If your iPhone 3GS was updated to iOS 5.1 then your device BB might be upgraded to baseband 5.16.05 and you would have lost the unlock. It happens when you restore your device without using custom firmware. You can’t unlock BB 05.16.05 with Gevey SIM or Ultrasn0w, but iPad baseband 06.15.00 can be installed in iPhone 3GS which can be unlocked with Ultrasn0w. Baseband downgrade is also out of question because Apple is not signing iOS 5.0.1 and older IPSW anymore.
Below you can follow our step-by-step guide to install iPad modem firmware 06.15.00 on iPhone 3GS running iOS 5.1 but before that you must read side-effects which might occur after using this method.
- This guide is not for people who own iPhone 3GS which was manufactured after week 28 of year 2011. Such owners shouldn’t use this tutorial because your modem firmware chip might end up bricked.
- Your device GPS might stop working
- You wouldn’t be able to use stock firmware but custom firmware cooked with Redsn0w or Sn0wbreeze can be used.
Unlock iPhone 3GS 5.1 Baseband 05.16.05
1. Plug your phone with Computer.
2. Run Sn0wbreeze you downloaded earlier and select the next button. Browse and locate iOS 5.1 IPSW file on your Computer. If you know about your device Bootrom, you can choose it yourself. Otherwise, you can select “Detect it for me” from the given choices.
3. Choose Blue Color Next Arrow and select “Expert Mode”. Check “Activate the iPhone (Hacktivate)” and hit the next button. After checking this option you wouldn’t need to use official carrier SIM Card.
4. The new Windows will present you with the option to install 06.15.00 iPad Baseband in iPhone 3GS. Check this option and hit the next arrow button again. Warnings for installing this BB are also mentioned on this screen.
5. Select “Build IPSW”. Sn0wbreeze will start creating custom IPSW for iOS 5.1. This step will take some time.
6. After finishing last step, it’ll ask you to put your phone in “PwnedDFU Mode”. Follow on-screen instructions to put your device in this mode.
7. After getting into this mode, run iTunes and select your phone. Hit the “Shift” key and select “Restore”. Find custom firmware file just created by Sn0wbreeze and let iTunes restore your phone.
8. Tethered boot your device by using Redsn0w or iBooty. For iBooty, you need to enter PwnedDFU Mode for Tethered Boot.
9. This method will also jailbreak your iPhone 3GS, therefore, you can now use Cydia. Open Cydia and add new source “http://repo.iparelhos.com” without quote. Firstly, Install “Ultrasn0w fixer for 5.1″ and then you need to install “Ultrasn0w 1.2.5″. Reboot your phone.
Note: If no service appears after following above procedure then try this after tethered boot with JustBoot. Turn off 3G from Settings > General > Network and then insert your SIM card. Carrier Signals will appear on your device.
Congrats! You’ve successfully unlocked iPhone 3GS on baseband 5.16.05.
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