My phone has full bars but the 4g let logo isn't there. I go to call or send a text or use data nothing work and a pop up comes across my screen saying "emergency calls only". This has happened multiple times in multiple locations including in my kitchen. I have a Samsung Galaxy s5 that I brought over from At&t. It there something I have to change in my phone. Also when making phone calls when my phone does say 4g let it has a long delay before it starts to ring.
Please help me understand why