Open source IP to Fax software?

[Bruce Labitt]

Not sure if this is a unicorn or it is common.  A simple search gave 
ambiguous results.  I'm looking for some program that will send a pdf 
file to a remote FAX machine.  I don't have a fax machine anymore.  I 
don't have a fax modem.  It's hard to remember how long ago that was 
even a thing...

I can solve this problem in a different way, but wondering if there was 
such a beast.  Thanks.