These are faxes that come through the Internet. The sender in area code 720 is a 3rd party faxing vendor. They may be in violation of the federal DNC legislation and the Telephone Consumer Protection Act, depending on how your phone and fax numbers are listed and whether they are registered. The ones we get to our fax line from this number are from a company purporting to be "M3 Global Research" with offices in Fort Washington, PA. They send to us several times a week, and our system isn't sophisticated enough to block them. They're a list building service, from what I can tell.