Hi, I just got back from Thailand back on July 26th and used my Iphone while in Bangkok. Guess what? my bill came out to be $348.57 ($241 for 10,975kb eg. for 0.03cents per/kb) At&t DO NOT CHARGE by minutes, but by kb you use. I notice something else too when I turn on my Iphone it takes on the strongest signal carrier (eg.. TRUE, DTAC, and other carrier depending where you are at instead of AT&T). So, I think that its best to leave the default carrier logo alone so you will know which carrier antena or carrier you are using. The best thing to do is turn on your airplane mode until someone figure how to unlock your Iphone.
should still switch to other carrier logo though since you are changing the att logo when it switched to another carrier it will go to their logo if you left those stock
Why bother? its software and even if you name it jasunto instead of AT&T it will not show this either in Thailand. The Iphone will show TRUE network 90% of the time in BKK. I was in Chaing Mai it switch from TRUE to AIS going up to Doi Suthep.