Dev Team finally made it. They created software called yellowsn0w, that unlocked iPhone 3G. Now you can use any carrier you want. I successfully unlocked my US version.It works much more stable than sim proxy method.
Please, back up everything on your iPhone before you start, just in case. Everything you do is your responsibility. I had to go through all 4 steps to make my iPhone 3G work. I used only my new sim without sim proxy.
Here are the steps:
Step 1: Restore your iPhone to version 2.2 (Not needed if you are already at 2.2 with baseband 02.28.00):
First of all Apple has addressed one common request within the iPhone’s Keyboard settings, allowing users to disable the iPhone’s auto-correction.
The other feature is for Japanese market – Japanese emoji icons. The lack of emoji support has been blamed as part of the reason for slow iPhone adoption in Japan.
The third new feature is Street View. It allows users to view panoramic street level photographs in select cities within the Google Mapsapplication.
Hopefully we will see more new features in this and next beta’s of 2.2 firmware.