The following method will help you to downgrade the baseband of iPhone 3G from 06.15.00 to 05.13.xx which is unlockable using Ultrasn0w. This method will also enable you to restore your device on official stock firmware using iTunes which was otherwise not possible on iPad’s 06.15.00 baseband.

This method currently only works with the iPhone 3G with boootloader 5.08. this procedure is fairly straightforward, however, we would not recommend novice users to try this. we also highly recommend you to backup everything on your device before following this it at your own risk.

if you are unsure about your iPhone 3G’s bootloader version then simply download F0recast from here

Requirement :

Jailbroken iPhone 3G with 5.08 bootloader version.
Fuzzyband Downgrader installed through Cydia
afc2add installed from Cydia
Certificate to use with Fuzzyband

Step 1:
Download the following certificate file – ICE2-06.15.00.cert

Step 2:

Install Fuzzyband from Cydia and start this app.

Step 3:

Connect your iPhone 3G with computer via USB cable.

Step 4:

Start i-FunBox/iPhone Browser and click File, then navigate to Applications/, right-click and then select Copy from PC.

Step 5:

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

Step 6:

Now simply disconnect your iPhone from your computer and reboot. Start Fuzzyband app (which you previously installed using Cydia) on your iPhone.

Step 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, Go to Settings>General>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 throwing errors.

Related posts:

  1. Fuzzyband Now Supports iPhone OS 4.0b1 Baseband Downgrade
  2. Fuzzyband Now Supports OS 3.1.3 Baseband Downgrade
  3. Dev Team Working on Baseband Downgrade for Easier iPhone Unlock
  4. How To Update iPhone 4 to iOS 4.2.1 While Preserving 01.59.00 Baseband[Windows/Mac]
  5. How To Update iPhone 4 To iOS 4.1 Without Updating the Baseband/Modem Firmware

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