My iPhone 7+ has made random calls while I was actually talking to someone else. This happened last week and again today. I have a folio case on the phone. The case was closed both times. One time it was in my hand (I was using my bluetooth headset). The next time it was sitting on the table while using my bluetooth. It called different people each time. People that I have numbers for, but, have never called. These were not FaceTime calls, though. Strange.