In order to enable the use of WebSocket, you must setto FollowHTTPService. Also, because WebSocket builds on HTTP, you must set to HTTP+HTTPS or HTTPS.
These configurations are available both from the web interface of the device, and in the API. Read the Advanced Settings article for information how to access the web interface and use the API.
The native API of a room or desk device is often referred to as the xAPI.
Read the xAPI over WebSocket Guide for details how to set up the WebSocket, and how to use JSON-RPC objects to convey API commands.
Refer to the API Reference Guide for a complete description of the xAPI itself.