Cisco WRP500 Administration Manual page 123

Appendix C Troubleshooting
R E V I E W D R A F T # 1 — C I S C O C O N F I D E N T I A L
Q. The WRP500 is behind a NAT device or firewall and I'm unable to make a call or I'm only
receiving a one-way connection. What should I do?
Complete the following steps.
Configure your router to port forward "TCP port 80" to the IP address of the WRP500. You should
1.
use a static IP address. (For help with port forwarding, consult the documentation for the NAT device
or firewall.)
2. On the Line tab of the Configuration Utility, change the value of Nat Mapping Enable to yes. On the
SIP tab; change Substitute VIA Addr to yes, and the EXT IP parameter to the IP address of your
router.
Make sure you are not blocking the UDP PORT 5060,5061 and port for UDP packets in the range
3.
of 16384-16482. Also, disable "SPI" if this feature is provided by your firewall. Identify the SIP
server to which the WRP500 is registering, if it supports NAT, using the Outbound Proxy parameter.
Add a STUN server to allow traversal of UDP packets through the NAT device. On the SIP tab of
4.
the Configuration Utility, 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 address:
http://www.voip-info.org/wiki-Open+Source+VOIP+Software
Note 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.
Cisco WRP500 Administration Guide
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