Composition for Enhanced SIP Presence

Presence has taken shape as a way to present a comprehensive view of the communications capabilities of a user or resource. Standardized protocols allow for receiving presence data from a variety of sources, such as a user´s communication devices, cellular provider, online calendar and sensors in his environment. This data can describe many different aspects of his communication capability, such as his device characteristics, activities, and even physical locations. The large number of presence sources may lead to irrelevant or inconsistent data. Also, the data may be incomplete and not as usable as it could be to the presence watcher. This paper proposes the use of presence composition to remove unusable data and create new more usable data. We discuss the details of this composition and present a format with which a user can specify a policy for composition.