Solution:
Class 1 refers to a fax modem standard designed to be an extension of the Hayes AT command set that permits computers to send and receive faxes using fax modems. This standard requires that most of the fax protocol work and image generation be handled by the software, and the basic communication handled by the modem. This standard is very sensitive to network traffic and maintaining the fax connection.
Class 2 refers to a more recent fax modem standard designed to be an extension of the Hayes AT command set that permits computers to send and receive faxes using fax modems. This higher-level standard lets the modem handle much of the fax protocol work and basic communication, freeing the software to manage the session and image generation.
Class 2.0 refers to the final version of the standard.
Because of the long time between (over two years) the availability of the first drafts of the Class 2 standard and this final approved standard, the "2.0" extension is used to distinguish this final version from the draft. This final version is not widely supported with the significant exception of U.S. Robotics and ZyXEL. See ITU-T T.32.
Ensure that the modem used on the Perle 833RAS supports Class 2 or 2.0 faxing.
Note that the Perle DSP modems on the 833AS and 833IS support Class 2 faxing.
Configure your fax application to use Class 2 or 2.0 faxing. This is usually located on the modem/serial configuration section of your fax application.