hi Jeremy,
Let me see if I can offer some help. Every X2 or higher comes with the fax capability, but does NOT include the phone number for the fax. It is possible to assign the inbound fax number to one user and have that fax be sent to multiple people (you can have more than one email address in the fax notification field). As for SENDING faxes, only the person who has the fax number assigned has the ability to initiate faxes from within the WORK-D soft client.
So, maybe a shorter answer is, if you want multiple people to be able to send faxes, they each need a number assigned in the fax settings of the user profile.