telephony Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is i ...

, an unlisted number (United States, New Zealand), ex-directory number (United Kingdom) silent number, silent line (Australia), or private number (New Zealand, and Canada) is a

telephone number A telephone number is a sequence of digits assigned to a landline telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices f ...

that, for a fee, is intentionally not listed in

telephone book A telephone directory, commonly called a telephone book, telephone address book, phonebook, or the white and yellow pages, is a listing of telephone subscribers in a geographical area or subscribers to services provided by the organization that ...

s. Although an unpublished number is not included in the phone book, an unlisted number may be available from the phone company's information operator. When used for residential households they're primarily for privacy and security concerns. When it has personal value it is called a ''vanity'' number.NYTimes: "includes the last four digits" of a person's address. Another form of anomity is being listed with just a first initial, for those with a relatively common family name; sometimes these listings also lack an address. No fee is charged for initially being so-listed.

Unlisted numbers as a paid service

NYNEX NYNEX Corporation was an American telephone company that served five states of New England (Maine, Massachusetts, New Hampshire, Rhode Island and Vermont) as well as most of the state of New York from January 1, 1984 to August 14, 1997. Histor ...

was charging $1.95 per month in 1994; in 1976 the same service was 93 cents monthly. In 1971 ''

The New York Times ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid d ...

'' wrote that some users of this service needed it to hide from bill collectors. Silent numbers are often

plant test number In telecommunications, a plant test number is a telephone number reserved for use by telephone installers or other workers to test an individual telephone line. Test number are typically unlisted. The North American Numbering Plan The North Am ...

s that link to specific tests or control apparatus for network maintenance staff such as ringback and

automatic number announcement circuit An automatic number announcement circuit (ANAC) is a component of a central office of a telephone company that provides a service to installation and service technicians to determine the telephone number of a telephone line. The facility has a tel ...

and are generally not for public use. In Norway (and some other countries) the directory services in the 1970s distinguished between secret number, unlisted number and listed number with a hidden address. The first type secret number was typically used by celebrities (in this case the address was hidden as well). The second type unlisted number was not listed in the (paper based) phone book, but was listed on the directory service (a voice call to 018 in the 1970s). Listed number with a hidden address is useful for

women's shelter A women's shelter, also known as a women's refuge and battered women's shelter, is a place of temporary protection and support for women escaping domestic violence and intimate partner violence of all forms. The term is also frequently used to ...

etc., where the number needs to be listed, but where the address shall be hidden from the general public. Naturally there are many changes when directory services became available on the Internet, but this case shows that separate user groups may have different needs to hide various parameters relating to privacy. These unlisted numbers are made known to call recipients who have

caller ID Caller identification (Caller ID) is a telephone service, available in analog and digital telephone systems, including voice over IP (VoIP), that transmits a caller's telephone number to the called party's telephone equipment when the call i ...

, and are captured and recorded when used to call toll-free numbers.

References

{{DEFAULTSORT:Unlisted Number Telephone numbers