User manual

VOPTech Document Four Channel’s GSM VoIP Gateway

3.4.5.2 Media NAT Traversal

Similar to Signaling NAT Traversal, this feature allows media packets (RTP) to be

routed properly in various network environments.

A） None

Select None to disable this feature.

B） STUN （RFC 3489 ）

STUN (Simple Traversal of UDP (User Datagram Protocol) through NATs (Network

Address Translators)) is a network protocol allowing a client behind a NAT (or

multiple NATs) to find out its public address, the type of NAT it is behind and the

internet-side port associated by the NAT with a particular local port.

Select STUN(RFC 3489) to use a STUN server for Signaling NAT Traversal. Enter the IP

Address or the domain name of the STUN server to be used.

C）Port forwarding Support

Port forwarding (sometimes referred to as tunneling) is the act of forwarding a

network port from one network node to another. This technique can allow an

external user to reach a port on a private IP address (inside a LAN) from the outside

via a NAT-enabled router.

In order for this feature to work, the local network Gateway must support this

feature and be set up properly. Please consult your network administrator for help

to enable this Port forwarding feature.

D） Relay Proxy

Relay proxy is a proprietary NAT traversal technology. Please consult your service

provider for more information.

Currently, the following 3 kinds of packaging mechanism are supported:

¾ Mode 1: The media uses UDP packets and (or) encrypt with multiple UDP port;

¾ Mode 2: The media uses UDP packets and (or) encrypt with single UDP port;

¾ Mode 3: The media uses TCP packets and (or) encrypt (UDP over TCP).