Two-way PC-fax interface

This circuit imitates a small telephone exchange, allowing a PC to dial a Fax machine, and vice versa, without actuaIly making use of the public telephone network. Very useful if you want to employ your fax as a scanner (switch it to high resolution!), or as a 200-odd dpi printer. For these applications, it is assumed that you have a fax card in your PC. The software supplied with this card will then enable you to convert scanned images into the widely used TIFP format. The circuit shown here is suitable for pulse dialing only. Fortunately, that is still supported by most fax machines and ec fax eards.