In the following guide you will learn how to unlock the iPhone 3G / 3GS with iOS 4.0.1 installed. This process can be completed using Ultrasn0w 0.93 and, taking in consideration that iOS 4.0.1 does not change the baseband, it works for baseband 05.13.04. If you are already unlocked on iOS 4.0, you can safely update to iOS 4.0.1, without the fear of locking your device. If have an unlocked OS. Before you unlock your iPhone 3G / 3GS 4.0.1, please note that you need to jailbreak it first. Use this for jailbreaking the iPhone 3G 4.0.1 or this for iPhone 3GS 4.0.1. Also, if you are an T-Mobile USA user, disable your 3G connection during the process.