title: how to check whether a phone number actually exists in US
body: <p>We have a database of contacts and their phone numbers, and we would like to validate whether these phone numbers actually exists. I googled and did not find any solution. I am looking for one of the following, though I prefer the first option.</p>
  
  <ol>
  <li><p>Write code using existing phone library to check whether the phone of the contact actually exists. Probably we make the phone ring once or twice</p></li>
  <li><p>Use an existing software that can be used to ring the phone and validate user contact number manually.</p></li>
  </ol>
  
  <p>Any help is greatly appreciated. </p>