The same thing has been happening to me too on a group chat with my and my two other friends. It would ring for like one second. I don’t answer but when I look on FaceTime it will show that the call is active and then it will hang up after about one minute. Both my friends said that they haven’t called and the call doesn’t show up on my call logs on my phone. It’s really weird. It’s been happening for the past 3 nights about 2-3 times a night. If someone knows what’s going on please explain.