In a method for determining whether a person is potentially unavailable for communication, sensors are provided at a location to obtain information regarding a state of availability for communication of a first person at the location. The information regarding potential unavailability of the first person for communication is presented to a second person. A system for determining whether a person is potentially unavailable for communication includes a data acquisition module that has sensor receiving ports and is configured to transmit signal data from the sensors over a network. An inferencing engine is configured to receive the signal data from the sensors over the network and to use the signal data to reach an inference regarding a person's presence and an inference regarding the person's potential unavailability for communication. A presence service presents the inferences to other persons over the network before such other persons attempt to communicate with the person.