In early 2013 I was curious to see if audacity supported modem modulations, as per response to my Avatar 3 grayscale fax format sound clip I uploaded to here.
Turns out you can actually do that, but with some limitations.

This LISP plugin I use was written by Rob H, a dear friend I had made, but no longer talk to. It simulates an FSK modem which can specify bitrate, Mark and space tones, etc. Also includes some other sections which are somewhat useful, but arent really that useful.
I was able to simulate Bell103 and Bell202 (shown here).

There is also an I/Q modulation plugin on github that can also do other formats of signal processing on the quad plane and imaginary planes (inverse).
This signal is seen on HF, VHF, UHF, etc. in the ham bands.