efax is a small ANSI C/POSIX program that sends and receives faxes
using any fax modem (Class 1, 2 or 2.0). [*]

efax is smaller and easier to install than HylaFAX or mgetty+sendfax.
As one user put it "EFAX is a nice simple program for single user
systems."

The "fax" command, a shell script, lets you send, receive, view and
print faxes. In larger systems, faxes can be sent by printing to a
"fax" printer and received faxes can be e-mailed as MIME attachments
to an administrator for distribution.  efax can also pass incoming
data calls to a getty program.

The efax package includes "efix," a program to convert between
various image file formats. To fax Postscript files you will need
Ghostscript. To view faxes you can use any program tha displays
PGM files.  efix can also convert received files to Postscript or HP
Laserjet formats for printing.

This program has only a command-line interface.
If you need a GUI-based fax solution, install efax-gtk instead.

[*] Any hardware-based fax modem, that is. If you have a "software
modem," a so-called "Linmodem," then you'll instead need to
download the alpha version of efax and modify this SlackBuild script
accordingly.

The alpha release can be found here:
https://www.cce.com/efax/download/efax-0.9a-001114.tar.gz