iOS 4.0.1 was released earlier today for iPhone 4, 3GS and 3G. Fortunately for all iPhone unlockers, the baseband wasn’t upgraded from 05.13.04, which means you can unlock your iPhone even on the latest iOS 4.0.1 firmware. Since currently there is no jailbreak tool available for iPhone 4 and iPhone 3GS (newbootrom), and the current jailbreak tools for iPhone 3GS (old bootrom) are not compatible with iOS 4.0.1, so the only device which can currently be jailbroken and unlocked on iOS 4.0.1 is iPhone 3G.
How to: Jailbreak iPhone 3G on iOS 4.0.1: Step 1: Follow the complete guide posted here to jailbreak your iPhone 3G using Redsn0w 0.9.5b5-5 on iOS 4.0.1.
How to: Unlock iPhone (Any Baseband) on iOS 4.0.1: Step 2: Once you are done with the jailbreak, you can now unlock your iPhone on any baseband using ultrasn0w 0.93 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:
Touch on “Edit” and then on “Add”. You will be prompted to enter a url source as seen in the screenshot below. Type “http://repo666.ultrasn0w.com” and touch on“Add Source”.
Cydia will now automatically update your sources by following a series of automated steps.
After installation is completed. Search for “ultrasn0w 0.93” 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 3G on iOS 4.0.1.
Disclaimer: This guide is for testing & educational purposes only. I’m not responsible for any loss of important data or malfunctioning of your iPhone.