A vertical service code (VSC) is a sequence of digits and the signals

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

(*) and number sign (#) dialed on a telephone keypad or rotary dial to enable or disable certain telephone service features. Some vertical service codes require dialing of 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 ...

after the code sequence. On a touch tone telephone, the codes are usually initiated with the star key, resulting in the commonly used name ''star codes''. On rotary dial telephones, the star is replaced by dialing ''11''. In North American

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 ...

, VSCs were developed by AT&T Corp. as Custom Local Area Signaling Services (CLASS or LASS) codes in the 1960s and 70s. Their use became ubiquitous throughout the 1990s and eventually became a recognized standard. As ''CLASS'' was an AT&T trademark, the term ''vertical service code'' was adopted by the North American Numbering Plan Administration. The use of ''vertical'' is a somewhat dated reference to older switching methods and the fact that these services can only be accessed by a local telephone subscriber, going up (''vertically'') inside the local central office instead of out (''horizontally'') to another telephone company.

Feature definitions

North America & elsewhere

The following are the vertical service codes generally recommended by the North American Numbering Plan Administration for use in the NANP territories. Not all of these services are available in all areas, and some are only available to landline or cellular telephones. Local Area Signalling Services (LASS) and Custom Calling Feature Control Codes:

References

External links

ETSI Supplementary service codes
{{FS1037C Calling features North American Numbering Plan Telephone numbers in Canada de:Vermittlungstechnische Leistungsmerkmale (öffentliche Netze)

Feature definitions

North America & elsewhere

See also

References

External links