Apple has recently released iOS 4.1. As anticipated, updating to iOS 4.1 also updates the baseband of your device to 2.10.4. However, if you update your jailbroken device to iOS 4.1 while preserving its baseband then you can easily unlock it with Ultrasn0w. If you jailbreak your iPhone 3GS(old Bootrom) with PwnageTool, it won't update the baseband and you can unlock it using Ultrasn0w 1.1-1.
Steps to Unlock iOS 4.1 on iPhone 3GS (old bootrom) with Ultrasn0w 1.1-1
- First jailbreak iOS 4.1 on iPhone 3GS (old bootrom) using PwnageTool. Refer to this guide for step wise procedure.
- Once jailbreaked, open Cydia on your jailbroken iPhone.
- Click on the "Manage" button at the bottom.
- Click on the "Sources" section.
- Click on "Edit" button at the top left of Cydia.
- Click on "Add" button at the top right of Cydia.
- Enter http://repo666.ultrasn0w.com as Cydia/APT URL and click on "Add Source" button.
- Wait while Cydia update your sources.
- Thats it! Now click on the "Search" tab at the bottom and search for "ultrasn0w 1.1-1". This app will automatically unlock your iPhone so that it can be used it with any official / unofficial carrier.
- Just restart your iPhone and you are good to go. Now, you should have fully unlocked and jailbroken iPhone 3GS on iOS 4.1.