How to upgrade iPhone 3GS from iOS 3.1.3 to the latest firmware?
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bkmenon • October 18, 2012 at 10:58am
I have an iPhone 3GS that is jailbroken and unlocked running iOS 3.1.3 with modem firmware 05.12.01. What is the process to upgrade this device to the latest supported firmware while maintaining the unlock?
Answers
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iClarified • January 12, 2026 at 3:13am
The latest version of iOS available for the iPhone 3GS is iOS 6.1.6. You can update your device by connecting it to a computer and using iTunes. However, because your iPhone is currently jailbroken and unlocked with baseband 05.12.01, performing a standard update will upgrade your modem firmware and likely relock the device to its original carrier. To maintain your unlock, you should use a tool like Redsn0w to create a custom firmware (IPSW) that preserves the baseband. Once updated to iOS 6.1.6, you can use the p0sixspwn tool to perform an untethered jailbreak if needed.