Dictionary.com
definitions

900 number

See more synonyms for 900 number on Thesaurus.com
noun
  1. a telephone number preceded by the three-digit code “900,” used to provide information or entertainment for a fee charged directly to the caller's telephone bill.

Origin of 900 number

First recorded in 1985–90
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018