ZyXEL Communications 2864 Series, User Manual, Page: 27 / 267

2–1
Chapter 2
MODEM AND FAX BASICS
This chapter is intended for those readers who want to know the details behind mo-
dem and fax operations; what's going on behind the scenes. In addition to introduc-
ing basic modem and fax terminology, this chapter helps users to understand and be
able to utilize the available features. Experienced modem and fax users may wish to
skip this chapter.
Modem
Modem is a compound word of MOdulator and DEModulator. A modem is used
for computer communications. Refer to Fig. 2.1 for a standard modem setup and
application.
A modem translates computer data to analog signals (modulation) that can travel
through the telephone network and reach another modem. The remote modem
translates the analog signal received back into data (demodulation) and sends the in-
formation to the receiving-end computer. Modems are telephones for computers,
what they use to talk to each other.
DTE and DCE
DTE and DCE are terminologies used in data communication. DTE stands for
Data Terminal Equipment and DCE stands for Data Circuit terminating Equip-
ment (Data Communication Equipment). Referring to Fig. 2.1, the computer or
terminal is the DTE and the modem is the DCE.
Modem
Modem
Fig. 2.1: Modems are used in computer communications.