How to Upgrade iPhone 3GS iOS While Preserving 05.13.04 Baseband for Unlock?
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mgradin • January 7, 2013 at 11:11pm
I have an unlocked iPhone 3GS running iOS 4.1 with baseband 05.13.04. I need to upgrade to a newer firmware version to use apps like WhatsApp but I must preserve my baseband for the unlock. What is the best firmware to upgrade to and which tools should I use to avoid updating the baseband?
Answers
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iClarified • January 12, 2026 at 4:52am
To upgrade your iPhone 3GS while preserving the 05.13.04 baseband for an ultrasn0w unlock, you must use custom firmware. The final supported version for the iPhone 3GS is iOS 6.1.6. You can use a tool like Redsn0w or Sn0wbreeze to create a custom IPSW file that excludes the baseband update. After creating the custom firmware, put your iPhone into Pwned DFU mode and restore it via iTunes. Once the restoration is finished, you will need to jailbreak the device and install the ultrasn0w package from Cydia to activate your unlock. Note that WhatsApp and many modern apps no longer support iOS 6, so functionality may still be limited.