Protect yourself from unwanted callers with this enhanced call blocker device. It features a 3" display screen which displays the number that is calling. It comes ready loaded with 5,000 known nuisance and scam callers and you can add up to 1,500 more just by hitting the large red "Block Now" button, when you receive a new nuisance call. It will only work with a phone line where the Caller ID facility has been enabled. Police approved.