Hello, I bought a razr maxx used to have at work as a spare phone (long battery life). I was under the impression I could use the straight talk Sim in it and it would talk and text fine, It would just not have 4G and that is ok. I have a working Sim from straight talk( the ATT version), and the droid just states its from an unknown source and wont get any signal. The triangle stays on the screen. I know the Sim works because I can use it in an old 3g iphone. Thanks very much for any help