I have just wrote about Pwnage Tool 3.1 which lets you jailbreak iphone 3.1 firmware but after jailbreaking 3.1 firmware your iPhone will not be able to work with any other carrier than AT&T until you unlock it.
So, here is a guide on How to unlock iphone 3G 3.1 Firmware using Ultrasn0w.
Before attempting to unlock your iPhone 3G make sure you have update and jailbroken your iPhone with 3.1 Firmware and make sure you have install Cydia at the time of jailbreaking.
- Once you have jaikbroken your iPhone 3G open Cydia on your iPhone.
- Now select on Manage tab at bottom and choose Sources.
- Now you will have to add repository, to do this tap on edit and then Add button now type following repository URL
- After the source has been added tap on “Return to Cydia”.
- Now go to Search menu from bottom menu, type “ultrasn0w” and press search.
- Now tap on the ultrasn0w and choose Install from the top right menu.
- After installation complete restart your iPhone and insert your SIM.
- Here you go, now your iPhone 3G is completely unlocked and ready to use with any carrier.