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Downgrade Baseband 6.15.00 to 5.13.04 and unlock with ultrasn0w 1.2

Downgrade Baseband 6.15.00 to 5.13.04 and unlock with ultrasn0w 1.2

By January 2, 2011 Fix 81 Comments
(Last Updated On: June 15, 2020)

First of all lets be clear that this method will only work for iPhone 3G with bootloader version 5.08 (5.8)! Otherwise, you can consider this.

You can quickly check your bootloader version by using TinyUmbrella. It should show your bootloader version right away. Alternatively, you can also use f0recast. The screenshot below shows an iPhone 3G with bootloader version 5.9.

Lets get straight to business!

Ingredients:

  1. Jailbroken iPhone 3G
  2. Fuzzyband – install this from Cydia
  3. afc2add – install this from Cydia
  4. i-Funbox – a file explorer for iPhone, Mac users can use DiskAid
  5. 6.15.00 certificate (ICE2-06.15.00.cert) for Fuzzyband

Steps:

  1. Launch Fuzzyband after installing the app via Cydia.
  2. Connect your iPhone to the computer.
  3. Launch i-FunBox and select File, then go to Applications/Fuzzyband.app, right-click and then select Copy from PC.
  4. Copy ICE2-06.15.00.cert you have downloaded earlier to this location
  5. Go back to Fuzzyband and you can now begin the downgrade process. If the downgrade is successfully, you should see “I Haz Downgrade”
  6. You can now unlock it with ultrasn0w and solve your GPS issue, error during restore etc.

Good luck and let us know how it goes!

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About Author

Joe the Device Unlock and Activation Specialist

Joe Wang studied electronics engineering and is a specialist in Apple and Android products. He has been fixing iPod and iPhone since 2008.

81 Comments

    « Older Comments
  1. ngoc Thanh

    Hello, would help!
    I'm using iphone 3G version 4.1 I have missed the lock version upgrade to the current modem firmware 06.15.00, you can help me how to reinstall version 5.0.1? raised to version 5.1 when the machine does not recognize sim Vinaphone, let me sincerely thank you very much! my email dnthanhtc@yahoo.com

    Reply
  2. xtzfla

    I have iphone 3g and I jailbreaked into 4.2.1 firmware ,and my baseband updated to 6.15.00 , I dl'ed fuzzy band from cydia I copyed the ICE2-06.15.00.cert into fuzzy folder with winscp then I runned fuzzy appear Bootloader version: 06.04 [G2M3S2] , Baseband version is ICE2-06.15.00 and Iphone OS Version 4.2.1 and down with red text its says sorry,downgrading will only work with baseband bootloader 05.08 .Can this be fixed or ?!

    Reply
  3. Hamz75

    I have a iPhone 3GS 16gb which is on iOS 5.0.1. My modem firmware is 6.15.00, can someone help me downgrade it to my original baseband 5.16.05?

    Reply
  4. Trilok

    I have iPhone 3GS 16Gb my boot loader is upgraded to 6.04 and baseband is 6.15.00 now how can i downgrade my boot loader and baseband???????????

    Reply
  5. Claudeel

    Thank you! It worked perfectly, I have bootloader 05.08 [G2M3S2]!

    Reply
  6. Andrei

    IS there any option for 06.04 to downgrade from 6.15.00? iPhone 3g

    Reply
  7. Tonii

    does it work for bootloader 5.9?

    Reply
  8. iPhone 3Gs

    What in a hell is this iFunBox?! Every time I click on it – nothing happens except for creating a file iFunBox_Build_0407_……..dmp ?!!!

    Reply
    9. « Older Comments

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