diff --git a/addressbook/inc/class.addressbook_groupdav.inc.php b/addressbook/inc/class.addressbook_groupdav.inc.php
index e21adb37f3..32714f93db 100644
--- a/addressbook/inc/class.addressbook_groupdav.inc.php
+++ b/addressbook/inc/class.addressbook_groupdav.inc.php
@@ -506,16 +506,9 @@ class addressbook_groupdav extends groupdav_handler
 			$contact = $this->read($save_ok);
 		}
 
-		// we should not return an etag here, as we never store the PUT vcard byte-by-byte
-		//header('ETag: "'.$this->get_etag($contact).'"');
+		// send evtl. necessary respose headers: Location, etag, ...
+		$this->put_response_headers($contact, $options['path'], $retval, self::$path_attr != 'id');
 
-		// send GroupDAV Location header only if we dont use carddav_name as path-attribute
-		if ($retval !== true && self::$path_attr == 'id')
-		{
-			$path = preg_replace('|(.*)/[^/]*|', '\1/', $options['path']);
-			header($h='Location: '.$this->base_uri.$path.self::get_path($contact));
-			if ($this->debug) error_log(__METHOD__."($method,,$id) header('$h'): $retval");
-		}
 		if ($this->debug > 1) error_log(__METHOD__."(,'$id', $user, '$prefix') returning ".array2string($retval));
 		return $retval;
 	}
diff --git a/calendar/inc/class.calendar_groupdav.inc.php b/calendar/inc/class.calendar_groupdav.inc.php
index da77c8ab2a..3e0492eaf1 100644
--- a/calendar/inc/class.calendar_groupdav.inc.php
+++ b/calendar/inc/class.calendar_groupdav.inc.php
@@ -703,13 +703,10 @@ class calendar_groupdav extends groupdav_handler
 			//header('ETag: "'.$etag.'"');
 			header('Schedule-Tag: "'.$schedule_tag.'"');
 		}
-		// send GroupDAV Location header only if we dont use caldav_name as path-attribute
-		if ($retval !== true && self::$path_attr != 'caldav_name')
-		{
-			$path = preg_replace('|(.*)/[^/]*|', '\1/', $options['path']);
-			if ($this->debug) error_log(__METHOD__."(,$id,$user) cal_id=$cal_id: $retval");
-			header('Location: '.$this->base_uri.$path.$this->get_path($cal_id));
-		}
+
+		// send evtl. necessary respose headers: Location, etag, ...
+		$this->put_response_headers($cal_id, $options['path'], $retval, self::$path_attr == 'caldav_name');
+
 		return $retval;
 	}
 
diff --git a/infolog/inc/class.infolog_groupdav.inc.php b/infolog/inc/class.infolog_groupdav.inc.php
index 5f95046add..79b49788f8 100644
--- a/infolog/inc/class.infolog_groupdav.inc.php
+++ b/infolog/inc/class.infolog_groupdav.inc.php
@@ -470,15 +470,9 @@ class infolog_groupdav extends groupdav_handler
 			$retval = '201 Created';
 		}
 
-		// we should not return an etag here, as we never store the PUT ical byte-by-byte
-		//header('ETag: "'.$this->get_etag($infoId).'"');
+		// send evtl. necessary respose headers: Location, etag, ...
+		$this->put_response_headers($infoId, $options['path'], $retval, self::$path_attr == 'caldav_name');
 
-		// send GroupDAV Location header only if we dont use caldav_name as path-attribute
-		if ($retval !== true && self::$path_attr != 'caldav_name')
-		{
-			$path = preg_replace('|(.*)/[^/]*|', '\1/', $options['path']);
-			header('Location: '.$this->base_uri.$path.self::get_path($infoId));
-		}
 		return $retval;
 	}
 
diff --git a/phpgwapi/inc/class.groupdav.inc.php b/phpgwapi/inc/class.groupdav.inc.php
index 417ee0e98c..979be2adba 100644
--- a/phpgwapi/inc/class.groupdav.inc.php
+++ b/phpgwapi/inc/class.groupdav.inc.php
@@ -238,6 +238,14 @@ class groupdav extends HTTP_WebDAV_Server
 			$this->dav_powered_by);
 
 		parent::HTTP_WebDAV_Server();
+		// hack to allow to use query parameters in WebDAV, which HTTP_WebDAV_Server interprets as part of the path
+		list($this->_SERVER['REQUEST_URI']) = explode('?',$this->_SERVER['REQUEST_URI']);
+		/*if (substr($this->_SERVER['REQUEST_URI'],-13) == '/;add-member/')
+		{
+			$_GET['add-member'] = '';
+			$this->_SERVER['REQUEST_URI'] = substr($this->_SERVER['REQUEST_URI'],0,-12);
+		}*/
+		//error_log($_SERVER['REQUEST_URI']." --> ".$this->_SERVER['REQUEST_URI']);
 
