The following method will help you downgrade the baseband version of iPhone 3G from 06.15.00 to 5.13.xx, which is unlockable using Ultrasn0w unlock tool. This method will also enable you to restore your iPhone 3G on the official stock firmware using iTunes which was not possible on iPad’s 06.15.00 baseband.






This method currently only works with the iPhone 3G (bootloader 5.8). ghly recommend you to backup everything on your device before following the procedure.

Requirements :

* Jailbroken iPhone 3G
* Fuzzyband installed via Cydia
* afc2add installed via Cydia
* i-FunBox (for Windows) OR DiskAid (for Mac)
* Certificate to use with Fuzzyband

Downgrade iPhone 3G BB 06.15.00 To 05.13.xx (iPhone 3G Bootloader 5.8 Only) [How To] :

1) Download the required certificate file ICE2-06.15.00.cert from here.

2) Install Fuzzyband from Cydia and launch it.

3) Connect your iPhone 3G to your computer via USB cable.

4) Start i-FunBox and click File, then navigate to Applications/Fuzzyband.app, right-click and then select Copy from PC.

5) Select the ICE2-06.15.00.cert file you downloaded earlier and then copy it to this location : Applications/Fuzzyband.app.

6) Now simply disconnect your iPhone 3G from your computer and start Fuzzyband app (which you previously installed using Cydia) on your iPhone 3G.

7) In Fuzzyband, you will now see your current version of Baseband, (which should still be 06.15.00). But now you will have the option to downgrade it to version 05.13.xx.

Once you have downgraded your iPhone 3G, Go to Settings > About, and scroll down to check your Baseband which should now read 05.13.xx (which is unlockable via Ultrasn0w). You can now also update or restore any firmware without iTunes showing errors.

                                   

If you have any problems or queries, please feel free to comment below.


[via Redmond Pie]