Hi,
if you are looking for a fax-server solution, that is managed by a webpanel, then
http://forums.contribs.org/index.php?topic=24047.0 is for you. Smerp works and is very easy to install.
If you are looking for a more "featureistic" solution, you should perhaps try the wonderful hylafax install script from Jesper Knudsen (search for hylafax here or go directly to
http://sme.swerts-knudsen.dk/.
In every case you should install a proper hylafax-client. I am using Jespers install script and rpm togehter with whfc.
The samba-fax printing solution from smerp in my opinion is a little weak breasted (no journal, no grapical print-interface).
For just receiving faxes, smerp will do.
Internet fax is a very rarely used technique, where you send a tiff-image or "fax" to a service provider, who puts it into a biiiigggg faxrouter - this kind of service is normally billed and shure will never be implemented into SME.