The high speed 33.6 kbps modem built into the Panasonic KX-FL421 is designed for super fast and efficient document transmissions. The built-in junk fax prohibitor feature helps prevent unwanted faxes from being received and wasting valuable toner and paper. The built-in ADF on the KX-FL421 allows the machine to be used as a desktop copier. Great for home office users who need to make an occasional copy. The KX-FL421 fax machine is caller ID3 compatible so you can see who's calling before answering. Utilizing the devices 2 line by 16 character LCD display, you're able to see the name and number of your incoming callers. You can even display and print a list of caller ID activity. All of this adds up to a great timesaving feature for both business and personal use.