A Brief History of PBX

Bringing communications to business, whilst sticking it to the man. The story of the PBX is one of wonder and excitement with a little bit of danger thrown in, too.

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Progressive technology companies have a habit of writing off their predecessors, sometimes even ridiculing them…

Even in our own industry, you’ll find some businesses having a go at traditional telephony solutions, bemoaning the messy wires, poor scaling options and extortionate maintenance costs.

Whilst these may be accurate points, we actually think that this is a cheap way of belittling a not-so-cheap system, firmly believing that we should focus on celebrating the achievements that were made by the previous and much, much older generation of communications instead.

Which is why we are looking at the history of traditional telephone solutions and showcasing how the IP PBX became to be.

You are doing what?!

Roll those tongues back in loyal fans, we’re not about to get a tattoo of a traditional phone system on our lower back just yet, we’re all about the education. So pull up a pew, sit back and relax, it’s history time!

Why PBX?

PBXs were developed to solve a very common problem. Originally, all calls placed had to go through the public network. This meant that if you were calling a colleague who was sitting just a couple of feet away, then you would have to pay the price of a local call – the idea of cost effective communications within an organisation was an attractive thought indeed and it wasn’t long before the business phone system was developed.

Photograph of Women Working at a Bell System Telephone Switchboard (3660047829)


PBX or Private Branch Exchange was a term that was first thrown about in the 1970s. It refers to a privately owned and operated telephone network comprising of extensions for making and receiving calls.

For anyone who doesn’t speak fluent BT, this was basically an in-house telephone solution that was operated manually by a telephone operator. If you’ve ever seen the intro to Hong Kong Phooey then you’ll know how it works; if you haven’t, then I suppose we’ll explain it: a call would come into the main switchboard, then an operator would have to connect the call to the correct line by hand. Imagine a virtual receptionist, take away the virtual aspect, and you’re pretty much there.

The first manual switchboard actually debuted just a couple of years after the invention of the telephone way back in 1878. If you’re struggling to picture a telephone system from the late 1800s, then we expect that you’re probably under the age of 100, and in which case, you’re not one of our regular readers. Welcome.

history ofAutomatic high-five

In the mid-1970s, after many decades of causing muscle spasms, someone finally decided to automate call switching. Aching arms and hands up and down the country high-fived in unison, before immediately realising that they were all out of jobs. Automated switches made the process entirely more efficient, as well as being cheaper, and it was at this point that many businesses who hadn’t previously invested in the business telephone system, started to get behind the idea.

To distinguish who was hip and who was not, two acronyms arose to describe which type of phone system you had. On one hand, you had the Private Automated Branch Exchange (PABX), and on the other you had the Private Manual Branch Exchange (PMBX).

The cool kids had the automatic version, whereas the old school ones went for the manual version, however, with the automatic version being much cheaper to run, eventually the PMBX died out. This ousting of technology is what is known as disruptive innovation.

All that was left was the PABX, and as the automatic part was no longer a distinguishing feature, they dropped the A from the acronym, leaving the term that would be widely used for the next 30 years. The PBX was born, and it was here to stay.

PBXs slowly improved over the years, adding features like music on hold, call transfer and call recording. By the 90s, they were a staple hold in offices around the world, whilst also starting to integrate with cost-saving VoIP solutionscloud technology and ISDN lines. The rest, as they say, is ancient history.

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