 		$this->egw_charset = translation::charset();
 		if (strpos($this->base_uri, 'http') === 0)
@@ -763,6 +771,13 @@ class groupdav extends HTTP_WebDAV_Server
 				$props['displayname'] = translation::convert(lang($app).' '.$this->account_name($user),$this->egw_charset,'utf-8');
 		}
 
+		// rfc 5995 (Use POST to add members to WebDAV collections): we use collection path with add-member query param
+		/* leaving it switched off, until further testing, because OS X iCal seem to ignore it and OS X Addressbook uses POST to full URL without ?add-member
+		if ($app && !in_array($app,array('inbox','outbox','principals')))	// not on inbox, outbox or principals
+		{
+			$props['add-member'][] = self::mkprop('href',$this->base_uri.$path.'?add-member');
+		}*/
+
 		// add props modifyable via proppatch from client, eg. calendar-color, see self::$proppatch_props
 		foreach((array)$GLOBALS['egw_info']['user']['preferences'][$app] as $name => $value)
 		{
@@ -1093,6 +1108,13 @@ class groupdav extends HTTP_WebDAV_Server
 	 */
 	function POST(&$options)
 	{
+		// for some reason OS X Addressbook (CFNetwork user-agent) uses now (DAV:add-member given with collection URL+"?add-member")
+		// POST to the collection URL plus a UID like name component (like for regular PUT) to create new entrys
+		if (isset($_GET['add-member']) || groupdav_handler::get_agent() == 'cfnetwork')
+		{
+			$_GET['add-member'] = '';	// otherwise we give no Location header
+			return $this->PUT($options);
+		}
 		// read the content in a string, if a stream is given
 		if (isset($options['stream']))
 		{
@@ -1446,7 +1468,9 @@ class groupdav extends HTTP_WebDAV_Server
 
 		$id = array_pop($parts);
 
-		$ok = $id && ($user || $user === 0) && in_array($app,array('addressbook','calendar','infolog','principals'));
+		$ok = ($id || isset($_GET['add-member']) && $_SERVER['REQUEST_METHOD'] == 'POST') &&
+			($user || $user === 0) && in_array($app,array('addressbook','calendar','infolog','principals'));
+
 		if ($this->debug)
 		{
 			error_log(__METHOD__."('$path') returning " . ($ok ? 'true' : 'false') . ": id='$id', app='$app', user='$user', user_prefix='$user_prefix'");
@@ -1525,9 +1549,9 @@ class groupdav extends HTTP_WebDAV_Server
 						': '.($name=='AUTHORIZATION'?'Basic ***************':$value).$msg_nl,$msg_type,$msg_file);
 				}
 			}
+			error_log(''.$msg_nl,$msg_type,$msg_file);
 			if ($this->request)
 			{
-				error_log(''.$msg_nl,$msg_type,$msg_file);
 				foreach(explode("\n",$this->request) as $line) error_log($line.$msg_nl,$msg_type,$msg_file);
 			}
 			error_log('HTTP/1.1 '.$this->_http_status.$msg_nl,$msg_type,$msg_file);
diff --git a/phpgwapi/inc/class.groupdav_handler.inc.php b/phpgwapi/inc/class.groupdav_handler.inc.php
index 77ffb072ab..db8e91a516 100644
--- a/phpgwapi/inc/class.groupdav_handler.inc.php
+++ b/phpgwapi/inc/class.groupdav_handler.inc.php
@@ -457,6 +457,29 @@ abstract class groupdav_handler
 		return $entry[self::$path_attr].self::$path_extension;
 	}
 
+	/**
+	 * Send response-headers for a PUT (or POST with add-member query parameter)
+	 *
+	 * @param int|array $entry id or array of new created entry
+	 * @param string $path
+	 * @param int|string $retval
+	 * @param boolean $path_attr_is_name=true true: path_attr is ca(l|rd)dav_name, false: id (GroupDAV needs Location header)
+	 */
+	function put_response_headers($entry, $path, $retval, $path_attr_is_name=true)
+	{
+		// we should not return an etag here, as EGroupware never stores ical/vcard byte-by-byte
+		//header('ETag: "'.$this->get_etag($entry).'"');
+
+		// send Location header only if we dont use caldav_name as path-attribute or
+		if ($retval !== true && (!$path_attr_is_name ||
+			// POST with add-member query parameter
+			$_SERVER['REQUEST_METHOD'] == 'POST' && isset($_GET['add-member'])))
+		{
+			$path = preg_replace('|(.*)/[^/]*|', '\1/', $path);
+			header('Location: '.$this->base_uri.$path.$this->get_path($entry));
+		}
+	}
+
 	/**
 	 * Return calendars/addressbooks shared from other users with the current one
 	 *