INT 2F - ZyXEL ZFAX v2.0-2.23 - INSTALLATION CHECK
        AX = DB00h
Return: AL = 5Bh installed
Program: ZFAX is the bundled FAX software which comes with the ZyXEL model
          fax modems.
SeeAlso: AX=CBDCh,AX=DA01h,AX=DA02h,AX=DA03h

.