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P-2000W_V2 User’s Guide
12.12.3 STUN
STUN (Simple Traversal of User Datagram Protocol (UDP) through Network Address Translators) allows the Prestige to find the presence and types of NAT routers and/or firewalls between it and the public Internet. STUN also allows the Prestige to find the public IP address that NAT assigned, so the Prestige can embed it in the SIP data stream. STUN does not work with symmetric NAT routers (see Section 12.11.2.4 on page 87) or firewalls. See RFC 3489 for details on STUN.
The following figure shows how STUN works.
1The Prestige (A) sends SIP packets to the STUN server.
2The STUN server finds the public IP address and port number that the NAT router used on the Prestige’s SIP packets and sends them to the Prestige.
3The Prestige uses the public IP address and port number in the SIP packets that it sends to the SIP server.
Figure 26 STUN
12.12.4 Outbound Proxy
Your VoIP service provider may host a SIP outbound proxy server to handle all of the Prestige’s VoIP traffic. This allows the Prestige to work with any type of NAT router and eliminates the need for STUN or a SIP ALG. Turn off a SIP ALG on a NAT router in front of the Prestige to keep it from retranslating the IP address (since this is already handled by the outbound proxy server).
12.13 NAT Traversal Configuration
Click NAT TRVSL to open the following screen where you can configure your Prestige to operate through a NAT router that is not
The following screen displays the IP address and port number of an outbound proxy server the Prestige uses to connect to the outbound proxy server.
| Chapter 12 User Web Configurator Screens | 89 |
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