I tried doing a google search for this but all I got was instructions on loading an unofficial carrier bundle onto a jailbroken iPhone 5. I bought an iPhone 5 from AT&T. It's officially unlocked, no weird tricks or hacks. After a year of using AT&T I decided to switch to T-Mobile. While I was at the store I noticed that the iPhone 5 had LTE on T-mobile's network. Later that day I switched LTE off to conserve battery. When I got home I switched it back on and noticed that it wouldn't appear. I tried shutting down the phone and restarting it again but it still wouldn't get back on LTE. I checked the service area for T-Mobile in my area and I do have LTE coverage. Has this happened to anyone? Is there something I'm missing?