Not long ago, fax modems were exotic, expensive, cutting-edge technology. Today they're standard equipment on many home and small business PC packages. In fact, it's hard to find a modem today that doesn't have fax capabilities built in.
Unfortunately, many users who have fax modems ignore their fax capabilities, passing up a handy, dual-purpose tool. Others buy fax modems thinking that at $100 to $200, they're cheap substitutes for an honest-to-goodness fax machine, which is not the case.
Most fax modems today have two functions. They can operate as standard modems for normal communications. They can run as fast as 14,400 bits per second (bps). That's the equivalent of 1,440 text characters a second, or enough to fill a computer screen in a second and a half. You can still find cheap modems that offer standard communications at only 2,400 bps, but the cost of high-speed communication has come down so quickly that the increased performance is well worth the extra money.
In addition to standard modem innards, fax modems have chips that emulate the transmission and receive circuitry in standard fax machines.
There's a big difference between the two types of communication, even if they're packaged in the same modem case. Let's say you're collaborating on a report or book with someone in another city. If you're using the same word processing software, you can use a standard modem to send the actual file you're working on. Your correspondent can call up that document, make changes, and send it back.
When you fax a document, all you're sending is a picture, a collection of dots that means something to you because your brain is smart enough to turn them into words and numbers. But those dots mean nothing to your word processor. Some high-end fax programs include optical character recognition software that can turn those dots back into usable text for your application programs, but the process is tedious and inaccurate at best.
In facsimile mode, fax modems also differ from desktop fax machines in the source of the images they send and the destination of the images they receive.
A desktop fax machine actually has three parts. There's a scanner, which converts documents into digital images; a telephone and facsimile modem that transmits and receives those images, and a printer that reproduces the image on paper. No matter how much you pay for a fax machine, the basic technology inside is the same. That's why different brands of fax machines can talk to one another without so much as a hiccup.
