I have been receiving these for the past 15 years, the latest one is requesting $487.00 for an internet yellow pages listing,
unfortunately this is a legal practice but the faxes themselves may not be, as someone above mentioned they would like contact from you to prove they have a  existing business relationship (EBR) with your company, this will void a citation for sending unwanted faxes.
I have been told to fax the fax to the fax police (a company that claims if you fax it to them, they will stop the fax and collect $20.00 for each unsolicited fax they receive)
This too is probably a scam. Below is the response to unwanted faxes from the BBB.

The FCC can issue warning citations and impose fines against companies violating or suspected of violating the junk fax rules, but does not award individual damages. If you have received a fax advertisement from someone who does not have an EBR with you or to whom you have not provided prior express permission to send fax advertisements, you can file a complaint with the FCC. You can file your complaint by completing the FCC’s on-line complaint Form 1088 at: www.fcc.gov/cgb/complaints.html <file:///cgb/complaints.html> ; e-mailing [email protected] <mailto:[email protected]> ; calling 1-888-CALL-FCC (1-888-225-5322) voice or 1-888-TELL-FCC (1-888-835-5322) TTY; faxing 1-866-418-0232