When I worked in telecommunications as an engineer (late 2000’s) Electronic Switching Systems had been pretty much taken over by software switching systems, but the hardware, closely coupled to that software, was still very much an important component.

While the call switching and routing was no longer achieved by thousands and thousands of hardware relays switching dedicated connections between each “phone line”, the hardware operated the same.

The installation process was pretty much the same as in this video, recorded in 1974. Pretty much everything done in this video was still being done 35+ years later.

The thousands and thousands of interconnecting cables connecting each hardware module were still needed. The teams of men (99% of my colleagues were men) were still needed to “dress” the cables. This jobhad been outsourced to “installation” companies who employed teams of men – usually a foreman (“gaffer”) and his team of often young fellas – would travel to each datacentre, stay for 5-6 days and carry out the installation of the hardware, the cables.

It was then the job of the “commissioning” engineer to manually check all the hardware and cables were correctly connected and seated. This was a laborious and tedious job which took days.

Then came the software commissioning – configuring the software manually building up thousand of commands line-by-line for the logical connections for the “telephone lines”, the call-tree rules for call switching and routing, what telephone connection to use for what type of call.

Once this was done, then loading the system configuration for the particular client network.

Wire wrapping a huge DSX frame with thousands of connections, by hand or with an electrical tool – took knowledge, a certain manual skill – nimble fingers, experience and attention to detail.

A DSX frame from the front
The same small DSX frame from behind where you had hundred of wire-wrapping posts, each needing to be wrapped manually.

At the time I didn’t fully appreciate the craftsmanship involved in the process – attention to detail and pride in their work the installation technicans had – and the sense of achievement you got when you had commissioned fully (either single handedly or more likely as part of a team) a huge piece of equipment.

The level human-computer interaction was pretty much as low as it could go (without going to machine langauge) – the commands executed by engineers was referred to collectively as “MML” – man-machine language.

Being “so close” to the actual hardware being able to see the blinking lights, the increase/decrease in the fan speeds – carrying people’s important telephone calls, SMS messages – gave a certain sense of awe.

Today the hardware is commercial-off-the-shelf computing servers like IBM Bladeservers. They’re essentially no different to a high-capacity webserver, mailserver, or router. The sense of awe is still there but it’s hidden in the software.

Instead of requiring separate teams of people for the installation, commissioning it’s now reduced to 1, maybe 2 people.


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