Do Not Disturb not blocking facetime calls
Sometimes when I'm working I turn on Do Not Disturb on my iPhone to stop distractions, but FaceTime calls always come through on the first attempt. I have tried blocking everyone and disabling second attempt for everyone but, today some random number spam facetimed me and it took me forever to reach the switch for do not disturb and once it was on the calls would not stop until I turned off my phone. After the attack I checked my settings and no one was allowed calls or second attempts. Is this a bug or is there something I'm missing?
iPhone 6s, iOS 11.1.2