Can I upgrade my iPhone 4 firmware and still use ultrasn0w for an unlock?
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pablomerio • February 10, 2013 at 4:52pm
I have an iPhone 4 currently running iOS 4.3.3 with modem firmware 01.59.00. Is it possible to upgrade to a newer iOS version and still use the ultrasn0w tool for a carrier unlock?
Answers
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iClarified • January 12, 2026 at 7:46am
Yes, you can upgrade your firmware while maintaining your ultrasn0w unlock, but you must avoid the standard update process in iTunes. If you perform a regular update, your modem firmware (baseband) will be upgraded to a version that ultrasn0w cannot unlock.
To stay on an unlockable baseband, you need to use a tool like PwnageTool for Mac or sn0wbreeze for Windows. These tools allow you to create a custom firmware file (IPSW) that upgrades the operating system but leaves the modem firmware untouched. After creating the custom IPSW, you put your device into Pwned DFU mode and restore to that specific file in iTunes. Once the update is complete, you can reinstall ultrasn0w from Cydia to activate the unlock.
To stay on an unlockable baseband, you need to use a tool like PwnageTool for Mac or sn0wbreeze for Windows. These tools allow you to create a custom firmware file (IPSW) that upgrades the operating system but leaves the modem firmware untouched. After creating the custom IPSW, you put your device into Pwned DFU mode and restore to that specific file in iTunes. Once the update is complete, you can reinstall ultrasn0w from Cydia to activate the unlock.