Concerts are one of the few times when smartphones aren't so much useful as really, really annoying. You're trying to be in the moment — and so is everyone else — but if you're also trying to capture that moment, you're inevitably interrupting someone else's experience. And a growing number of artists are not cool with that. Adele recently called out a member of her audience for blocking the view of others with her phone and not enjoying the concert in the moment. (Talk about embarrassing.) But Alicia Keys just adopted a no-cell-phone policy that makes Adele's shutdown look positively lenient.Concert attendees won't be prevented from entering the show with their cell phones. However, upon arrival, they'll have to place their phones in a Yondr case. According to Today , these cases lock your phone and can only be opened by tapping the case on a metal disk found in the concert's lobby. This ensures that guests will have to excuse themselves during concerts if they need to make a phone call or send a text.