I've been receiving fax attempts from the same two numbers for at least a year now. I just tracked down the company that sources these fax lines and they're called Venali, Inc. After calling them, the customer service rep pointed me to their website, http://fax.venali.com. When you go there, there's a tab for "Support" and under that tab is a link to Report Nuisance Calls. I guess the idea is, you fill out the form and they'll track down the person trying to fax you using their service.
Here's the direct link to their "Support" page - http://www.fax.venali.com/content/support
Thanks! your information helped to contact the company but of course nothing was done! I have put them on the do not call list several times, I have privacy director and cant believe I still receive the calls! I am so annoyed, the phone is ringing late at night, I have a baby sleeping in the house. This occurs 4 - 8 times in a row three times a month. They deserve to get fined for the constant disruption!