User manual

Http://www.hybertone.com HT-822P VoIP FXS+PSTN Gateway
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the “Call Settings à Media Setting” configuration page, the “Codec Preference” screen
will be displayed as below.
Codec preference is the order of voice codec. The default one is up transmitting, which is
the set mode for common users.
4.4.5 NAT Traversal
4.4.5.1 Signaling NAT Traversal
Click on the “Signaling NAT Traversal” in the “Call Settings” configuration page’s “Advance
Settings”, the “NAT Traversal” screen will be displayed as follows.
Signaling NAT Traversal can make and receive calls through any type of NAT device.
There are three kinds of NAT traversal:
A） None
None means there is no traversal mechanism supported.
B） Port-forwarding Support
Port-forwarding is the action of forwarding network ports on the LAN interface to PCs or
servers in LAN network. Virtual servers use this technique to allow external users, in most
cases via internet, to reach services provided by internal servers such as FTP, HTTP,
Telnet, etc.
Port-forwarding support includes gateway address and echo server address. Gateway is a
communication device that connects two different networks. Echo server is a standard
service implementing the ECHO protocol.
C） STUN （RFC 3489 ）
STUN stands for Simple Traversal of UDP over NAT. It is a protocol which enables the SIP