Teletype mode on Xiaomi phone: what it is, how it works and why you need it

Have you ever noticed a mysterious "Teletype Mode" in call or feature settings on your Xiaomi smartphone? Many users encounter this feature by accident, such as dialing a number or while talking, when the screen suddenly switches to an unfamiliar text interface. Don't be afraid: it's not a virus or a system failure, but a useful (though rarely used) option for people with disabilities.

In this article, we will go into detail about what Teletype Mode (TTY) is on Xiaomi phones, how it works on models like the Redmi Note 12, POCO X5 or Mi 11, and why it is sometimes turned on by mistake. You will learn how to activate or deactivate this feature through Android settings, what problems it can solve, and why it is better not to use it unnecessarily. And we will answer frequent questions: does TTY affect the quality of communication, can you send SMS through it, and why some carriers (for example, MTS or Beeline) do not support this mode.

What is Teletype Mode (TTY) and Why You Need It

Teletypewriter (TTY) is a technology that allows real-time text messages to be sent over a phone line, originally designed for deaf and hard of hearing people to communicate on their phones without voice communication, and instead of speaking, users type text on a keyboard that is instantly displayed on the person's screen (provided that they also have TTY on).

On Xiaomi smartphones (as well as other Android devices), the teletype mode is integrated into the system as part of special features.

• 📞 TTY Full - full-fledged two-way text exchange (both interlocutors use the same language). TTY).
• 📤 TTY HCO — You only hear the text and the answers are in your voice (for people with speech impairments, but with a preserved hearing).
• 📥 TTY VCO — You speak in your voice and read text answers on the screen (for the hearing impaired).

It is important to understand that TTY is not the same as SMS or messengers, text is transmitted directly over the voice channel, so the mode requires support from a mobile operator. Unfortunately, in Russia and CIS countries, this technology is almost not used: most operators (including MegaFon, Tele2) do not provide TTY services, and the devices themselves often turn on the mode by mistake.

How does the mode of teletype on Xiaomi: signs of activation

If your Xiaomi has suddenly turned on teletype mode, you will notice the following changes:

On some Xiaomi models (such as Redmi 10 or POCO F3), when activated, TTY also loses the ability to use speakerphones or Bluetooth headphones during a conversation, which is because the teletype mode monopolizes the audio channel for text data.

⚠️ Attention: If you do not use TTY In this mode, voice quality is reduced by 30 to 50 percent by converting sound into text signals, even if you're not sending messages.

Step-by-step: how to turn on or off teletype on Xiaomi

There are two ways to disable Xiaomi’s teletype mode: through Android settings or through the engineering menu (if the standard method doesn’t work).

Method 1: Through phone settings (recommended)

This method works on all modern Xiaomi smartphones with the shell MIUI 12-14:

1. Open the Settings app (cog icon).
2. Go to Special Features (or Additional Settings → Special Features on older versions).
3. Find the Hearing or Teletype Mode (TTY) option.
4. Choose Disable or Off.
5. Confirm the action if a request appears.

On some models (for example, Xiaomi 13 Lite) the path may be different:

Settings → System → Language and input → Additional → Teletype mode

Open settings of special opportunities|The "hearing" section is found, or "TTY"|Teletype mode is translated to the "off" position."|Reloaded phone (if no changes are applied)-->

Method 2: Engineering menu (for experienced users)

If the standard method didn’t work (for example, due to a MIUI failure), try disabling TTY via the engineering menu. Be careful – the wrong actions here can disrupt the network!

1. Open the phone app and dial the combination: ##4636##.
2. In the menu that opens, select Phone Information.
3. Scroll down to the TTY Mode block.
4. Click on it and select TTY Off.
5. Go back and restart the phone.

⚠️ Note: Some Xiaomi firmware (especially custom ones) may not have an engineering menu or have a different access code. SIM-map!

Why Teletype Mode is Turned On By Itself: Causes and Solutions

Many Xiaomi users complain that TTY is activated without their involvement, which can be due to the following reasons:

• 🤖 Software failure after update MIUI. Often the mode is turned on after installing a new firmware version (for example, when switching from the new version of the firmware). MIUI 13 on MIUI 14).
• 📱 Pressing hot keys on some models (e.g, POCO X3) TTY You can activate it by randomly pressing a combination of buttons (usually Volume up). + Loudness down + Power button).
• 🔄 The problem with hearing-impaired apps is that programs like Live Transcribe or Sound Amplifier can automatically switch your phone to teletype mode.
• 📡 Problems with SIM-If the operator does not correctly determine the capabilities of the device, it can force activation. TTY (rare, but occurs in Yota or virtual operators).

To prevent the spontaneous activation of TTY:

1. Check to see if there are apps on your phone for people with hearing impairments, and delete them if you're not using them.
2. Update MIUI to the latest version via Settings → About Phone → System Update.
3. Reset network settings: Settings → SIM-maps and mobile networks → Resetting network settings.
4. If the problem repeats, reset all settings (without deleting data): Settings → About phone → Reset settings.

💡

If the teletype mode is turned on after connecting Bluetooth headphones, try to disable the function "Bluetooth audio in hearing aid mode" in the settings of the connected device.

Does the teletype mode affect the quality of communication and battery?

Yes, TTY mode significantly degrades voice communication, even if you're not texting.

• 📶 The phone switches to a narrower frequency band (300–3,000 Hz instead of the standard 50–7,000 Hz), which makes the voice of the interlocutor less legible.
• 🔋 The load on the processor increases due to constant coding/deksignaling, which leads to accelerated battery discharge (on the 10–15% faster).
• 📡 There may be interference when connecting to networks 4G/5G, so TTY Optimized for the old standards (2G/3G).

We tested the Xiaomi 12T with active teletype mode:

As you can see from the table, the teletype mode almost negates the advantages of modern networks, returning the quality of communication to the level of button phones of the 2000s.

💡

If you are not deaf or hard of hearing, TTY mode on Xiaomi is better to keep off – it degrades communication and consumes the battery without benefit.

Alternatives to Xiaomi Teletype Mode: What to Use Instead of TTY

If you need text exchange while calling, but the carrier doesn’t support TTY, consider these alternatives:

• 💬 Subtitled video calls. Apps like Google Meet or Zoom can recognize speech and display it as text in real time.
• 📱 Applications for the deaf. List of applications for replacement TTY Live Transcribe (from Google) – translates speech into text with support for 80+ Rogervoice is a dedicated deaf software that supports relay calls, Ava is a group chat with speech recognition for collective communication, and these programs are over the Internet and do not require operator support.
• 📧 SMS If the person is also deaf, it is easier to exchange messages on WhatsApp, Telegram or standard ones. SMS.
• 🎧 Bluetooth hearing aid devices: Modern models (such as the Xiaomi FlipBuds Pro) can connect directly to hearing aids via protocol. ASHA (Audio Streaming for Hearing Aids).

The advantages of these solutions over TTY:

• ✅ Work for any operator (including Tinkoff Mobile or SberMobile).
• ✅ Do not impair the quality of voice for other subscribers.
• ✅ Support multimedia (video, stickers, voice messages).

Frequent questions about the teletype mode on Xiaomi