"Griefers behind the pranks call as many as 31 numbers at a time. When a person receiving one of the calls hangs up, a different number will immediately call ba

"Griefers behind the pranks call as many as 31 numbers at a time. When a person receiving one of the calls hangs up, a different number will immediately call back. FaceTime doesn’t have the ability to accept only FaceTime calls coming from people in the user’s address book. It also requires that all numbers in a group call must be manually blocked for the call to be stopped." There should definitely be a setting to only allow calls from people in your contacts.