diff --git a/calendar/inc/class.calendar_timezones.inc.php b/calendar/inc/class.calendar_timezones.inc.php
index 0b7ac0a3ab..a41a31b62a 100644
--- a/calendar/inc/class.calendar_timezones.inc.php
+++ b/calendar/inc/class.calendar_timezones.inc.php
@@ -111,7 +111,7 @@ class calendar_timezones
 		// if not tzid queried, resolve aliases automatically
 		if ($data && $data['alias'] && $what != 'tzid' && $what != 'alias')
 		{
-			$data = self::is2tz($data['alias'],null);
+			$data = self::id2tz($data['alias'],null);
 		}
 		return !$data ? $data : ($what ? $data[$what] : $data);
 	}
@@ -206,4 +206,36 @@ class calendar_timezones
 		$GLOBALS['egw']->framework->render('<h3>'.self::import_sqlite()."</h3>\n",lang('Update timezones'),true);
 	}
 }
-calendar_timezones::init_static();
\ No newline at end of file
+/*
+if (isset($_SERVER['SCRIPT_FILENAME']) && $_SERVER['SCRIPT_FILENAME'] == __FILE__)	// some tests
+{
+	$GLOBALS['egw_info'] = array(
+		'flags' => array(
+			'currentapp' => 'calendar',
+		)
+	);
+	include('../../header.inc.php');
+	calendar_timezones::init_static();
+
+//	echo "<h3>Testing availability of VTIMEZONE data for each tzid supported by PHP</h3>\n";
+//	foreach(DateTimeZone::listIdentifiers() as $tz)
+	echo "<h3>Testing availability of VTIMEZONE data for each TZID supported by EGroupware</h3>\n";
+	foreach(call_user_func_array('array_merge',egw_time::getTimezones()) as $tz => $label)
+	{
+		if (($id = calendar_timezones::tz2id($tz,'component')) || $tz == 'UTC')	// UTC is always supported
+		{
+			$found[] = $tz;
+			//if (substr($tz,0,10) == 'Australia/') echo "$tz: found<br />\n";
+		}
+		else
+		{
+			$not_found[] = $tz;
+			echo "$tz: <b>NOT</b> found<br />\n";
+		}
+	}
+	echo '<h3>'.count($found).' found, '.count($not_found)." <b>NOT</b> found</h3>\n";
+
+	if ($not_found) echo "<pre>\n\$no_vtimezone = array(\n\t'".implode("',\n\t'",$not_found)."',\n);\n</pre>\n";
+}
+else*/
+calendar_timezones::init_static();
diff --git a/phpgwapi/inc/class.egw_time.inc.php b/phpgwapi/inc/class.egw_time.inc.php
index face3916cd..5fafb7ff51 100644
--- a/phpgwapi/inc/class.egw_time.inc.php
+++ b/phpgwapi/inc/class.egw_time.inc.php
@@ -430,8 +430,51 @@ class egw_time extends DateTime
 			'Arctic'     => array(),
 			'UTC'        => array('UTC' => 'UTC'),
 		);
+		// no VTIMEZONE available in calendar_timezones --> do NOT return them
+		static $no_vtimezone = array(
+			'Europe/Tiraspol',
+			'America/Atka',
+			'America/Buenos_Aires',
+			'America/Catamarca',
+			'America/Coral_Harbour',
+			'America/Cordoba',
+			'America/Ensenada',
+			'America/Fort_Wayne',
+			'America/Indianapolis',
+			'America/Jujuy',
+			'America/Knox_IN',
+			'America/Mendoza',
+			'America/Porto_Acre',
+			'America/Rosario',
+			'America/Virgin',
+			'Asia/Ashkhabad',
+			'Asia/Beijing',
+			'Asia/Chungking',
+			'Asia/Dacca',
+			'Asia/Macao',
+			'Asia/Riyadh87',
+			'Asia/Riyadh88',
+			'Asia/Riyadh89',
+			'Asia/Tel_Aviv',
+			'Asia/Thimbu',
+			'Asia/Ujung_Pandang',
+			'Asia/Ulan_Bator',
+			'Australia/ACT',
+			'Australia/Canberra',
+			'Australia/LHI',
+			'Australia/North',
+			'Australia/NSW',
+			'Australia/Queensland',
+			'Australia/South',
+			'Australia/Tasmania',
+			'Australia/Victoria',
+			'Australia/West',
+			'Australia/Yancowinna',
+			'Pacific/Samoa',
+		);
 		foreach(DateTimeZone::listIdentifiers() as $name)
 		{
+			if (in_array($name,$no_vtimezone)) continue;	// do NOT allow to set in EGroupware, as we have not VTIMEZONE component for it
 			list($continent,$rest) = explode('/',$name,2);
 			if (!isset($tzs[$continent])) continue;	// old depricated timezones
 			$datetime = new egw_time('now',new DateTimeZone($name));