diff --git a/calendar/freebusy.php b/calendar/freebusy.php
index ebaf512589..df89edce17 100644
--- a/calendar/freebusy.php
+++ b/calendar/freebusy.php
@@ -32,11 +32,16 @@ $GLOBALS['egw_info'] = array(
 require_once __DIR__.'/../api/src/autoload.php';
 if (!($logged_in = !empty(Api\Session::get_sessionid())))
 {
-	// support basic auth for regular user-credentials
-	if (!empty($_SERVER['PHP_AUTH_PW']) || !empty($_SERVER['REDIRECT_HTTP_AUTHORIZATION']))
+	// support basic auth and $_GET[cred] for regular user-credentials
+	if (!empty($_SERVER['PHP_AUTH_PW']) || !empty($_SERVER['REDIRECT_HTTP_AUTHORIZATION']) || !empty($_GET['cred']))
 	{
 		$GLOBALS['egw_info']['flags']['autocreate_session_callback'] = Api\Header\Authenticate::class.'::autocreate_session_callback';
 		$logged_in = true;	// header sends 401, if not authenticated
+		// make $_GET[cred] work by using REDIRECT_HTTP_AUTHORIZATION
+		if (!empty($_GET['cred']))
+		{
+			$_SERVER['REDIRECT_HTTP_AUTHORIZATION'] = 'Basic '.$_GET['cred'];
+		}
 	}
 	else
 	{
@@ -54,7 +59,7 @@ if (!$logged_in)
 // fix for SOGo connector, which does not decode the = in our f/b url
 if (strpos($_SERVER['QUERY_STRING'],'=3D') !== false && substr($_GET['user'],0,2) == '3D')
 {
-	foreach(['user', 'email', 'password', 'cred'] as $name)
+	foreach(['user', 'email', 'password'] as $name)
 	{
 		if (isset($_GET[$name])) $_GET[$name] = substr($_GET[$name],2);
 	}
@@ -79,43 +84,14 @@ if ($user === false || !($username = $GLOBALS['egw']->accounts->id2name($user)))
 }
 if (!$logged_in)
 {
-	if (empty($_GET['cred']))
-	{
-		$GLOBALS['egw_info']['user']['account_id'] = $user;
-		$GLOBALS['egw_info']['user']['account_lid'] = $username;
-		$GLOBALS['egw']->preferences->account_id = $user;
-		$GLOBALS['egw_info']['user']['preferences'] = $GLOBALS['egw']->preferences->read_repository();
-		$cal_prefs = &$GLOBALS['egw_info']['user']['preferences']['calendar'];
-		$logged_in = !empty($cal_prefs['freebusy']) &&
-			(empty($cal_prefs['freebusy_pw']) || $cal_prefs['freebusy_pw'] == $_GET['password']);
-	}
-	else
-	{
-		$credentials = base64_decode($_GET['cred']);
-		list($authuser, $password) = explode(':', $credentials, 2);
-		if (strpos($authuser, '@') === false)
-		{
-			$domain = $GLOBALS['egw_info']['server']['default_domain'];
-			$authuser .= '@' . $domain;
-		}
-		else
-		{
-			list(, $domain) = explode('@',$authuser, 2);
-		}
-		if (array_key_exists($domain, $GLOBALS['egw_domain']))
-		{
-			$_POST['login'] = $authuser;
-			$_REQUEST['domain'] = $domain;
-			$GLOBALS['egw_info']['server']['default_domain'] = $domain;
-			$GLOBALS['egw_info']['user']['domain'] = $domain;
-			$GLOBALS['egw_info']['flags']['currentapp'] = 'login';
-			$GLOBALS['egw_info']['flags']['noapi'] = false;
-			$logged_in =  $GLOBALS['egw']->session->create($authuser, $password, 'text');
-			session_unset();
-			session_destroy();
-		}
-	}
-	if (!$logged_in)
+	$GLOBALS['egw_info']['user']['account_id'] = $user;
+	$GLOBALS['egw_info']['user']['account_lid'] = $username;
+	$GLOBALS['egw']->preferences->account_id = $user;
+	$GLOBALS['egw_info']['user']['preferences'] = $GLOBALS['egw']->preferences->read_repository();
+	$cal_prefs = &$GLOBALS['egw_info']['user']['preferences']['calendar'];
+
+	if (!($logged_in = !empty($cal_prefs['freebusy']) &&
+		(empty($cal_prefs['freebusy_pw']) || $cal_prefs['freebusy_pw'] == $_GET['password'])))
 	{
 		throw new Api\Exception\NoPermission\AuthenticationRequired(lang("freebusy: unknown user '%1', or not available for unauthenticated users!", $_GET['user']));
 	}
@@ -126,7 +102,7 @@ if ($_GET['debug'])
 }
 else
 {
-	Api\Header\Content::type('freebusy.ifb','text/calendar');
+	Api\Header\Content::type('freebusy.vfb','text/calendar');
 }
 $ical = new calendar_ical();
 echo $ical->freebusy($user, $_GET['end']);
\ No newline at end of file