Secondly, I've even opened the phone to see if there is anything loose.. I used to repair phones, and hardware wise everything looks fine. Plus, the issue can happen while the phone is just sitting there, it isn't caused by the phone being moved that I can tell.
So I might suddenly have a voicemail show up, because my phone didn't have signal. Or if I call out, it never gives an error of any kind, it just doesn't ring.. same idea with text, sometimes they just come in all at once.
But the whole time, it SHOWS I have signal. If I search for networks(Settings>more>networks>available networks) when I have no issues, it searches, and shows US or AT&T(which is odd since I have tmobile, but whatever).. if I do this while I AM having the issue - it doesn't search, and nothing shows. Hitting search doesn't do anything.
If I put into airplane mode and take it back out, it will show no signal until the problem goes away. Restarting the phone doesn't appear to solve the issue.
I'm at a total loss here. I've searched - a LOT. This is kind of a hard issue to search for, haven't seen anyone else describe something similar.. so I am just throwing this out here, hoping someone might have some thoughts?