ZyXEL P-2602HW Guida Utente

Chapter 10 Network Address Translation (NAT) Screens

P-2602H(W)(L)-DxA User’s Guide

Some NAT routers may include a SIP Application Layer Gateway (ALG). A SIP ALG allows 
SIP calls to pass through NAT by examining and translating IP addresses embedded in the 
data stream. When the ZyXEL Device registers with the SIP register server, the SIP ALG 
translates the ZyXEL Device’s private IP address inside the SIP data stream to a public IP 
address. You do not need to use STUN or an outbound proxy if your ZyXEL Device is behind 
a SIP ALG.
Use this screen to enable and disable the SIP (VoIP) ALG in the ZyXEL Device. To access 
this screen, click Network > NAT > ALG.

Figure 85   Network > NAT > ALG

Each field is described in the following table.

Table 50   Network > NAT > ALG

Enable SIP ALG

Select this to make sure SIP (VoIP) works correctly with port-forwarding and 

address-mapping rules.

Apply

Click this to save your changes and to apply them to the ZyXEL Device.

Reset

Click this to return to previously saved configuration.