The iPhone OS 3.0 unlock is ready. The Dev-Team released their 3.0 jailbreak only a few days ago and now they have released their highly sought after unlock tool, Ultrasn0w. The only catch is that the unlock will not work with the iPhone 3GS because they haven’t found a way to jailbreak it yet and the unlock requires jailbreaking, so don’t even try.
Unlocking your iPhone 3G should be a fairly simple process since the Dev-Team has posted a complete walkthrough, so just follow their instructions and you should be fine. But, as always, install at your own risk.
After unlocking, can I still remain on the ATT network? I just want to have it for now while I save enough to buy a 3gs.
Yes, once you unlock your phone you can use it on any network including AT&T. The only exception is that the iPhone has a GSM chip in it, so you will need to use a GSM network. The only other GSM network in the United States is T-Mobile
Reza
Though an unlocked phone will still work on AT&T’s network, ultrasn0w is a software hack, and therefor CAN cause instability with the phone. If you are remaining on AT&T network there is no reason to use ultrasn0w. This is for those that need to get the phone on to other networks than the one the phone is locked to.