John wants to know how he can limit the number of calls on his mobile device to only his contact list. Leo says that's called White Listing and since we're now being bombarded with spam and robo calls, that would be a very good idea. Google Voice can do it, but he'd need to get a new number. He can forward his number through it and Google Voice will then filter out unwanted calls, though.
Do Not Disturb
Mike has noticed that in iOS, you can ask Siri to enable 'Do Not Disturb' mode. After the latest update to iOS 9, you have to unlock the phone to do it. It's a new security feature. It's possible to turn that off, though. Now it's been fixed, and Apple says it was a bug.