UltraSn0w has now been updated to version 1.2.1 and can be used to unlock your iOS devices jailbroken on iOS 4.3.1.
[NOTE] Please do not update with stock (original) firmware from iTunes. Install custom firmware only, which doesn't update your baseband.
[NOTE] You have to jailbreak your device before unlocking.
[NOTE] Please reboot your device after installing UltraSn0w using 'slide to switch off'.
[NOTE] T-Mobile customers, switch off 3G mode in Settings -> General -> Network.
- Jailbreak - You will need to jailbreak your iPhone 4 device on iOS 4.3.1. You can do this using Redsn0w, PwnageTool or Sn0wbreeze jailbreak tools. These methods will preserve the device baseband and ensure that you can unlock your device.
- Unlock - Once you have jailbroken you will need to install UltraSn0w 1.2.1 which is available in Cydia:
- Start 'Cydia' on your iPhone.
- Click the 'Manage' tab.
- Click 'Sources' which will be available in the Manage tab.
- Click 'Edit' and then 'Add'.
- When prompted enter the following url: "http://repo666.ultrasn0w.com" and click 'Add Source'. [URL may already be available]
- Allow Cydia to update sources.
- Now Click Search and Type "ultraSn0w"
- Select ultrasn0w 1.2.1 which will appear on a list. and install it.
- Restart - Once you have install you will have to restart your device. Now your device is both Jailbroken and unlocked to work on iOS 4.3.1 on any network.
For iPhone 3GS Users
iPhone 3GS users who wish to upgrade to iOS 4.3.1 will have to upgrade their baseband to 06.15,00 to unlock their devices using Ultrasn0w 1.2.x. You will have to first have to jailbreak your device to iOS 4.1/ 4.2.1 (jailbreak guide) before you can proceed with the steps provided