Sn0wbreeze 3.1.3 for Windows brings jailbreak for iPhone 2G, 3G and iPhone 3GS (older bootroms only) which can preserve your older baseband while upgrading you to the latest iPhone OS 3.1.3 firmware. This effectively means that once yu jailbreak using Sn0wbreeze, you can also unlock your iPhone 3G and 3GS using the latest version of ultrasn0w (for 04.26.08 baseband) or blacksn0w (for 05.11.07 baseband) as they both are compatible to work with the respective older baseband versions.
iPhone 3G and 3GS users can follow the step-by-step guide posted below for unlocking using ultrasn0w. iPhone 2G users need to follow the guide posted here
2. Once your iPhone is jailbroken, start “Cydia” on your iPhone and touch on “Manage” tab on the bottom. Now touch on “Sources” as seen in the screenshot below:
Note: T-Mobile users should disable 3G before installing ultrasn0w.
3. Edit and Add “
http://repo666.ultrasn0w.com“. Cydia will now automatically update your sources by following a series of automated steps.
4. Search for “ultrasn0w” in Cydia and install this application. The latest version 0.92 of this app will automatically unlock your iPhone so that you can use it with any carrier with proper carrier name/logo.
5. Now simply restart your iPhone.
You should now have a fully unlocked iPhone 3G/3GS on firmware 3.1.3!