Configuring SIP, SPCP, and NAT
Managing NAT Transversal with Cisco IP Phones
Cisco Small Business SPA300 Series, SPA500 Series, and WIP310 IP Phone Administration Guide 144
4
• Send Resp To Src Port
• STUN Enable
STEP 3 Enter the IP address for your STUN server in the STUN Server field.
STEP 4 Click Ext_n.
STEP 5 Set NAT Mapping Enable to yes.
STEP 6 (Optional) Set NAT Keep Alive Enable to yes.
The service provider might require the phone to send NAT keep alive messages to
keep the NAT ports open. Check with your service provider to determine the
requirements.
STEP 7 Click Submit All Changes.
STEP 8 Configure the firewall settings on your router to allow SIP traffic. See Configuring
SIP.
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, 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
syslog messages.
To Determine Whether the Router Uses Symmetric or Asymmetric NAT:
STEP 1 Verify that the firewall is not running on your PC. (It can block the syslog port.) By
default, the syslog port is 514.)
STEP 2 Click Voice > System and navigate to Optional Network Configuration.
STEP 3 Enter the IP address for the Debug Server and port number of your syslog server,
if the port number is anything other than the default, 514. It is not necessary to
include the port number if it is the default.
To Next Page
Loading...
Need help?
General
