When the alarm is tripped, this screw terminal outputs 12V to enable the siren. This would be a good place to monitor for an alarm trip. [Don] is using an Arduino nano to monitor the alarm signal.

All you need is an Arduino, a motion sensor, a few wires and headers, and the code provided at the site below. Hit the link to see step-by-step instructions on how to put it together.

SMB has unveiled a new open source Arduino SMS switch box and gateway they have created called the SensorMessageBox, which is Arduino compatible and provides a simpler way to control SMS messages ...