Cisco SPA942 - Cisco - IP Phone User Manual

Configuring SIP, SPCP, and NAT
Network Address Translation (NAT) and Cisco IP Phones
110 Cisco SPA and Wireless IP Phone Administration Guide
5
NAT Mapping with Session Border Controller
It is strongly recommended that you choose an ITSP that supports NAT mapping
through a Session Border Controller. With NAT mapping provided by the ITSP, you
have more choices in selecting a router.
NAT Mapping with SIP-ALG Router
If the ITSP network does not provide a Session Border Controller functionality, you
can achieve NAT mapping by using a router that has a SIP ALG (Application Layer
Gateway). The WRV200 router is recommended for this purpose, although any
router with a SIP-ALG can be used. By using a SIP-ALG router, you have more
choices in selecting an ITSP.
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 113.
• 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 Click Admin Login and advanced.
STEP 2 Click the SIP tab.

Cisco SPA942 - Cisco - IP Phone Specifications

General

Brand	Cisco
Model	SPA942 - Cisco - IP Phone
Category	IP Phone
Language	English