server 2003 fax service - outgoing e-mails not pretty

I hope this is the right group, and I hope someone here can help give me
some ideas of where to start with this. I set up the fax service on a
Windows Server 2003. The modem is on the hardware compatibility list; it is
a MultiTech World Modem Desktop Business Modem. Receiving faxes works just
fine. But sending faxes usually doesn't. The most frequent problem is that
sent faxes come across a piece at a time - I'll try to explain - a one-page
fax of just a cover sheet can show up on the other end as 6 pages, each with
a little more of the picture, but even the last page doesn't yet have the
whole page - and sometimes the fax server rates this as a fax sent
successfully. It has also happened that what is sent is just junk -
described as "little boxes."
We have tried sending from Word and Outlook. Usually the faxes sent from
Outlook seem to look better at the receiving end, but that could just be a
fluke.
Any ideas where I should start troubleshooting with this?
Thanks,
Angie