A rules-based real-time messaging system for groups of users, in which an availability status may be maintained in association with each user. Clients are communicably coupled to a real-time messaging server, which maintains indications of the online/offline presence status of each user, as well as other...http://www.google.de/patents/US20040161080?utm_source=gb-gplus-sharePatent US20040161080 - Rules based real-time communication system
