Index: res/res_musiconhold.c
===================================================================
--- res/res_musiconhold.c	(revision 93179)
+++ res/res_musiconhold.c	(working copy)
@@ -1556,7 +1556,31 @@
 
 static int unload_module(void)
 {
-	return -1;
+        int res = 0;
+        struct mohclass *class = NULL;
+
+	AST_RWLIST_RDLOCK(&mohclasses);
+	AST_RWLIST_TRAVERSE(&mohclasses, class, list) {
+		if (class->inuse > 0) {
+			res = -1;
+			break;
+		}
+	}
+	AST_RWLIST_UNLOCK(&mohclasses);
+	if (res < 0) {
+		ast_log(LOG_WARNING, "Unable to unload res_musiconhold due to active MOH channels\n");
+		return res;
+	}
+
+	ast_uninstall_music_functions();
+	ast_moh_destroy();
+	res = ast_unregister_application(play_moh);
+	res |= ast_unregister_application(wait_moh);
+	res |= ast_unregister_application(set_moh);
+	res |= ast_unregister_application(start_moh);
+	res |= ast_unregister_application(stop_moh);
+	res |= ast_cli_unregister_multiple(cli_moh, sizeof(cli_moh) / sizeof(struct ast_cli_entry));
+	return res;
 }
 
 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "Music On Hold Resource",