Give it some deoxit (j/k, works for everything else), pull it's sim card and let it sit for a bit and reinstall then recharge it.
It could also be that your network had a failure somewhere. Or maybe Trump wants to know how you do it.
My friend Cory seems to have had similar problems a couple years ago, he thought they hacked his phone. I think his network got messed up, he does use T-Mobile.