Two wire systems diverged in a campus, what should the less traveled one do?

January 27, 2012 12:48 PM

University campus switching to VOIP. The landlines are perfectly good. What else can they be used for?

Aside from a backup system, how else could the old system be used? I'm vaguely aware of a plan to use it to send out a campus radio station signal awhile back. Was it carrier current transmission? Can phone lines be used for that? Assume Ethernet is all over, and wireless is good in most places. Is a wireless antenna possible for the harder locations? Are any science experiments possible? Anything else?

posted by jwells to technology (10 answers total)

You can use them for additional DSL or Ethernet loops, if you want.
posted by empath at 12:50 PM on January 27, 2012

Most likely they're going to be useless though, unless you pull it and sell it for scrap.
posted by empath at 12:53 PM on January 27, 2012

Emergencies seems like one obvious use.
posted by fshgrl at 1:04 PM on January 27, 2012 [2 favorites]

You can get 10 megabit Ethernet on a lot of phone wiring, depending on when it was installed. Cat3 is technically required, but I've seen it work on some older Cat1/2 wiring as well, although if you already have a working Ethernet network I'm not sure that's terribly useful. Still, there are specific instances where having a physically separate connection between two points might be useful. You can also (with appropriate adapters) run serial over UTP for fairly significant distances, which might be good for out-of-band management of switches and routers.

I wouldn't pull it out, unless you really need the space in the conduits for something else. At the very least I would keep it around so that you could use it with some old surplus analog phone gear as a private line / intercom system, if you wanted to. The parts you need to make a phone work on a copper pair are very minimal. Making the phones at either end ring is actually the hard part, but if you have a lot of spare pairs, you can just rig up a separate circuit to ring a buzzer or blink a light to get the other end's attention. (If you have normal Cat3 phone wiring in a building, each endpoint probably has two pairs; you can use one for the voice and the other for the signaling, if you wanted to.)

If you can, try to document as much of it as you can before the institutional knowledge about where the wires are run fades. Long inter-building runs especially, because those are probably the most useful. Seeing a 25 or 50-pair disappear down a hole in a basement with no idea where the other end comes out is ... frustrating. Wiring inside smaller buildings is probably the least useful, but it'd be so labor-intensive to remove that I doubt it's worth it for scrap unless you're really desperate.

When I did a live-remote video setup in college, we used some extra pairs in a 50-pair trunk (terminated in a 66 block) running between the two buildings as a low budget intercom and cue light system. It was a lot easier than trying to superimpose the intercom and cue-light signals on top of the video on the coax.

Anyway, there's still a lot of copper wiring in the world, and having a phone system that students could play around with -- without having to worry about actually breaking everyone's phones -- is pretty neat. I would try to retain as much of it as possible just for that reason. Knowing my way around a punchdown block and a wiring closet has come in handy to me a bunch of times, and it's not a skill that's really easy to acquire, because people are normally pretty reluctant to just let you mess around with big phone / data systems.
posted by Kadin2048 at 1:17 PM on January 27, 2012 [1 favorite]

Also, phone lines tend to contain their own power, which is useful during an outage. I don't know if this will be the case when they switch.
posted by the man of twists and turns at 1:25 PM on January 27, 2012

the man of twists and turns: the phone lines will likely lose power when the old phone switch is turned off. If they designed the voip system correctly, the phones will be on POE and the ethernet switches would be on UPSs, providing the same uptime as the old phone system. Or more, since the UPSs would be presumably newer.
posted by gjc at 2:06 PM on January 27, 2012 [1 favorite]

Why bother? Seriously, no one uses wired intercoms either anymore.
posted by spitbull at 4:34 PM on January 27, 2012

Some fire alarm systems use copper wiring still, but other than that most of our time is spent making sure that when a construction project is coming through the copper that will be removed isn't needed any more. Unless you have a redundancy critical application (like above fire alarm concerns) there isn't much you'll be able to do over a few copper pair that couldn't be done easier and faster on fiber.

But, it isn't likely that copper scrap will be going down in value in the future so no need to rush to pull it all out.
posted by meinvt at 6:44 PM on January 27, 2012

The correct answer is nothing useful. This resource is no longer a useful resource to maintain for any purpose. Now, in the event of some crazy petro-collapse we might be able to reuse them, but most likely not. The return on investment was achieved so many years ago that these wires are essentially "cost-neutral" and provide zero value for any infrastructure needs. Yes you could use them for some interesting fun project, but the cost of maintaining that project will take money away from some other useful need, so really, the most useful thing for these wires would be selling them for scrap, or just leaving them there.

The more useful parts are the PBX system, cards and digital interconnects. Those might be useful somewhere. But again, most likely not.
posted by roboton666 at 12:14 PM on January 28, 2012

And as far as the 50-pairs connecting the campus, trenching fiber (especially vertically inlaid fiber) is such an inexpensive option when looking at the useful lifespan, bandwidth and maintenance costs, that the copper looks absolutely quaint in comparison.

Especially at a university, where growth and research is the idea, not holding onto the past because it feels like a waste.
posted by roboton666 at 12:18 PM on January 28, 2012