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How to Upgrade iPhone 4 to iOS 4.3.4 While Preserving Baseband?

Hi guys, I was thinking if it’s possible to jailbreak iPhone 4 to iOS 4.3.4 while preserving its unlockable baseband. Yes, I am also planning to unlock my iPhone 4 if possible. Any idea how to do it?

Asked by: Jing from Sacramento, California

Hello Jing, as much as possible, we don’t recommend upgrading / restoring your iPhone 4 to iOS 4.3.4 as there is no stable or untethered jailbreak available for the new iPhone firmware. As for the Ultrasn0w unlock, I don’t think that the Dev Team will release an updated version of Ultrasn0w to unlock iPhones on iOS 4.3.4. Maybe they release it after iOS 5. Anyway, you can preserve the baseband version of your iPhone 4 while restoring it to iOS 4.3.4 using the PwnageTool 4.3.3 and PwnageTool Bundle for iOS 4.3.4 on iPhone 4. If you aren’t familiar with the steps, then you can follow the tutorial posted below:

Note: No untethered jailbreak method available for iOS 4.3.4 on all iOS devices at the moment. The following tutorials used a tethered jailbreak method, which means you have connect your jailbroken iOS device into your Mac Or PC and boot it in tethered jailbreak state.

Step 1: Fist, you will need to have iTunes 10.3.1 installed on your Mac. Also, download PwnageTool bundle for iPhone 4 using this rapidshare link (courtesy by RedmondPie). Extract the .zip on your desktop and you should see a .bundle file. (iPad and iPod Touch users should use the right bundle file for your device) Move the .bundle file to your desktop.
Step 2: Download PwnageTool 4.3.3 from here [Mirror 1 | Mirror 2] and then copy it to the /Applications directory.
Step 3: Right click on the PwnageTool icon, click on Show Package Contents, navigate to the following address and place the bundle file in FirmwareBundles directory.


Step 4: Download the stock iOS 4.3.4 from this link for your iPhone and save it on your desktop.
Step 5: Then launch PwnageTool 4.3.3 and go to Expert Mode and select your device.
Step 6: Browse for the downloaded iOS 4.3.4 firmware for your iPhone 4 and then click on Build.
Step 7: PwnageTool will now create a pre-jailbroken iOS 4.3.4 IPSW firmware file for your iPhone 4 and save it on your desktop.
Step 8: Rest of the instructions to jailbreak iOS 4.3.4 using PwnageTool 4.3.3 and PwnageTool Bundle patch PwnageTool can be found here. Follow from step 14 to step 28.

  • In Step 20, choose the custom pre-jailbroken iOS 4.3.4 IPSW firmware file which you have created previously.
  • In Step 22, download the tetheredboot utility from this link.
  • In Step 23, create a copy of the custom iOS 4.3.4 firmware file which you created and rename it to .zip instead of .ipsw. Then extract the file. You’re going to use kernelcache.release.n90 and iBSS.n90ap.RELEASE.dfu from the extracted directory.
  • In step 26, use the following TetheredBoot Utility command:


Preserve iPhone 4 Baseband on iOS 4.3.4

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