diff --git a/resources/templates/provision/yealink/t21p/{$mac}.cfg b/resources/templates/provision/yealink/t21p/{$mac}.cfg
index 78242eef24..d8f4e2c6e9 100644
--- a/resources/templates/provision/yealink/t21p/{$mac}.cfg
+++ b/resources/templates/provision/yealink/t21p/{$mac}.cfg
@@ -205,7 +205,11 @@ account.1.out_dialog_blf_enable = 0
 ##account.X.shared_line =
 
 #Assign account1 as shared line; 0-Disabled (default), 1-Broadsoft SCA, 2-BLA;
-account.1.shared_line =
+if isset($shared_line_1) }
+account.1.shared_line = {$shared_line_1}
+{else}
+account.1.shared_line = 0
+{/if}
 
 #Configure BLA number for account1 and the subscribe period (in seconds). It ranges from 60 to 7200, the default value is 300.
 account.1.bla_number =