I support a variety of medical clinics and faxing is still one the mainstays for transmitting documents electronically due to security compliance. For many clinics, a physical fax machine is overly archaic and not robust enough to work alongside their electronic medical records systems and so they require a fax server or virtual fax service. The latter is out of the question, again due to the compliance issues. The product we've found best suited has been the US Robotics 56k USB Modem 5637. This little USB modem plugs in to a computer and can be integrated with Windows Fax and Scan feature found in Windows Vista and onwards.