A videoconference system holds a videoconference among N (a plurality of) communication centers connected by a communication line. Each communication center includes: N-1 display devices for displaying images from the other communication centers participating in the videoconference; N-1 speaker devices...http://www.google.co.uk/patents/US6037970?utm_source=gb-gplus-sharePatent US6037970 - Videoconference system and method therefor
