Linksys SPA1001 Administrator User Manual page 72

Troubleshooting and Configuration FAQ
C. Make sure you are not blocking the UDP PORT 5060,5061 and port for UDP packets in the
D. Add a STUN server to allow traversal of UDP packets through the NAT device. On the SIP tab of the
Note
Linksys ATA Administrator Guide
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range of 16384-16482. Also, disable "SPI" if this feature is provided by your firewall. Identify
the SIP server to which the Linksys ATA is registering, if it supports NAT, using the <Outbound
Proxy> parameter.
administration web server, set <STUN Enable> to yes, and enter the IP address of the STUN server
in <STUN Server>.
STUN (Simple Traversal of UDP through NATs) is a protocol defined by RFC 3489, that allows a
client behind a NAT device to find out its public address, the type of NAT it is behind, and the port
associated on the Internet connection with a particular local port. This information is used to set up
UDP communication between two hosts that are both behind NAT routers. Open source STUN
software can be obtained at the following website:
http://www.voip-info.org/wiki-Open+Source+VOIP+Software
STUN does not work with a symmetric NAT router. Enable debug through syslog (see FAQ#10),
and set <STUN Test Enable> to yes. The messages indicate whether you have symmetric NAT
or not.
Chapter 3 Configuring Linksys ATAs
Document Version 3.1