The iOS 4.2.1 firmware was released some days before and the jailbreak for the iOS 4.2.1 firmware was made available through redsn0w 0.9.6 beta 4. Now the Ultrasn0w 1.2 have been released to unlock iOS 4.2.1 firmware on iPhone 3G / 3GS ( iPhone 4 users have to wait for another Ultrasn0w update ). Follow the steps given below to unlock iOS 4.2.1 firmware on iPhone 3G or 3GS.

NOTE : You would first have to update to 06.15 baseband using PwnageTool 4.1.3 or Redsn0w 0.9.6 b5 ( Guide ).

1. Launch Cydia.

2. Choose the ” Manage ” tab at the bottom.

3. Choose the ” Sources ” option.

4. Tap the ” Edit ” button and then on the ” Add ” button.

5. Then add the source ” http://repo666.ultrasn0w.com “.

Unlock iPhone 3GS 4.1 Firmware

6. After the source is added, search for ” ultrasn0w 1.2 ” in Cydia.

Unlock iOS 4.2.1 With Ultrasn0w 1.2

7. Install the Ultrasn0w 1.2 app to unlock iOS 4.2.1 firmware.

8. Restart your iPhone.

That’s it! Now you have an unlocked your iPhone 3G / 3GS running iOS 4.2.1.