National Do Not Call Registry applies to jurisdiction United States of America
The National Do Not Call Registry is a database maintained by the United States federal government, listing the telephone numbers of individuals and families who have requested that telemarketers not contact them. Certain callers are required by federal law to respect this request. Separate laws and regulations apply to robocalls in the United States.
The Federal Trade Commission (FTC) opened the National Do Not Call Registry in order to comply with the Do-Not-Call Implementation Act of 2003 (Pub. L. 108–10 (text) (PDF), was H.R. 395, and codified at 15 U.S.C. § 6101 et seq.), sponsored by Representatives Billy Tauzin and John Dingell and signed into law by President George W. Bush on March 11, 2003. The law established the FTC's National Do Not Call Registry in order to facilitate compliance with the Telephone Consumer Protection Act of 1991.  A guide by FTC addresses a number of cases.Registration for the Do-Not-Call list began on June 27, 2003, and enforcement started on October 1, 2003. Since January 1, 2005, telemarketers covered by the registry have up to 31 days (initially the period was 90 days) from the date a number is registered to cease calling that number. Originally, phone numbers remained on the registry for a period of five years, but are now permanent because of the Do-Not-Call Improvement Act of 2007, effective February 2008.Consumers may add landline or cellular numbers to the registry, but FCC regulations prohibit telemarketers from calling a cellular phone number with an automatic dialer under almost all circumstances. In 2005, a rumor began circulating via e-mail that cell phone providers were planning on making their number directories available to telemarketers. The FTC responded by clarifying that cell phones cannot legally be called by telemarketers. Similarly, fax numbers do not need to be included in the 
registry due to existing federal laws and regulations that prohibit the sending of unsolicited faxes.
If a person does not want to register a number on the national registry, they can still prohibit individual telemarketers from calling by asking the caller to put the called number on the company's do-not-call list.