Network Address Translation - Yealink SIP-T2XP Administrator's Manual

Administrator's Guide for SIP-T2xP IP Phones

Network Address Translation

Network Address Translation (NAT) is essentially a translation table that maps public IP
address and port combinations to private ones. This reduces the need for a large
number of public IP addresses. NAT ensures security since each outgoing or incoming
request must first go through a translation process. But in the VoIP environment, NAT
breaks end-to-end connectivity.
NAT Traversal
NAT traversal is a general term for techniques that establish and maintain IP
connections traversing NAT gateways, typically required for client-to-client networking
applications, especially for VoIP deployments. STUN is one of the NAT traversal
techniques supported by IP phones.
STUN (Simple Traversal of UDP over NATs)
STUN is a network protocol, used in NAT traversal for applications of real-time voice,
video, messaging, and other interactive IP communications. The STUN protocol allows
applications to operate behind a NAT to discover the presence of the network address
translator, and to obtain the mapped (public) IP address and port number that the NAT
has allocated for the UDP connections to remote parties. The protocol requires
assistance from a third-party network server (STUN server) usually located on public
Internet. The IP phone can be configured to act as a STUN client, to send exploratory
STUN messages to the STUN server. The STUN server uses those messages to determine
the public IP address and port used, and then informs the client.
The NAT traversal and STUN server are configurable on a per-line basis.
Procedure
NAT traversal and STUN server can be configured using the configuration files or locally.
Configuration File
Local
To configure NAT traversal and STUN server via web user interface:
180
<MAC>.cfg
Web User Interface
Configure NAT traversal and
STUN server on the IP phone.
For more information, refer to
Network Address Translation
page 345.
Configure NAT traversal and
STUN server on the IP phone.
Navigate to:
http://<phoneIPAddress>/servl
et?p=account-register&q=load
&acc=0
on