Linksys SPA922 Cisco SPA9000 Voice System Administration Guide - Page 55

Configuring Your System for ITSP Interoperability Network Address Translation (NAT) and Voice over IP (VoIP) 3 STEP 6 Click Submit All Changes. NOTE You also need to configure the firewall settings on your router to allow SIP traffic. See "Firewalls and SIP," on page 54. 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. NOTE This procedure assumes that a syslog server is configured and is ready to receive syslog messages. STEP 1 Make sure you do not have firewall running on your PC that could block the syslog port (port 514 by default). STEP 2 Connect to the administration web server, and choose Admin access with Advanced settings. STEP 3 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. SPA9000 Voice System Administration Guide 53