Want to update your iPhone 4 or iPhone 3GS to iOS 5, but need to preserve your unlockable baseband for a future UltraSn0w unlock?

Early this morning, the Dev Team released an update to RedSn0w, which as we told you, incorporates some of the baseband preservation features normally found in PwnageTool.

Inside, you’ll find an easy to follow video walkthrough that shows you how to preserve your baseband for a soon to be released UltraSn0w unlock

[tube]http://www.youtube.com/watch?v=jiwiERBoIOY[/tube]

You will need the latest version of RedSn0w to follow this tutorial, which you can download from our Downloads page. The latest version is 0.9.9b5 and it’s Mac only at this point, though a Windows version should be available shortly according to the Dev Team.

How to Preserve Your Baseband With iOS 5:

Step 1: Open RedSn0w 0.9.9b5 and select ‘Extras’ and ‘Custom IPSW’

Step 2: Select the iOS 5 Firmware. (It will be in ~/Library/iTunes/iPhone Software Updates/ on the Mac.)

Step 3: Once it builds the new firmware, select ‘Pwned DFU’ from RedSn0w.

Step 4: Put your iPhone into DFU Mode, and RedSn0w will take over and put your device into Pwned DFU mode.

Step 5: Close RedSn0w, Open iTunes, and it should recognize your iPhone in recovery mode.

Step 6: While holding Option on your Mac’s keyboard, click ‘Restore’ and select your NO_BB firmware that was created in Step 3. BE SURE THAT YOU SELECT THE NO_BB firmware, and not the stock firmware, or else you will update your baseband.

Step 7: Once your iPhone is restored and back to the home screen, you can either jailbreak now, or wait until UltraSn0w is updated for iOS 5.

Note: This is not a jailbreak, this only allows you to preserve your baseband for future unlocks with UltraSn0w.

Will you continue to preserve your unlockable baseband? Let us know in the comments below.