[SOURCE: Ultras0w]
Along with Redsn0w 0.9.6RC15, the iPhone Dev Team has released a new version of Ultrasn0w 1.2.3 which unlocks iPhone 4, 3GS on iOS 4.3.3 for those who are already rely on unlock. Ultrasn0w 1.2.3 guide below. Ultrasn0w 1.2.3 supports 01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00 basebands.
STEP 1: First, you will have to jailbreak your iPhone 4 or 3GS on iOS 4.3.3. Instructions on how to jailbreak iOS 4.3.3 using Redsn0w 0.9.6RC15 can be found here.
STEP 2: Once you are done with the jailbreak, you can now unlock your iPhone on the supported basebands using Ultrasn0w 1.2.3 from Cydia. To do this:
- Start “Cydia” on your iPhone.
- Touch on “Manage” tab on the bottom.
- Now touch on “Sources” as seen in the screenshot below:
After installation is completed. Search for “ultrasn0w 1.2.3” in Cydia and install this application. This app will automatically unlock your iPhone so that you can use it with any carrier.
STEP 3: Now simply restart your iPhone and voila! you should now have a fully unlocked iPhone 4 or 3GS, running iOS 4.3.2 !