Dictionary.net

(Or "wardialer") A program which uses a modem todial a series of phone numbers (say, from 770-0000 to770-9999), and keeps a log of what phone numbers answer with amodem carrier. The results of such a search were generallyused by people looking to engage in random mischief inrandom machines.Since the 1980s, wardialers have generally fallen into disuse,partly because of easily available "caller ID" technology,partly because fax machines are now in wide use and wouldoften be logged as a carrier by a wardialer, and partlybecause there are so many new and more interesting venues forcomputerised mischief these days.