Introduction

Imagine a machine that could send a written message from Stockholm to Tokyo in under a minute, decades before the internet existed. A machine that ran twenty four hours a day, seven days a week, with no human operator needed at the receiving end. A machine so trusted that a message from it carried the same legal weight as a signed letter. That machine was the telex, and for the better part of the twentieth century, it was the backbone of global communication. Not the telephone. Not the fax. The telex.

Today we're going to trace the story of this extraordinary network, from a German postal engineer's dream in the nineteen thirties to its quiet death at the hands of email in the two thousands. Along the way, we'll meet the inventors, the Cold War spies, the shipping magnates, and the news agencies who all depended on this clattering, paper-spewing machine. And we'll discover why, in some corners of the world, the telex refused to die for far longer than anyone expected.

The Typewriter That Talked to Wires

To understand telex, you first have to understand the teleprinter. And to understand the teleprinter, you have to go back to a frustrated French engineer named Emile Baudot. In the eighteen seventies, Baudot was working for the French telegraph service, watching skilled Morse code operators tap away at their keys. The problem was obvious. Morse required highly trained people at both ends of the wire. You needed someone to encode the message into dots and dashes, and someone equally skilled to decode them on the other end. Baudot thought this was ridiculous. What if, instead, you could just type on a keyboard and have the letters appear on the other side?

Baudot designed a coding system where each character was represented by five electrical pulses, either on or off. Five bits, as we'd say today. That gives you thirty two possible combinations, which is just barely enough for the alphabet plus some control characters. His system was brilliant, but the machines of his era were clunky and unreliable. It would take another fifty years and several more inventors before the teleprinter became practical.

The real breakthrough came from an American named Charles Krum and his son Howard. Working in Chicago in the early nineteen hundreds, they built the first reliable teleprinter, a device that looked like a heavy-duty typewriter connected to a telegraph line. You typed on one end, and a matching machine on the other end printed the same characters on a roll of paper. No Morse code. No trained operator. Just typing and reading. The Krums' company eventually became Teletype Corporation, and the word teletype became almost synonymous with the technology itself.

But a teleprinter by itself was just a point-to-point tool. You could connect two machines with a wire and send messages between them, like a very expensive chat application. The real magic happened when someone figured out how to build a network.

The Germans Build a Network

That someone was the German Reichspost, the national postal and telecommunications service. In the early nineteen thirties, Germany was rebuilding its infrastructure and looking for modern ways to move information. The telephone was growing, but it had a limitation that frustrated businesses. A phone call required both parties to be available at the same time. If you called a factory in Hamburg and the manager was at lunch, you got nothing.

The teleprinter solved this beautifully. You could send a message at any time, and it would print out on the receiving machine whether anyone was standing there or not. The paper would be waiting when they got back. It was, in effect, the first asynchronous text messaging system.

In nineteen thirty three, the Reichspost launched a public switched teleprinter network and gave it a name that combined the words telegraph and exchange. Telex. The name stuck, and it would outlive the country that coined it by more than seventy years.

The early German telex network worked much like the telephone system. Each subscriber got a telex number. You dialed the number on your machine, waited for a connection, and then typed your message. The receiving machine would clatter to life and print everything you sent. When you were done, you hung up. Simple, elegant, and remarkably fast for the era.

What made telex special wasn't just the technology. It was the legal framework built around it. The German postal authorities declared that a telex message constituted a legally binding document. This was enormous. Previously, if you wanted to send a binding communication, you had to physically mail a signed letter. Now you could send one electronically and have it carry the same weight. Businesses loved this. Banks especially loved this.

The Answerback That Changed Everything

Here's a detail that might seem small but turned out to be revolutionary. Every telex machine had something called an answerback code. This was a short string of characters, usually the subscriber's name or abbreviation plus their country code, hardwired into the machine. When you connected to another telex, you could request its answerback, and the machine would automatically transmit this code.

Think about what this means. You now had a way to verify, at both ends of a connection, exactly who you were talking to. The sending machine's answerback confirmed who sent the message. The receiving machine's answerback confirmed who received it. This created an authentication system decades before we started worrying about digital signatures and encryption keys.

This little feature is why telex became the language of international banking and trade. When a bank in Zurich sent a telex to a bank in Singapore authorizing a funds transfer, both sides had machine-verified proof of who sent what. The answerback was the closest thing the pre-internet world had to a verified digital identity. It's no exaggeration to say that billions of dollars moved around the world every day on the strength of those little answerback codes.

How the Signals Actually Traveled

Let's talk about what was happening on the wire, because it's wonderfully simple compared to modern networking. Telex used a system called frequency shift keying. Instead of sending digital pulses of ones and zeros, the machine sent two different audio tones. One tone meant "mark," which was a one, and a slightly different tone meant "space," which was a zero. These tones traveled over ordinary telephone lines, and because the bandwidth required was so tiny, you could actually squeeze multiple telex channels into the space used by a single voice call.

The standard speed was fifty baud. That's fifty bits per second. To put that in perspective, a modern broadband connection is roughly a million times faster. At fifty baud, using the five-bit Baudot code plus start and stop bits, a telex machine could transmit about sixty six characters per second. That's roughly four hundred words per minute, which is considerably faster than any human can type. In practice, operators typed at maybe sixty words per minute, so the machine spent most of its time waiting.

This glacial speed had an unexpected benefit. Because the bandwidth was so low, telex connections were cheap. Ridiculously cheap compared to voice calls. An international phone call in the nineteen sixties might cost several dollars per minute. A telex connection to the same destination cost a fraction of that, and you got a permanent written record as a bonus. For businesses sending routine messages like orders, confirmations, and shipping instructions, telex was an absolute bargain.

The World Gets Wired

After the war, telex spread rapidly. Britain launched its network in nineteen fifty four. France, Italy, and the Scandinavian countries followed. By the early nineteen sixties, telex networks existed on every continent, and an international numbering plan let you dial directly from one country to another. The International Telecommunication Union, or ITU, coordinated the whole thing, assigning country codes and managing the interconnection standards.

The country codes tell their own story. Germany was number one, because they started it. Britain was number two. France was number three. The United States, interestingly, didn't get heavily into telex until relatively late. Americans preferred the telephone, and the existing domestic telegraph system run by Western Union filled some of the same niche. When the US finally joined the international telex network, they got country code number twenty three.

Sweden was an enthusiastic early adopter, and this is where the story comes close to home. Swedish businesses, especially those in export-heavy industries like timber, mining, and manufacturing, embraced telex wholeheartedly. A sawmill in Norrland could communicate directly with buyers in London or Hamburg without waiting for postal deliveries that might take a week during winter. For a country that's geographically remote but economically connected to the world, telex was transformative.

By nineteen seventy, there were roughly one hundred thousand telex subscribers worldwide. By the peak in the mid nineteen eighties, that number had grown to approximately one point seven million machines in more than two hundred countries. The telex network was, after the telephone, the largest electronic communication system on earth.

The News Never Sleeps

If there's one industry that telex truly defined, it was news. The major wire services, Reuters, Associated Press, United Press International, and Agence France-Presse, ran on telex like blood runs through veins. Their business model was straightforward. Reporters filed stories from wherever news was happening, those stories were transmitted via telex to the agency's headquarters, edited, and then retransmitted via telex to subscribing newspapers, radio stations, and television networks around the world.

In a typical newsroom of the nineteen sixties or seventies, the telex machines never stopped. They ran around the clock, spewing out a continuous stream of paper with the latest stories from everywhere. The sound of a busy telex room, that mechanical rattling and clattering, became synonymous with breaking news. Some old-time journalists still get nostalgic about it.

Reuters had a particularly clever setup. They operated a store-and-forward network that could take a single story filed from, say, Beirut, and automatically retransmit it to hundreds of subscribers simultaneously. This was essentially a primitive version of what we'd now call a content delivery network. The infrastructure was massive. Reuters maintained telex switching centers in London, New York, Hong Kong, and several other cities, creating a globe-spanning web of clattering machines.

The urgency of news also drove one of telex's most distinctive features: the bell. Telex machines had a special character in the Baudot code that triggered an audible bell on the receiving machine. Wire services used a system of bells to indicate the importance of incoming stories. One bell meant routine news. Two bells meant urgent. Three bells meant a bulletin. Four bells meant a flash, the highest priority. Five bells was reserved for events of truly global significance. In the entire Cold War era, five bells rang only a handful of times. The assassination of President Kennedy was one.

Spies, Banks, and Shipping Containers

The intelligence community loved telex for the same reason banks did: the answerback code provided authentication, and the written record provided documentation. But they also loved it for a reason that might seem counterintuitive. Telex was relatively easy to intercept.

