zlacker

As a kid doing some urban exploring... I encountered a pentaconta crossbar in the wild, around ~1976. It was in a cinder block building on the grounds of a resort hotel behind an unlocked door. I turned on the single bulb hanging from the ceiling and beheld its awesome beauty in that room with bare grimy walls. Two racks just for the crossbars. And of course it was operational, routing three-digit calls between hotel rooms, room service and 'dial 9' outside.

It was a 'private branch exchange' built by ITT. Our own local telephone company had crossbar switches in use until 1980 but I never got to see those until 1987 -- when I was working at the phone company itself (owned by ITT actually!). The entire function of the the ground floor with its banks of crossbar switching cabinets had long since been routed upstairs to an ITT 1210 digital switch, and line cards of four lines each in dense racks also upstairs, and all voice traffic and several trunk functions with other adjacent digital exchanges (classes 3,4,5) was exchanged on a digital bus.

The crossbar beasts had been silent on the floor below for years, waiting for a potential buyer (perhaps in Central America) that was still committed to this reliable technology. That buyer never happened, and they were finally acquired for copper and gold, with the provision that the cabinets not be swept. Every one had a pile of metallic dust in the bottom.

But I'll never forget the smaller beast that connected the hotel, the slaps of call routing and teardown, the stepping relays counting digit dialling and redialing trunks. Many people still alive today feel an emotional connection to this technology. Fewer and fewer.