They don't have it on machines that don't sit on a desk basically, fax is mostly dead out dated technology and this type of MFP rarely resides near enough to a person to make the option viable.
As for not calling Xerox, the only option (limited to USA/Canada) is to use Fast track to the Experts links on the support pages.
But you will eventually end up on the phone (assuming the device has a maintenance agreement). Most of us who work for Xerox in 2nd level support dream of the day they will allow us to work by email, but so far they do not allow it at all, even if the customer uses the fast track option and lists email as the primary contact method :-(