This is a really rough cut at spidering the Twilio API

spider.php

<?php

$mapped = array();
spiderAPI('https://XXXX@api.twilio.com/2010-04-01');

function spiderAPI($url) {
    global $mapped;
    $url = str_replace('XXXX', 'ACxxxx:authToken', $url);

    $xml = simplexml_load_file($url);
    $mySubUris = $xml->xpath('//SubresourceUris/*');
    if ($mySubUris) {
        foreach ($mySubUris as $item) {
            if(!isset($mapped[$item->getName()])) {
                echo $item." -- ";
                echo $item->getName()."\n\n";
                $mapped[$item->getName()] = $item;
                $subUrl = 'https://XXXX@api.twilio.com'.$item;
                spiderAPI($subUrl);
            }
        }
    }
}