Introduction: why you need a teletype mode in modern smartphones
Have you ever noticed a mysterious teletype mode (TTY) item in your Xiaomi Redmi 9 settings and wondered what it is? This feature, seemingly from the last century, still applies to a certain category of users. Teletype mode is a specialized technology that allows people with hearing or speech impairments to communicate on the phone via text messages in real time.
Although Redmi 9 was released in 2020, it has not been a coincidence that TTY is supported, and in many countries, including Russia, teletype operators are legally required to provide teletype services, and it can also be useful in emergency situations where voice is not possible, but text is critical. Let's see how it works in practice and who really needs it.
What is TTY and how does it work on Xiaomi Redmi 9?
Teletype (TTY, Text Telephone) is a system that allows text messages to be sent over phone lines. Unlike conventional SMS, which is sent over a mobile network, TTY works directly during a phone call, converting the typed text into audio signals and back. On Xiaomi Redmi 9, this mode is implemented software-based, without the need to connect external devices (although this is also possible).
Technically, the process looks like this:
- 📱 The sender typed text on the keyboard of the smartphone.
- 🔄 The phone converts the symbols into special tonal signals (according to the Baudot protocol or the scaling of the phone). ASCII).
- 📡 Signals are transmitted over a voice channel, as in a normal call.
- 📲 Recipient (included) TTY) Decodes signals back into text.
It is important to understand that both interlocutors must use compatible devices or applications to work with TTY. Redmi 9 supports three main modes:
- TTY Full – full-fledged two-way text exchange.
- TTY HCO (Hearing Carry-Over) – text is sent and the answer is received by voice.
- TTY VCO (Voice Carry-Over) – a voice is sent and the answer is received by the text.
Who needs a teletype mode in 2026?
Despite the development of instant messengers and video chats, TTY remains in demand in several key scenarios:
| Category of users | Reason for using TTY | Alternatives |
|---|---|---|
| People with hearing impairments | The ability to communicate on the phone without voice communication | Video calls with sign language, SMS |
| Users in areas with poor internet | TTY works via voice channel, does not require data | Voice calls (if audible) |
| