How does the fax module work?

I’m trying to figure out how the fax module works. Not fax pro, just the included one. When freepbx receives a fax, where does it go? How do I see it?

Yes I realize you said you don’t want to know about Fax Pro. But this document talks about both.

http://literature.schmoozecom.com/Fax_Pro(XactFax)-module/UserGuide/Fax_Pro_Module-Userguide.pdf

Thank you!!!