title: Error when trying to answer a call using Twilio Client: "Missing audio element in offer"
body: <p>Here's the console output when I set up Twilio.Device in debug mode:</p>
  
  <pre><code>[Device] Stream is ready
  twilio.js:2115 [Connection] Received HANGUP from gateway
  twilio.js:2115 [Connection] Received an error from the gateway:
  twilio.js:2115 Object {code: 31100, message: "Missing audio element in offer", connection: Connection}
  twilio.js:2115 [Device] 31100: Missing audio element in offer
  twilio.js:1103 Uncaught Twilio.Exception: 31100: Missing audio element in offer
  </code></pre>