Not strictly, IPv6 has enough addresses for every device to have a public IP. Some organizations still use NAT66 for privacy / security.

What Is NAT?

Q: How does NAT cause VoIP problems

SIP embeds IP addresses in the packet payload. Without NAT-awareness, the far end may send replies to a private IP that cannot be reached. SBC, STUN, or outbound proxies fix this.

Q: How many types of NAT exist

Static NAT, dynamic NAT, PAT (port-based), symmetric NAT, full cone NAT, each behaves differently especially for VoIP and WebRTC.

2026-05-07 2 min readSIPPER Team

NAT translates IP addresses between private LANs (192.168.x.x, 10.x.x.x) and the public internet. Every office router and firewall uses it so many devices can share a single public IP.

Definition

Common NAT is actually PAT (Port Address Translation) or NAPT, it translates outbound source IP + port to the router's public IP + a unique port, then reverses the mapping for return traffic.

Usage

Routers and firewalls use NAT so every office user shares a single public IP for outbound internet (many-to-one NAT).

Related Concepts

NAT Traversal helps applications like SIP / RTP work through NAT, using STUN, TURN, ICE, or SBC NAT helpers, since SIP carries IPs inside the payload that NAT needs to rewrite.

Frequently Asked Questions

How does NAT cause VoIP problems

How many types of NAT exist

Does IPv6 need NAT

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