diff --git a/resources/templates/provision/yealink/t23g/{$mac}.cfg b/resources/templates/provision/yealink/t23g/{$mac}.cfg
index f2799dae4c..9be0780ca7 100644
--- a/resources/templates/provision/yealink/t23g/{$mac}.cfg
+++ b/resources/templates/provision/yealink/t23g/{$mac}.cfg
@@ -120,10 +120,10 @@ account.1.reg_fail_retry_interval =
 ##account.X.nat.nat_traversal = 0
 
 #Enable or disable the NAT traversal; 0-Disabled (default), 1-STUN;
-account.1.nat.nat_traversal = 0
+account.1.nat.nat_traversal = {if isset($stun_server)}1{else}0{/if}
 
-account.1.nat.stun_server =
-account.1.nat.stun_port = 3478
+account.1.nat.stun_server = ${stun_server}
+account.1.nat.stun_port = {if isset($stun_port)}${stun_port}{else}3478{/if}
 
 #Enable or disable the NAT keep-alive; 0-Disabled, 1-Default (default), 2-Option, 3-Notify;
 account.1.nat.udp_update_enable = 3
@@ -3002,4 +3002,4 @@ expansion_module.1.key.{$row.device_key_id}.xml_phonebook =
 #expansion_module.2.key.1.label =
 #expansion_module.2.key.1.xml_phonebook =
 #expansion_module.2.key.1.type =
-#expansion_module.2.key.1.label = 
\ No newline at end of file
+#expansion_module.2.key.1.label =