[mod.telecom] Line-powered off-hook indicator?

kevinb@nosc.ARPA@pnet01.UUCP (01/24/87)

Does anyone know of a preferably line-powered off-hook indicator circuit? I'd
like to add this to my system to prevent people in my household from picking
up my line when I'm on-line, or at least warning them with an LED indicator.
  Does anyone know of the circuit design for such a device, or where one might
be found?
                                        -Kevin