The infamous Dev-Team has finally released the much awaited ultrasn0w 0.8 for iPhone 3GS users which will enable you to unlock your iPhone 3GS so that you can use it with any carrier SIM. Just follow the simple steps below to fully unlock your iPhone 3GS running iPhone OS firmware 3.0:
Step 2: Launch iTunes. Make a backup of your phone’s data by right clicking on your iPhone name in the left-hand side sidebar and then click on backup.
Step 3: Now close iTunes and start redsn0w to jailbreak your iPhone 3GS using redsn0w. Please follow the guide here to jailbreak your iPhone 3GS using redsn0w.
Step 4: Once you are done with the jailbreak, you can now unlock your iPhone 3GS running jailbroken firmware 3.0 by using ultrasn0w 0.8. To do this:
Start “Cydia” on your iPhone 3GS.
Touch on “Manage” tab on the bottom.
Now touch on “Sources” as seen in the screenshot below:
Touch on “Edit” and then on “Add”. You will be prompted to enter a url source as seen in the screenshot below. Type “http://repo666.ultrasn0w.com” and touch on “Add Source”.
Cydia will now automatically update your sources by following a series of automated steps.
After installation is completed. Search for “ultrasn0w” in Cydia and install this application (T-Mobile users should disable 3G before installing ultrasn0w). This app will automatically unlock your iPhone 3GS so that you can use it with any carrier.
Step 5: Now simply restart your iPhone 3GS. Voila! You are now running a fully unlocked and jailbroken iPhone firmware 3.0 on your iPhone 3GS.
Please take a look at the guides I posted here, here and here in order to unlock and jailbreak iPhone 2G or iPhone 3G with firmware 3.0.
I will also recommend you all to check out the following guides: