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Table 4-5 Description of SIP NAT Settings
Items
Description
Enable
STUN
STUN (Simple Traversal of UDP through NATs) is a protocol for assisting
devices behind a NAT firewall or router with their packet routing.
STUN
Address
The STUN server allows clients to find out their public address, the type of NAT
they are behind and the internet side port associated by the NAT with a particular
local port. This information is used to set up UDP communication between the
client and the VOIP provider and so establish a call.
External IP
Address
The IP address that will be associated with outbound SIP messages if the system is
in a NAT environment.
External Host
Alternatively you can specify an external host, and the system will perform DNS
queries periodically. This setting is only required when your public IP address is not
static. It is recommended that a static public IP address is used with this system.
Please contact your ISP for more information.
External
Refresh
Interval
Used to identify the local network using a network number/subnet mask pair when
the system is behind a NAT or firewall.
Some examples of this are as follows:
“192.168.0.0/255.255.0.0”: All RFC 1918 addresses are local
networks; “10.0.0.0/255.0.0.0”: Also RFC1918;
“172.16.0.0/12”:Another RFC1918 with CIDR notation;
“169.254.0.0/255.255.0.0”: Zero conf local network. Please
refer to RFC1918 for more information.
NAT
Mode
Global NAT configuration for the system; the options for this setting are as follows:
Yes = Use NAT. Ignore address information in the SIP/SDP headers and reply to
the sender's IP address/port.
No = Use NAT mode only according to RFC3581.
Never = Never attempt NAT mode or RFC3581 support. Route
= Use NAT but do not include rport in headers.
Allow RTP
Reinvite
By default, the system will route media steams from SIP endpoints through itself.
Enabling this option causes the system to attempt to negotiate the endpoints to
route packets to each other directly, bypassing the system. It is not always
possible for the system to negotiate endpoint-to-endpoint
media routing.
3) Codecs
We can choose the allowed codec in XT-800FXO Gateway, a codec is a
compression or decompression algorithm that used in the transmission of voice
packets over a network or the Internet.
