extract root node value

$xml = <<<EOD
<?xml version="1.0" encoding="UTF-8"?>
<SENDBATCH user='username' password='password' application='50' reply='EMAIL:dokwii@smsmedia.info'>
This is a test message
	<SMSLIST>
		<SMS_SEND to='256791040262' uid='1'/>
		<SMS_SEND to='256754819815' uid='2'/>
	</SMSLIST>
</SENDBATCH>
EOD;

$xmlObject = new SimpleXMLElement($xml);
//get the message which is This is a test message
$msg = (string)($xmlObject->SENDBATCH);

//question
how do i extract the message(This is a test message) from the root node(SENDBATCH) ?