I was on the forums with my 5s when suddenly my 5c lights up. I look over and realized that the call screen was on! It was calling my guy on its own. Yesterday my guy told me that I called his mother and she called back and heard me talking. I was at work with my phone (Screen off) sitting in the drawer... I'm not jailbroken. It's 7.1. Hopefully a restore and wipe with set up as new will help... If not, I'm stumped.