// Load developer-specific configuration data from ini file
$config = parse_ini_file('ebay.ini', true);
$site = 'sandbox';
$dev = $config[$site]['devId'];
$app = $config[$site]['appId'];
$cert = $config[$site]['cert'];
$token = $config[$site]['authToken'];
$location = $config[$site]['gatewaySOAP'];
// Create and configure session
$session = new eBaySession($dev, $app, $cert);
$session->token = $token;
$session->site = 0;
// 0 = US;
$session->location = $location;
// Deliver messages to the following URL
try {
    $client = new eBaySOAP($session);
    $params = array('Version' => 525, 'ApplicationDeliveryPreferences' => array('ApplicationURL' => 'http://www.trachtenberg.com/ebay/notifications/listener.php'));
    $results = $client->SetNotificationPreferences($params);
    print_r($results);
} catch (SOAPFault $f) {
    print $f;
    // error handling
}
/*
// Uncomment below to view SOAP envelopes
print "Request: \n".$client->__getLastRequestHeaders() ."\n";
print "Request: \n".$client->__getLastRequest() ."\n";
print "Response: \n".$client->__getLastResponseHeaders()."\n";
print "Response: \n".$client->__getLastResponse()."\n";
*/