I've a billion dollar idea for some tech startup. No not another car service, something better, hear me out.
Create a phone answering service that intercepts all calls with a questionaire. Ask questions like "What is your name, who are you calling from, why are you calling?" Send a little message to the receiver with the option to take call or decline.
Caller name: Joanna
From: GEICO insurance
Subject: Saving 15% or more on car insurance
Answer or Decline
Paid version allows a "whitelist" of pre-approved phone numbers to bypass this (wife, Dad, boss, etc.)
Take the idea and run. Just give me the app for free and I'll call it a fair deal. :+P