title: Dialogflow Facebook messenger webhook - TTS response
body: <p>I integrated my Dialogflow chatbot with Facebook Messenger and I was so far able to successfully send custom text and audio files from my node.js webhook.<br />
  The problem is that in order to send audio it must be online and I have to provide its URL. Something like this:</p>
  <pre><code>            {
                  &quot;payload&quot;: {
                      &quot;facebook&quot;: {
                          &quot;attachment&quot;: {
                              &quot;payload&quot;: {
                                  &quot;url&quot;: &quot;https://actions.google.com/sounds/v1/alarms/bugle_tune.ogg&quot;
                              },
                              &quot;type&quot;: &quot;audio&quot;
                          }
                      }
                  },
                  &quot;platform&quot;: &quot;FACEBOOK&quot;
              }, 
  </code></pre>
  <p>My main goal is to be able, based on a decision that I make, to choose whether to send the response back to Messenger as text or as text-to-speech of the usual text response.</p>
  <p>For Example: if the user says hi and the chatbot should answer by &quot;hello&quot;, I want based on certain conditions to be able to either forward the &quot;hello&quot; as text or to send it as a vocal message (ssml or text to speech).</p>
  <p>Based on my search I'm kind of convinced that fulfillment payloads for facebook do not include the SSML type. If true, is there a turnaround solution for my problem?  Is there another way to send text-to-speech?</p>
  <p>(The platform doesn't necessarily have to be Facebook, but should be feasible to integrate with Dialogflow)</p>