QuickLink II
From Just Solve the File Format Problem
QuickLink software was early telecommunications software developed by Smith Micro. QuickLink II was a popular fax/data and voice communication software for DOS, Windows & Macintosh. Its native format was graphics format with the extension QFX, based on TIFF.
Format Identification
QFX files are based on TIFF, early versions begin with "51 4C 49 49 46 41 58
" or "QLIIFAX" in ASCII. Later versions are TIFF's with the ascii "QL2FAXW" at byte 8.