If you use the Sensaphone 400 or Sensaphone 800 to stay in contact with your home or vacation home when you're away, you can add a photoelectric smoke detector to your system to receive an instant alert in the event of a fire. The Sensaphone Smoke Detector w/Battery Backup has a relay/contact closure output to trigger the Sensaphone alarm dial out.# Smoke detector # Mounting template # Wiring diagram # Wire connector # Mounting plate # Instructions