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Subscriber Information
Display Name
User ID
Password
Auth ID
Use Auth ID
4.5.
Configuration for NAT Traversal
In general, there are 3 general approaches to enable NAT traversal available on the PHONE
ADAPTER: STUN (Simple Traversal of UDP through NAT), Using an outbound rewriting "proxy", and
manual configuration. If the PHONE ADAPTER is not "behind" a NAT, the default settings should be
used.
Note: The Linksys model RT31P2 includes NAT (Network Address Translator) functionality. As long
as the IP address of the "WAN Port" is a public IP address, the RT31P2 can be configured with all
NAT Traversal features (NAT Traversal off), since the PHONE ADAPTER portion shares the same IP
address as the WAN Port. If the address obtained on the WAN Port is already a private address, then
the RT31P2 still needs to be configured for NAT traversal.
The Outbound Proxy approach works through more than 99% of NATs, but it requires the service
provider to relay RTP media packets for every call. To use this approach, set the following
parameters: Outbound_Proxy, Use_Outbound_Proxy, NAT_Keep_Alive_Dest,
NAT_Keep_Alive_Msg, NAT_Keep_Alive_Intvl, and NAT_Keep_Alive_Enable. If the
NAT_Keep_Alive_Msg parameter is set to blank, the PHONE ADAPTER will send a Carriage-
Return/Line-Feed as the Keep-Alive Message.
The STUN approach works through more than 95% of home NATs when there is only a single
PHONE ADAPTER in use behind the same NAT. The STUN approach requires a STUN server setup
by the provider, but uses very few resources. The actual media flows directly between the PHONE
ADAPTER and its peer. To configure STUN set the following parameters: STUN_Enable,
STUN_Test_Enable, STUN_Server, NAT_Mapping_Enable, Substitute_VIA_Addr,
NAT_Keep_Alive_Dest, NAT_Keep_Alive_Msg, NAT_Keep_Alive_Intvl, and
NAT_Keep_Alive_Enable.
The Manual Configuration approach requires coordinated administration of the NAT and the PHONE
ADAPTER. It is not practical for general retail use, but can be used behind symmetric NATs
occasionally found in larger businesses, for troubleshooting, and in circumstances where other
mechanisms have been exhausted. The configure the PHONE ADAPTER for manual NAT traversal,
set the EXT_IP parameter to the public/translated/outside/external IP address, the EXT_SIP_Port
parameters (per line) to the translated port number for this line and PHONE ADAPTER, and the
EXT_RTP_Port_Min parameter to the first translated port number reserved for this PHONE
© 2004 Linksys Proprietary (See Copyright Notice on Page 2)
parameter is useful only if the primary and backup
proxy server list is provided to the PHONE
ADAPTER via DNS SRV record lookup on the
server name. (Using multiple DNS A record per
server name does not allow the notion of priority
and so all hosts will be considered at the same
priority and the PHONE ADAPTER will not attempt
to fall back after a fail over)
Subscriber's display name to appear in caller-id
Subscriber's user-id. Usually a E.164 number
Subscriber's a/c password
Subscriber's authentication ID
If set to "yes", the pair <Auth ID> and <Password>
are used for SIP authentication. Else the pair <User
ID> and <Password> are used.
Str23
Str47
Str23
Str39
Bool
No
49
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