You can configure new fax numbers by ordering numbers in termination manager, and configuring them as fax numbers.
Video Guide: A video guide that includes this process is available here
1. Go to the Fax webApp
2. Click [Inbound] > [Fax Numbers] > [Order a New Number]
3. Select a location and phone number
4. Enter the e-mail address you'd like to route the phone number to
5. Click Save
Faxes sent to your new number will now be delivered to the e-mail address specified. Inbound faxes can also be retrieved from the fax webApp, or via Communicator.