To receive a fax on your One40 number, you must have your number set up to "Play my main greeting".

Visit the Settings --> Your Numbers section

All of your voicemails and faxes will appear in your phone system's inbox.    

Use the built-in filters to narrow down your search results. For example, you can use the filter option "Type" set to "FAX" to show only your faxes.

When viewing your faxes you have the option to download, add a note, forward, or delete any fax. Each fax is held in your inbox for 30 days.