Automatic number identification

Automatic number identification is a feature of Inward WATS Service (Wide Area Telephone Service) which permits subscribers to display or capture the telephone numbers of calling parties. Inward WATS Service is purchased by businesses so that prospective customers (for example) can call the business toll free. The business is issued a distinctive telephone number beginning with a special area code such as "800" or "888".

A related piece of information conveyed to the "800" service subscriber is the DNIS or Dialed Number Information Service. This is the number that the caller dialed when accessing the "800" service. With the information, the service provider can have several "800" numbers directed to the same call center and provide unique service based on the number dialed.

Privacy note

It is very important to realize that, when calling an "800" or other toll-free number, your telephone number and telephone line type can always be captured by ANI equipment at the "800" number site -- whether or not you would otherwise be able to "block" transmission of your telephone number via Caller ID. ANI overrides Caller ID blocking.

Bill collectors and private investigators have often conducted skip tracing of missing people by sending them postcards, enticing them to call their "800" numbers. The "skip" reveals his or her whereabouts by dialing the number.

Similar Services in Other Countries

• UK: caller line identification