Under --> Servers -> Application Servers -> RTCGWServer -> ports, click on Details. Select SIP_DEFAULTHOST and in the host field, enter the external hostname of the Sametime Gateway.
Under --> Environment -> Virtual Hosts -> default host -> host aliases, select port 5060 and add the external name of the Sametime Gateway.
But can i see this in any configuration file, whats the name of the file that holds this.