Teletype (TTY) Xiaomi phone: what it is, how it works and why you need it

Owners of Xiaomi smartphones (Redmi series, POCO or Mi) sometimes encounters a mysterious teletype function (TTY) You can see a call settings, and suddenly, a Mode notification will appear on the screen. TTY It's active, or you can add it to the call menu, and what is this technology, why does it appear on modern Android devices, and how to use it -- let's go through it in detail.

Many people mistakenly think that teletype is an outdated feature left over from the era of button phones. TTY (Text Telephone is still widely used as a means of communication for people with hearing or speech impairments. MIUI It's at the Android system setting level, but it's disabled by default, but sometimes it's activated by accident, like after a software update or a reset. TTY If you can’t make a regular call, don’t panic: most likely, the problem is solved in two clicks.

In this article, we will not only explain what a teletype is in a Xiaomi phone, but also show you how to control it: turn it on, turn it off, adjust it to your needs, and also analyze common errors (for example, why the sound disappeared during a call) and give recommendations for security. If you are not a user who needs TTY, But function interferes with work - here you will find a solution.

What is a Teletype (TTY) and why you need it in a smartphone

Teletype (TTY, Text Telephone or Teletypewriter is a text-based call technology originally developed for people with hearing or speech disabilities that allows real-time text messaging to be exchanged during a phone conversation. TTY It was used with special devices connected to the phone line, but in modern smartphones (including Xiaomi) the function is built into the software level.

How does this work in practice? Instead of voice, subscribers exchange printed messages.

• 📱 The sender typed text on the keyboard of the smartphone.
• 📡 The signal is transmitted via a mobile network as a regular call, but in data format.
• 📱 The recipient sees the text on their screen and can respond in a similar way.

Important: For work TTY Both subscribers must support this feature, and if you turn on your Xiaomi teletype, and the other person uses a regular phone without the need for a phone. TTY, no connection.

Xiaomi (as well as other Android smartphones) implemented several modes TTY:

• 🔹 TTY Full (Full) – text is transmitted in both directions.
• 🔹 TTY HCO (Hearing Carry Over – You hear the voice of the person you are talking to, but you respond with text.
• 🔹 TTY VCO (Voice Carry Over – You speak in your voice but read text responses.
• 🔹 TTY Off – function disabled (standard call mode).

Why? TTY Despite the development of messengers (WhatsApp, Telegram), text calls remain in demand in several cases:

• 🏥 Emergency services (e.g. 112 in Russia) are required to maintain TTY to communicate with people with disabilities.
• 📡 Weak Network Signal: Text messages can pass where voice communication is interrupted.
• 🔒 Confidentiality: TTY-Calls are harder to listen to than voice calls.

How to turn on or off teletype on Xiaomi: step-by-step instructions

If you want to test it. TTY Or accidentally activated this mode, return normal calls is easy. MIUI 12–14, including Redmi Note 12, POCO X5, Mi 11 et al. The only difference is the location of the menu items.

Step 1. Open your phone settings

Go to the Settings app (the gear icon on the home screen) and select Special Features (or Additional Settings) → Special Opportunities on Older Versions MIUI).

Step 2. Find the Teletype section (TTY)»

Scroll down to the Hearing or Calling block (TTY). Some models may have different paths:

Settings → System → Additional → Special. capabilities → Teletype

Step 3. Select mode TTY

You will have 4 options available (see description in the previous section). TTY Off If you want to turn on, specify the appropriate mode (Full, HCO or VCO).

Step 4: Save the changes

Click Ready or go back, the settings will apply automatically. TTY, Make a test call to another phone with this feature.

Make sure the regimen TTY included|Check the balance (some operators charge for a fee) TTY-call-up)|Make a test call to a supported number|Turn it off. TTY After the test, if you do not plan to use-->

⚠️ Note: If after activation TTY It's normal behavior -- it blocks the voice channel. Just turn off the teletype in the settings as described above.

