How to preserve iPhone 4 baseband while upgrading to iOS 5

If you are planning to upgrade to iOS 5 from your unlocked iOS 4.X.X, you will have to preserve your iPhone 4 baseband in order to keep your unlock. Here are the steps on how to preserve your iPhone 4 baseband while you upgrade to iOS 5. Just follow the instructions and the baseband will be saved for you. To do this you will need to have downloaded iOS 5, iTunes 10.5 and Redsnow 0.9.9b5.

Step 1

Tether your iPhone to your computer and open Redsn0w 0.9.9b5

Step 2

Select Extras and then choose Custom IPSW to create pre-jailbroken  custom firmware.

Step 3

Once you do this Redsn0w will creating your custom IPSW and it will be available to you in few minutes.

Step 4

Select “Pwned DFU” from Redsn0w once you get your firmware.

Step 5

Now bring your iPhone into DFU mode. Follow the instructions onscreen to do so.

Step 6

Once your phone comes into DFU mode, close Redsn0w. Once you close it, open iTunes 10.5 which is already downloaded. You phone should now be in recovery mode.   

Step 7

Now hold the option key on your Mac and hit on Restore. Point iTunes into your iPhone 4 Custom iOS 5 IPSW which will begin with NO_BB.

[WARNING: do not select the stock one as you will lose Your unlock.]

Your iPhone is now in preserved baseband and you will be able to unlock your iPhone 4 using the Ultrasn0w guide.

Posted in: iOS 5 for iPhone, iphone, iphone unlock, jailbreak to iOS 5