Replace the doorbell with a screen, and 3 buttons.

The screen poses a general question and each button corresponds to an answer choice - the answer that the caller thinks that you, the occupier, would give.

Each button triggers a different ring tune. Tune (1) is a bright fanfare, Tune (2) is nondescript but pleasant while Tune (3) is simply a huge repeating klaxon.

If the caller knows you, they'll likely answer correctly; if they don't they may go for the answer they'd like to hear. So you get a rough idea of 'friend or foe' at the door based on the tune played.

The buttons are, of course, scrambled each time so button (1) will not always match to the 'right' answer.

Example:

"If the occupier found $10 in the street, what would they do with it?

(1) Keep it.
(2) Give it to Charity.
(3) Ask themselves 'what would Jesus do?' "

<Loud Klaxon sounds> "Shirl, it's the fekkin' God Squad again."