The iOS 4.2.1 firmware was released some days before and the jailbreak for the iPhone 3GS on iOS 4.2.1 firmware was made available through redsn0w 0.9.6 beta 5 ( upgrading to baseband 06.15.00 ). Now it is time to unlock iPhone 3GS 4.2.1 firmware. Follow the steps given below to unlock iPhone 3GS 4.2.1 firmware.

NOTE: Read the jailbreak guide carefully as there are many difficulties.

1. Jailbreak iPhone 3GS on iOS 4.2.1.

2. Launch Cydia.

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

4. Choose the ” Sources ” option.

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

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

Unlock iPhone 3GS 4.1 Firmware

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

8. Install the Ultrasn0w 1.2 app to unlock iPhone 3GS 4.2.1 firmware.

Unlock iPhone 3GS 4.2.1 iOS

9. Restart your iPhone 3GS.

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