source: pro-violet-viettel/sourcecode/application/modules/services/views/chargingBalance.php

<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
  <soap:Body>
    <Balance xmlns="http://tempuri.org/">
      <user><?php echo $user?></user>
      <pass><?php echo $pass?></pass>
      <MSISDN><?php echo $MSISDN?></MSISDN>
    </Balance>
  </soap:Body>
</soap:Envelope>