DIS (DTC) / DCS perspective

Before starting communication, the sender and the receiver communicate their functions to each other before starting communication, and determine the communication function and speed.

The receiving fax machine transmits its own functions to the sending fax machine using a DIS signal. The sending fax machine receives the DIS signal from the receiving fax machine, selects the maximum function set by the sending device from the functions that can be used by both the sending device and the receiving device, and receives the selected communication mode using the DCS signal. Tell the side fax.

By examining the DIS (DTC) information, the contents of the capability declaration of the receiving fax can be found, and by examining the DCS information, the communication mode selected by the sending fax can be known.

Protocol monitor log is recorded and printed in one communication. If the protocol log becomes too long to fit on one page due to communication of multiple pages, the first protocol log is deleted, and only the last protocol log is recorded and printed.

DIS (DTC) / DCS records and prints on the protocol log so that the contents can be understood even if the first protocol log is deleted.

Fax communications are made in accordance with ITU recommendations, with the main recommendations involved being T.30 and T.4.

Documents of these recommendations are published online and can be downloaded from the following sites.

DIS (DTC) / DCS interprets the contents of the FIF (Facsimile Information Field) with reference to the bit assignment table of DIS (DTC) / DCS. The bit assignment table for DIS (DTC) / DCS is described below. The bit assignment table for DIS (DTC) / DCS is described below.

  • T.30 Document facsimile transmission procedure on the general switched telephone network
    Facsimile Information Field (FIF) / JT-T30 (ITU-T T.30)