Two video surrogates are used in each office. One is on the desktop("near") and one by the door (far). Each consists of a camera, monitor and speaker. People entering or glancing into an office appear by the door. As with physically present visitors, they only enter when invited. Having these two surrogates means that one is better able to preserve conventional social mores concerning social distance, approach, and departure.
The near/far camera uses are controlled by the Desk Area Network(DAN). The a/v connections are done using the standard server protocol and the DAN routes the incoming and outgoing feed to the appropriate near/far devices.
The approach is simple to deploy and results in a significant change from conventional desk-top video.
There are few, other than logistical issues of switching and deploying the additional gear. Also, the technique is not easily adapted when the video is digital rather than analog.