If you have FaceTime enabled you can be evesdropped on without your consent. A user simply calls you with FaceTime and before you answer they add themselves as a caller. They can instantly hear your phone without you knowing or having the option to stop it. If you attempt to it may transmit video. Simple solution though is to just go to Settings / FaceTime and disable it until the patch comes out later this week. Read about it here: https://www.cnbc.com/2019/01/28/apple-facetime-bug-lets-you-listen-even-if-someone-doesnt-answer.html Or basically anyplace on the net right now.