My dad's modem was 75 baud, on the TRS80. You didn't plug a phone line directly into it. This was still in the era of rotary phones before push button blue tone ones. You put the handset of the phone (which had the microphone and speaker) into a cradle. It looked like this[1].

[1] https://opengear.com/wp-content/uploads/2014/09/acousticcoup...

Coincidentally, in the picture, that big box that is as big as an early desktop PC that the modem is sitting on, is a whopping 5 megabyte hard drive. State of the art for consumer hard drives at the time. I still have my dads in the garage. I vividly remember having to type "park" to park the hard drive heads before you turned it off, or it could corrupt everything on the drive when you turned it back on and the heads went back to the MBR.