A telefacsimile (fax) machine is a device that scans a document a narrow band at a time converting it into tones that can be conveyed over traditional telephone lines to a receiving device that reproduces a facsimile—exact duplicate—of the document. A fax machine typically has a paper feeder that can be used for feeding multiple-page documents, a telephone key pad and handset, and a status display, as shown in Figure 6.5.
Transmission rates of fax machines are typically limited by the use of traditional telephone lines. The data transmission uses the same method as a dial-up computer modem. A Group 3 fax machine has a maximum data rate of 14.4 kilobits per second (Kbps), but if the phone connection is poor, it will drop down to lower speeds automatically until it can establish a reliable connection between machines.
The Group 3 fax machine digitizes data in a form that is compatible with computers and the fax function is often integrated with other computer functions. A multifunction device, such as the one shown in Figure 6.6, can scan a document and save it as an image, send it as a fax, or print multiple copies.
Fax machines have been around a long time and enjoy a high level of trust for transmitting documents accurately. In many countries, a fax of a signed contract is legal, but a computer-scanned image is not.
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