Cisco TelePresence SX20 and Codec C series Enter the IP address of the device in your browser. Enter your username and password. Navigate to Configuration > System Configuration > H323. In the NAT section, select Off for the Mode. Configure the following and click Save after each option: Select Gatekeeper for the CallSetup Mode. Select Dynamic for the PortAllocation. Enter the LoginName. This is the extension of the device. Select On for the Mode. Enter the Password. Enter the Gatekeeper Address Select Manual for Discovery. Enter the device extension in the E164 and ID fields.