What’s a Telex?

What’s a Telex?


What if I told you we had the ability to text
each other in 1933. What?!? Well, before the advent of texting and even
before faxing (I’m sure some of you young people are now wondering what a fax was),
there was the Telex, which stood for “Telegraph Exchange”. It’s a now long-forgotten technology used
mainly by businesses to transmit short messages to each other, kinda like texting, but attached
to telephone wires using devices you definitely couldn’t put in your pocket. The telex began in Germany as an R&D project
in 1926 that became an operational teleprinter service in 1933. The service, operated by the Reichspost (the
German postal service) had a speed of 50 baud – approximately 66 words per minute. Compare that to dial-up, which made it to
around 30,000 baud before we all jumped ship and switched to broadband around 2000 because
dial-up was so heinously slow! Telegrams had been popular since the late
19th century, even before the telephone. Telegrams were short messages sent between
telegram offices by specially trained telegram operators who would feverishly tap out your
message. Once the message had been manually sent and
received, it would be delivered by telegram messenger, probably on a penny farthing, because
it was the 19th century and that’s what everyone rode. Probably. By the late 19th century this was becoming
automated, but telegrams were still processed through central telegraph offices. Telex’s were essentially the next generation
of telegram. Instead of having to schlepp down to a telegraph
office and tell your confidential message about your super-secret business deal to some
snooty oik of a telegraph operator, you simply typed the message into your Telex machine
and it was automatically sent to a similar machine somewhere else in the world where
it could be read instantaneously on a small piece of paper tape. Telegraphy had originally used Morse Code
to transmit messages, but by the 1870s human operators were being replaced by teleprinters
and Morse Code was replaced by the Baudot character encoding system which had the advantage
of using the same 5-bit length code for every character, so making it easier to automate
using the machinery of the day. Baudot was the forerunner of the familiar
ASCII character codes used in computers today. Instead of ASCII’s 8 bits, Baudot had 5
bits to encode the data, which amounted to 32 different combinations. The smart ones among you will realise that
a 26 letter alphabet and 10 digit numbering system that really doesn’t fit into 32,
so Baudot codes in the 19th century only used A to Z, plus a couple of control characters. Baudot ITA 2, which was the next generation,
was used for Telex and this uses two control codes to move between Letters and Figures
mode, providing most common characters plus control codes familiar to those who use ASCII
such as carriage return and line feed. Like ASCII has versions for different countries,
Baudot had country specific versions so characters like the UK £ sign could be added. Interestingly the most common letters used
the fewest holes because it minimised the fatigue on the machinery. Baudot of course missed the whole concept
of emojis, so thankfully Telex machines were incapable of printing eggplants or poops. The usual method of operation was that the
message would be prepared off-line, using paper tape. So, if you’ve ever wondered why paper tape
in early computers had five holes, now you know! Many early telex machines incorporated a five-hole
paper-tape punch and reader. Once the paper tape had been prepared, the
message could be transmitted in minimum time. Telex billing was always by connected duration,
so minimizing the connected time saved money. However, it was also possible to connect in
“real-time”, where the sender and the recipient could both type on the keyboard and these
characters would be immediately printed on the distant machine. Telex messages were routed by addressing them
to a telex address, e.g., “14910 ERIC S”, where 14910 is the subscriber number, ERIC
is an abbreviation for the subscriber’s name and S is the country code, in this case Sweden. It was also possible to automatically route
of message to different telex terminals within a subscriber organisation, by using different
terminal identities, e.g., “+T148”. The machines would start conversing by sending
a series of regularly timed pulses, to essentially determine the baud communication rate. Once connected, the “Who are you” code
would establish a connection and then communication could begin. With concerns today about privacy and messaging
apps like Whatsapp using 128-bit encryption, it’s odd to see there was almost no communication
security in the Telex system. In the USA the Teletypewriter Exchange Service
(TWX) was introduced by AT&T in 1931, transmitting at the same 50 baud, but they soon developed
a second generation of TWX called “four row” that went at a blistering 110 baud! Bell Labs created a competing system in the
1930s running at 75 baud. TWX used the public switched telephone network. In addition to having separate area codes
for the TWX service, the TWX lines were also set up with a special Class of Service to
prevent connections from regular phone lines to TWX and vice versa. Western Union purchased the TWX system from
AT&T in January 1969. Canada operated a similar service through
the CPR Telegraph Company and CN Telegraph in 1957. In the UK, Telex began as an evolution from
the 1930s Telex Printergram service. It started as a direct Teleprinter to Teleprinter
service in 1932, but by 1945 as the traffic increased it was decided to have a separate
network for telex traffic and the first manual exchange opened in London. In the late 1950s the decision was made to
convert to automatic switching and this was completed by 1961; there were 21 exchanges
spread across the country, with one international exchange in London. Telex service spread within Europe and (particularly
after we’d all stopped fighting in 1945) around the world. Long before automatic telephony became available,
most countries, even in central Africa and Asia, had at least a few high-frequency (shortwave)
telex links. By 1978 West Germany alone had over 120,000
telex connections. Even the place where my mum worked had a Telex
and I remember looking at it and thinking what a cool piece of tech it was and that
I really wanted to mess with it. But given I’d mess with I’d break when
I was a kid, they rightly didn’t let me anywhere near it! By the early 1990s Telex was quickly replaced
by the Fax machine, which allowed whole sheets of paper to be digitised and sent, allowing
not just short messages but whole business documents. Fax had a much shorter life than the Telex,
with communications over the Internet making it largely irrelevant in just 20 years. Telex machines quickly went the way of the
dodo. British Telecom stopped offering the telex
service to new customers in 2004 and discontinued the service in 2008. They sold off their services to SwissTelex
which still provide Telex services to this day. iTelegram offers telex-like service without
subscriber telex lines. Individual subscribers can use Deskmail, a
Windows program that connects to the iTelegram telex network but this is via IP as the last
mile.

