Create the WebSocket

First, handle the connection event so that you can report when your webhook server is online and ready to receive the call audio:

expressWs.getWss().on('connection', function (ws) {
  console.log('Websocket connection is open');
});

Then, create a route handler for the /socket route. This listens for a message event which is raised every time the WebSocket receives audio from the call. Your application should respond by echoing the audio back to the caller with the send() method:

app.ws('/socket', (ws, req) => {
  ws.on('message', (msg) => {
    ws.send(msg)
  })
})