How to Upgrade iPhone 3GS (New Bootrom) to iOS 5.1.1 and Keep Baseband Unlock
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aguiarcampos • October 30, 2012 at 8:44pm
Is it possible to upgrade an iPhone 3GS with the new bootrom from iOS 4.3.3 to iOS 5.1.1 while preserving the 05.13.04 baseband for an unlock? I need to ensure the jailbreak remains untethered and the device can still be unlocked after the update.
Answers
0
iClarified • January 12, 2026 at 3:29am
Yes, you can upgrade your iPhone 3GS with the new bootrom to iOS 5.1.1 while preserving your unlockable baseband and achieving an untethered jailbreak. Since your current baseband is 05.13.04, you must avoid a standard iTunes update or restore, which would upgrade your baseband to 05.16.05 and make it impossible to unlock using Ultrasn0w.
To perform this upgrade safely:
1. Use a tool like Redsn0w to create a Custom IPSW for iOS 5.1.1. This custom firmware will be stripped of the baseband update, allowing you to keep version 05.13.04.
2. Put your iPhone into Pwned DFU mode using Redsn0w to prepare it for the custom restore.
3. Open iTunes and hold the Alt/Option key (Mac) or Shift key (Windows) while clicking Restore. Select the custom firmware you just created.
4. Once the restore is finished, use Redsn0w or Absinthe 2.0 to perform the jailbreak. This will be an untethered jailbreak for the 3GS new bootrom on 5.1.1.
5. After the jailbreak is complete, open Cydia and install Ultrasn0w to activate your unlock.
Because you have already successfully downgraded from the 06.15.00 iPad baseband in the past, your phone is fully compatible with this process.
To perform this upgrade safely:
1. Use a tool like Redsn0w to create a Custom IPSW for iOS 5.1.1. This custom firmware will be stripped of the baseband update, allowing you to keep version 05.13.04.
2. Put your iPhone into Pwned DFU mode using Redsn0w to prepare it for the custom restore.
3. Open iTunes and hold the Alt/Option key (Mac) or Shift key (Windows) while clicking Restore. Select the custom firmware you just created.
4. Once the restore is finished, use Redsn0w or Absinthe 2.0 to perform the jailbreak. This will be an untethered jailbreak for the 3GS new bootrom on 5.1.1.
5. After the jailbreak is complete, open Cydia and install Ultrasn0w to activate your unlock.
Because you have already successfully downgraded from the 06.15.00 iPad baseband in the past, your phone is fully compatible with this process.