I May have figured this out.
credit goes to the people in this link though:
http://www.macosxhints.com/article.php?story=20050204171237879&query=fax
It appears that the fax modem is not actually handled as a printer. So you cannot share it like a printer. It is though, when shared on a server anyway, somewhat confusingly controlled in the print section of Server Admin.
*On the server, make a garbage text document.
*Tell the server to print and then choose "fax PDF" from PDF pop up in the bottom left of the print dialog. If the "fax machine" has not been set up yet, the server will do it for you. You will get the usual fax dialog box.
*Insert a fax number and send.
The server has now sent a fax directly from its own "fax machine"
*Open Printer Setup Utility on the server itself.
*Select "show fax list" in the View menu. You should have the server's "internal modem" shown as a fax.
*Select "internal modem" from the list and press the "show info" icon in the bar at the top of the window. You get a window similar to the one where you would set up a printer's options on a client (or server for that matter).
*Change the name of the fax from "internal modem" to something that will make it easy to spot later. I choose "ServerFax." I did not test if spaces are permitted. This is done because all faxes are called "internal modem" by Apple and we will want to find the shared one later.
Go to a client, for the time being I assume that the following works only on the local subnet as with CUPS hosted printers. My client is VPN'd in so it thinks its on the same subnet as the server.
*On the client, make a garbage text document, "print" the document, but tell the client to "fax PDF" by selecting the PDF menu at the bottom left of the print dialog.
*Under "modem" in the fax dialog you hopefully now have "shared faxes" just like when we get "shared printers" on the same subnet from the server.
*If you renamed the server's fax to "ServerFax," that is what you will see in the "shared faxes" list. Choose the shared fax.
*Insert destination information as usual and "fax"
If you open the "ServerFax" queue on the client computer, the job will dissapear but not show up in the "completed jobs" list. However, if you go back to the queue "ServerFax" in printer setup utility>show faxes on the server itself you will see your job from the client there.
You will also now find that you have a new print queue in Server Admin "ServerFax." and that you can monitor existing fax jobs in the same way you monitor existing print jobs in the queues.
The key here appears to be that once the "fax machine" is created on the server... It is already being "served" as a fax queue.
The only issue with all of the above is that I do not currently (midnight EST) have a phone line plugged into my server which is at a remote location. I will confirm that this actually results in a sent fax in the next day or so. Currently my test faxes are on hold automatically in the queue on the server.
An additional detail: You don't need a server to do this. Following the above for any combination of machines (two non-servers for example) will lead to a shared "fax machine" on one of them. This last bit I gather from the web page referenced above. I did not test it.
If anyone gets this to work, please follow up with any changes.
I am hoping this will work across multiple subnets...but I doubt it. Of course I am looking for CUPS on Apple OS X to do the same for printers, but have yet to find the answer to that one.
