Just wanted to post this for those anyone having trouble with setting up Hylafax, and get the above message.
I was able to specify the modem speed by guessing what it was in the faxaddmodem program:

faxaddmodem -s 19200

I also had to run:
<pre style="font-style: italic;">/usr/sbin/faxmodem ttyS0

</pre>And fix the entry in /etc/inittab
mo:2345:respawn:/usr/lib/fax/faxgetty /dev/ttyS0

After I did this, it took the settings and my faxes sent.

Tips

Try: ps -aux | grep fax and it will show you some useful info. You should see something like the following:

fax 4545 0.0 0.7 5044 1816 ? Ss 15:13 0:00 /usr/lib/fax/faxgetty /dev/ttyS0
fax 5346 0.0 0.5 4944 1352 ? Ss 15:23 0:00 /usr/sbin/faxq
fax 5349 0.0 0.4 4644 1140 ? Ss 15:23 0:00 /usr/lib/fax/hfaxd -i hylafax -o 4557 -s 444

These URL’s are pretty handy:
HylaFAX
HylaFAX+
Installing Hylafax Fax Server
lf196, Applications: The Easy Fax Server!
Modem-HOWTO: Trying Out Your Modem (Dialing Out)