I was thinking about the same for phone calls. I wish there would be a way to filter calls. Is on whistlist (phone contact list) -> ring, is not on whistlist, ask for a PIN code (I could give togheter with my phone on a business card or in an email, it can be valid for single use, multiple use, valid for a period only,...), blacklist -> redirect to the local police station or a sex shop whatever 🤣