How To Manage Voice Traffic - ZyXEL Communications ZyWALL USG Series Application Note

4.6.3 What Can Go Wrong
• The ZyWALL checks the firewall rules in order and applies the first firewall rule the traffic matches.
If traffic matches a rule that comes earlier in the list, it may be unexpectedly blocked.
• The ZyWALL does not apply the firewall rule. The ZyWALL only apply's a zone's rules to the
interfaces that belong to the zone. Make sure the WAN interface is assigned to WAN zone.

4.7 How to Manage Voice Traffic

Here are examples of allowing H.323 and SIP traffic through the ZyWALL.
4.7.1 How to Allow Incoming H.323 Peer-to-peer Calls
Suppose you have a H.323 device on the LAN for VoIP calls and you want it to be able to receive
peer-to-peer calls from the WAN. Here is an example of how to configure NAT and the firewall to
have the ZyWALL forward H.323 traffic destined for WAN IP address 10.0.0.8 to a H.323 device
located on the LAN and using IP address 192.168.1.56.
Figure 46
4.7.1.1 Turn On the ALG
Click Configuration > Network > ALG. Select Enable H.323 ALG and Enable H.323
WAN to LAN H.323 Peer-to-peer Calls Example
192.168.1.56
10.0.0.8