Yesterday, the iPhone Dev Team released Redsn0w 0.9.6 and PwnageTool 4.3 for iOS 4.3.1 untethered jailbreak. Later, iH8sn0w released Sn0wbreeze 2.5 for iOS 4.3.1 untethered jailbreak on iPhone, iPad, iPod touch and Apple TV2. However, ultrasn0w 1.2 was broken on iOS 4.3.1, meaning that you could not unlock your iPhone on old baseband, using ultrasn0w 1.2. Now, @pushfix has announced the release of ultrasn0w fixer for iOS 4.3.1, which will unlock your iPhone 3GS, iPhone 4 on iOS 4.3.1.
Ultrasn0w fixer for iOS 4.3.1 will unlock basebands 01.59.00, 04.26.08, 05.11.07, 05.12.01, 05.13.04 and 06.15.00 and will not unlock iPhone 4 iOS 4.3.1 on baseband 02.10.04, 03.10.01, 04.10.01, 05.14.02 and 05.15.04.
How To Unlock iPhone 3GS, iPhone 4 On iOS 4.3.1
Step 1: Load Cydia
Step 2: At the bottom right corner, tap Manage
Step 3: Tap on Source
Step 4: Tap Edit on the top right corner followed by Add on the top left corner.
Step 5: Add the following repository – http://cydia.pushfix.info
Step 7: Once installation successfully completes, go to Search and write Ultrasn0w Fixer
Step 8: Install Ultrasn0w fixer to unlock iOS 4.3.1 on iPhone 3GS and iPhone 4
Step 9: After installation completes successfully, simply restart your device, and you will have your iPhone 3GS, iPhone 4 unlocked on iOS 4.3.1.
Let us know if you face any difficulties during the procedure.