ZyXEL P-660HW-T1 v3 User Guide - Page 181

The SIP ALG Screen, NAT Technical Reference

Page 181 highlights

Chapter 9 Network Address Translation (NAT) 9.5 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 73 Network > NAT > ALG The following table describes the fields in this screen. Table 49 Network > NAT > ALG LABEL DESCRIPTION Enable SIP ALG Select this to make sure SIP (VoIP) works correctly with portforwarding and address-mapping rules. Apply Click this to save your changes. Reset Click this to restore your previously saved settings. 9.6 NAT Technical Reference This chapter contains more information regarding NAT. 9.6.1 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 P-660HW-Tx v3 Series User's Guide 181

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Chapter 9 Network Address Translation (NAT)
P-660HW-Tx v3 Series User’s Guide
181
9.5
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 73
Network > NAT > ALG
The following table describes the fields in this screen.
9.6
NAT Technical Reference
This chapter contains more information regarding NAT.
9.6.1
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
Table 49
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.
Reset
Click this to restore your previously saved settings.