A vanity number is a local or toll-free telephone number for which a subscriber requests an easily remembered sequence of numbers for marketing purposes.
While many of these are phonewords (such as 1-800-Flowers, 313-DETROIT, 1-800-Taxicab or 1-800-Battery), occasionally all-numeric vanity phone numbers are used.
Accorging to Google Books the expression is from the late ’80s but why ‘vanity’?
Is vanity number the more common expression to refer to these often used numeric/alphanumeric numbers?
Is it only AmE usage or is it used also in British or other English dialects?