Linksys ATA Administration Guide
39
Network Address Translation (NAT) and Voice over IP (VoIP)
Configuring Your System for ITSP Interoperability
Configuring NAT Mapping with a Static IP Address
If the ITSP network does not provide a Session Border Controller functionality, and if other
requirements are met, you can configure NAT mapping to ensure interoperability with the ITSP.
Requirements:
•
You must have an external (public) IP address that is static.
•
The NAT mechanism used in the router must be symmetric. See
”Determining Whether the
Router Uses Symmetric or Asymmetric NAT,” on page 41
.
•
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.
1. Connect to the administration web server, and choose Admin access with Advanced
settings.
2. Click
Voice tab > SIP
.
3. Scroll down to the
NAT Support Parameters
section, and then enter the following settings to
support static mapping to your public IP address:
•
Handle VIA received, Insert VIA received, Substitute VIA Addr:
yes
•
Handle VIA rport, Insert VIA rport, Send Resp To Src Port:
yes
•
EXT IP:
Enter the public IP address for your router.
Voice tab > SIP: NAT Support Parameters
4. Click
Voice tab > Line
N
, where
N
represents the line interface number.
5. Scroll down to the
NAT Settings
section.
•
NAT Mapping Enable:
Choose
YES
.
•
NAT Keep Alive Enable:
Choose
YES
(optional).
Voice tab > Line N > NAT Settings
