatible with Gevey SIM.
A new way discovered by a developer allows you to unlock any iPhone 4s , iPhone 4 , iPhone 3Gs AT&T carrier. This method no need to any software , jailbreak or hardware change.You can simply test this method on another carriers and report .