warning on startup

kamailio/registrar-role.cfg

@@ -254,7 +254,7 @@ route[SAVE_LOCATION]
         }
     }
 
-    if(@contact.expires) {
+    if(@hf_value_exists.contact.expires == "1") {
         $var(expires) = @contact.expires;
     } else {
         if(is_present_hf("Expires")) {