title: Alternative to IMEI in iOS
body: <p>I am developing a banking app.
  The functionality is </p>
  
  <ol>
  <li>User will fill out registration in a form. He/She will provide a unique device identifier  (like IMEI, or serial) number. The identifier length should be user-friendly.  For Android apps it's already done with the IMEI number.</li>
  <li>The bank will keep this unique device identifier on file for this account. So the number must be appear on the device and should have a maximum length of 15.</li>
  <li>When a user logs in from the app, we will send  this device identifier every time.</li>
  <li>When the user resets the phone, the identifier will remain the same.</li>
  </ol>
  
  <p>For security reasons,<br>
  we do not save any data locally. The bank requires that every time we pick up the identifier programmatically.</p>
  
  <p>We don’t permit using the mobile number as an alternative to IMEI .</p>
  
  <p>What can we use for this?</p>