The Evolution of the Telephone December 4, 2012Posted by truthspew in Uncategorized.
Tags: Bell System, science, Switching, technology, Telephone
A thought occurred to me. The evolution of the telephone is fascinating. It was established in 1876. By this point a hard waging battle over the type of current transmitted to homes would be, Direct Current favored by Thomas Edison, and Alternating Current favored by Nikola Tesla and George Westinghouse.
The telephone system of course uses a 48V DC circuit.
But the phone started as an instrument first in a common area of the home, one where you had to stand in front of the device to speak to the distant party.
But by the start of the 20th century – phones were rapidly evolving. It became readily apparent early on that you couldn’t hire enough switchboard operators to handle the rising call volumes seen by the early Bell System.
The dial telephone was invented by Almon Brown Strowger in 1891. But the Bell system didn’t fully adopt it until the late teens of the 20th century.
But adopt they did – using Strowgers Step by Step (SxS) system. You literally manipulated the switch train as you dialed. It was sort of a horribly inefficient system though.
Anyhow back to the 1920′s we started to see the phones with handsets and dials on them. But those phones required their network and ringing components to be located separately from the instrument itself.
Another development of the teens were the development of Panel switching. This was the very first of the common control types of switching equipment. In essence, everyone shared the same major elements in the switch train.
But Panel couldn’t keep up. In the mid 1920′s the started developing the #1 Crossbar. It was an ungainly beast of a switch but had capacities that far exceeded what Panel and Step by Step switches could handle. In addition, the #1 Crossbar introduced the element that you could use a specific switch element multiple times to complete calls.
By this point newer telephone with all components internal including network and ringer and handsets versus a separate ear piece and transmitter.
This is when you started seeing phones move from the common areas to the bedrooms, offices, etc.
And it carried on like this for another 50 years with moderate improvements in the telephone instrument. The 500 series represented the last great breakthrough in modern telephone service. And the Touch Tone derivative, the 2500 is still seen today.
And switching technology improved dramatically. The toll routing network was vastly improved in that time, to the point where it got so inexpensive that Bell couldn’t keep charging the exorbitant rates for long distance. This is what ultimately destroyed the Bell System. The MCI law suit challenged them on interconnection and they won.
Some of the notable switching improvements was the invention of the #5 Crossbar for local service, and the number 4A Crossbar for the toll network. Those increase the amount of common control and automation in the phone network.
But then, in the late 1950′s the Bell System started working with Electronic Switch Systems (ESS). The first ESS was a test in Morris, IL. They had to rework the whole system – the phones were different, the method of connection was different. But the key thing was, it proved advanced features like call waiting, Caller ID, three way calling, call forwarding, Centrex, etc.
But here’s where it gets interesting. The Bell System came up with the idea for cellular telephony back in the late 1930′s. They just lacked a critical element that we take for granted, widespread computing hardware in order to implement a cell system. It would take 40 years before they’d try again and this time with wild success.
Telephones then started moving from every room of the house to your cars and trucks.
But then micro-miniaturization gave us something luggable, then a brick, then a tiny brick, etc. so you could put the phone in your pocket.
But then the microprocessor revolution happened and now what we carry in our pockets has more computing power then some of the big main frame computers of the 1950′s and 1960′s. You most definitely have more computing power in your current phone than they did for the Apollo moon missions. In fact more than the computing power on the Space Shuttles.
Now we use our phones EVERYWHERE. We use them to talk to others and not just over the phone. I have an app called Echolink that lets me talk over amateur radio repeaters all over the world. And the phones have gained a measure of utility, like texting, web surfing, facebook, kindle and they’ve also become our music libraries.
So there has been progress made on the phone front. I suspect if A.G. Bell himself could see it he’d be astounded at what his simple invention has become.