User's Manual
GXP2130/GXP2140/GXP2160/GXP2170/GXP2135   
ADMINISTRATION GUIDE 
Page 69 of 85 
NAT SETTINGS 
If the devices  are kept within a private  network behind a firewall, we  recommend using STUN Server. 
Thefollowing settings are useful in the STUN Server scenario: 
  STUN Server 
Under Settings->General Settings, enter a STUN Server IP (or FQDN) that you may have, or look up 
a free public STUN Server on theinternet and enter it on this field. If using Public IP, keep this field 
blank. 
  Use Random Ports 
It is under Settings->General Settings.This setting depends on your network settings. When set to 
"Yes", it will force random generation ofboth the local SIP and RTP ports. This is usually necessary 
when multiple GXPs are behind thesame NAT. If using a Public IP address, set this parameter to "No". 
  NAT Traversal 
It is under Accounts X->Network Settings.Default setting is "No". Enable the device to use NAT 
traversal when it is behind firewall on a privatenetwork. Select Keep-Alive, Auto, STUN (with STUN 
server path configured too) or other optionaccording to the network setting. 










