A radio frequency communication device includes a receiver; a transmitter; an interface for receiving one or more sensor signals based on sensor-acquired data that is indicative of a predetermined condition; and electronic components. The electronic components are arranged and configured such that the device operates in at least two states. In the first state, the device responds to a Present Broadcast by making a Present Response. In the second state, the device does not respond to a Present Broadcast with a Present Response. The electronic components further are arranged and configured such that the device enters the second state from the first state upon responding to a Present Broadcast with a Present Response, and such that the device enters the first state from the second state upon receiving, through the interface, one or more sensor signals based on sensor-acquired data that is indicative of a predetermined condition.