Determining The Router's Nat Mechanism - Cisco Small Business Pro SPA9000 Administration Manual

Configuring Your System for ITSP Interoperability
Network Address Translation (NAT) and Voice over IP (VoIP)
STEP 6
STEP 1
STEP 2
STEP 3
SPA9000 Voice System Administration Guide
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Click Submit All Changes.
You also need to configure the firewall settings on your router to allow SIP
NOTE
traffic. See
Determining Whether the Router Uses Symmetric or
Asymmetric NAT
STUN does not work on routers with symmetric NAT. With symmetric NAT, IP
addresses are mapped from one internal IP address and port to one external,
routable destination IP address and port. If another packet is sent from the same
source IP address and port to a different destination, then a different IP address
and port number combination is used. This method is restrictive because an
external host can send a packet to a particular port on the internal host only if the
internal host first sent a packet from that port to the external host.
This procedure assumes that a syslog server is configured and is ready to receive
NOTE
syslog messages.
Make sure you do not have firewall running on your PC that could block the syslog
port (port 514 by default).
Connect to the administration web server, and choose Admin access with
Advanced settings.
To enable debugging, complete the following tasks:
a. Click Voice tab > System.
b. In the Debug Server field, enter the IP address of your syslog server. This
address and port number must be reachable from the SPA9000.
c. From the Debug level drop-down list, choose 3.
manuals search engine
"Firewalls and SIP," on page 54.
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