public static function GetCallingURL()
    {
        $sURL = '/';
        if (array_key_exists(self::SESSION_PARAM_NAME, $_SESSION)) {
            $sURL = $_SESSION[self::SESSION_PARAM_NAME];
        } else {
            $sURL = self::getPageService()->getLinkToPortalHomePageAbsolute();
        }

        return $sURL;
    }