Telephone slamming is an illegal telecommunications practice, in which a subscriber's telephone service is changed without their consent. Slamming became a more visible issue after the deregulation of the telecommunications industry in the mid-1980s, especially after several price wars between the major telecommunications companies. The term slamming was coined by Mick Ahearn, who was a consumer marketing manager at AT&T in September 1987. The inspiration for the term came from the ease at which a competitor could switch a customer's service away from AT&T by falsely notifying a telephone company that an AT&T customer had elected to switch to their service. This process gave AT&T's competitors a "slam dunk" method for the unauthorized switching of a customer's long-distance service. The term slamming became an industry standard term for this practice.[1]
Variations of this concept include "merchant account slamming" or "credit card processing slamming" in which a business's debit and credit card processing terminal is reprogrammed so that charges are processed through a different company, and "domain slamming" where an Internet domain name registrar is changed.