So, short answer, it is possible, although it's a pretty big pain in the ass these days as you might expect.
Over VoIP, you can indeed make a modem work, with very specific settings on the ATA (Linksys PAP2, or similar, for example) - disabling for instance any kind of compression algorithms on the audio stream.
For this experiment I used voip.ms as my provider, a Linksys PAP2T and a US Robotics 33.6K external modem.
If you are able to truly get a POTS landline, it will be significantly easier to accomplish what you're after (Comcast/Xfinity as suggested is not - that is VoIP; and it most likely will not work).
Some notes from when I had this working..
https://www.voipmechanic.com/voip-fax-settings-linksys.htm
https://www.voip-info.org/linksys-pap2t/
https://toao.net/VoIP/linksys-ata-configuration.html
I'm forcing G711u (Preferred codec = G711u; Use Pref Codec Only = yes)
I'm also disabling all of the echo/silence cancellation or adaptation features. Jitter level will be something I need to play with I figure, but for now it is set "very high". Jitter buffer adjustment is also disabled.
On the SIP tab, I changed RTP Packet size to 0.020.
Once you get everything configured, you can give https://dialup.world/ a shot. It's a small ISP set up for giggles.
Is this all worth it in the end? Maaaaaaybe? You might actually have more fun cruising the current BBS scene from a retro PC. Cue up a dialup handshake sample from YouTube or elsewhere to help set the mood.
(that all aside, I can absolutely confirm all that was said about WinModems and how garbage they are/were. They were all about cost cutting. Get the "good" stuff if you're really going to go down this specific rabbit hole..)