diff --git a/resources/install/scripts/app/ring_groups/index.lua b/resources/install/scripts/app/ring_groups/index.lua
index 9f2d3bcb03..bf4d2a193f 100644
--- a/resources/install/scripts/app/ring_groups/index.lua
+++ b/resources/install/scripts/app/ring_groups/index.lua
@@ -453,6 +453,7 @@ local log = require "resources.functions.log".ring_group
 					else
 						--external number
 						y = 0;
+						dial_string = '';
 						previous_dialplan_uuid = '';
 						for k, r in pairs(dialplans) do
 							if (y > 0) then