Even if this were a function only available to those on dial-up, the printer driver for the fax would have to have been installed.
If the user didn't do it, who did and that is I believe the underlying question is.
I have got dial-up, but I don't have a Fax option in the Print drop down list of options, those that I do have other than the actual Printer had to be specifically installed, see image1. So you have to set up faxing, if you click that option, you are going to be asked for a CD or a location for the driver, image2; so this sort of thing can't really happen by accident, but by design.