title: When do device ID's reset for alexa skills and can the device IDs be reliably used?
body: <p>I am aware you can retrieve a <strong>unique ID</strong> for the device a custom Alexa skill was requested from via <code>context.System.device.deviceId</code>, however, I've noticed the <em>ID for a given device changes time to time</em> which leads me to a couple questions:</p>
  
  <ol>
  <li>When does it reset?</li>
  <li>Can this in someway be reliably used to always identify which device a request was made from? i.e. is there a work-around?</li>
  </ol>
  
  <p>I want to be able to make room specific responses for a property without the need for the user to specify the room through identifying a given device. </p>
  
  <p>Thanks </p>