# STUN
> Session Traversal Utilities for NAT – helps VoIP endpoints discover their public IP address

STUN enables VoIP endpoints behind NAT to discover their public IP for call connectivity.

## What is STUN?
STUN (Session Traversal Utilities for NAT) is a protocol that allows a VoIP endpoint behind a [NAT](/voip-glossary/nat-traversal/) device to discover its public-facing IP address and port. This information is then embedded in [SIP](/voip-glossary/sip/) signaling so the remote party knows where to send media.

## STUN limitations
STUN works well for most NAT types but fails with symmetric NATs commonly found in large corporate networks. In those cases, TURN (Traversal Using Relays around NAT) relays the media through an intermediary server. ICE combines both STUN and TURN for maximum connectivity.

## Related Terms
- [NAT Traversal](/voip-glossary/nat-traversal/)
- [Firewall Traversal](/voip-glossary/firewall-traversal/)