I was messing around with my iPhone 4 with iOS 4.1 and 02.10.04. I installed ultrasn0w from cydia, hit respring, when it was done I immediately went into setting, turned airplane mode on, then off. After a few seconds, a new item appeared in my settings called Carriers. I opened it up, waited for the network to be discovered and was presented with three options, AT&T 3G and AT&T, I was able to select one and actually have it register but I don't have access to a different provider's sim card that I can cut up to put into my phone to test. Also, the Carriers option disappears again if you back out of it or make a change but it does stay on the previous selection until you reboot.
If anyone cares, please try it out and reply back. It's a bit of a hassle but if it works it's better than no unlock, right?
If anyone cares, please try it out and reply back. It's a bit of a hassle but if it works it's better than no unlock, right?