War dialing
jargonhackingISP & telecom
Dialing whole ranges of telephone numbers automatically to find the ones answered by a modem - the reconnaissance technique of the dial-up era, and the direct ancestor of the port scan.
The name comes from WarGames, whose protagonist does exactly this to find a games company and reaches NORAD instead; the film named the technique retroactively, and tools like ToneLoc made it routine. The war- prefix then spread across security vocabulary to wardriving, warwalking and warchalking for wireless.
Also known as: wardialing, demon dialing, toneloc