Snowbreeze for iPhone 3.1.3 is available and can be used to jailbreak your iPhone 2G, 3G and 3GS (old bootroms only) on iPhone OS 3.1.3.
To do that you can follow our guide on how you can jailbreak your iPhone using snowbreeze and unlock it using ultrasn0w.Ultrasn0w unlock is only for iPhone with baseband 04.26.08 and if you happen to be on 05.11.07 baseband then you can use blacksn0w unlock for your iPhone that was released last year by “Geohot” along with blackrA1n.
Follow the instructions posted below to unlock your iPhone 3G and iPhone 3GS (old bootroms only) on iPhone 3.1.3 using blacksn0w. iPhone 2G users can use redsnow to jailbreak/unlock their devices on iPhone 3.1.3.
Follow this complete guide to jailbreak iPhone 3.1.3 3G, 3GS with snowbreeze 1.4.
Once your iPhone is jailbroken, start “Cydia”, and touch “Manage” tab on the bottom. Now touch on “Sources”.
Touch on “Edit” then on “Add” and you will be prompted to add a url source. Type “http://blackra1n.com” and touch on “Add Source”.
Now Cydia will automatically update your sources following a series of automated steps.
Once it has been added successfully, search for “blacksn0w” in Cydia and install this application. This application will automatically unlock your iPhone to work with any carrier.
Now simply restart your iPhone, and you will have an unlocked iPhone 3G/3GS on iPhone firmware 3.1.3.