Chapter 19 ALG

can receive incoming calls from the Internet, LAN IP addresses B and C can still make calls out to the Internet.

Figure 202 VoIP Calls from the WAN with Multiple Outgoing Calls

VoIP with Multiple WAN IP Addresses

With multiple WAN IP addresses on the ZyWALL, you can configure different firewall and NAT (port forwarding) rules to allow incoming calls from each WAN IP address to go to a specific IP address on the LAN (or DMZ). Use policy routing to have the H.323 (or SIP) calls from each of those LAN or DMZ IP addresses go out through the same WAN IP address that calls come in on. The policy routing lets the ZyWALL correctly forward the return traffic for the calls initiated from the LAN IP addresses.

For example, you configure firewall and NAT rules to allow LAN IP address A to receive calls through public WAN IP address 1. You configure different firewall and port forwarding rules to allow LAN IP address B to receive calls through public WAN IP address 2. You configure corresponding policy routes to have calls from LAN IP address A go out through WAN IP address 1 and calls from LAN IP address B go out through WAN IP address 2.

Figure 203 VoIP with Multiple WAN IP Addresses

Finding Out More

•See Section 6.5.12 on page 100 for related information on these screens.

•See Section 7.9 on page 139 for a tutorial showing how to use the ALG for peer- to-peer H.323 traffic.

•See Section 7.11 on page 146 for an example of making an IPPBX using SIP or a SIP server in the DMZ zone accessible from the Internet (the WAN zone).

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ZyWALL USG 50 User’s Guide