Anyone can call you through FaceTime and hear audio from your phone or watch videos before answering. This bug becomes viral on social media, and the only protection is disabling FaceTIme.
We learned about 9to5Mac. In summary, all you have to do is start a FaceTime call. Swipe up from the bottom of the screen during the call, tap Add Person, and add your own phone number. A group FaceTime call starts and includes the other person, even if they have not been answered yet. It looks as if they have answered, but the call is still ringing on the lock screen.
You can only disable FaceTime to prevent others from searching for you. If a FaceTime request appears on your phone, someone might listen to you. There is no way to limit FaceTime to our knowledge to only your friends.
Apple told BuzzFeed News that "this issue is known and we found an update that will be released later this week in a software update." 1
– Benji Mobb ™ (@BmManski) January 28, 2019
Because Apple has this problem not with sufficient urgency, we recommend to disable FaceTime for the time being.
On an iPhone or iPad, go to Settings> FaceTime and turn off FaceTime. You must repeat this process on all your devices, for example, if you have both an iPhone and an iPad.
To disable FaceTime on a Mac, open the FaceTime app and choose FaceTime> Turn Off FaceTime. You must repeat this step on all your Macs.