Thanks to the hard work of the iPhone Dev Team, the UltraSn0w unlock for iPhone has been updated to play well with iOS 4.3.3. As mentioned in our previous post about UltraSn0w, this will only work with iPhone 4 baseband 1.59.00, and iPhone 3G/3GS basebands 4.26.08, 5.11.07, 5.12.01, 5.13.04, and 6.15.00.

If your baseband is different from these, then you can’t unlock for the time being. If your baseband matches one of those above but you are on an older firmware, use PwnageTool to update while preserving the baseband.

In this tutorial, we will show you how to unlock your iPhone 4.3.3 using UltraSn0w…

Step 1: Make sure your baseband matches any of the basebands listed above. If it doesn’t, you can’t unlock. If it does, you may update your iPhone to 4.3.3 while preserving the baseband using PwnageTool. Note that you don’t have to update to 4.3.3. If for example you are still on iOS 4.1, you may stay there and still use UltraSn0w.

Step 2: Make sure your iPhone is jailbroken. The easiest way is to use RedSn0w, although it can be tricky as you might accidentally update your baseband. Which is why I suggest you use PwnageTool instead. PwnageTool will not update your baseband.

Step 3: After jailbreaking, go to Cydia and search for “UltraSn0w”. Download and install the app, then reboot your iPhone.

That’s it. Your iPhone should now be unlocked.

If you use T-Mobile, make sure to turn 3G OFF in your iPhone settings.