MediaProxy is a media relay for RTP/RTCP and UDP streams that works in tandem with OpenSIPs to provide NAT traversal capability for media streams from SIP user agents located behind NAT.


MediaProxy 2.0 is the second generation media relay application which is based on a completely new design that allows for major improvements in areas such as scalability (an order of magnitude more scalable than previous version) and security (communication between relay and dispatcher is encrypted). NAT (Network Address Translation) is a technology used for broadband connections like ADSL or cable which allows multiple computers to share one connection for accessing the Internet. The disadvantage is that Peer to Peer applications (like VoIP) do not work behind NAT without complex settings which are most of the time out of reach for the end-users.

The current best practices for standards-based NAT traversal are based on J. Rosenberg's Interactive Connectivity Establishment (ICE), a methodology for NAT traversal for Multimedia Session Establishment Protocols like SIP. The ICE approach utilizes existing protocols like STUN and TURN.

As any many other techniques, TURN has disadvantages. One that stands out is that the media traffic must pass central points on public Internet visible from all sides participating in the SIP sessions. AG Projects compensated this drawback by designing an architecture with no single-point of failure, addressing privacy requirements of end-users and providing 100% reliable accounting that cannot be achieved by SIP stateful proxies alone.


  • Scalability of thousands of calls per server limited only by the Linux kernel networking layer and network interface bandwidth
  • TLS encryption between the relays and dispatcher
  • T.38 fax support
  • Graceful shutdown capability
  • Modular design for custom selection algorithms of the relay location
  • Automatic load balancing and redundancy among all servers
  • Real-time sessions statistics
  • Web page for media sessions with search capability
  • Configurable IP and UDP port range
  • Support for any combination of audio and video streams
  • Radius accounting of IP network traffic
  • Logging of complete media information including all streams, their type, their codec and duration.

Some features that were present in the previous version have been removed:

  • Support for specifying media relays per domain has been discontinued
  • Support for DNS records has been discontinued
  • Support for asymmetric clients has been discontinued
  • Support for other operating systems than Linux has been discontinued (only for the media relay, as the dispatcher has no such limitation)

The web page for the previous version MediaProxy 1.x is available here


MediaProxy is an Open Source project. You may use the software free of charge under the GNU General Public License. Under commercial license, AG Projects delivers NAT traversal solutions with geographical distribution based on customized logic and lawful interception.

The software can be downloaded from