A security system comprises a system control panel for arming and disarming the security system. A door sensing unit comprises a first radio frequency (RF) transceiver interconnected with the system control panel over a network. The first RF transceiver is mounted proximate to a door that defines at least a portion of a perimeter around an area to be monitored by the security system. The first RF transceiver has an RF detection field proximate to the door. A disarm device comprises a second RF transceiver that automatically transmits a disarm device packet. The first RF transceiver receives the disarm device packet when the second RF transceiver is within the RF detection field. The first RF transceiver sends a disarm message to the system control panel over the network to disarm the security system based on at least the disarm device packet.