Not all fax boards can handle data (some are fax only). Most (all?
external fax modems can handle data as well as fax. Some (but not all) fax modems and software can automatically distinguish between data and fax calls and answer them appropriately. Some DOS/WINDOWS based products can automatically distinguish between voice and fax/data calls and operate as a digital answer machine as well as a fax machine. Also, several companies sell devices which can switch incoming calls between a fax machine, a telephone answering machine, and a modem.
