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Tuesday, July 26, 2011

Recycling my school's phone lines as dialups

My high school was pretty different in terms of how it handled computers and Internet access. For one thing, it actually offered it to faculty and students long before there was much to see on it. It even had a bunch of dialup lines so that people could use it from home, including the students. There were obvious restrictions involving acceptable content and students weren't always the violators, but that's another story.

At some point, we started granting SLIP and then PPP access to faculty and staff. The students weren't given this sort of access, since it basically meant an unfiltered pipe to the net. Granted, most of the browsing type stuff you'd do back then involved Gopher, Archie and Veronica, but the powers that be decided to stay out of that mess with students entirely. Any student who wanted actual IP connectivity at home could get an account with a local ISP.

This access became rather popular. The students found ways to do things with their shell accounts, and the faculty and staff members really started enjoying their SLIP/PPP access. We started to have a phone line problem.

Initially, that machine had three phone lines and three modems. One was internal and served as our link to the outside world. Yep, we shared a 14400 bps pipe and we liked it! Those other two modems were strictly for incoming users. One, ttya0, was for anyone with an account. The other, ttya1, had a "secret" phone number, and it was a "non-student" line. This didn't last too long.

This same school had hosted an old BBS on Fidonet for a couple of years, and it had pretty much fizzled. There was a juicy phone line just sitting there, and the decision was made: kill this BBS, or at least get it out of the school, and put that line on the Unix box! We did that, and now there were two all-access lines: ttya0 and ttya2. Even that was not enough.

Someone figured out that the school had a bunch of wacky ground start analog phone lines arranged in a pool. If you called the main number, it would ring down through them, and if you pushed 9 for an outside line, the PBX would grab one. Outside of business hours, they really didn't do much. It turned out you could call their real numbers directly and it would just ring that one line and nothing else.

We decided to skip the first lead-in number and the second and started hooking up modems to the remaining lines. Obviously, we couldn't have these things just sitting there screeching at human callers during the day, so there was another hack which worked really well: a timed light switch. This was one of those things you might use to turn lamps on and off when you're on vacation. We threw caution to the wind and put a power strip full of modem bricks behind it.

Every night at 5, those modems would come to life, and the users would pile on. They could do whatever they needed until 6 AM, at which point they would be forcibly disconnected when the modems were powered off.

Finally, we had the kind of dialup pool which could keep up with user demand. That, plus more terminals being installed in classrooms gave people the chance to do what they needed on their own time. Users were happy, and the system had a vibrant little community going.

I bet most people don't get to learn sysadmin skills in high school with real users and real problems and all of that. It's been far more useful than any official computer-related class ever was.