diff --git a/conf/directory.xml b/conf/directory.xml
index 7a42fd73dc..feb371b080 100644
--- a/conf/directory.xml
+++ b/conf/directory.xml
@@ -25,6 +25,8 @@
       <!--<param name="expire-seconds" value="60"/>-->
       <!--/// do not register ///-->
       <!--<param name="register" value="false"/>-->
+      <!-- which transport to use for register -->
+      <!--<param name="register-transport" value="udp"/>-->
       <!--How many seconds before a retry when a failure or timeout occurs -->
       <!--<param name="retry_seconds" value="30"/>-->
       <!--Use the callerid of an inbound call in the from field on outbound calls via this gateway -->
diff --git a/conf/sofia.conf.xml b/conf/sofia.conf.xml
index b279540e9c..409336fec2 100644
--- a/conf/sofia.conf.xml
+++ b/conf/sofia.conf.xml
@@ -28,6 +28,8 @@
 	  <!--<param name="expire-seconds" value="60"/>-->
 	  <!--/// do not register ///-->
 	  <!--<param name="register" value="false"/>-->
+	  <!-- which transport to use for register -->
+	  <!--<param name="register-transport" value="udp"/>-->
 	  <!--How many seconds before a retry when a failure or timeout occurs -->
 	  <!--<param name="retry_seconds" value="30"/>-->
 	  <!--Use the callerid of an inbound call in the from field on outbound calls via this gateway -->