'Presence' awareness has rapidly become one of the most compelling features of Instant Messaging (IM) applications. Never before in the history of communications have we been able to tell whether the person we want to communicate with can actually be reached before we try to engage with them.

Image source: ACMQueue

Presence indicators allow us to decide how and when we should communicate with someone else. If we are able to be made aware that the person we want to contact is in a meeting, or out to lunch, or on the phone, or travelling from A to B, or on vacation, we can then make our own judgement call as to when and how best to reach them - by phone, voicemail, email, IM, fax, letter and so on.

However, simply knowing about someone's 'presence' doesn't tell us about their 'availability', or how 'receptive' they are to being communicated with.

Existing technologies are great for determining presence, but are sorely lacking when it comes to understanding availability or receptivity.

Availability or receptivity can be thought of as a person's willingness to be interrupted.

In a research paper presented at the Association for Computing Machinery (ACM) Conference on Computer Supported Cooperative Work, held in Chicago on November 6-10, 2004, a team from Sun Microsystems, MIT and IBM Almaden Research, presented a prototype system, called Lilsys.

"Another way to manage availability is to have a system gather clues from your environment and present an inference about your availability. Researchers at Carnegie Mellon University conducted a study to determine the most salient sensors in making an availability inference of an office worker.