title: How can we detect a proxy/virtual mobile number?
body: <p>To filter scammers, we validate user accounts with a sms verification system.</p>
  <p>As you can imagine, some people are using virtual numbers.</p>
  <p>Some <a href="https://en.wikipedia.org/wiki/Mobile_Network_Code" rel="nofollow noreferrer">MCCMNC</a> can easily be banned as they are favored by scammers. But most scammer numbers have the MCCMNC of a &quot;clean&quot; telco.</p>
  <p>How can we detect that?</p>