The National Do Not Call Registry is a service created by the U.S. government to help consumers reduce unwanted telemarketing calls. By registering their phone numbers, individuals can indicate that they do not wish to receive sales calls from telemarketers. This registry is free and available to anyone with a phone number, including landlines and cell phones. Once a number is registered, telemarketers are required to remove it from their calling lists within 31 days. Consumers can register their numbers online or by phone, and they can also file complaints against companies that violate the rules of the registry.