The system itself is a Yeastar with ESI's own flavor on it. They are developing the firmware for the systems so it does not work with the Yeastar product line (Linkus) but they are setting up new products to work with it. Ie, ESI Communicator and the Application Server. The phones also seem to be manufactured by someone else, or at least in part with someone else which is Fanvil. The Fanvil products look and work pretty good as we have them in our office. Overall like stated it seems to be a pretty good system, and is VERY expandable with their new TITAN series which you would load onto a server or virtual server. anyone else using this system? Dislikes / Likes?