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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
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NAT Mapping with Session Border Controller
We recommend that you choose an service provider that supports NAT mapping
through a Session Border Controller. With NAT mapping provided by the service
provider, you have more choices in selecting a router.
NAT Mapping with SIP-ALG Router
NAT mapping can be achieved by using a router that has a SIP Application Layer
Gateway (ALG). By using a SIP-ALG router, you have more choices in selecting an
service provider.
NAT Mapping with a Static IP Address
You can configure NAT mapping on the phone to ensure interoperability with the
service provider.
•
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
.
Use NAT mapping only if the service provider network does not provide a Session
Border Controller functionality. To configure NAT mapping on the phone:
STEP 1
Click
Voice
>
SIP
and navigate to NAT Support Parameters.
STEP 2
Set the following parameters to
yes
:
•
Handle VIA received
•
Insert VIA received
,
•
Substitute VIA Addr
•
Handle VIA rport
•
Insert VIA rport
•
Send Resp To Src Port
STEP 3
Enter the public IP address for your router
EXT IP
field.
STEP 4
Click the
Ext_n
tab and navigate to
NAT Settings
.
STEP 5
Set
NAT Mapping Enable
to
yes
.