Typical problems with TTY Xiaomi and their solutions

While teletype is a useful feature, it can cause malfunctions, especially if it was turned on accidentally, and here are the most common problems and ways to fix them:

If after the shutdown TTY Problems with sound persist, follow the following steps:

1. Reboot the phone.
2. Check if the mode is activated on the plane or Do not disturb.
3. Update the firmware MIUI Up to the latest version (sometimes bugs with the TTY patch-fix).
4. Reset network settings: Settings → SIM-maps and mobile networks → Resetting network settings.

⚠️ Note: Some Xiaomi models (e.g. Redmi) 9A or POCO M3) post-update MIUI 13/14 option TTY It may disappear from the menu, in which case it can be returned via the engineering menu (see next section).

Hidden settings TTY: engineering menu and ADB-team

If the standard settings do not give access to the teletype (for example, after a reset or firmware), you can use the engineering menu or ADB-These methods are suitable for experienced users.

Method 1: Engineering menu (code ##4636##)

1. Open the Phone app and enter the combination: ##4636##.
2. Go to the tab Information about the phone.
3. Scroll down to the block. TTY Mode and select the desired mode.

⚠️ Warning: Do not change other options in the engineering menu unless you are sure of their purpose.

Method 2: ADB-Teams (for advanced users)

If the engineering menu is not available, you can manage it. TTY Android Debug Bridge via Android (ADB). For that:

1. Install. ADB-PC drivers.
2. Connect Xiaomi to your computer and activate Debugging USB developer-setting.
3. Enter in command line: adb shell settings put global tty_mode [The [[S]] is a [[S]] [[S]] [[S]]] [[S: 0 — TTY Off 1 — TTY Full 2 — TTY HCO 3 — TTY VCO

Support TTY Telecom operators in Russia and the world

Even if your Xiaomi supports teletype, it requires compatibility with a mobile operator. TTY looks like:

Most of Europe and the United States TTY In the United States, for example, all operators are required to provide text calls to emergency services (911). №181-FZ "On Social Protection of Disabled Persons».

If you are planning to use TTY abroad, check with your operator:

• 🌍 Is roaming supported for text calls.
• 💰 Is there an additional fee for TTY roaming.
• 📶 Whether the inclusion of VoLTE (voices through) 4G) function.

💡

Before traveling abroad, keep the local emergency numbers on your phone. TTY. In the EU, for example, it is a single number 112, which is required to receive text messages.

Security and privacy when using TTY

Although teletype was originally designed as a means of accessibility, it has features worth knowing about:

• 🔐 Encryption: TTY-Calls are not encrypted by default (unlike messengers like Signal or WhatsApp), and can theoretically be intercepted.
• 📡 Localization: The operator can see what you are using. TTY, Not the content of the message (unlike the content of the message) SMS).
• 🚨 Emergency services: In some countries TTY-call-up 112/911 They have priority over the usual.

If privacy is critical, consider alternatives:

• 💬 Messengers: Telegram (secret chats), Signal or Session with end-to-end encryption.
• 📞 Video Calls: Zoom or Google Meet with subtitles.
• 📧 Email: For non-urgent correspondence (for example, with government agencies).

⚠️ Note: Never pass through the TTY sensitive data (passwords, card numbers, pin codes) This feature is not intended for secure transmission of information.

Alternatives TTY Xiaomi: What to use instead of text calls

If teletype is not suitable for you (for example, due to lack of support from the operator), consider modern alternatives for text conversations:

For owners of Xiaomi is especially interesting feature RCS (Rich Communication Services, which is built into the standard Messages app to activate it:

1. Open the messages. → Settings → Chat functions.
2. Enable the option to Enable chat functions.
3. Confirm the phone number (will be available) SMS coded).

After activation, you will be able to exchange text messages with other subscribers who support you. RCS, without the Internet (via mobile network).

💡

If you need it. TTY exclusively for emergency services, please check with the operator whether it supports alternative methods of text calls (for example, SMS 112).

FAQ: Frequent questions about Xiaomi teletype