A common short code (CSC) is a short telephone number, usually consisting of five digits, that is used to address SMS and MMS messages from a cellular telephone. Common short codes may also be called mobile short codes or short numbers. Each common short code is designed to be unique to each operator.
CSCs are used for additional wireless services like television voting, polling, ordering ringtones, making donations and queries to Google's SMS search engine. CSCs are typically billed at a higher rate than SMS or MMS messages.
Although CSCs have been popular in Europe for years, they only gained wide-spread adoption in the United States after their use as a voting method on the immensely popular "American Idol" television show. Cross-carrier CSCs were launched in the United States in 2003.
A similar but unrelated term, shortcode, refers to a pseudocode interpreter for mathematics problems used on BINAC and UNIVAC.