Today we will be discussing ways to unlock your iPhone 3GS. After unlocking your iPhone 3GS, you will be able to use any GSM SIM card from any network carrier all around the world. The tool we are going to use to unlock your iPhone 3GS is called UltraSn0w. You have to keep in mind that if you are running your iPhone 3GS on iOS version 4.2.1, then the baseband or modem firmware number of your device must be 06.15.00, in order to make this process work.
Basebands
In addition to that, other basebands that are supported by the UtraSn0w unlock are 04.26.08, 05.11.07, 05.12.01, 05.13.04, 06.15.00 or 01.59. You have to make sure that your device has one of the basebands mentioned above, or else you won’t be able to unlock your iPhone 3GS through this process.
Must be Jailbroken
Additionally, another thing that you need to do is to make sure that your iPhone 3GS has been jailbroken before you start the unlock process. Last but not the least, if you are currently using a SIM card from T-Mobile, we suggest you to turn of the 3G before starting the process to avoid any issues later.
Procedure
So, as your device has already been jailbroken, you will have a jailbreak app named Cydia on your SpringBoard. Launch Cydia app and there you will see a tab named as Manage on the bottom. Tap the Manage tab and you will see three options, tap the second option that says Sources. Now you will have to press edit button and then press Add button to add a new repo where you will find UltraSn0w app to unlock your iPhone 3GS.
Above is the source link for the repo where you will be able to find UltraSn0w tool. After adding the source link, return to Cydia and find this new Source that you have just added. Now, you will see a list of packages, search for the file saying Ultrasn0w and tap it. The new screen will appear, press Install button to begin the process. After that, in the next screen you will have to press Confirm button. At the end of the process, the last screen will show a button saying Restart SpringBoard, press it.
If you have followed all the steps mentioned above correctly, now your iPhone 3GS is successfully unlocked and you will be able to run any GSM network SIM card in your iPhone 3GS.
