A special unlock edition PwnageTool 4.1.3 has been released by Dev Team to support the unlock of iOS 4.2.1 / 4.1 on iPhone 3GS and 3G. It allows to update to baseband 06.15.00 which is required to unlock iOS 4.2.1 / 4.1. But you could face some troubles in the future if you update to it ( Given below ).

  1. There is no way to come back down from 06.15, and there’s no hiding the baseband version from Apple.  You’ll be voiding your warranty in a very obvious way.
  2. If some future baseband comes out with a critical fix, you won’t be able to update to it if it remains down in the 05.xx sequence (then again, you wouldn’t update to it if you wanted to keep your unlock anyway).
  3. Starting with FW 4.2.1 if you have 06.15 on your iPhone you won’t ever be able to restore to stock firmware (it will fail).  You’ll need to only restore to custom IPSWs (then again, if you’re unlocker you should already be doing that).

Now follow the below steps to update to 06.15.00 baseband.

NOTE: Do this at your own risk as I have mentioned the drawbacks of this above.

1. Download iOS 3.2.2 IPSW for iPad.

2. Download iOS 4.2.1 firmware. If you want to unlock iOS 4.1, then download that.

3. Download PwnageTool 4.1.3.

4. Launch PwnageTool and browse to the iOS 4.2.1 or 4.1 firmware.

5. Now click on ” Yes ” when asked to update baseband to 06.15.00.

6. Now browse to iOS 3.2.2 IPSW. PwnageTool will replace iOS 4.2.1 / 4.1 ‘s baseband with its 06.15.00 baseband.

7. Click on ” Yes ” and move forward.

8. Now go into recovery mode by pressing the power and buttons for 10 seconds and then release the power button, but keep holding the home button until the iOS 4.2.1 jailbreak process begins.

9. Now restore your device with this firmware you created now through iTunes.

That’s it! Now you have updated your iPhone 3GS / 3G baseband to 06.15.00.