25 thoughts to “What’s a Telex?”

  1. Fax still used a lot by GPs, Doctors etc for letters, referrals because of transmission guarantees and the fact it's immediately printed out and you don't need a PC to read it.

  2. Very interesting to see a concise video on the Telex! I left school & started work in 1985 and was taught how to use the Telex for general messaging and one to one operation. A couple of years later ,my next employer owned a Fax machine , but back then you didn't just chuck A4 or A3 paper in , you had specific "Fax rolls" which were like giant rolls of Izal medicated toilet paper which were slightly yellow and the print would start to fade away after a few days.

  3. Very interesting, I think the marine industry were the likely last users of this system. I remember in 04 or 05 when I sailed round the world in container ship, a lot of the weather information and indeed pirate information was transmitted through a Telex machine in the bridge and this was on a brand new vessel. Not sure whether the marine industry still use this system as a redundant backup system on ships these days.

  4. I remember it was always very nervous to type on a connected line so I personal often pre wrote the message and then connected and sent of the message with the strip with holes. I worked in a bank and messages was always in a foreign language and to other countries. We even had a special department only working with sending these messages. With special code books you could calculate a number to verify that the sender where authentic.

  5. Wast Telex ticker tape and the paper wast from holes that was used as confetti thrown from widows from office buildings in city parades in years past.

  6. Brilliant. Concise, to the point, no sponsors or ads. Just great interesting information that geeks like me love! Thank you.

  7. As a mobile network applications developer it's interesting to see how addressing is pretty much the same for telex and mobile messaging. The only difference is that mobile messaging also has the provider code.

  8. Those machines made the best confetti! My mums work had a telex up till the mid 80s when I was a young lad. The confetti I brought home from emptying their machines was most excellent.

  9. Great video – I saw a telex at my mom's office in the mid 70s and I, too, very much wanted to play with it and was also prevented from doing so 🙁

    The computer that ran the test equipment I used in the Navy still had a mylar tape reader in it, but no one had used it for a decade. It was installed in the equipment rack near the floor and made a good foot rest. That was '91.

  10. What is the point in an internet to telegram service? If the sender has a computer, but the recipient does not, then just print a letter and post that!

  11. A few years ago I bought a USB fax modem and I think I only used it 3 times to fax customs for importing stuff. Cause I did not have their email address at the time….

  12. In 2008 I was working for a telecom provider and we had a pretty cool task to build a system for automating setting up phone calls between here and some far far places in Russia. It worked by generating a a certain time (lets say two weeks after current time) and sending it as a message over Telex network. Then the telex message was delivered to the person you wanted to have a call with, and he'd have to go to the nearest post office (which could be hundreds of KMs away) on the time and date mentioned on the Telex. Then the system would automatically call both these numbers and bridge the calls. Since lots of people were deported in 1940s to Siberia, Russia, people still have relatives there who they want to stay in touch with. And turns out telex and automated calling is the easiest way to accomplish that. I don't know if it is still in use today tho.

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