I'm going to go back in time a little bit for this one. I had just finished two years of community college, studying electronics. I decided that college wasn't for me and started looking for a job, hoping that I could find one before the summer ended and I would have to go back to school. Bell was advertising in the newspaper for entry level workers, so I applied with them. They had me take an aptitude test, which I must have passed, and I started a lineman training program in July.
It was awkward calling myself a lineman. I'd always pictured linemen as guys that hung harnessed to the top of a pole with a tool bag and a helmet. When I was a kid I'd see guys like that around my neighborhood, so that's how I'd always pictured them. During training I climbed a few poles, but once I was in a truck I worked almost exclusively with the underground plant. At that time long distance trunks were underground, as were most of the trunks and many lines in bigger cities, but many suburbs still relied on poles. Our town used underground for about half of the trunks and poles for the rest and for the distribution to residences. I was one of a few linemen dedicated to the underground plant.
When your job was to maintain underground lines you had two main functions. The first was to repair trunks that had been damaged by backhoes. Construction companies didn't always bother calling Bell before digging (they always made sure to call the electric company.) Repairing trunks damaged in this way was dirty work and could take several days. The second function was to troubleshoot and repair malfunctioning circuits in the underground distribution. The distribution consisted of green 'pedestals' used as splice boxes, and distribution cabinets called cross-boxes. There was similar equipment in manholes that had to be taken care of. Since underground cables were heavily sheathed and full of compressed fluid, they were very reliable and problems almost always occurred at the junction points.
I worked in outside plant for two years. During those years we had one place that always gave us trouble. It was a manhole in the run-down part of town. That part of town was serviced by poles, but a trunk ran underneath it from the central office to newer neighborhoods that used underground lines. During my time in outside plant we narrowed down a problem to that manhole dozens of times. In every case the issue was physical damage to the lines. Sometimes a few pair were disconnected from the terminal block. Sometimes one of the smaller feeder lines that branched off the main trunk in the manhole would be damaged, with a slice or a chunk cut out.
Others attributed the damage to vandalism. That never made sense to me. That manhole led to an old steam tunnel, which was big enough for a man to crawl through, but not big enough to spend any appreciable amount of time in comfortably. There was never any debris down there aside from telco stuff. No needles, no bottles, no spray paint. None of the stuff I'd seen many times when repairing vandalism. I didn't want to attribute the damage to vermin either. I'd also seen a lot of that kind of damage and it had its own tell-tale signs. I didn't know what was causing the damage down there, but I didn't think it was vandalism or pests.
I usually rode in the truck with another guy, Doug. Doug was an old Bell head who had about five years left until retirement. He called in sick a lot and I'd have to ride alone once in awhile. That was the case the last time I visited that manhole. I got a ticket from the office to fix a pair that ran through there, and that location had become my first place to check in cases like that. Since Doug had called in I took my tools and headed there alone.
There was nothing ominous about that morning. It was Spring, the sun was shining. The kids were in school so when I parked my truck and popped the manhole cover there was nobody bothering me. The problem was obvious the moment I descended. A few wires had been ripped out of the terminal block. I was relieved as that had an easy fix: just find the correct location on the block and punch the wires back down. It took five minutes.
We always tested the lines after we fixed them. There were four pair that had been damaged and I tested the path back to the central office on each by connecting to the block with my handset and calling a number designated for such tests. Everything worked fine except one of the pairs had static when calling out and, strangely, there was an audible buzzing in the manhole space when that pair was off-hook. I dialed a few times from that pair and each time the manhole filled with the buzzing. I left the line off-hook and sat down on my toolbox to think about the problem, listening to the buzzing and trying to think of potential causes.
I was doing just that when something walked out of the steam tunnel. This thing resembled a very dirty human. It walked upright and as far as I could tell had mostly human physical characteristics. The notable exceptions were that it was about two feet tall, and its eyes were covered with a thin white film or membrane. The creature (person?) walked up to the terminal block, looking my way with an expression that I'm pretty sure was meant to convey annoyance. My mouth and eyes were wide open as the thing reached up to the terminal block and ripped away at wires until it managed to disable the pair that was causing the buzzing. It then walked back into the steam tunnel without bothering to give me another look.
I was in shock. I punched down the wires it had pulled out, glancing at the steam tunnel every couple of seconds. I went back to the office and didn't say anything about what had happened. Before I left the manhole I had written down the pair number of the buzzing line and I spent the next few days troubleshooting the buzzing. I didn't talk about what happened; I was trying my best to forget it.
I fixed the troublesome line by replacing a filter on a card. It may seem strange that a filter on the line card could cause an audible noise on a terminal block in the outside plant; what it probably boiled down to was AC in the broken card coupling to the pair, and some electromagnetic effect on the block due to this. If you've ever shaken a punch-down block you might see how that could happen - the punch-down receptacles are loose in their housing and vibrate fairly easily.
Anyway, that's just my theory. The important thing is that after I replaced the filter card the static on the line was gone, so I hoped that the buzzing in the steam tunnel was gone as well. And it must have been, because after that I never had any trouble with that manhole.