This ISP was a bit earlier. They did move to T1 PRI eventually, but before that we had stacks of modems attached to Livingston Portmasters (I think?) There was basically an octopus of cables coming out of the wall, dozens of individual phone lines, then serial cables, power bricks, power strips three layers deep. It was also always like 100 degrees on one of the POPs. It looked like the plastic was melting on some of the modems.