Teletype or TTY  What is it and how does it work? ▷ 2020

This German device had its heyday in late 1945 and it was widely accepted in the postal companies of European governments due to the practicality of the implementation of this system.

In this article, We will show you what a telex is and what it is for. In addition, we will talk about its origin and evolution to this day and we will tell you who are the people who use this tool today.

We bring you all the information you need to know about a TTY. Keep reading until the end of this article and you will find out all the details.

What is a teletypewriter or TTY and what are these devices for?

TTY or teletypewriter is a device similar to a typewriter. It has an alphanumeric keyboard that manages to write messages for later sending. It also allows you to receive typewritten messages from point to point, joined by a telegraph cable for later printing.

Most modern models use a screen, on which you can print telephone communications. At present this mechanism is obsolete, but it is used in people who have hearing problems so that they can get the telephone conversation in print.



This device telegraph has its origin in Germany, in the mid-20s of the last century. It was used for the Reich postal service with which a little more than 60 words per minute could be transmitted. After the end of the Second World War it was possible to expand to the whole world.

After more than 50 years of its creation, the postal services of the main European governments initiated short wave radio links, the standard being the “R.44”, belonging to “ITU Telecommunication Standardization Sector”. Where the data transmission was done by a division in time according to time slots in a cyclical way, generating a set of bits as a result.

The communication system I had was carried out through direct current. Where it is interrupted in a very similar way to dialing a landline telephone, using a point for the beginning and a line for space, ending again with a point to define a cycle.

Evolution and history

Most of these teletypes used the 5-bit code (called Baudot or ITA2), which had as a limit 32 characters. Where, to enter some numbers special characters, exclusive keys should be used for these.

At first the teams used a bit for start and stop, due to its electromechanical design. As time passed, the devices became synchronous, often making the task of synchronizing their mechanical components difficult.

So it was decided to continue using the 5-bit Baudot code, where special versions were created to be able to apply them in certain reports, such as meteorological ones.

The postal and telegraph services that did not have great economic resources carried out their operations on TOR or telex channels-radio to obtain a higher value of them. In this way, with the passage of time, the cost of these equipment has decreased considerably and as of 2016 people who are radio amateurs use this shortwave system known as RTTY.

How does a telex work to send and receive typed messages?

These equipments They have a keyboard to compose and a receiving device that is used to print the reception of messages. Which are made through printed characters defined by electrical signals, which consist of different combinations of electrical impulses, both positive and negative.

In this way, different characters are sent and they are interrupted according to a predetermined encryption by some standard. It is a system very similar to a fixed telephone dialing. Once the characters have reached the receiving telex, it begins to print them according to the assignment of standards.

Telex vs Fax, which is better and how is each different?

While is true that both devices have a similar physical appearance (considering the latest teletypes, since they were large and heavy in their beginnings), the technological difference that exists in each of them is very great.

As with telex you can send and receive messages via an integrated keyboard, while with a fax also, there is a courier service, but images can be incorporated that the first mechanical equipment does not support.

In addition, the texts that are generated in the fax are not created on the same device, but a separate text computer is needed to obtain a written message.

In this way, we can conclude that a fax is currently much better to send and accept messages than a telex is. This is because, not only can you send or receive texts, but you can also send different images or forms of drawings that can be digitized with special software and sent by email.

If you have any questions, leave them in the comments, we will answer you as soon as possible, and it will also be of great help to more members of the community. Thank you! 😉

You may be interested:

Rate this post

Leave a Comment