Rotary Phones and the Birth of a Network

I can’t help but wonder how long it will be before the movie title “Dial M for Murder” becomes mysterious to most of the population. After all, who has seen a dial phone lately? Sure, there are a few retro phones, but they aren’t in widespread use. It may not be murder, but it turns out that the dial telephone has its roots in death — or at least the business of death. But to understand why that’s true, you need to go back to the early days of the telephone.

Did you ever make a tin can phone with a string when you were a kid? That dates back to at least 1667. Prior to the invention of what we think of as the telephone, these acoustic phones were actually used for specialized purposes.

We all know that [Alexander Graham Bell] made a working telephone over a wire, drawing inspiration from the telegraph system. However, there’s a lot of dispute and many others about the same time were working on similar devices. It is probably more accurate to say that [Bell] was the first to successfully patent the telephone (in 1876, to be exact).

No Telephone is an Island

A telephone by itself isn’t very useful. You need at least two. And that’s how the early telephones worked. You would put one phone at home and another in your business, for example. Or two offices might have a telephone, allowing them to communicate.

In the same year that [Bell] patented the telephone, [Tivadar Puskás] was working for [Thomas Edison] on a telegraph exchange — a switchboard that allowed different telegraph stations to interconnect. He realized the same technique would be useful for a telephone and, in 1878, The District Telephone Company of New Haven went into operation with 21 users. For $1.50 a month, any of those users could call one of the others. The switchboard, designed by [George W. Coy] could handle 64 users, but only two connections at once. In a month, they published a directory with 50 subscribers. London’s Telephone Company Ltd formed in 1878 with even fewer initial subscribers.

However, an operator had to work the switchboard, making up to six connections per call. With 20 or 30 phones, not all of which would be in use at once, that was manageable. You’d pick up the phone and tell the operator who you wanted. They’d make the connections required on your behalf.

In the early days, you’d let the operator know you wanted assistance by whistling into your phone! Eventually, a bell was put into phones. Early phone systems often had multiple wires to accommodate things like the bell.

Making Connections the Manual Way

There is an obvious problem, of course. If you had thousands of phone lines, you are going to need a lot of operators. However, in a time when labor was cheap, that wasn’t what motivated the invention that would put most phone operators out of business.

There is a less obvious problem discovered by a man named [Strowger] You might think that [Almon Brown Strowger] was some electrical engineer and an expert in telephones. But, in fact, he was an undertaker in Kansas City. In 1888 [Strowger] was frustrated. People would pick up the phone and tell the operator they wanted “the undertaker” or “the funeral home.” The problem was that [Strowger] had a competitor and the competitor’s wife (or girlfriend, depending on the source you read) was one of the phone operators. You can imagine that if a caller wasn’t specific, she was going to connect the call to her husband’s business.

Who Has Time for Multiple Button Presses?

You can read [Strowger’s] 1891 patent that covers how he solved the problem. You’ll see that it used a set of buttons, one for each digit and another to hang up. So to “dial” phone 46, you would press the first button 4 times, and the second button 6 times. A third button would hang up.

While this doesn’t resemble the dial phone we know, the elements are all there. The only difference is that the dial creates the multiple button pushes automatically. [Strowger] formed a company, the Strowger Automatic Telephone Exchange Company, and worked out the dial and a way to avoid having a separate input for each digit. They also invented the busy signal.

Not only was the system convenient and economical, but unlike other manual and automatic exchanges, it was technically very easy to expand the system to handle new phones. That scalability ensured its success, despite [Bell’s] efforts to stop the fledgling company. [Strowger’s] company was eventually sold to GTE and after many years of changes, is now a part of Alcatel-Lucent.

By the way, [Stowger] sold his patents for $1,800 and then sold his share in one of the subsequent companies for $10,000. In 1916, the patent sold for $2.5 million — a staggering sum in those days.

You can see a Telstra video showing a reasonably modern Strowger switch in operations, below. You’ll find these are sometimes called SXS or step-by-step equipment.

As late as the 1970s, there were still a few operator-connected exchanges left. AT&T’s history center has a short film that shows what life was like for a telephone operator, that you can see below.

Designed to Last

When something is used for many years by many people, it often results in design changes that can be very subtle but important. After World War II, much of the rural parts of the United States were not connected to the phone system. But as people left the cities to move to the suburbs, they wanted phone service. Most phones at the time didn’t have the range required and the phone company was unwilling to create new central offices for just a few rural subscribers.

Instead, the phone company commissioned industrial designer [Henry Dreyfuss] to create a rugged phone: the Model 500. The iconic desk phone had several improvements, but one, in particular, stands out. Previous phones had the numbers under the dial (like the giant phone in the video, below, or the model 302 to the right). Repeated dialing would wear the numbers off.

The Model 500 (left) had the numbers outside the dial and tests showed a 50% reduction of misdials because of this change. Over 80 million of these phones were made and many are still in service.

It is hard to imagine, but in the 1940s, the dial was new-fangled and exotic. The phone company made some propaganda films to show how “yummy” it was having a dial phone, like the one below.

Rotary Phone in the Modern World

Dial phones eventually gave way to tone signaling and keypads, but most regular phone systems will still accept pulse dialing. You probably won’t get it to work on voice over IP lines, though. If you have the urge for some retro decor, you can still buy rotary phones (BoldOldPhones is one site that specializes in them).

Despite being a relic from the past, we still hear phrases like “dial 911” and I have to wonder how long that will last.

You can read more about [Strowger] at the aptly-named strowger.net site. Those interested in the history and technology of the phone network have a great book to finish off their summer reading. And if you want to see something more hackish, check out the video below. [Glasstronic] takes a surplus German switch and shows how it works with an old phone. Or you could always dial Bluetooth.

Filed under: Hackaday Columns, History, Retrotechtacular http://ift.tt/2vJATqg http://ift.tt/2aM8QhC

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