The H.323 and SIP ALGs also perform this function. Many VoIP devices and servers use NAT (Network Address Translation) to open and close ports automatically.

Generates log messages for auditing purposes.

Makes sure that VoIP connections use standard H.323 protocols.

Opens the ports necessary to make and receive calls, and to exchange audio and video media.

This can help you to troubleshoot any problems. We recommend you make sure that VoIP connections work successfully before you add an H.323 or SIP ALG. Other solutions require you to set up and maintain a gatekeeper on your network.Ĭoordination of the many components of a VoIP installation can be a difficult task. For example, some VoIP providers host a gatekeeper on their network that you must connect to before you can place a VoIP call. A gatekeeper manages VoIP calls for a group of users, and can be located on a network protected by your Firebox or at an external location. With H.323, the key component of call management is known as a gatekeeper. The call management system can be self-hosted, or hosted by a third-party service provider. In a peer-to-peer connection, each of the two devices knows the IP address of the other device and connects to the other directly, without the use of a proxy server to route their calls.Ĭonnections managed by a call management system (PBX). It is important to understand that you usually implement VoIP by using either:

To determine which ALG to add, consult the documentation for your VoIP devices or applications. You can use both H.323 and SIP ALGs at the same time, if necessary. H.323 is commonly used on videoconferencing equipment. These ALGs have been created to work in a NAT environment to maintain security for privately addressed conferencing equipment protected by your Firebox.

An ALG is created in the same way as a proxy policy and offers similar configuration options. If you use Voice-over-IP (VoIP) in your organization, you can add an H.323 or SIP (Session Initiation Protocol) ALG (Application Layer Gateway) to open the ports necessary to enable VoIP through your Firebox.

Application layer gateway service