During the Cold War, signals intelligence agencies on both sides devoted enormous resources to intercepting telex communications. The British Government Communications Headquarters, or GCHQ, and the American National Security Agency, or NSA, ran programs that tapped into undersea cables and satellite links carrying telex traffic. The Soviet KGB did the same. Because telex used simple, unencrypted Baudot code at a slow speed, intercepting and reading it was straightforward compared to breaking voice encryption.

This led to an arms race of sorts. Diplomatic and military telex traffic started using cipher machines, devices that encrypted the Baudot code before transmission and decrypted it on the other end. Commercial users, for the most part, sent their messages in the clear. The spies read everything.

On the banking side, the telex network eventually gave birth to one of the most important financial systems in the world. In nineteen seventy three, a group of two hundred and thirty nine banks from fifteen countries got together and decided that the existing telex-based system for international money transfers was too slow, too error-prone, and too insecure. They founded the Society for Worldwide Interbank Financial Telecommunication, better known as SWIFT. The first SWIFT messages were essentially standardized telex formats, and even today, decades after SWIFT moved to its own proprietary network, the DNA of telex lives on in its message structures.

The shipping industry was perhaps telex's most devoted customer. Container shipping, which revolutionized global trade from the nineteen sixties onward, generated an enormous amount of documentation. Bills of lading, manifests, customs declarations, booking confirmations, and arrival notices all needed to travel between shipping lines, ports, freight forwarders, and customs offices around the world. Telex handled all of it. A container ship might generate hundreds of telex messages on a single voyage from Shanghai to Rotterdam.

The Sound of the Machine

Let's pause the history for a moment and talk about what it was actually like to use a telex machine. Because the experience was genuinely unique, and it shaped how an entire generation thought about electronic communication.

A typical telex machine was a beast. It weighed somewhere between thirty and sixty kilograms, sat on its own dedicated table, and was connected to the telephone network by a dedicated line. The most common models were made by Siemens in Germany, Olivetti in Italy, Creed in Britain, and Teletype Corporation in America. They looked like industrial typewriters crossed with small printing presses.

To send a message, you first prepared it. Many offices used a paper tape punch. You typed your message on a keyboard, and instead of sending it immediately, the machine punched holes in a narrow paper tape. Each row of holes represented one character in Baudot code. Once your message was complete, you fed the tape through a reader, dialed the recipient's number, and the machine transmitted the tape contents at full speed. This was important because telex connections were charged by time, so sending a pre-punched tape was much cheaper than typing live.

The receiving machine printed on a continuous roll of paper, usually about twenty centimeters wide. The printing mechanism was typically a type cylinder or type wheel that spun to the correct character and then struck the paper through an inked ribbon. It was loud. Imagine a aggressive typewriter running at several hundred characters per minute. In offices with multiple telex machines, the noise was considerable.

There was a ritual to telex communication that had a certain elegance. You'd start a connection by dialing. The receiving machine would send its answerback. You'd send your answerback. Then you'd type or transmit your message. At the end, you'd exchange answerbacks again to confirm the connection had held. Then you'd send the disconnect signal. It was formal, verifiable, and left a complete paper trail on both ends.

The Scandinavian Connection

The Nordic countries developed their own distinctive telex culture. The Scandinavian telex network was tightly integrated, and you could dial between Sweden, Norway, Denmark, and Finland almost as easily as making a domestic call. For Nordic businesses that traded heavily with each other, telex was indispensable.

In Sweden, Televerket, the state telephone monopoly, managed the telex network with typical Swedish thoroughness. Every subscriber had a listing in the telex directory, a thick book published annually that was the teleprinter equivalent of the phone book. Swedish telex numbers began with the country code zero fifty four, and the network grew steadily through the sixties and seventies.

One fascinating corner of Swedish telex history involves the maritime industry. Swedish shipping companies, particularly those based in Gothenburg, were among the heaviest telex users in the world. A company like Broström or Transatlantic, managing fleets scattered across every ocean, depended on telex for daily communication with their ships. Coastal radio stations like Gothenburg Radio received telex messages and retransmitted them to ships at sea via radio telegraphy. Ships could send messages back the same way. It was slow and expensive, but it worked, and it kept the global supply chain moving.

