I have a Verizon Samsung flip phone that is sort of smart, but the owner/operator is dumb. I have it strictly for emergencies and work. If I did not need it for work I would not even own a cell phone. I receive or make an average of one legitimate call every two or three days. I receive an average of five to ten illegitimate and/or unwanted calls every hour. What I am looking for is an app or service that will block every call from anywhere in the universe, except for numbers that I personally enter into a (very short) whitelist. Does this exist?