I apologize in advance if I posted this in the wrong thread. I recently purchased an ATT Lumia 1520 from the Microsoft Store and had ATT provide me with an unlock code. I'm currently using it on T-Mobile's network and everything except internet sharing is working. I have unlimited data and I know T-Mobile hasn't blocked my ability to tether because I called them and tested my T-Mobile SIM on another device with tethering enabled with no trouble. What could possibly be the problem? Any help would be greatly appreciated.