The increase of communication efficiency brings an enormous gain in performance of all business activities in an Office environment. In particular, teleconferencing is attracting a great deal of attention due to adventages it creates, such as reduction of cost and time spent in conferences and meetings. LANBRETA-GCS is a LAN besed real- time audio-graphics conferencing system that is beeing developed by Puc/RJ and CC-Rio of IBM Brasil and is the subject of this dissertation. At first, the concept of teleconferencing is introduced and a taxonomy based on observatios of various other systems´ characteristics is presented. Then, the general specification of the system is presented, together with the justifications of the several choices made. Although the attention is directed towards specification, some details concerned to the current implementation are commented, in order to demostrate the system`s viability in a local area network environment.