ZyXEL Communications U-336E, User Manual

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46 Fax Operation
entity, or individual. In order to program this information into the
fax function of your modem, please refer to the documentation of
the fax software you will be using.
Modem as Fax Machine
Modems can also be designed to include a fax transmitting and
receiving function similar to a fax card. Since the modem's interface
with the computer is the standard serial RS-232 interface, this
interface is used for both modem and fax operations. Fax image
coding and decoding must be done in the computer. Modem/Fax,
also called fax/modem, can be either an external stand-alone unit or
a plug-in card. External stand-alone units can be connected to any
computer with a standard RS-232 serial port.
Your modem supports Group 3 send and receive facsimile
functions. For normal fax operation, you must connect the modem
to a computer, usually a PC. The computer serves as the
input/output device for the fax function. The RS-232 serial
connection or the ZyXEL serial port interface connects you modem
to the computer. Your modem uses the same interface for both data
and fax applications. In fax operations, the modem performs
protocol handshaking and image data transfer. The computer
handles image data creation, capturing, conversion, compression,
decompression, retrieval, and storage.
ITU-T T.30 Fax Protocol
The ITU-T T.30 fax protocol is known as the G3 fax handshake
signals and procedures. The modem takes full control of this
protocol - initiating and terminating fax calls, managing the
communication session, and transporting the image data. Therefore,
the modem relieves the computer fax software of the T.30 protocol
handling.