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 (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
(*) 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 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, 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:
See also
*
Mobile dial code
*
Pat Fleet – Prompt voice for most U.S.
AT&T implementations of VSC features
*
Public switched telephone network
The public switched telephone network (PSTN) provides Communications infrastructure, infrastructure and services for public Telecommunications, telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that ...
*
Short code
*
Signalling System 7
*
References
External links
ETSI Supplementary service codes
{{FS1037C
Calling features
North American Numbering Plan
Telephone numbers in Canada
de:Vermittlungstechnische Leistungsmerkmale (öffentliche Netze)