INT 2F - FaxBIOS interface - COMMAND SUBMISSION
        AX = 80FBh
        BX = function number (see below)
        DX:DI -> command buffer (see below)
Return: AL = FFh if submitted OK
        CX = result code (see below)
Note:   FaxBIOS may use any multiplex number from 80h through FFh
SeeAlso: AX=CBDDh