Why can't I call the Cloud Recording RESTful API from a browser?
Updated
To call the Cloud Recording RESTful API from a web page, the browser must send a cross-origin request. Under the CORS specification, the browser first sends an OPTIONS request to check whether the server allows cross-origin requests, and only then sends the actual POST request. The Cloud Recording RESTful API does not support the OPTIONS method, so you cannot call it from a browser.
To use the Cloud Recording RESTful API, send the requests from your app server instead.