I recently bought a MI3 from a Unicom store in Shanghai. I brought it back to the US, and everything seems to work great. I have Straight Talk service, a contract-less brand using AT&T's network. I plugged the SIM card in and it recognized it on the network by displaying a label "AT&T 3G" on the MI3. Strange thing is, I cannot connect to the internet. I checked the "Mobile networks" settings and everything is on and it automatically recognizes the Network Carrier as AT&T. In fact, I'm able to make and receive calls. I just cannot get connected to the Internet. Is there a setting somewhere I need to change to enable 3G? Wifi works beautifully.