Plain-Paper Fax Machines

What defines a plain-paper fax machine

A plain-paper fax machine is a facsimile device that prints incoming documents onto ordinary cut-sheet office paper, the same stock used in a copier or desktop printer, rather than onto the heat-sensitive coated rolls used by earlier direct-thermal fax machines. The defining characteristic of the class is therefore the marking engine and the media it prints on, not the way the image travels down the line. A plain-paper machine forms the received page with a laser (electrophotographic) mechanism, an LED array, an inkjet head, or a thermal-transfer ribbon, any of which deposits toner or ink onto plain paper. Because the label describes output rather than transmission, plain-paper and thermal-paper machines can implement the very same ITU-T facsimile standards and interoperate freely.

Plain paper versus thermal paper

The contrast that gives the class its name is with direct-thermal fax machines, which image a chemically coated paper by selectively heating it. Reference literature notes that such thermal output is eradicable and brittle and tends to detach from or fade on the medium after long storage, so thermal faxes are generally not accepted in archives or courts as documentary evidence without first being photocopied. Plain-paper output, by contrast, is produced with the same permanent toner or ink used in office printing: it does not fade, lies flat instead of curling, and can be filed directly. Encyclopedic histories place the broad transition to plain paper from the mid-1990s, as laser and inkjet marking became inexpensive enough to build into fax and multifunction devices.

Marking technologies used

Plain-paper fax machines borrow their imaging directly from the printer world. Laser and LED models use the electrophotographic process, charging and exposing a photoconductor drum and fusing dry toner to the page, and produce sharp, permanent text well suited to business records. Inkjet models spray liquid ink and can additionally support color, although color faxing between different manufacturers was historically limited by the absence of a universal color-fax standard. Thermal-transfer models sit between the two worlds, melting pigment or wax from a ribbon onto ordinary paper rather than onto special thermal stock. In practice the class is now most often encountered not as a stand-alone fax unit but as one function of a multifunction laser or inkjet device that also copies, prints, and scans.

Transmission standards: still Group 3

Whatever their marking engine, the overwhelming majority of plain-paper fax machines are ITU-T Group 3 terminals that send and receive over the ordinary switched telephone network. Group 3 was standardized in 1980 and is defined by two ITU-T Recommendations working together: T.4, which specifies the image resolutions and the source coding used to compress a page, and T.30, which specifies the call-establishment and negotiation procedures by which two machines identify each other, agree a speed, and confirm each page. Group 3 image data is compressed with the Modified Huffman and Modified READ schemes of T.4. A separate digital family, Group 4, is defined for ISDN by Recommendations such as T.563 (terminal characteristics) and T.6 (Modified Modified READ coding); plain-paper output is equally compatible with either family, which is why the output class and the transmission group are independent of one another.

Documented resolutions and speeds

Under ITU-T T.4, a Group 3 machine scans and prints at a standard resolution of about 203 x 98 dots per inch, corresponding to roughly 8 picture elements per millimetre horizontally and 3.85 lines per millimetre vertically, with 1728 pels across the nominal scan line. A fine mode doubles the vertical detail to about 203 x 196 dpi (7.7 lines/mm), and an optional superfine mode roughly doubles it again. Transmission speed is set by the V-series voiceband modems the machine negotiates through T.30: V.27ter carries 4.8 or 2.4 kbit/s, V.29 carries 9.6 or 7.2 kbit/s, and V.17 reaches up to 14.4 kbit/s. Later Super Group 3 machines add a V.34-based fax modem that raises the ceiling to 33.6 kbit/s. These figures describe the Group 3 standard the machines implement rather than any single model.

Reference scope

This page describes plain-paper fax machines at the level of a class, and every specification above is a property of the ITU-T standards the class implements or of the marking technologies it uses, each cited to an authoritative source. It does not assign resolutions, speeds, prices, or dates to any individual model, because those vary by product and the source policy for this archive forbids inventing per-unit figures. Facts that could not be traced to an ITU-T Recommendation or a reputable encyclopedic or industry reference have been omitted rather than estimated. It is not a buying guide and quotes no current pricing or availability.