at least one presentity user agent for issuing a request to register a presentity in at least one of a plurality of roles, and for generating context messages relating to changes in context of said presentity;

at least one watcher user agent for issuing a role-based subscription request for said availability information;

a presence service for maintaining role-based watcher subscriptions and issuing availability messages in response to generation of said context messages;

a role manager for (i) receiving each request to register a presentity in said at least one at said plurality of roles and in response managing presentity registration in said plurality of roles, and (ii) receiving each said role-based subscription request, and in response managing each role-based watcher subscription to said availability information within said presence service;

wherein said presence service comprises:

a shared database stored in said memory for publishing a subscribe event and a notification event in response to receiving each said subscription request and context message, respectively; and

at least one presence agent for receiving said subscribe event and in response triggering a set of subscription policies that either confirm or reject each of said role-based watcher subscriptions, and for receiving said notification event and in response triggering a set of notification policies to selectively generate said availability messages;

wherein said role manager is a role group manager for effecting user-centered management of roles by registering said presentity with said at least one presence agent in said at least one of said plurality of roles, and subscribing said watcher within said least one presence agent to said presentity in said at least one of said plurality of roles; and

wherein said role-based subscription request identifies said presentify and includes a role definition therefor.