I worked for an ISP in the 90s as a teenager, and was also a backup SysOp. We had high end gear- SGI servers, racks and racks of USRobotics Courier modems. "Go

I worked for an ISP in the 90s as a teenager, and was also a backup SysOp. We had high end gear- SGI servers, racks and racks of USRobotics Courier modems. "Good" ISPs had a 10:1 user:modem ratio. Crappy ISPs had a 13:1 ratio. Get much over 10:1 and you start risking busy signals. We didn't really track user sessions but we'd occasionally hop onto one of the Lucent Portmasters and if someone had an egregiously long session, you might reset their port. I was logged in all the time from my family home because we had a 2nd phone line leftover from the 1 year my dad had a home business. I ran the line down through some ductwork into my bedroom, and had switch boxes so I could switch which line went into the modem if I had to. From 1995 I had a Slackware Linux box online 24x7 and also (later, I guess) setup ipmasq and an ethernet interface so I could provide internet service to a 2nd computer we got in the late 90s (since, after all, the family computer had been co-opted by me, put in my bedroom, and Linux installed on it. It was always via modem, we could never get ISDN or DSL until much later (like 2002 later). A funny anecdote about leaving your modem online in those days. We had 2 phone lines coming into our demarc box, and the ringers of the phones had a strong current draw that required a capacitor (?) in the demarc box be topped up. We started having issues with quiet/silent phone rings on the "voice" line, and the modem dropping at the same time. Turned out having the modem on all the time didn't allow the capacitor to charge up, so when the phones in the house tried to draw a ton of current to ring the ringer bell, you'd basically get no current to anything, and the modem would fall over. Funny how primitive that sounds to describe it. Then again, the phone system wasn't exactly cutting edge in the 90s.