Finally , iPhone 3G OS 3.0 unlock is here with UltraSn0w. Unlike its predecessor YellowSn0w,UltraSn0w will unlock your iPhone 3G no matter what bootloader or baseband you have, as long as you have the new 3.0 firmware installed.
The unlock process is dead simple, and you dont have to worry about screwing up. All you need to do is to install UltraSn0w from Cydia or Icy, and then reboot your iPhone and enjoy. Way to go iPhone Dev-Team.
NOTE: UltraSn0w is only valid for the iPhone 3G. According to the Dev Team, this hack may be applicable to the new iPhone 3Gs if it can be jailbroken, which should happen sometimes soon.
1. Ensure you have upgraded to iPhone OS 3.0
2. Jailbreak your iPhone 3G using redsn0w or PwnageTool (this will also install Cydia/Icy)
3. Run Cydia or Icy
4. Please add the repo repo666.ultrasn0w.com to Cydia or Icy. That last “o” is actually the number zero “0”! If you use the letter “o” you’ll get an error.
5. Search for ‘ultrasn0w’ in cydia or icy and install ultrasn0w
6. Reboot your iPhone 3G
NOTE: T-Mobile USA users should disable 3G before using ultrasn0w