ZyXEL Elite 2864 User Guide - Page 155

Chapter 15 FAX OPERATION The 2864 series universal modems support the Group 3 sending and receiving facsimile function. For normal fax operation you must connect the modem to a computer, usually a PC. The computer is the input/output device for the fax function. The interface between the modem and the computer is the normal RS-232 serial connection or the ZyXEL parallel port interface. The modem uses the same interface for both data and fax applications. In fax operation, it performs protocol handshaking and image data transfer, and the computer does the job of image data creation, capturing, conversion, compression, decompression, retrieving, and storing. The 2864 series modems include some new fax functions, namely a direct fax recceiving and printing function that uses the modem's parallel port, as well as a standalone fax receiving and storing functionusing the optional DRAM add-on. These operations are described at the end of this chapter. In the sections below, we will describe the ITU-T T.30 fax protocol, the class 2 fax commands and the ZyXEL extended fax AT commands. The status report result codes and the flow control protocol associated with ZyXEL fax AT commands, as well as some fax applications are also covered. The instructions for using the included modem/fax/voice utility program are contained in the document file in the software disk. Please refer to the document disk file for software usage instructions and the latest developments. Some distributors and dealers also include other software with the modem. Refer to the accompanying documentation - printed or on disk. ITU-T T.30 Fax Protocol The ITU-T T.30 fax protocol describes the G3 fax handshake signals and procedures. The modem takes full control of this protocol, initiates and terminates fax calls, manages the communication session, and transports the image data. The modem shields the computer fax software from the T.30 protocol handling. Besides T.30, the 2864 series modems provide the highest fax speed of up to 14400 bps using the fax transmission standard V.17. When connected to an existing nonV.17 fax device, the modems provide a highest speed of 9600 bps and will automatically fall back to 7200, 4800, and 2400 bps if the line quality is not good enough. Connections to a V.17 machine may achieve a 14400 bps transmission speed. It will fall back to 12000, 9600, or 7200 bps if the line quality is not good enough. 15-1