I. Before You Begin
1. This will work on the iPhone 3G, iPhone 3GS, and iPhone 4 on iOS 4 (aka iPhone OS 4).
2. This will work on all basebands up to 5.13.04 (check your baseband by going to Settings > General > About and looking for Modem Firmware).
3. In order to unlock the iPhone, you must have jailbroken your iPhone. If you have not, then please do one of our procedure to jailbreak your iPhone model:
How To: Jailbreak iPhone 3G
How To: Jailbreak iPhone 3GS (Coming ASAP)
How To: Jailbreak iPhone 4 (Coming ASAP)
II. Unlock the iPhone
1. If you jailbroke your iPhone, you have an app called Cydia on your phone. Click on it.
2. If this is your first time opening Cydia, allow it to update itself and choose Graphical Only when asked. It may reboot a few times.
3. Once it is done updating and setting up, click the Manage tab at the bottom.
4. Select the Sources button.
5. Click Edit at the top right, then click Add at the top left.
6. Enter http://repo666.ultrasn0w.com for the source url (KEEP IN MIND THE 0 is a “zero” not an “oh”). Then click ok.
7. Click Return to Cydia button then click Done.
8. Select the Repo666.UltraSn0w.com under User Entered Source.
9. Select UltraSn0w the app
10. Then click Install at the top right of the screen and then Confirm in the same place.
11. Once installed press Reboot, and the phone will reboot.
12. Now goto Settings > General > Network and turn OFF 3G (if you are using T-Mobile USA) and ON Data Roaming.
13. Pop in the SIM you want to use and viola! Enjoy!
Issue: Says searching forever after I finished this procedure and won’t recognize the new SIM.
Solution: Simply goto Settings > General >Reset > Reset Network Settings (do NOT click reset ANYTHING ELSE besides Network Settings). Phone will reboot and find the network.