I had my Iphone 3g unlocked with yellowsnow and I was in Thailand using a Thai sim card. It worked perfectly there.

Then I came back to the USA, and Im still here until Sunday. I still have my Thai sim card in my phone. When i got back to the USA, my phone automatically starting using AT&T (I'm assuming its the sister network to the Thai network).

I just updated and jailbroke to 3.0...and today I installed ultrasn0w via wifi. When I put in my Thai sim card...i got "no service". I tried restarting many times, and even reinstalled ultrasn0w....NOTHING.

THen, when I went into "carrier" under "settings"...I noticed that "automatic" was checked. I also noticed that "AT&T" was a choice. I selected AT&T and now I have service. I never had to do that with yellowsn0w. Does this mean my phone is not unlocked, or is AT&T the only carrier in my area? Why didnt my phone pick it up under the "automatic setting".

Also...I've noticed that I have no Edge or 3G. In fact, when I turn on 3G i have no service at all. WHen I launch the app store it just says i need to connect to wifi.

Can anyone give me some answers and some help??

Thanks everyone!