3Com NBX 100 Installation Manual page 191

To add a broadband connected telephone behind a NAPT device:
1 Make sure the NBX system is set up for IP operations, either Standard IP
or IP On-the-Fly. 3Com recommends that you use a VPN connection to
establish access from your home system to the NBX system network to
avoid security issues on the NBX system.
2 Use the NBX NetSet utility to enable Auto Discover Telephones
(System-wide Configuration > Auto Discovery) and then connect the NBX
Telephone to the NBX system.
Auto discovering the telephone while it is connected locally to the NBX
network allows the system to configure the phone in the database and
assign an extension number. You could manually add the telephone to
the database instead of using the Auto Discover feature.
3 Move the telephone to its intended location. Connect it to power and
then use the telephone Local User Interface (LUI) utility to program these
settings:
NCP MAC address — Required only when the network has more than
one Network Call Processor.
Telephone IP address — A private IP address matching the IP address
scheme on the LAN side of the NAPT device but outside of the DHCP
address range configured in the NAPT device. The telephone must
have a static IP address. For pcXset, this would be the IP address of the
computer.
NCP IP address — The IP address of the NCP that the phone must
communicate with. If you are not connecting to the network through
a VPN connection, the NBX system must have a public IP address.
Subnet Mask — The address mask in use on the LAN side of the NAPT
device.
Default Gateway — The IP address of the NAPT device on the LAN.
For details on how to start the LUI utility, see the NBX Administrator's
Guide.
4 Configure the NAPT device:
Use the device's user interface to map UDP ports 2093-2096 to the NBX
telephone IP address. These UDP ports are registered ports for NBX
operations. This mapping feature, known as virtual server, port mapping,
port range forwarding, or rules, is required to allow traffic to pass to and
from the NBX Telephone.
Configuring IP Telephony 191