A client-server application that lets users of OpenStage phones belonging to the same local network (clients) exchange instant messages via a central service that runs on some other machine in the same network (server).
This application is a demo app created in year 2011 with use of OpenStage Software Development Kit, which is an SDK for OpenStage 60/80 SIP phones, in Java.
SDK's repository is here: https://github.com/mbdevpl/OpenStageSDK