Pregunto, porque en la prueba gratuita no te permite usar Websocket?
(apologies for the answer in English, my Spanish poor and using auto-translation is not usually a good idea)
You are correct, WebSocket support is not available in free accounts, as that feature of our platform is often subject to abuse. If you have an application in mind which will make use of the WebSocket support, please send an email to support@fastly.com and they will work with you to get it enabled on your account.