1. A video teleconferencing system comprising: at least one site, each of said at least one site having at least one station, each of said at least one station accommodating one of a plurality of participants; a videocamera associated with each station, said video camera positioned wherein a participant at said each station is located within said videocamera's field of view; a plurality of microphones, wherein each of said participants is positioned within the acoustic range of at least one of said microphones; an automated video switching system that automatically selects, from among a plurality of video signals provided by said videocameras at said at least one site, a video signal for transmission to one or more remote videoconferencing sites, based on: an audio activity level of at least one of said microphones; and selection parameters specified by an active operating mode among a plurality of available operating modes.