This relay MUST be connected in-series with the device that goes off-hook on the line. You can make just about anything happen when the phone goes off-hook with this relay!
The line powered Modular In-Use Relay has two mod jacks on one side of the box. These two jacks are for the phone line and the telephone or CPE device. It doesn't matter which jack you use for which, but the electricity must pass through this device before getting to the phone for the relay to operate when the phone is off-hook.
The DPDT relay contacts are brought out on a 6 Pin Modular Jack on the opposite side of the box (spec sheet with pinout diagram below) through a short solid wire 6 conductor cord (included) that can be punched down to a block or spliced to other wires (use UY connectors / B-Wire Connectors – not included).
Modular Line In-Use Relay Specs: