$username = "admin";
$password = "1234" ;
$verb = 'GET'
$url = "https://xxx.xxx.xxx/api.phtml/login" ;

$params = array("username"=>$username, "password"=>$password);
$params = http_build_query($params);
$url .= '?' . $params;

$cparams = array( 'http' => array(  'method' => $verb,
                                    'ignore_errors' => true ) );

$context = stream_context_create($cparams);
$fp = fopen($url, 'rb', false, $context);