iPhone Unavailable

If my iPhone has been in my pocket, I sometimes get "iPhone Unavailable Try again in XX minutes" messages. I understand that this message should appear if I enter too many wrong passcodes. I didn't enter any passcodes. Is my phone bouncing around enough to think a passcode is entered when the screen is bumped?

Is there a way to turn this "feature" off? I overextended myself yesterday on a hike. I wanted to call my wife to ask her to make a delivery I was scheduled to make. I had to wait 29 minutes. If I hit the "emergency" button, does that call 911?