Other than Game Center, the iOS 4.1 comes with a new version of baseband (i.e. 2.10.4) for iPhone 4. As of now, there is no unlock tool to unlock this baseband. If you want to upgrade to iOS 4.1 and preserve the unlock, you need to take extra steps for the upgrade.
In this guide, I’ll walk you through how you can upgrade to iOS 4.1 but without updating baseband. As the baseband (i.e. 01.59.00) can be preserved, you can still use ultrasn0w to unlock your iPhone 4 after upgrading to iOS 4.1.
Before you proceed, make sure you read through the following notes carefully:
- This guide is for iPhone 4 ONLY. Please do not use it for other models of iPhone.
- Make sure you use the latest version of iTunes (i.e. 10.0.1). If you haven’t upgrade the iTunes. you can download it here.
- This guide is catered for both Windows and Mac users.
- The procedures are tested using my iPhone 4. It works really well. However, there is no 100% guarantee that it’ll work on your iPhone. Use it at your own risk.
Okay, let’s get started.