The Sip Alg Screen; Nat Technical Reference; Nat Definitions; Figure 76 Network > Nat > Alg - ZyXEL Communications P-660HN User Manual

Table 48 Network > NAT > Address Mapping: Edit (continued)
LABEL
Apply
Cancel

8.5 The SIP ALG Screen

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 76 Network > NAT > ALG
The following table describes the fields in this screen.
Table 49 Network > NAT > ALG
LABEL
Enable SIP ALG
Apply
Reset

8.6 NAT Technical Reference

This chapter contains more information regarding NAT.

8.6.1 NAT Definitions

Inside/outside denotes where a host is located relative to the ZyXEL Device, for example, the
computers of your subscribers are the inside hosts, while the web servers on the Internet are
the outside hosts.
Global/local denotes the IP address of a host in a packet as the packet traverses a router, for
example, the local address refers to the IP address of a host when the packet is in the local
network, while the global address refers to the IP address of the host when the same packet is
traveling in the WAN side.
P-660HN-Fx User's Guide
DESCRIPTION
Click this to save your changes.
Click this to restore your previously saved settings.
DESCRIPTION
Select this to make sure SIP (VoIP) works correctly with port-forwarding and
address-mapping rules.
Click this to save your changes.
Click this to restore your previously saved settings.
Chapter 8 Network Address Translation (NAT)
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