war dialer
 n.

    [originally from ?wargames dialer?, a reference to the movie War Games] A
    cracking tool, a program that calls a given list or range of phone numbers
    and records those which answer with handshake tones (and so might be entry
    points to computer or telecommunications systems). Some of these programs
    have become quite sophisticated, and can now detect modem, fax, or PBX
    tones and log each one separately. The war dialer is one of the most
    important tools in the phreaker's kit. These programs evolved from early
    demon dialers.