Teletype (TTY) in Xiaomi smartphones: purpose, configuration and features

Introduction: Why does your Xiaomi have a teletype mode?

Have you ever gone into Xiaomi's call settings and stumbled across the mysterious "TTY" item? If so, you've probably wondered why a modern smartphone needs a feature that seems like a relic of the last century? In fact, Android's teletype is not an archaic thing, but an important accessibility tool that is still actively used by people with hearing or speech impairments.

TTY (Teletypewriter) technology dates back to the 1960s as a way to send text messages over phone lines, and is now integrated into mobile operating systems, including MIUI on Xiaomi, Redmi and POCO smartphones, to provide connectivity for users who can't use voice calls. But how exactly does that work in 2026, when there are instant messengers and video calls? And why is that feature disabled by default? Let's get a handle on it.

In this article, we will explain in detail:

• 🔹 What is it? TTY How it works on modern smartphones
• 🔹 Why you need a teletype in Xiaomi and who uses it
• 🔹 How to turn on or off the teletype mode in MIUI
• 🔹 What problems can arise when using TTY And how to solve them.

What is Teletype (TTY) and how does it work?

TTY (Teletypewriter) is a technology that allows real-time text messages over a phone line, originally designed for people with hearing or speech impairments to communicate by phone, typing messages on a special device, and is now built into smartphones, including Xiaomi devices, to make communication accessible to all categories of users.

In today's Android smartphones, teletype works through special protocols that convert text into audio signals and back again. TTY In Xiaomi, the phone starts encoding the text you type into sound pulses that are transmitted over the phone line. TTY-The mode receives these signals and sees them as text on its screen.

It is important to understand that for the work of the teletype, both interlocutors must have an on-line TTY-If one of the people on the call doesn't support this feature, you can't make a connection. TTY It only works on networks. 2G/3G — into 4G/5G Other technologies are used for text calls, for example, RCS ViLTE.

⚠️ Attention: Initiation of the regime TTY It can temporarily disable some voice functions, such as conferencing or recording conversations. TTY These functions will be automatically restored.

Why do you need a teletype in Xiaomi smartphones?

Xiaomi’s main purpose is to make teletype available to people with disabilities, but there are other uses for this feature:

• 🦻 For people with hearing or speech impairments. TTY So you can talk on the phone without having to hear or talk, and the user just types the message, and the person sees it on their screen.
• 📡 In poor communication, in some cases, texting through TTY They can pass better than the voice, especially in areas with unstable surfaces.
• 🔒 For confidential conversations. Text messages through TTY They can’t be overheared, unlike voice communication.
• 🛠️ To test networks, engineers and technicians sometimes use them. TTY Diagnosing problems with telephone lines.

While there are alternatives to messaging apps (WhatsApp, Telegram) or sign language video calls today, TTY remains popular because of its simplicity and reliability, it doesn’t require an internet connection and works even where there is no 4G/5G coverage.

In addition, some government services and emergency numbers (e.g. 112) support the use of the service. TTY-Calls, making this feature important for the safety of users with disabilities.

💡

If you often communicate with a person who uses TTY, save their number in contacts marked "TTY" so you will not forget to turn on the mode before calling.

How to turn on or off the teletype on Xiaomi?

Turning on and off TTY mode on Xiaomi, Redmi or POCO smartphones takes just a few steps. The instructions may vary slightly depending on the version of MIUI, but the overall algorithm remains unchanged.

Step-by-step:

1. Open the phone application (pipe icon).
2. Press three points (⋮) in the upper right corner and select Settings.
3. Go to Calls or Additional Settings (depending on the MIUI version).
4. Find the Teletype (TTY) item and click on it.
5. Select one of the available modes: TTY Full - text input and output; TTY HCO - text output, voice input; TTY VCO - voice output, text input; Disabled - standard mode.

Save the changes and exit the menu.

After inclusion TTY-The next time you call, you'll see a text box to type in messages. TTY on your device, otherwise the connection will not be established.

Enable TTY mode in the phone settings |

Make sure the interviewee also includes TTY|

Check the network coverage (TTY only works 2G/3G)|

Use an external keyboard for ease of dialing (optional)-->

Teletype modes: which one to choose?

Xiaomi smartphones have several TTY modes available, each of which is suitable for different situations.

The choice of mode depends on your needs and the capabilities of the interlocutor, for example, if you are communicating with a person who can not hear, but can talk, the optimal mode will be TTY HCO. If both interlocutors can not use their voice, TTY Full is suitable.

⚠️ Attention: When using regimes TTY HCO or TTY VCO There may be delays in the transmission of messages due to the conversion of voice to text and back. TTY Total delays are minimal.

Teletype problems on Xiaomi and their solution

While TTY technology has been tested over time, there may be some problems with it on Xiaomi smartphones, and let’s look at the most common ones and how to fix them.

Problem 1: TTY is not turned on or saved.

If the settings are not saved or the function is not activated after selecting TTY mode, try the following:

• 🔄 Reboot your smartphone and try again.
• 📱 Check if it is blocking the work. TTY any third-party application (such as a call manager or antivirus).
• 🔧 Reset the phone application settings in the Settings menu → Annexes → Application management → Phone. → Warehouse → Reset the settings.

Problem 2: TTY messages are not received or distorted.

This can be due to poor communication quality. TTY is sensitive to interference, so:

• 📶 Move to a more stable area 2G/3G.
• 📞 Try using an external antenna or signal amplifier.
• 🔊 Make sure the volume of the call is set to maximum (in mode) TTY Audible signals are important for data transmission).

Problem 3: TTY is in conflict with other functions.

In TTY mode, some features, such as recording conversations or speakerphone, may not work properly. This is normal behavior, since TTY uses an audio channel to transmit data. If you need these features, temporarily disable TTY.

Xiaomi Teletype Alternatives: What to Use Instead of TTY?

If you need text communication but TTY doesn’t work for some reason, consider alternative ways to communicate on Xiaomi smartphones:

• 💬 Call-enabled messengers: apps like WhatsApp, Telegram, or Viber allow you to send text messages and make sign language video calls, and the main advantage is that you work over the Internet, not over the phone network.
• 📹 Sign language video calls: Services like Zoom or Google Meet support gesture recognition and automatic text translation.
• 📞 Specialized applications for people with hearing impairments, such as Rogervision or Ava, offer advanced capabilities for text calls and live speech broadcasting.
• 🆘 Emergency services with support SMS. In many countries, including Russia, emergency numbers (112) are accepted. SMS-Messages from users who cannot call.

The advantage of these alternatives is that they are not tied to the phone network and often offer more features than TTY. However, they also have downsides: Internet dependency, the need to install additional applications, and possible privacy issues.

If you care about reliability and simplicity, TTY remains one of the most stable ways to text, especially when there is no Internet or a weak 4G/5G signal.

💡

TTY is not an outdated technology, but an accessibility tool that is still relevant for people with disabilities and in emergency situations, and its main advantage is that it works without the Internet and is compatible with traditional telephone networks.

FAQ: Frequent questions about Xiaomi teletype