If you want to unlock iPhone 3GS baseband 05.16.01 or 05.16.02, you must first upgrade it to iPad baseband 06.15.00. After upgrading to iPad baseband, you can use Ultrasn0w 1.2 to unlock your iPhone. You can either use Sn0wbreeze 2.4b1 or Redsn0w 0.9.6b5 to upgrade your iPhone 3GS baseband to 06.15.00 but for some reason, upgrading my iPhone 3GS baseband 05.16.02 to 06.15.00 using Sn0wbreeze ended up in iTunes 1002 error.
IMPORTANT UPDATE: DO NOT use this guide as it is outdated. Use this guide to fully jailbreak and unlock iPhone 3GS baseband 05.16.02 on iOS 4.3.3.
UPDATE#1: iH8sn0w has just released Sn0wbreeze 2.5.1 which allows you to upgrade to iPad baseband without any 1002 or other restore error. Just download Sn0wbreeze 2.5.1 from here and follow this guide to upgrade to iPad baseband (Works on iOS 4.3.1).
UPDATE#2: Downgrade iPad baseband 06.15.00 to 05.13.04 is very much possible!
UPDATE#3: Fix iPhone 3GS (iPad Baseband) Battery Life Issues on iOS 4.3.3 [Tips]
Steps to Upgrade iPhone 3GS Baseband 05.16.01/02 to 06.15.00:
- Make sure your iPhone 3GS is running iOS 4.1 or iOS 4.2.1. If you are on iOS 4.3.1 or iOS 4.3, use this guide to downgrade your firmware to iOS 4.2.1.
- Download stock iOS 4.1 or iOS 4.2.1 IPSW for iPhone 3GS.
- Download Redsn0w 0.9.6b5 for Windows or Mac OS X
- Launch Redsn0w and click on Browse button. Choose stock iOS 4.1 or iOS 4.2.1 IPSW which you downloaded in step 2.
- Now wait while Redsn0w processes the firmware file you provided.
- hoose YES if you have iPhone 3GS with newer bootrom, otherwise choose NO. You can check the bootrom of your iPhone 3GS through iDetector software which you can download from here.
- Once IPSW has been successfully identified by Redsn0w, click on the Next > button.
- Wait while Redsn0w patches the kernel in IPSW.
- Choose "Install iPad Baseband" option from the list and click on the Next > button.
- Connect your iPhone to your PC or Mac via USB cable and make sure it is completely powered OFF.
- Now use the following instructions to put your iPhone in DFU mode:
- Hold down the Power (corner) button for 3 seconds.
- Without releasing the Power button, also hold down the Home (bottom center) button for 10 seconds.
- Without releasing the Home button, release the Power button BUT KEEP holding the Home button for 15 seconds until Redsn0w detects your iDevice in DFU mode.
Contact Us for News Tips, Corrections and Feedback
Note: I used this method because Sn0wbreeze 2.4b1 was not working for me. It might work for you but as confirmed by Salracing and Radio, those iPhone 3GS users who have baseband 05.16.01 or 05.16.02 might get error 1002 while restoring custom IPSW made with Sn0wbreeze tool. Also Redsn0w will fail to upgrade your baseband to iPad baseband if your iPhone 3GS is running iOS 4.3 or iOS 4.3.1, it has been confirmed by Jhey and Marcel. Keep in mind that upgrading to iPad baseband may cause you to lose your GPS functionality and downgrading iPad baseband back to 05.16.01 or 05.16.02 is also not possible for now.