The National Cellular Director is a directory of cell phone listings. Because cell phone companies are unable to provide the numbers of their customers, the list only contains the information of those who volunteer their numbers for the listings.
Although initially users had to opt in to the National Cellular Directory, providing their cell phone numbers in order to search the listings. As of 2015, they no longer are required to do so. A paid service is also available to subscribers that entitles them to more in-depth cell phone number searches. This service is also provided for free one hour per day during the time designated as Happy Hour.