Configuring Your System for ITSP
Interoperability
Network Address Translation (NAT) and Voice over IP (VoIP)
Cisco Small Business ATA Administration Guide
This chapter provides configuration details to help you to ensure that your
infrastructure properly supports voice services.
Network Address Translation (NAT) and Voice over IP (VoIP), on page 42
Firewalls and SIP, on page 48
Configuring SIP Timer Values, on page 48
NAT is a function that allows multiple devices to share the same public, routable, IP
address to establish connections over the Internet. NAT is present in many
broadband access devices to translate public and private IP addresses. To enable
VoIP to co-exist with NAT, some form of NAT traversal is required.
Some ITSPs provide NAT traversal, but some do not. If your ITSP does not provide
NAT traversal, you have several options.
NAT Mapping with Session Border Controller, on page 43
NAT Mapping with SIP-ALG Router, on page 43
Configuring NAT Mapping with a Static IP Address, on page 43
Configuring NAT Mapping with STUN, on page 45
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