As you might already be aware iPhone Dev team have given the popular jailbreaking tool redsnow a major upgrade recently. The upgrade was the ability to downgrade A5 devices, as a result it over shadowed some other important features of redsnow and that is the ability to create custom IPSW file for iPhone 4 and iPhone 3GS.
You might be wondering why do you need to create a custom IPSW file for iOS 5.1.1. Well this guide is for those people who rely on unlocking their iPhone. If you have an iPhone which is carrier locked and you want to update to a new version without changing baseband you will need to create a custom IPSW file.
Well folks if you were looking to create a custom IPSW file for iOS 5.1.1, look no further as we have the guide right here.
Create Custom IPSW For iOS 5.1.1 To Preserve Baseband
Download redsnow 0.9.11b4
Download original IPSW iOS 5.1.1 For iPhone 4/3GS
Procedure To Preserve Baseband
STEP 1: Download redsnow from the above link
STEP 2: Start redsnow and head over to Extras > Custom IPSW.
STEP 3: Select the original IPSW file for your iOS device which you downloaded from the above link.
STEP 4: Redsnow will now create the custom IPSW file, the one that has preserved the baseband meaning you will still be on the previous version (baseband).
STEP 5: Enter into Pwned DFU mood by going to Extras > Pwned DFU. Just follow the on-screen instructions.
STEP 6: Once your iPhone is in Pwned DFU mood, go to iTunes and press Shift+Restore (Windows) or Option+Restore (Mac). You will need to select the correct IPSW file it will have a prefix “NO_BB”.
STEP 7: As this is a tethered jailbreak you will need to boot tethered while it is trying to reboot after restoring. To boot tethered simply go to Extras > Just Boot.
You will now have a custom IPSW running on your iPhone 4 or iPhone 3GS for iOS 5.1.1 with a preserve baseband and get your iPhone 4 and iPhone 3GS unlocked via Ultrasnow fixer.
SAM Unlock iOS 5.1.1
Those folks who have unlocked via SAM method can create a custom IPSW and run iOS 5.1.1 (with saved unlock activation tickets) but as this is a tethered jailbreak it will create many problems so I advise you not to do so until we get an untethered jailbreak.
For any other questions hit the comment section below.