Do Not Disturb not working?

Just got a new iPad Air 2, and I turned on Do Not Disturb this evening, but the ringer on the iPad still went off when my iPhone 5s rang. Allow Calls from no one was checked on the iPad settings. Using most recent iOS 8.1.3 update on both. iPad was sitting off to the side, not in use with magnet cover on, so it should've been in sleep mode. Phone was set to vibrate only, as I was at a public event, but the iPad ringer still went off when a call came through. What am I missing?