title: Issue with Opentok and CallKit
body: <p>I am trying to use <code>Opentok</code> and <code>CallKit</code> for audio and video calling purpose, I have followed this demo provided by OpenTok <a href="https://github.com/opentok/CallKit/tree/master/CallKitDemo" rel="nofollow noreferrer">https://github.com/opentok/CallKit/tree/master/CallKitDemo</a></p>
  
  <p>The issue I am facing is when I am doing audio call to another person it starts speaker instead of Built-in-Receiver. I tried their demo and it also has the same issue.</p>
  
  <p>Then I tried <a href="https://developer.apple.com/library/content/samplecode/Speakerbox/Introduction/Intro.html#//apple_ref/doc/uid/TP40017290" rel="nofollow noreferrer">https://developer.apple.com/library/content/samplecode/Speakerbox/Introduction/Intro.html#//apple_ref/doc/uid/TP40017290</a> which is provided by Apple, but after implementing the <code>AudioController</code>, the new call starts with Built-in-Speaker and it automatically switched to Speaker and there is no way to make output change.</p>