I got my phone from Amazon on 3 September sim free and used my o2 sim. It was only today when the phone stopped working on o2. I tried a 3, lyca and virgin they ALL work. Why does my o2 sim not work if any of u have same problem? If it was barred non of the other 3 sim cards I tried would've worked. I tried my sim on another mob and it worked. Tried my bird's sim which is o2 and no success. Mine is a simplicity sim card.