diff --git a/overlay/packages/apps/CarrierConfig/res/xml/vendor.xml b/overlay/packages/apps/CarrierConfig/res/xml/vendor.xml
index 6ee6802d..ffa69c96 100644
--- a/overlay/packages/apps/CarrierConfig/res/xml/vendor.xml
+++ b/overlay/packages/apps/CarrierConfig/res/xml/vendor.xml
@@ -90,6 +90,7 @@ IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.-->
         <boolean name="carrier_rtt_downgrade_supported" value="false"/>
         <boolean name="show_rtt_visibility_setting_bool" value="false" />
         <boolean name="rtt_always_enabled_bool" value="false" />
+        <int name="default_rtt_mode_int" value="0" />
 
         <!-- HD/VOLTE icon support -->
         <boolean name="config_update_service_status" value="false"/>