IBM says these all came with 2400bps internal modems, and had Prodigy pre-installed
it appears it was upgraded to 28.8kbps around 1994
and it has a whole load of Micron RAM in it, manufactured in 1996
this is 32mb! that's the max the board supports and a hell of a lot of RAM to have in a 486
i had 16mb in mine back in the day and that was plenty to run anything you'd want to run on a 486 🙃
an early Windows 95 will run great on this old beast