Sprintnet and Timenet were magical beasts. My adventure began when I got an article, published in Phrack or someplace, by somebody who had wardialed Sprintnet/Timenet—that is, connected to every conceivable address to see what was there.
The idea, was that they were dialup gateways for corporate online services, with local numbers almost everywhere. Once you got on, there were banks, things that were just weird, and even some eerily professional BBSes.
AOL used Sprintnet and Timenet before AOL had any of its own numbers, and whenever AOL finally added its own numbers in your city it was a big deal because Sprintnet and Timenet themselves were super slow. (AOL was only notable to me then because it was humorously easy to get free accounts and stockpile massive amounts of warez in your email box that you never downloaded because, well, Sprintnet and Timenet were so slow.)
The magical thing was, you’d dialed up the local numbers of some random networks you’d never heard of and could in fact give it commands that would connect you to computers around the world, for free, from your room, in a really old school ASCII terminal sort of way.
Sometimes sites would use codes to change the color of text or make it blink, and it blew my mind.