Parlay X Presence over SIP/IMS enables client applications to publish the presentity's presence information to the presence server, and retrieves the presentity presence information from the presence server-either by looking up information or asking for notifications.
By integrating with this Web service implementation, your client applications can use Web Services to subscribe to a presentity, synchronously query the current presence information for a presentity, receive asynchronous notifications about changes in the presence information for a presentity, publish the presence information of a presentity, and unsubscribe from a presentity.