Question about HylaFAX - pdf to fax conversion

Hi,

I am having a problem with HylaFax through Elastix.

Faxes are being received correctly, and sent fine. I have a problem with
the quality of the fax sent from PDF.
e.g. if I send a PDF through the sendfax commandline, or through the
Elastix UI, the PDF is being converted to a TIFF for the fax sending using
this command:

/usr/bin/gs -q -sDEVICE=tiffg4 -dNOPAUSE -dSAFER=true -sPAPERSIZE=a4
-dFIXEDMEDIA -dMaxStripSize=0 -dBATCH -r209.10x196
-sOutputFile=docq/doc604.pdf;c1 docq/doc604.pdf.604

(this is the command that is being ran by the pdf2fax script).

the output file's quality is very poor, what causes the fax sent to be in
poor quality, and sometimes not readable.

I tried playing with the conversion, and noticed that when using
-sDEVICE=tiffgray the file is better, but not able to send it through the
sendfax, because its not compressed with Group 3 or Group 4 compression.

What's the best method to convert pdf2fax so it'll make it black/white but
in good quality and sharp, and not bad quality?

Thanks,
Ido