Below is a step-by-step guide on how to unlock an iPhone 3G using ultrasn0w. In order to use ultrasn0w, you must have baseband 04.26.08…which means you need to be on the 3.0 firmware. Your iPhone also must be jailbroke in order to use ultrasn0w.
Note: T-Mobile USA users should disable 3G before using ultrasn0w
How to unlock an iPhone 3G using ultrasn0w
8. This will bring up a pop-up in which you can enter the url for the source. Do not delete the http://. Just begin typing the url after the http://. The source url needs to be typed into your iPhone/iPod Touch perfectly. The source url is repo666.ultrasn0w.com. The o in snow in actually a zero. If you put on o, it will not work.
17. Restart your Device (hold power and home button at the same time).
18. Your iPhone will now be unlocked. You can remove the SIM from the top of the device and insert a new one. You may need to restart your iPhone after inserting the new SIM. Below are screenshots of an iPhone with no service, no SIM, searching for service after inserting the new SIM and finally the iPhone with service after inserting the new SIM.