The Limera1n jailbreak tool is now out to jailbreak iPhone 4 on iOS 4.1.Â But since iOS 4.1 upgrades your baseband while updating to it, you will loose your unlock. So you should update your iPhone 4 to iOS 4.1 without upgrading baseband and then jailbreak and unlock it. Here are the steps to unlock iPhone 4 iOS 4.1 firmware.
1. Update iPhone 4 to iOS 4.1 without upgrading the baseband. The guide to do that is given here.
3. Now open Cydia and choose the ” Manage ” tab.
4. Choose the â€ Sources â€ option.
5. Tap the â€ Edit â€ button and then on the â€ Add â€ button.
6. Then add the source â€ http://repo666.ultrasn0w.com â€œ.
7. After the source is added, search for â€ ultrasn0w 1.1-1 â€ in Cydia.
8. InstallÂ the Ultrasn0w 1.1-1 app to unlock iPhone 4 4.1 firmware.
9. Restart yourÂ iPhone 4.
That’s it! You will have an unlocked iPhone 4 with you now.