iPhone’s Facetime Has A Major Bug That You Need To Know About
There is currently an issue with Facetime on iPhone's. There is a bug that basically allows someone who is making a FT call to listen in the person they are calling without that person actually answering the call. This is apparently happening with any pair of iOS devices running iOS 12.1 or later.
Apple is working on a fix and should be out soon but until then, it is recommended that you shutoff your Facetime in Settings.