diff --git a/plugins/calendar/calendar.php b/plugins/calendar/calendar.php
index 2ce4f7f8..a42bd3e1 100644
--- a/plugins/calendar/calendar.php
+++ b/plugins/calendar/calendar.php
@@ -1732,6 +1732,18 @@ class calendar extends rcube_plugin
       $settings['identity'] = array('name' => $identity['name'], 'email' => strtolower($identity['email']), 'emails' => ';' . strtolower(join(';', $identity['emails'])));
     }
 
+    // freebusy token authentication URL
+    if (($url = $this->rc->config->get('calendar_freebusy_session_auth_url'))
+      && ($uniqueid = $this->rc->config->get('kolab_uniqueid'))
+    ) {
+      if ($url === true) $url = '/freebusy';
+      $url = rtrim(rcube_utils::resolve_url($url), '/ ');
+      $url .= '/' . urlencode($this->rc->get_user_name());
+      $url .= '/' . urlencode($uniqueid);
+
+      $settings['freebusy_url'] = $url;
+    }
+
     return $settings;
   }
 
diff --git a/plugins/calendar/calendar_ui.js b/plugins/calendar/calendar_ui.js
index 68661a77..8690882a 100644
--- a/plugins/calendar/calendar_ui.js
+++ b/plugins/calendar/calendar_ui.js
@@ -3200,6 +3200,27 @@ function rcube_calendar_ui(settings)
       }
     };
 
+    // show free-busy URL in a dialog box
+    this.showfburl = function()
+    {
+      var $dialog = $('#fburlbox');
+
+      if ($dialog.is(':ui-dialog'))
+        $dialog.dialog('close');
+
+      $dialog.dialog({
+        resizable: true,
+        closeOnEscape: true,
+        title: rcmail.gettext('showfburl', 'calendar'),
+        close: function() {
+          $dialog.dialog("destroy").hide();
+        },
+        width: 520
+      }).show();
+
+      $('#fburl').val(settings.freebusy_url).select();
+    };
+
     // refresh the calendar view after saving event data
     this.refresh = function(p)
     {
@@ -3601,7 +3622,7 @@ function rcube_calendar_ui(settings)
     calendars_list.addEventListener('select', function(node) {
       if (node && node.id && me.calendars[node.id]) {
         me.select_calendar(node.id, true);
-        rcmail.enable_command('calendar-edit', 'calendar-showurl', true);
+        rcmail.enable_command('calendar-edit', 'calendar-showurl', 'calendar-showfburl', true);
         rcmail.enable_command('calendar-delete', me.calendars[node.id].editable);
         rcmail.enable_command('calendar-remove', me.calendars[node.id] && me.calendars[node.id].removable);
       }
@@ -4162,6 +4183,7 @@ window.rcmail && rcmail.addEventListener('init', function(evt) {
   rcmail.register_command('calendar-delete', function(){ cal.calendar_delete(cal.calendars[cal.selected_calendar]); }, false);
   rcmail.register_command('events-import', function(){ cal.import_events(cal.calendars[cal.selected_calendar]); }, true);
   rcmail.register_command('calendar-showurl', function(){ cal.showurl(cal.calendars[cal.selected_calendar]); }, false);
+  rcmail.register_command('calendar-showfburl', function(){ cal.showfburl(); }, false);
   rcmail.register_command('event-download', function(){ cal.event_download(cal.selected_event); }, true);
   rcmail.register_command('event-sendbymail', function(p, obj, e){ cal.event_sendbymail(cal.selected_event, e); }, true);
   rcmail.register_command('event-copy', function(){ cal.event_copy(cal.selected_event); }, true);
diff --git a/plugins/calendar/config.inc.php.dist b/plugins/calendar/config.inc.php.dist
index 83864edd..3d91e2d9 100644
--- a/plugins/calendar/config.inc.php.dist
+++ b/plugins/calendar/config.inc.php.dist
@@ -166,4 +166,9 @@ $config['kolab_invitation_calendars'] = false;
 // LDAP directory configuration to find avilable resources for events
 // $config['calendar_resources_directory'] = array(/* ldap_public-like address book configuration */);
 
+// Enables displaying of free-busy URL with token-based authentication
+// Set it to the prefix URL, e.g. 'https://hostname/freebusy' or just '/freebusy'.
+// See freebusy_session_auth in configuration of kolab_auth plugin.
+$calendar['calendar_freebusy_session_auth_url'] = null;
+
 ?>
diff --git a/plugins/calendar/localization/en_US.inc b/plugins/calendar/localization/en_US.inc
index 496b1e5c..ebbd3e47 100644
--- a/plugins/calendar/localization/en_US.inc
+++ b/plugins/calendar/localization/en_US.inc
@@ -112,6 +112,8 @@ $labels['nmonthsback'] = '$nr months back';
 $labels['showurl'] = 'Show calendar URL';
 $labels['showurldescription'] = 'Use the following address to access (read only) your calendar from other applications. You can copy and paste this into any calendar software that supports the iCal format.';
 $labels['caldavurldescription'] = 'Copy this address to a <a href="http://en.wikipedia.org/wiki/CalDAV" target="_blank">CalDAV</a> client application (e.g. Evolution or Mozilla Thunderbird) to fully synchronize this specific calendar with your computer or mobile device.';
+$labels['showfburl'] = 'Show free-busy URL';
+$labels['fburldescription'] = 'Use the following address to access Free-Busy information from other applications. You can copy and paste this into any calendar software that supports free-busy information in iCal format. No authentication is required for this URL.';
 $labels['findcalendars'] = 'Find calendars...';
 $labels['searchterms'] = 'Search terms';
 $labels['calsearchresults'] = 'Available Calendars';
diff --git a/plugins/calendar/skins/larry/calendar.css b/plugins/calendar/skins/larry/calendar.css
index 74da6c31..b21f3d4f 100644
--- a/plugins/calendar/skins/larry/calendar.css
+++ b/plugins/calendar/skins/larry/calendar.css
@@ -433,6 +433,7 @@ pre {
 	background-color: #c7e3ef;
 }
 
+#fburl,
 #calfeedurl,
 #caldavurl {
 	width: 98%;
diff --git a/plugins/calendar/skins/larry/templates/calendar.html b/plugins/calendar/skins/larry/templates/calendar.html
index e7f89c26..07a4750d 100644
--- a/plugins/calendar/skins/larry/templates/calendar.html
+++ b/plugins/calendar/skins/larry/templates/calendar.html
@@ -74,6 +74,9 @@
 		<li role="menuitem"><roundcube:button type="link" command="calendar-remove" label="calendar.removelist" classAct="active" /></li>
 		<roundcube:endif />
 		<li role="menuitem"><roundcube:button type="link" command="calendar-showurl" label="calendar.showurl" classAct="active" /></li>
+		<roundcube:if condition="!empty(env:calendar_settings['freebusy_url'])" />
+		<li role="menuitem"><roundcube:button type="link" command="calendar-showfburl" label="calendar.showfburl" classAct="active" /></li>
+		<roundcube:endif />
 		<roundcube:if condition="env:calendar_driver == 'kolab'" />
 		<li role="menuitem"><roundcube:button type="link" command="folders" task="settings" label="managefolders" classAct="active" /></li>
 		<roundcube:endif />
@@ -361,6 +364,11 @@
 	</div>
 </div>
 
+<div id="fburlbox" class="uidialog">
+	<p><roundcube:label name="calendar.fburldescription" /></p>
+	<textarea id="fburl" rows="2" readonly="readonly"></textarea>
+</div>
+
 <roundcube:object name="plugin.calendar_css" />
 
 <script type="text/javascript">