$xml='<?xml version="1.0" encoding="iso-8859-9"?>
<mainbody>
   <header>
      <company>NETGSM</company>
      <usercode>kullanici adi</usercode>
      <password>sifre</password>
      <startdate></startdate>
      <stopdate></stopdate>
      <type>1:n</type>
      <msgheader>Baslik</msgheader>
      </header>
      <body>
      <msg><![CDATA[buraya mesaj gelecek.]]></msg>';
      foreach($row as $value){
      $xml.='<no>'.$value->Gsm.'</no>';
      }
      $xml.='</body>
</mainbody>';
Bu şekilde kullanabilirsiniz.