Hi,
The server has two Ethernet ports, one is LAN the other is WAN.
LAN interface
allow-hotplug eth0
auto eth0
iface eth0 inet static
address 192.168.20.100
netmask 255.255.255.0
####gateway 192.168.20.1
WAN interface(Sip Provider)
allow-hotplug eth1
auto eth1
iface eth1 inet static
address...