A communication exchanger has a memory which memorizes a presence state table for all of users and a forwarding destination table for each of the users. In the presence state table, presence information of all users is registered. In the forwarding destination table, forwarding destination information...http://www.google.co.uk/patents/US7123706?utm_source=gb-gplus-sharePatent US7123706 - Communication exchanging system capable of changing forwarding destination according to notification of presence change of user
