Teletype (TTY) Xiaomi: A Complete Guide to Setup and Use

Have you ever noticed a mysterious “Teletype” item in your Xiaomi settings (or TTY) And they wondered why they needed it, and if they didn't, you're not alone, and it's so deeply embedded that most people don't even know it exists. Meanwhile, teletype in Xiaomi smartphones (as in other Android devices) plays a critical role for people with hearing impairments, allowing them to communicate on the phone via real-time text messages.

In this article, we will understand what is teletype in practice, how it works in firmware. MIUI HyperOS, what modes are supported, and most importantly, how to set it up correctly on your Redmi, POCO You'll also learn why this feature can interfere with normal calls and how to turn it off if it's activated by accident.

What is a teletype (TTY) Why do you need it in smartphones?

Teletype (TTY, Teletypewriter is a technology that allows real-time text messages to be sent over a phone line, invented in the 1960s for the deaf and hard of hearing, and is still used in modern smartphones, including Xiaomi devices. Instead of voice communication, subscribers exchange printed messages that are displayed on the screen.

In the context of MIUI HyperOS Teletype is integrated at the system level and supports several modes:

• 📞 Full TTY — both parties use TTY-device.
• 🔄 HCO (Hearing Carry-Over – You hear the voice of the person you are talking to, but you respond with text.
• 🗣️ VCO (Voice Carry-Over – You speak in your voice but read text responses.

Without this function, people with hearing impairments would have to rely on only hearing loss. SMS or messengers, which is not always convenient in emergency situations (for example, when calling the rescue service).

It is important to understand that teletype in Xiaomi is not just an “old feature”; in some countries (for example, in the United States and Canada), operators are required to support the service. TTY-In fact, modern versions of the connection are legal. MIUI automatically switch to mode TTY, if compatible equipment is detected (for example, specialized keyboards for deaf people).

How does teletype work in Xiaomi: technical details

Xiaomi's teletype is technically at the modem firmware and operating system level. TTY, The smartphone starts encoding text characters into audio signals that are transmitted over a standard telephone line (similar to a fax), on the other side, these signals are decoded back into text, which takes place in real time, but with a slight delay — usually 1-2 seconds.

Here are the key points of the job TTY into MIUI/HyperOS:

• 📶 Uses a standard voice channel (does not require internet).
• 🔋 Consumes more power than a regular call (due to coding)/dekodination).
• 🛠️ Requires operator support (not all networks are properly handled) TTY-signal).
• 📱 It only works on frequencies. 2G/3G (into 4G/5G can be automatically switched off).

Interesting fact: some Xiaomi models (e.g. Redmi Note 12 Pro)+) Teletype may conflict with VoLTE (voice via voice) 4G). If, after activation, TTY missing HD When you call, it's normal. To get VoLTE back, you need to turn off the teletype in the settings.

Where is the setup of teletype in Xiaomi

Find the teletype settings in MIUI or HyperOS is not that simple, they're hidden in the back of the menu, and the path may vary slightly depending on the model and the firmware version, but the overall layout is this:

1. Open the Settings app (cog icon).
2. Go to the Special Features section (HyperOS may be called Convenience).
3. Choose the Rumor. → Teletype (TTY).
4. Tapping on the item Mode TTY Choose the right option (Full, HCO, VCO off).

In some models (for example, POCO F5) The path may be different: Settings → System system → Additionally. → Special facilities → Teletype.

If you don’t find this item, your firmware may not support it. TTY. You can check this through the engineering menu:

1. Open the phone app.
2. Enter the code ##4636##.
3. Go to the tab Information about the phone.
4. Check the line. TTY Mode – if it exists, the function is supported.

💡

If, after activation, TTY If you're not listening to the speaker, try rebooting your phone. Sometimes the system doesn't properly switch audio routes.

Step-by-step: how to enable teletype on Xiaomi

Activation of the teletype takes less than a minute, but requires attention to detail.

