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Comment by cm2187 | Hacker News Reader

Surely most of these massive, older telephone exchange buildings must be empty now, with a single rack of servers in the middle?

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Oh, my sweet summer child. How do you terminate 60,000 pairs of copper on a single rack? If they were all bundled together, the bundle itself would be larger than you. This still takes a large frame and lots of line-equipment racks.

Newer switches are smaller than older ones, but line-equipment can only get so dense and still have room to work on it. Some multi-floor offices have entire floors sitting empty because a new switch was installed elsewhere in the building and then the old one decommissioned and removed. But there's still tons (literally, probably dozens of tons) of transport equipment, cross-connect, power and cooling, etc.

I assumed that we had switched to some sort of switching infrastructure a long time ago, where you wouldn’t pull every single copper wire all the way to the exchange

Outdoor infrastructure is built and maintained on the timescale of decades and centuries. It's not like software that you just apt-get upgrade. If we were building from scratch today, that might be how we'd do that, but for it to be done that way now, the technology would've had to be proven, reliable, affordable, environmentally rugged, and better than every alternative back in the 60s or 70s.

Terminating the local loop pairs takes up a huge amount of space, and there's still a lot of copper out there alongside the fibre

Doesn’t that happen in the local street cabinet?

Only in a small percentage of cases, typically exurbs where the subdivisions have been wired with such cabinets as pairgain equipment. Usually those cabinets are just cross-connects, basically patch panels, to assign individual subscriber drops to lines within the distribution plant. All the lines go back to the CO for termination, at least for the majority of subscribers that're fairly close to the CO and thus it doesn't make sense to deploy pairgain less than a mile away.

More likely to be sold or leased out, and the server is somewhere far away. Basically all telephony nowadays is VOIP, even if you have an old fashioned landline it'll be analog only at the last mile.

Not yet. Most still have switching equipment inside. This serves the analog customers who are left.

They are not empty. Very much necessary for fiber termination, relays, PoPs. Copper also is used.

But I thought a lot of these massive exchanges were built for the physical switching devices, which must have been completely miniaturised when they switched to digital.

When they went digital they were downsized. But for the most part they're still there.

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