After a brief visit with AT&T today, they installed a SIM card from their carrier into my phone, but it would not get speeds grater than EDGE at the time. 3G may have been possible, but it didn't see it right away. Also, they had to update the APN settings in the Settings -> More settings -> Mobile networks -> Access Point Names. Lastly, after searching the internet, Verizon carrier locks the GSM in the states. In other words, they make it so you can use GSM OUTSIDE the US but not allow AT&T or T-Mobile SIMS to be used in their devices. This is a carrier lock, not SIM lock, so they can get around the whole "well, our phones are sold SIM unlocked" bs. After calling a level two tech support, he told me that there is no such thing as a carrier lock or SIM lock, and he could not give me a code. The phone was able to make a voice call and send a normal text, but data sucked.