There are some "Call-Blocker" apps that allow you to select phone numbers or entire area codes to block. When someone from the "Blocked List" calls, the "Call Blocker" app blocks the call and sends it to voicemail. The problem is that there is a 0.5 second delay, before it blocks the call. The ringtone still sounds before the call is blocked. I built a 0.75 second delay into this ringtone. I've tried it and it works. If someone from the "Blocked Numbers List" calls, the call is blocked before the ringtone sounds.