Ultrasn0w 1.2.1 – Unlock your iPhone 4 & iPhone 3GS running iOS 4.3.1

Today, iPhone Dev Team has released the updated version Ultrasn0w 1.2.1 unlock to fix signal bar issues with iOS 4.3.1 running iPhone 4 & iPhone 3GS.

We’ve pushed out the 4.3.1 compatibility fix for ultrasn0w in Cydia – it’s now at version 1.2.1.  If you’re not already at 4.3.1 and you need the unlock,please be sure you understand how to get to 4.3.1 using a custom IPSW that doesn’t update your baseband.

This isn’t a new unlock! It’s to allow those who are already unlocked to use FW 4.3.1.  It also fixes the signal bar issue for those who aren’t using the unlock but retain an older baseband intentionally.

AFTER INSTALLING ULTRASN0W 1.2.1, PLEASE REBOOT YOUR iPHONE using the normal “slide to power off” swipe.  T-Mobile users in the USA also should disable 3G mode in Settings->General->Network.

This new version of Ultrasn0w support basebands:

iPhone 3GS - 4.26.08, 05.11.07, 05.12.01, 05.13.04 and 06.15.00 (iPad Baseband)

iPhone 4 – 01.59.00

Currently, there is no unlock available  for iPhone 4 baseband 2.10.01, 3.10.01, 4.10.01. Please do not update your iPhone to iOS 4.3.1 firmware without preserving the existing, otherwise you may loose the carrier unlock for devices.

Now follow the guide to unlock iPhone 4, iPhone 3GS on iOS 4.3.1 firmware.

Unlock your iPhone 4 & iPhone 3GS on iOS 4.3.1 using Ultrasn0w 1.2.1.

1: First jailbreak iOS 4.3.1 on iPhone 4 & iPhone 3GS using PwnageTool 4.3 or Sn0wbreeze 2.5.

2: Launch Cydia store and Tap on the Manage tab at the bottom of the screen.

3: Go to the Sources > Edit and press the Add button at the top left screen.

4: Now enter repo666.ultrasn0w.com and tap on Add Source. (Note – Ultrasn0w is spelled with a zero, not the letter “o”.)

5: Once Cydia has added the source click on Return to Cydia button.

6: Once the installation is completed, Search for Ultrasn0w in Cydia and install it.

When the installation process finished, reboot your iPhone 4 / iPhone 3GS. Now you should have unlocked iPhone 4, 3GS running iOS 4.3.1 basebands.

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