How does WinRPI work with the fax mode of my modem?
Facsimile transmission does not require V.42/V.42bis or MNP4/MNP5 for error correction and data compression. On modems supporting RPI+, WinRPI transparently passes data between the modem and the application software. On modems supporting the original RPI, WinRPI must be disabled using the Windows applet called “WinRPI Enhancer” (WRPIEN.EXE) before executing the fax application. See the WinRPI release notes for more information.