y asi ?
$tabla="<table id='tabla'>
<tr><td width='150px'><strong>HOSTNAME </strong></td><td><div id='disponible'>".$datos[0]."</div></td></tr>
<tr><td><strong>IP</strong></td><td>".mostrarIP($datos[1])."</td></tr>
<tr><td></td><td>".$codigoB = $_GET['m']."
<iframe width='100%' height='150' src='test.php?code=$codigoB&t=50' frameborder='0'></iframe></td><td></td>
</tr></table>";