title: How can I use es6 syntax to import sip.js library
body: <p>I keep getting errors when trying to import sip.js library to my project, I have installed it via npm </p>
  
  <pre><code>npm install sip.js --save
  </code></pre>
  
  <p>I have tried, but kept on getting errors.</p>
  
  <pre><code>import { SIP } from 'sip.js'
  </code></pre>
  
  <p>Your help is highly appreciated. </p>