war dialer

war dialer n.  A cracking tool, a program that calls a given
   list or range of 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 dialer}s.