demon dialer

n.

A program which repeatedly calls the same telephone number. Demon dialing may be benign (as when a number of communications programs contend for legitimate access to a BBS line) or malign (that is, used as a prank or denial-of-service attack). This term dates from the blue box days of the 1970s and early 1980s and is now semi-obsolescent among phreakers; see war dialer for its contemporary progeny.