When a person is located within a private network, they might not have a unique global IP address. For example, a lot of people may have assign as their private network addresses for SIP phones. So how can a SIP server or a SIP UA distinguish you from the rest of the people who have that same IP address?

Many SIP devices try to go over NAT (Network Address Translation) using products such as a STUN (Session Traversal Utilities for NAT) server that doesn't work with all types of NAT, or UPnP, which requires hardware supported UPnP and even then it sometimes can't go over NAT.

From the introduction of our SIP server, we have supported SIP-NAT. Here is how we do it:

Solving Near-End NAT Traversal

  • Brekeke SIP Server resides within a LAN (Local Area Network)
  • A SIP UA that is registered with the SIP server within the same LAN connecting with a SIP UA outside of the LAN

The Brekeke SIP Server does address mappings between SIP UA's local IP addresses and the global IP address. All SIP and RTP packets are relayed through Brekeke SIP Server.  

Solving Far-End NAT Traversal
  • A SIP UA is located within a LAN
  • Brekeke SIP Server is located outside the LAN

Far-End NAT Traversal can be a little more complicated, but the Brekeke SIP Server performs the same kind of process as it does in the Near-End NAT Traversal. All SIP and RTP packets are relayed through Brekeke SIP Server.

©2012 Brekeke Software, Inc.