Up in Norrland, the forest industry used telex extensively. Lumber companies, pulp mills, and paper manufacturers communicated with buyers across Europe by telex. An order placed by telex from a paper buyer in London would arrive at a mill in Sundsvall within minutes, be confirmed by return telex the same day, and the shipment would be on its way. Before telex, the same transaction might have taken a week or more by post.

The Long Goodbye

Telex began its decline in the nineteen eighties, but it was a remarkably slow death. The fax machine was the first serious competitor. Fax could transmit images, diagrams, handwritten notes, and signatures, things telex simply couldn't handle. By the late eighties, fax machines were everywhere, and a lot of the routine business communication that had gone by telex shifted to fax instead.

Then came email. The internet's killer application didn't just compete with telex, it obliterated the entire value proposition. Email was faster, cheaper, more flexible, and could carry attachments. By the mid nineteen nineties, telex traffic was falling off a cliff in most developed countries.

But here's where the story gets interesting. Telex didn't disappear overnight. Not even close. The network kept running in many countries well into the two thousands. There were several reasons for this.

First, legal status. In many jurisdictions, telex messages still had legal standing that email didn't. Courts accepted telex as evidence of communication in a way they were reluctant to do with email, which could be forged, altered, or lost. For high-value commercial transactions, some companies kept their telex machines running purely for the legal protection.

Second, reliability. The telex network was extraordinarily robust. It ran on dedicated infrastructure, separate from the internet, and it almost never went down. In regions with unreliable internet connectivity, particularly in parts of Africa, South America, and Asia, telex remained a dependable fallback. You could always get a telex through, even when the internet was flaky and email was bouncing.

Third, inertia. Replacing a communication system that millions of people know how to use is harder than it sounds. The shipping industry, in particular, was slow to migrate away from telex. Some shipping lines were still using telex for certain documentation well into the twenty tens.

The last major telex networks shut down at various points. India's network closed in two thousand and thirteen. A few African networks hung on even longer. The ITU quietly stopped maintaining the international telex numbering plan. The machines, once the beating heart of global commerce, became curiosities in technology museums.

What Telex Taught Us

Looking back, telex was remarkable not just for what it did but for what it anticipated. Every major feature of modern digital communication was present in telex, in primitive form.

Asynchronous messaging. You send it, the recipient reads it when they're ready. That's telex. That's also email, text messages, and Slack.

Store and forward networking. The telex network could hold messages and deliver them when the recipient's machine was available. That's essentially how email servers work today.

Machine authentication. The answerback code was a hardware-based identity verification system. Today we use digital certificates and cryptographic keys, but the principle is identical. Prove who you are before the conversation begins.

Global addressing. The telex numbering plan, with its country codes and subscriber numbers, was a worldwide addressing system that let any machine reach any other machine. Sound familiar? It should. It's the same concept as email addresses, phone numbers, and IP addresses.

Standardized message formats. Telex developed conventions for how messages should be structured, with headers, bodies, and signatures. SWIFT formalized these into rigid templates. Today, every API and data format carries echoes of this thinking.

Even the cultural norms of telex communication feel familiar. The practice of keeping messages short and clear because you were paying by the minute. The use of abbreviations to save time. The expectation of a prompt reply. The anxiety when a message wasn't acknowledged. Anyone who's ever stared at a read receipt on a messaging app knows exactly how a telex operator felt in nineteen seventy five.

The Ghosts in the Machine

There's something poignant about telex's disappearance. Unlike many obsolete technologies that were clearly inferior to their replacements, telex had genuine advantages that nothing has fully replicated. The legal standing of a telex message was clearer than email. The authentication provided by the answerback was more straightforward than our current tangle of passwords, two-factor authentication, and digital signatures. The dedicated network was more reliable than the internet.

We gained speed, flexibility, and multimedia capability. We lost simplicity, legal clarity, and a certain mechanical trustworthiness. Whether that was a good trade depends on who you ask.

What we can say for certain is that telex deserves its place in the history of communication technology. For fifty years, it was the invisible infrastructure that held global business together. Orders were placed, contracts were confirmed, ships were directed, news was transmitted, money was transferred, and diplomatic crises were managed, all through those clattering machines and their endless rolls of paper.

The next time you send a message and wait for a reply, spare a thought for the telex operators who did exactly the same thing, just with more noise, more paper, and a whole lot more mechanical charm.