If you are asking how to configure it to use an external GK, then you need to configure the external GK address in the config h323gw area.
If you do not have an external GK, then you should not make any changes to the internal GK as it will not affect your use. Keep in mind that the tenor is always a gw with a built in gk.
If you need help on configuring your tenor for your application, then you can contact me directly at mike_voip@hotmail.com.
Mike M