How To Downgrade Baseband 4.12.01  to 4.11.08 4.10.01 01.59.00 on iPhone 4:

People who updated their iPhone 4 to iOS 5.1 unintentionally lost their unlocks
(GEVEY SIM). There’s still no unlock available for Baseband 4.12.01 but
there’s a solution for that. As Apple is still signing their previous version
of iOS, iOS 4.3.5 you can still downgrade your iPhone 4 to baseband 4.10.01
which is unlockable with Gevey.


Things you will be needing during this process: 

  • A restore copy of iOS 4.3.5 

Before you downgrade, please remember you can only downgrade your iDevice firmware if, and only if, you have saved your SHSH blobs somewhere safely, hopefully with Saurik’s Cydia server, or locally on your machine.

From now on, I will assume you have saved your blobs on Saurik’s Cydia server.

STEP 1: To start with, you need to make sure you have a copy of iOS 4.3.5 or whatever firmware you need to downgrade for your device which you can find and download from here.

STEP 2: Next, you need to make sure your hosts file is pointing to Saurik’s server, and not Apple’s. If you haven’t done this then please check this guide.

Alternatively, use TinyUmbrella to make iTunes look at Cydia’s Server in the Advanced options.


         Downgrade iPhone Baseband
         Downgrade any BB  04.12.01 – 01.59.00



STEP 3: Now plug in your iOS device, and switch it off, but leave it plugged in.

STEP 4: Put your device into DFU mode, our guide here.

STEP 5: Select your firmware manually to restore to. (Shift on Windows, and option on a Mac)

It says that it will talk to Apple when really, it is talking to the Cydia servers.

But, should  your phone should now have an error, such as error 1015, DO NOT PANIC! This is normal and has a quick fix. Just download anduse Recboot to kick it out of recovery mode – check guide

Download RecBoot for Windows |
Download RecBoot for Mac OS X |


  • iTunes 10.4  windows which you can download from here 

Step 1: Download and install iTunes 10.4 or earlier. You will need to remove iTunes 10.5 first.

Step 2: Download iOS 4.3.5 IPSW for iPhone 4

Step 3: Put your device into DFU mode .

Step 4: Connect to iTunes and it will say that your device is in recovery mode and needs to be restored.

Step 5: Go ahead and click shift+restore (Windows) or option+restore (Mac). Select the IPSW you just downloaded.

Step 6:  iTunes will verify with Apple server and begins restoring your device. Once completed you will need the official SIM card to activate it. You can use TinyUmbrella to confirm that you now have baseband 4.10.01.


This is it you can now unlock your iPhone 4 running iOS 4.3.5 using Gevey SIM, if you want to to run iOS 5 on your iPhone 4 and unlock it with Gevey SIM follow our step by step guide  to create a iOS 5 custom firmware IPSW file which will preserve your baseband to 4.12.01 which will allow you to unlock your iPhone 4 using Gevey SIM.

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Also: How To Downgrade iPhone 4 iOS 6 Baseband 4.12.02 to 01.59.00

Also: How to Downgrade Apple TV 2 Firmware

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