diff --git a/dom/telephony/nsITelephonyService.idl b/dom/telephony/nsITelephonyService.idl
index 56872631ebd4..5867af321f2c 100644
--- a/dom/telephony/nsITelephonyService.idl
+++ b/dom/telephony/nsITelephonyService.idl
@@ -240,7 +240,7 @@ interface nsITelephonyDialCallback : nsITelephonyCallback
  * XPCOM component (in the content process) that provides the telephony
  * information.
  */
-[scriptable, uuid(79188caa-046a-48e1-b9c5-2e891504dc7a)]
+[scriptable, uuid(6fa2d94b-80ee-4085-b6a0-535811ba9bb6)]
 interface nsITelephonyService : nsISupports
 {
   const unsigned short CALL_STATE_UNKNOWN = 0;
@@ -296,6 +296,8 @@ interface nsITelephonyService : nsISupports
 
   void conferenceCall(in unsigned long clientId);
   void separateCall(in unsigned long clientId, in unsigned long callIndex);
+  void hangUpConference(in unsigned long clientId,
+                        in nsITelephonyCallback callback);
   void holdConference(in unsigned long clientId);
   void resumeConference(in unsigned long clientId);