When I was a teenager (20+ years ago), the sirens where I grew up could be triggered by calling a phone number from a pay phone and entering a four-digit code.

When I was a teenager (20+ years ago), the sirens where I grew up could be triggered by calling a phone number from a pay phone and entering a four-digit code. Another four-digit code would turn them off. Uh, well, that's what I heard anyways...