ZyXEL Communications P-2602H - Manual (Page 148)

Chapter 10 Network Address Translation (NAT) Screens
P-2602H(W)(L)-DxA User’s Guide
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10.6.2 SIP ALG
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
LABEL DESCRIPTION
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.