title: what is the USSD to get mobile number
body: <p>i have an android application which requires to get the mobile number. i tried this</p>
  
  <pre><code>TelephonyManager tm = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
          String number = tm.getLine1Number();
  </code></pre>
  
  <p>but it returns null, after I read the documentation of the <code>TelephoneManager</code> I understood that some phones don't have the mobile number they are working on.</p>
  
  <p>the solution was to send an USSD code to get it.</p>
  
  <p>I couldn't find that, any help please?</p>