What is the best iOS version for an iPhone 4 that needs to be unlocked with UltraSn0w?
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makemind • May 20, 2013 at 8:43pm
I am currently using iOS 5 on an iPhone 4 and using UltraSn0w to unlock it. I would like to know which iOS version is recommended for this device while maintaining the ability to unlock.
Answers
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iClarified • January 13, 2026 at 3:58am
For an iPhone 4 that relies on UltraSn0w for unlocking, the most important factor is your modem firmware (baseband). UltraSn0w only supports the 01.59.00 baseband on the iPhone 4. If you have this baseband, you must use a custom firmware created with a tool like PwnageTool or Sn0wbreeze to update your iOS without updating the baseband. Regarding performance, iOS 6.1.3 is widely considered the best balance of features and speed for the iPhone 4. While iOS 7.1.2 is the final supported version, it can be significantly slower on this hardware. If you choose to update, ensure you have your SHSH blobs saved for the version you want to move to, as Apple is no longer signing older firmware.