diff --git a/lib/kolab_sync_data_calendar.php b/lib/kolab_sync_data_calendar.php
--- a/lib/kolab_sync_data_calendar.php
+++ b/lib/kolab_sync_data_calendar.php
@@ -308,7 +308,11 @@
                 $status = isset($attendee['status']) ? $this->attendeeStatusMap[$attendee['status']] : null;
 
                 if ($this->asversion >= 12) {
-                    $att['attendeeType']   = $type ?: self::ATTENDEE_TYPE_REQUIRED;
+                    if (isset($attendee['cutype']) && strtolower($attendee['cutype']) == 'resource') {
+                        $att['attendeeType'] = self::ATTENDEE_TYPE_RESOURCE;
+                    } else {
+                        $att['attendeeType']   = $type ?: self::ATTENDEE_TYPE_REQUIRED;
+                    }
                     $att['attendeeStatus'] = $status ?: self::ATTENDEE_STATUS_UNKNOWN;
                 }
 
@@ -503,6 +507,10 @@
                     'email' => $attendee->email,
                 );
 
+                if (isset($attendee->attendeeType) && $attendee->attendeeType == self::ATTENDEE_TYPE_RESOURCE) {
+                    $_attendee['cutype'] = 'RESOURCE';
+                }
+
                 if (isset($attendee->attendeeStatus)) {
                     $_attendee['status'] = $attendee->attendeeStatus ? array_search($attendee->attendeeStatus, $this->attendeeStatusMap) : null;
                     if (!$_attendee['status']) {