How to Upgrade an Unlocked and Jailbroken iPhone 3GS With 06.15.00 Baseband to iOS 5.1
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simply.abhay • December 26, 2012 at 11:28am
I am looking for instructions on how to upgrade a jailbroken and unlocked iPhone 3GS with the 06.15.00 iPad baseband to iOS 5.1 without losing the carrier unlock.
Answers
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iClarified • January 12, 2026 at 4:32am
To upgrade an iPhone 3GS with the 06.15.00 iPad baseband to iOS 5.1 while maintaining your unlock, you must use a custom firmware to avoid iTunes errors and baseband issues. First, download the iOS 5.1 firmware for iPhone 3GS and the latest version of RedSn0w. Open RedSn0w, go to Extras, then Custom IPSW, and select the iOS 5.1 firmware you downloaded. This will create a new IPSW file that preserves your current baseband.
Next, use RedSn0w to enter Pwned DFU mode by selecting Extras and then Pwned DFU. Once the device is in this state, open iTunes, hold the Shift key for Windows or Option key for Mac, and click Restore. Select the custom firmware file created by RedSn0w. After the restore is complete, you can jailbreak using RedSn0w and install Ultrasn0w from Cydia to restore your carrier unlock.
Next, use RedSn0w to enter Pwned DFU mode by selecting Extras and then Pwned DFU. Once the device is in this state, open iTunes, hold the Shift key for Windows or Option key for Mac, and click Restore. Select the custom firmware file created by RedSn0w. After the restore is complete, you can jailbreak using RedSn0w and install Ultrasn0w from Cydia to restore your carrier unlock.