I've had this problem a lot latley but usually restarting it seems to fix it but today it's just not working. My IMEI says unknown, I've tried a factory reset, popping the battery and sim out, restarting multiple times and nothing is working. How can I fix this?
I'm assuming you are in an area with generally good coverage while this is happening? It's kind of strange how your IMEI number is not being detected... It sounds to me that you may need a new SIM card, especially if you've had your current one for a few years or so. You can stop by any AT&T corporate store and get it replaced for free.