If you possess an AT&T iPhone that is out of contract with AT&T or you purchased an iPhone without AT&T contract, you can easily unlock it for use on any other network. You can unlock the iPhone through AT&T by calling a special direct line or you can unlock an iPhone through web with the help of AT&T’s online technical support chat or you can fill out a request form to unlock your iPhone. You can also unlock iPhone 5 by using these methods. Here is how to unlock your iPhone in different ways:
Ultrasn0w 1.2.3 has been released to make the unlock compatible with iOS 4.3.3 on iPhone 4 and 3GS, running on the old baseband. This release of Ultrasn0w is not a new unlock for iPhones with newer basebands, instead, it only fixes the compatibility issues on the existing devices, which are jailbroken (with preserved basebands: 01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00) on iOS 4.3.3. Updating iPhone 3GS baseband to iPad’s 06.15.00 might result in loss of GPS functionality. Proceed to the step by step guide to unlock iOS 4.3.3 on iPhone 4, 3GS Using Ultrasn0w 1.2.3.
iOS 4.3.3 has been released by Apple for iPhone 4, 3GS, iPad, iPod touch 4G/3G to fix the location tracking bug found in iOS 4.x devices. If you have upgraded to iOS 4.3.3, and now want to downgrade back to iOS 4.3.2, iOS 4.3.1, iOS 4.3, or iOS 4.2.1, simply follow the instructions below to downgrade iOS 4.3.3 on iPhone 4, 3GS, iPod touch, iPad 2 and iPad 1 to iOS 4.3.2, iOS 4.3.1, iOS 4.3, iOS 4.2.1. This guide will only work if you have SHSH blobs saved for the respective firmware you downgrading to. Proceed to downgrade guide.
Sn0wBreeze is a jailbreak tool that only works for Windows. The following guide will help you to perform tethered jailbreak for iOS 4.3 on iPhone 4, 3GS, iPod Touch 4G, 3G, iPad 1 using Sn0wBreeze 2.3 b1 (iPad 2 is not supported). Do not upgrade your iDevice to iOS 4.3 if you rely on unlock.