When using a VoIP phone with the G18/G20, the SIP Passthrough option may need to be enabled for that phone to have full functionality. In other situations, it may be recommended by the VoIP phone manufacturer to disable SIP Passthrough. By default, SIP Passthrough is enabled. This document describes how to disable SIP Passthrough in the G18/G20.
NOTE: Contact the VoIP phone manufacturer to determine the SIP Passthrough configuration.
Disable SIP Passthrough
- Launch a web browser, such as Internet Explorer, Firefox, or Safari.  Enter http://192.168.0.1 into the address box, and press the Enter key.  The https:// Redirect page will appear.  Â
 - The SURFboard Web Manager is redirecting to a more secure connection, click the Proceed button to continue.  The Gateway > Login page will appear.
 - A security or private risk alert may appear on the web browser advising users to proceed with caution when accessing the Web Manager. There is no risk in proceeding to the Web Manager. For instructions to bypass the alert screen, refer to article # 18181 - Alert Message for Web Manager Access.
NOTE: The Home Network Wizard will appear if this is the first time accessing the Web Manager. For assistance with the wizard, refer to article # 19602 - G18/G20: Web Manager First Time Login.
 - The Username field has admin populated, enter the custom password in the Password field.
NOTE: If the Login page prompts for an email address and password, retrieve the email address and password in the app to sign in. For detailed instructions in the app, refer to article # 19069 - SURFboard Central: Web Manager Access.
 - Click the Login button.  The Gateway > Summary page will appear.
 - On the left-hand menu, click the Advanced link, then click the ALG sub-menu link.  The Advanced > ALG page will appear. Â
 - Uncheck the SIP box, then click the Save Settings button.
