[click170]

I use a similar feature on Android.

What I really want though is a very simple feature. I don't want my phone to accept phone calls unless the number is in my address book already. Its so straightforward and already implemented in other communication mediums, I do not understand why it is not a feature yet.

Just one vendor including this feature would force all of them to.

My parents do this the old fashioned way. They don't pickup unless they recognize the number.

In fact, my colleagues do the same, and this has actually caused problems for On call if the colleague calling at 4am isn't in the callee's circle of friends.

[jordanthoms]

Android 5+ (or maybe 5.1) includes this - you can set it to priority notifications only, and then turn calls on but say to only include calls from your contacts.

[yoasif_]

Cyanogenmod, at least in the CM11 (KitKat version) offers this functionality. It also lets you know via notification what the number was.