The new driver in fax.

Plain-paper fax is the new driver in the fax machine marketplace. Of course, such technology isn't new. Fax machines capable of printing documents on plain bond paper instead of conventional thermal paper were introduced into the mass market more than three years ago. But a $5,000 price tag kept them out of reach for most buyers.

But prices have been edging downward to a starting point that is under $1,000. This is good news for a growing number of business professionals for whom the investment in a plain-paper fax machine is now cost-effective.

In addition to producing a crisp, clear document on paper that doesn't curl up or fade (as does thermal paper), plain-paper machines can lower overall fax costs. For one, a fax no longer has to go through a copier to be transferred to regular paper, which usually is what happens first to an incoming thermal fax.

You can get the highest quality output and the richest formatting options with plain-paper fax machines with laser printing technology. But it is going to cost you a little more money. Two laser fax models that are around $3,000 are the UX2100 from Sharp Electronics Corp., Mahwah, N.J., and the KX-F5000 from Panasonic Communications & Systems Co., Secaucus, N.J. In comparison, the price range for ink-jet fax machines, such as the Fax 200 from Cupertino, Calif.-based Hewlett-Packard, is $1,500.

A lower-cost laser fax option is available if you have a laser printer. Interfaces that sell from $300 to $800 allow you to upgrade your printer into a receiving device that outputs laser quality faxes. For Hewlett-Packard LaserJet printers or compatibles, the HP Laser-Jet Fax ($1,395) is an add-on accessory that has send-and-receive capability and can be integrated with a computer enabling PC files to be sent as faxes.

Laser fax machines selling for $2,000 and up offer the full range of fax features. A good example is the JetFax 8000D, which lists for $2,695. It offers more features than models priced significantly higher. Such capabilities include fast scanning, in which the machine can scan a page into memory in two or three seconds. Other features are a 30-page auto-feeder and 60-page memory.

Becoming more common among top-end machines are high-speed modems (14,400 bits per second) that transmit a fax page in six seconds and at significantly lower transmission costs.

Atlanta-based Lanier Worldwide Inc. offers the FaxWriter series of desktop fax machines. Enhanced features include voice response for telephone and fax calls, speed dialing and relay broadcasting. The FaxWriter 3275 ($2,995) is a memory-equipped unit (optional 2 MB) that allows documents to be scanned, stored and sent to multiple units.

Don't be misled. Plain-paper fax isn't pushing thermal fax out the office backdoor. Or at least not yet.

Thermal machines are better bargains than ever. They define the low end of the market and remain the best cost option for many small companies and home offices.

Bare bones fax machines sell from $350 to $500 and are marketed as entry-level machines for the home office. Those units that don't have a paper cutter or an automatic document feeder may be too bare-boned for some people.

A reliable machine for a home-based business is the M700, from Dallas-based Murata/Muratec, which sells for $599. The M700 is half the size of a standard fax, with mainstream features such as an autodialer and built-in telephone.

Designed for small or remote site offices, machines with a fax/telephone switch eliminate the need for a separate fax phone line. Some machines have an interface that allow you to connect an answering machine.

The Panasonic KX-F90, which sells for around $850, offers its own built-in machine. But be warned: With only one phone line, you can't send or receive a fax and take a call at the same time. Anyone whose fax traffic is more than 10 a day needs to have a second phone line.

Industry forerunner Pitney Bowes Inc. in Stamford, Conn., is still a dominate player the market. The vendor's family of laser quality plain-paper fax machines include the model 9500/9550. These units offer such features as a 14.4 kbps modem, 30-page automatic document feeder, automatic reduction, 2 MB optional memory card and multi-tasking. The 9550 has an optional RS-232 communications interface.

For the average business user, selecting a fax machine often comes down to two issues: Is it easy to use, and does it have the features you need? According to recent surveys, the most desirable fax machine features are plain paper, memory, speed broadcasting and multi-tasking. Most top-of-the-line machines make faxing quick and simple and offer similar features. But since features do vary, you might want to keep in mind the following:

* Auto-feeder: This feature eliminates manual feeding. So, there's no waiting from page to page when you send a fax. Normally, the bigger the better. However, a 10-page feeder is a good standard minimum.

* Auto-dialer: Units with this feature are capable of storing from 20 to more than 150 phone numbers in memory, which you can automatically dial by pressing a few keys. Fax machines in the $500 to $800 range typically can hold from 30 to 80 numbers. Make sure the dialer can hold all the numbers on a regular fax distribution list.

* Memory: a word of caution. Manufacturers rate the number of pages that can be held in memory based on an industry standard of a business letter that runs one-half of a double-spaced page. You'll need to calculate your memory requirements if you send single-spaced pages. Also, memory is needed for certain other features, including broadcasting and confidential reception.

* Broadcasting: This feature allows the same document to be faxed to a programmed group of locations with a single send command. The number of user-defined groups that can be stored in memory is higher on pricier machines.

* Confidential transmission: Faxes sent between compatible machines from the same manufacturer can be tagged confidential with this feature. The incoming fax is stored in memory and can only be printed out when the receiver enters a special code.

* Gray Scale: Such a feature represents the number of halftones that a machine can transmit. For sending the best reproduced photos or illustrations, a machine with 32 or 64 gray scales is advised.

What fax machines share in common with most office equipment is inflated price tags. List prices can be a third or more higher than what a machine actually sells for at a discount dealer or office superstore. Office equipment dealers, which often have fewer brand selections, can't match the discounters in price, but they may offer better follow-up service.