Cisco Systems SPA9000 manual Configuring NAT Mapping with Stun, Click Submit All Changes

Configuring Your System for ITSP Interoperability	3
Network Address Translation (NAT) and Voice over IP (VoIP)

Voice tab > Line N > NAT Settings

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.

Configuring NAT Mapping with STUN

If the ITSP network does not provide a Session Border Controller functionality, and if other requirements are met, it is possible to use STUN as a mechanism to discover the NAT mapping. This option is considered a practice of last resort and should be used only if the other methods are unavailable.

Requirements:

•STUN is a viable option only if your router uses asymmetric NAT. See

“Determining Whether the Router Uses Symmetric or Asymmetric NAT,” on page 53.

•You must have a computer running STUN server software.

•The LAN switch must be configured to enable Spanning Tree Protocol and Port Fast on the ports to which the SPA devices are connected.

NOTE Use NAT mapping only if the ITSP network does not provide a Session Border Controller functionality.

STEP 1 Connect to the administration web server, and choose Admin access with Advanced settings.

STEP 2 Click Voice tab > SIP.

SPA9000 Voice System Administration Guide 51