A
vertical service code (
VSC) is a special code dialed prior to (or instead of) a
telephone number that engages some type of special telephone service or feature. Typically preceded with an
asterisk, or
* (star), key on the
touch tone keypad and colloquially referred to as
star codes, most are two digits in length; as more services are developed, those that use
2 or
3 as the first digit are sometimes three digits in length.