If you're looking to have your alarm system monitored over a landline the RJ31X allows a simple solution. It uses an 8-line telephone interface giving your alarm system the ability to seize the phone line in the event that an alarm is present and a signal needs to be reported.

Without line seizure, the alarm system cannot report signals on in-use phone lines. Without a properly installed RJ31X jack, a burglar could in theory kick in a door and go grab a phone off hook thereby preventing the system from dialing out to a monitoring station

To hook up the RJ31X simply remove the cover, use the screw terminals to hook up your landline wires, and use the provided cable to connect the RJ31X to your alarm system's landline terminals.