Chosen Solution
But Sim Network Showing Properly. Despite being connected to the network, I am unable to make calls or receive calls on my HTC Desire 816 Dual Sim. When I try to make a call, the phone immediately shows “call failed” even without any ringing. When others call my number, they report that my phone is ‘disconnected or Out of coverage area’. What is wrong? How can I correct this?
I had this happen one time. I accidentally put my phone on airplane mode. When your phone is in airplane mode your wifi and phone signal are disabled even though they are connected. Press and hold your menu button. A power off, airplane mode, and silent buttons may come up. Tap or uncheck airplane mode. If it is on, this should turn it off. If this does not work go to settings ( the little gear). Tap wifi and you should see airplane mode. Uncheck it . If this does not work, while still in settings and wifi look the button more . Airplane mode will be under it. Uncheck it. I hope this works for you. There is a short untube video that may help. I looked up how do you reset airplane mode.
