we will start a simple step by step tutorial on how to unlock the iPhone -Four with UltraSn0w [IOS 4.0 or 4.0.1]. For starters, make sure your device is released. http://www.jailbreakme.com jailbreak with you. this is often a very easy to jailbreak, just go to this website and escape slides. expect to jailbreak the device, this may take a few minutes looking at how fast your WiFi or 3G. Then, if you are unlocking T-Mobile USA, go to Settings, and then usually after then disable 3G network.
After that, go to Cydia and type in ultrasn0w. Ensure Ultrasn0w version is 1.0-1 or higher. If not, try repo666.ultrasn0w.com. Next, click Install, then make sure, and the device can currently be unlocked.
Here is a video demonstration.