I hate that too and I actually changed my fax number and they still call. I don't understand how they got my new number. It is wicked annoying. Maybe they have some automated thing doing it. I don't bother calling those phone numbers at the bottom to be removed because then it's kinda like spam emails, now they know it's a real fax number and they probably sell it.
I listed my all numbers on the national do not call listing. I wish their fax numbers would show up but most times they don't, I can torture them back with faxes and tie up their machine and use up their ink film cartridges that cost a fortune
now I unplug the damn thing and plug it in when I need to send out stuff.