Modems in general were either entirely PnP or a total goddamn nightmare in my experience. There was no in between. I remember setting up Slackware in the late 90s and my serial modem just worked. Even after I changed it, it worked. Even after I installed an internal modem, it worked. A few years later I set up Debian or one of its kids (probably knoppix, but I won’t testify to it) and couldn’t get a modem to work to save my life. It was so bad that I just didn’t use any Linux until I got DSL.