I am using Honor 5x with T-mobile for about a week . I have seen in the last few days my calls get dropped automatically . if the call is for less than 20 mins, then the call would not drop. But for any calls that last more than 20 mins, call gets automatically dropped. Is there any issue or workaround to the problem ? Also, i am using Aomax® Armor [Dual Bumper] slim fit skin silicon case + PC bumper frame for the phone. Could that be the reason for call drops ?