The usage of communication systems is improved. An IM server 4 manages presence information regarding each of IM clients and usable media and user information such that each of the IM clients can obtain these kinds of information. In order to perform text chatting, the IM server 4 manages a connection...http://www.google.com.au/patents/US20040001480?utm_source=gb-gplus-sharePatent US20040001480 - Communication system and communication method
