title: Azure Communication Service Video Call recording - startRecordingAsync requires callbackURI
body: <p>Starting a recording of a video call requires a callbackUri.  What do I use for this callbackUri?  Anything I can find on it is very vague.  If it is a url that I'm supposed to build the api, what does it pass in? What response is it expecting back? How do I handle using localhost for testing?</p>
  <pre><code>using Azure.Communication.CallingServer;
  ...
  var startRecordingResponse = await callingServerClient
                  .InitializeServerCall(serverCallId)
                  .StartRecordingAsync(                   
                     new Uri(&quot;https://what_the_heck.com&quot;),
                     RecordingContent.AudioVideo,
                     RecordingChannel.Mixed,
                     RecordingFormat.Mp4
                  ).ConfigureAwait(false);
  </code></pre>