This article highlights Woodbridge Township's decision to implement a reverse 911 system, in order to quickly notify residents in case of an emergency. Elaborates on the technology that uses mapping technology to create a geographically defined calling zone (as small as one block or as big as the entire township) and then delivers a voice message to those residents within the zone. Describes additional applications of such a system. Reprinted with permission of the New Jersey League of Municipalities.