Tilstedev¶relsetjenester i H.323 baserte kommunikasjonsnett

摘要

A Presence Application Server (PAS) holding a presence list for each user is introduced. The presence list of a first user comprises other network registered users for which the first user, wants to track registration status. The registration status of each user corresponds to the user's registration status in their associated Gatekeepers. Each time a change in registration status for a user occurs in its associated Gatekeeper, the Gatekeeper will send a message including an identification of both the user and the Gatekeeper, in addition to information concerning the change of status (register or unregister). The presence lists affected by the change of the registration status of said user is updated in the PAS. Then the associated users are informed by messages sent from the PAS via the Gatekeeper to the user's EndPoints. The messages are adapted to refresh URL's at the EndPoints pointing at the user's presence list.