| 
        
 *In computing Presence is defined as the "availability
        and willingness of the user (presentity) for communication."
        Presence information is published by individuals to other
        systems users, known as 'watchers' or 'subscribers', to indicate
        their communication state. Although not limited to IP communications
        it has become synonymous with IP applications such as VoIP and
        Instant Messaging.en.wikipedia.org/wiki/Presence_(IP_communication)
 
 |