audio conferencing is carried out in stereo by centrally assigning a position in the stereo spectrum and instructing each conference endpoint to transmit at the stereo position assigned to it . in this way signals from a number of endpoints can be simply added to one another in order to provide a composite broadcast signal . this method also facilitates multiple server conferences in which endpoints attached to additional conference servers can be instructed to change their virtual stereo position in the case of a conflict with the stereo position of an existing conferee .