title: Verify phone number using PhoneNumbers.dll with C#, Visual studio 2010
body: <p>I am trying to verify phone number using PhoneNumbers.dll(File version 8.9.0.0) for twillio SMS API with C# (Visual studio 2010) </p>
  
  <p>Lines of Code used in application:</p>
  
  <pre><code>private static PhoneNumberUtil phoneUtil = PhoneNumberUtil.GetInstance();
  private static List&lt;string&gt; supportedRegions = phoneUtil.GetSupportedRegions().ToList&lt;string&gt;();
  </code></pre>
  
  <p>After application build, facing below error </p>
  
  <blockquote>
    <p>The type 'System.Object' is defined in an assembly that is not
    referenced. You must add a reference to assembly  'netstandard,
    Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'.</p>
  </blockquote>
  
  <p><a href="https://i.stack.imgur.com/t01PQ.png" rel="nofollow noreferrer">enter image description here</a></p>
  
  <p>In case same dll used in .Net 2015 no error results with build successed.
  Please suggest to over come system.object error in .net 2010</p>