public function getByTrackingId($id) {
    	// Request syntax needed to track by tracking id
    	$this->request['SelectionDetails'] = array(
			'PackageIdentifier' => array(
				'Type' => 'TRACKING_NUMBER_OR_DOORTAG',
				'Value' => $id // Tracking ID to track
			)
		);

    	$req = $this->buildRequest($this->request);

    	return $this->getSoapClient()->track($req);;

    }