1. Check Compatibility: Make sure your carrier supports TTY (check on the website or by phone support services. In Russia, this is MTS, Beeline, MegaFon and Tele2.
2. Select the mode: Go to the settings TTY (See the previous section and select the appropriate mode: 🔹 Full TTY — if both subscribers are using TTY. 🔹 HCO — If you are hearing impaired but want to hear your voice. 🔹 VCO — If you speak in your voice, but the interlocutor is deaf.

Connect the equipment (optional)

USB-C

Bluetooth

Settings → Connected devices

Make a test call.

8-800-700-50-50

After inclusion TTY call-outs:

• ❌ Check if the operator is blocking the function (sometimes you need to activate it through the operator). USSD-team, for example, *111*123#).
• ❌ Make sure you are not roaming — TTY You may not be working abroad.
• ❌ Turn the network to 3G (In Settings → SIM-maps and mobile networks → Preferred type of network).

Frequent Teletype Problems in Xiaomi and Their Solutions

Despite the simplicity of the technology, Xiaomi users often face difficulties when working with the company. TTY. Here are the most common problems and ways to solve them:

⚠️ Note: If after activation TTY If normal calls stop working, reset your network settings. → SIM-maps and mobile networks → Reset the network settings. This will delete the stored access points. APN, So they're going to have to be reconfigured.

Another typical situation: after the update MIUI The teletype stops working, and that's because newer versions of the firmware can reset the modem settings:

1. Go to Settings → About Phone → MIUI version.
2. Slip 7 times on the kernel version line to open the hidden modem settings.
3. Select Band Mode and install Auto (PRL).
4. Reset the device.

If nothing helps, try resetting the network settings to factory:

adb shell settings put global tty_mode 0

This team will shut down. TTY through ADB (Developer mode is required).

How to turn off the teletype if it is switched on accidentally

Sometimes the teletype will activate on its own, for example, after resetting or connecting an incompatible Bluetooth device, in which case all calls will be texted, and voice communication will become impossible, to return everything to normal:

1. Open "Settings» → Special facilities → Rumor.
2. Find the Teletype (TTY) item and tap it.
3. Select Off mode (disabled).
4. Reboot your smartphone so that the changes take effect.

If Teletype is not on the menu, try an alternative method:

1. Enter the code #889## in the phone application.
2. In the menu that opens, select TTY Settings.
3. Set the value of Disabled.

⚠️ Note: Some Xiaomi models (e.g. Mi 11 Ultra) are disabled TTY through the engineering menu can reset the settings IMEI. Before using the codes, make a backup copy of the data!

If the teletype continues to turn on on on its own, check:

• 🔌 Is it connected to a smartphone? TTY-device USB Bluetooth.
• 📱 Are there any third-party applications for the hearing-impaired (e.g. Rogervision) TTY).
• 🔄 Is the developer mode activated with forced-TTY (check Settings) → Additionally. → For developers).

💡

If the teletype is activated accidentally, just turn it off in the settings of special features. Rebooting the smartphone will accelerate the application of changes.

Alternatives to Teletype in 2026: what is better to use

While teletype remains an important tool, modern technology offers more convenient alternatives for the hearing-impaired. TTY Xiaomi:

• 📱 Subtitled video calls: Apps like Google Duo or Zoom support automatic speech-to-text decoding.
• 💬 Voice messaging: WhatsApp, Telegram and Viber allow you to send audio messages that can then be read in text form.
• 📞 Relay Operator Services: Some countries have voice-to-text and back services (e.g. Federal Relay in the U.S).
• 🎧 Bluetooth Hearing Aids: Modern devices (such as Phonak Marvel) connect directly to Xiaomi and broadcast sound from the microphone.

The advantage of these alternatives is that they do not require support from the operator and work even in the field of the 4G/5G. But TTY It works without the internet and can be used for emergency calls when other communication channels are not available.

If you choose between TTY With modern solutions, be guided by your needs:

• 🆘 For emergency calls (police, ambulance) — TTY.
• 💼 For everyday communication – instant messengers or video calls.
• 👂 For people with residual hearing – Bluetooth devices.

FAQ: Answers to Frequent Questions about Xiaomi Teletype