The fax server products I looked at shared a number of features. You simply select the appropriate entry in your phone book to send a fax, instead of keying in the fax number. You can print and view documents at both the server and client levels. Your fax server can act like a conventional fax machine if you set it up to print everything it receives. This is the minimal set of capabilities.
Some products provide support for additional fax-generation techniques.
Some fax servers can run on either a Windows NT Workstation or Windows NT Server system while others function only on an NT Server system. An application can embed fax command codes in a file or print stream. The fax server uses those codes to determine where to send the fax and how to format it. Support for embedded fax-command codes enables you to generate faxes with the information contained in a database or other external data structure. You can even receive faxes via email, in which case the fax image is mailed as an attachment file.