add to header

channels/chan_brcm.h

@@ -106,6 +106,7 @@ typedef enum dialtone_state {
 	DIALTONE_UNOBTAINABLE,
 	DIALTONE_HOWLER,
 	DIALTONE_UNKNOWN,
+	DIALTONE_MWI_OFF,
 	DIALTONE_LAST,
 } dialtone_state;