title: TelephonyManager returns null for IMEI number: what can cause this?
body: <p>I'm working on an Android app and am getting <code>null</code> back for the IMEI number when using <code>TelophonyManager</code>. This is happening on several Huawei phones. (All of them are Ascend Y530s).</p>
  
  <p>The phones all have sim cards and otherwise seem to be operating normally. I was under the impression that only a broken phone would return <code>null</code> IMEI. Clearly this is not the case..</p>
  
  <p>Questions. What exactly is this IMEI number - i.e where is it stored on the device? And what does it mean when a seemingly fine phone returns its value as <code>null</code>?</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>I should mention that the IMEI number is not always <code>null</code>. About half the time it seems to be valid (though this is very difficult to measure since we have 5 phones returning null IMEI numbers \ <em>sometimes</em> )</p>