It works for what it's supposed to, legitimate telemarketers ONLY. Not scammers, political calls, surveys, or debt collectors. If you want to cut back on the volume of garbage calls you receive, let unknown numbers ring and ring and ring without being taken by answering machines. You should gradually see a decrease. You can also invest in a call blocker, but simply not answering works as well, and scammers get nothing when they dial your number.