<?php
$xml = <<<XML
<?xml version="1.0" standalone="yes"?>
<people xmlns:p="http://example.org/ns" xmlns:t="http://example.org/test">
<p:person t:id="1">John Doe</p:person>
<p:person t:id="2" a:addr="123 Street" xmlns:a="http://example.org/addr">
Susie Q. Public
</p:person>
</people>
XML;
$sxe = new SimpleXMLElement($xml);
$namespaces = $sxe->getDocNamespaces(TRUE);
var_dump($namespaces);
?>