What is TTY Mode & How to Use It?

Have you ever heard of the TTY mode? Or wondered what it implies? No, then learn about “what is TTY mode” here.

TTY mode is one of the features of mobile devices. This term stands for “text telephone” or “teletypewriter.” Teletypewriters are devices that are designed especially for hearing impaired people or those who cannot speak properly.

A teletypewriter interprets signals into words and then, displays the same on the screen for others to read. Moreover, this device re-encodes written texts into audio for the challenged person to hear out clearly.

Here, the term “TTY” refers to all kinds of teletypewriters. Meanwhile, the term “TTY mode” only refers to mobile devices. So, let’s know more about “what is TTY mode” further on!

PS: here, you will learn more about how to read someone’s text messages without installing software on their phone.

What is TTY mode?

A teletypewriter is really old technology. However, this technology has been modified for a new kind of media to continue offering access to people who are speech-impaired or hearing-impaired. The Federal Communications Commission (FCC) mandated that mobile phones need to be compatible with TTY. This is so to preserve connectivity in so far as possible regardless of the ease of access requirements. Hence, the TTY mode came into being.

Before the epoch of the internet and cell phones, teletypewriters were originally employed in newsrooms. These teletypewriters would be kept there in a line as they keep on printing and producing lots of noise.

With these teletypewriters, messages used to be sent from one part of the country to another. It is considered to be the telephone network at that time. Once mobile phones, email, and internet emerged, TTYs became a thing of the past.

Nowadays, these teletypewriters are mostly used by people who suffer from speech or hearing impairment. After getting to know about “what is TTY mode,” you might be wondering how this technology actually works. If you really like to know, keep reading on!

How does TTY mode work?

TTY devices or teletypewriters work like a regular typewriter. However, teletypewriters comprise of a little display screen. Most of the teletypewriters even print out messages, where it entirely depends on the TTY model you are using. The best part about TTYs is that one can connect them to compatible mobile phones with the help of a TTY cable. Hence, these devices will act as SMS devices for you.

It is really easy and simple to use a teletypewriter. All you have to do is type the message on the TTY and ensure the same on the display screen. Once confirmed, the message will be passed onto the mobile device over the cable. Now, your mobile device will send it through the carrier.

Now, the person on the receiving side will get the message and read the same direction on their phone or through their teletypewriter. So, this mode is actually a legacy technology.

The TTY mode allows many speech- or hearing-impaired persons to utilize SMS for communication. Meanwhile, there are concurrent IP technologies, too, which make communication a lot easier. However, in order to use these technologies, you require digital telephone lines or data lines. Here, the TTY mode comes handy.

This interesting mode has been retained for individuals who are constrained to analog phone lines. Moreover, it is for people who do not have access to mobile data. Accessibility rallies onwards but still not everywhere. So, this model remains a significant mode of communication for a wide range of people.

How to make use of the TTY mode?

In order to use the TTY mode, you require a handset that is compatible with the mode. It is really simple to use this mode on these compatible handsets. You require certain things to make it work, though. These things include a TTY cable, a teletypewriter, and your cell phone.

Generally, you have to connect the TTY cable to the audio jack of your phone. After that, you have to switch on the TTY mode and run from there. If you enable the TTY mode, it is possible that some functions will not work properly on your phone. It totally depends on your phone. However, there are chances you cannot use normal voice calls or SMS while enabling this mode.

Just in case, you do not employ a teletypewriter; it is better to switch OFF the TTY mode. In this way, you will be able to use full functions on your phone. When it comes to TTY mode, there are generally four settings that you can choose from. These options include TTY VCO, TTY HCO, TTY OFF, and TTY FULL. So, let’s know these settings from closer!


Out of all the settings, TTF Off is pretty straightforward. As its name suggests, TTF Off implies the settings for a teletypewriter is not enabled. Here, the TTY mode is not ON, and hence, you cannot use this mode for carrying out communication.


The next setting for the TTY mode is TTY Full. This option is just for text-focused communications in both ways. Here, you cannot make an interaction using audio components. One can send or receive texts only.

TTY FULL is helpful in cases, where both parties are having either hearing or speech impairments. This setting sends or receives messages only in the text through the teletypewriter at both ends.


Here, the term “HCO” elaborates to Hearing Carry Over. Under this setting, you are free to send messages through texts. Meanwhile, you receive responses through audio from the other end. This setting works best for people who are speech-impaired only. Here, just grab the idea of programs like text-to-speech, and you will follow the gist of the setting, TTY HCO.

TTY HCO is a helpful setting when the caller suffers from speech impairments, but the receiver does not. Here, the teletypewriter sends the message through text, but responses will be in audio forms.


Here, the term “VCO” elongates to Voice Carry Over. This particular setting allows you to convey your messages through speech, whereas the teletypewriter converts the same into a textual form at the opposite end. Hence, the other person will receive the message in the text.

TTY VCO works great for people who are hearing-impaired. In order to get the gist of TTY VCO setting, think about the programs like speech-to-text.

TTY VCO is useful in cases, where the caller suffers from hearing impairments but claims no problems with speech. Here, the caller receives messages through audios or sends them in a text form. So, that’s all to the four settings of the TTY mode.

If you like to converse with someone like hearing-impaired, but they do not own a TTY-friendly phone, it is best to make use of the Telecommunications Relay Service in the United States. This service works 24 hours, which can be availed by anyone by making a call on 711.

Here, a skilled operator will put in your spoken message on a teletypewriter and send the same to the concerned person on your behalf. After that, the person will translate the answer into audio. So, that’s how this service works.

However, this service sounds a bit 18th Century but works absolutely fine. If you do not own a teletypewriter, it becomes indispensable to use this service. It is the only best way to communicate with hearing- or speech-impaired person.


So, that’s everything you require to know regarding the TTY mode. Now, if you hear someone using the term “TTY mode,” you no longer have to wonder “what is TTY mode”!

This mode comes in handy if you regularly come in contact with people who require help. The TTY mode is a significant feature of your next cell phone. It is a great way to have some extra accessibility choices.

Just in case, you do not require the spare help or do not frequently communicate with people who do need help; then you will not require the TTY mode. But, it is better to be clear about some terms like what is TTY mode.

Now, we think that you know almost everything about this interesting mode. Tell others if they are not yet familiar with “what is TTY mode.”


Ten years of experience in information and computer technology. Passionate about electronic devices, smartphones, computers, and modern technology.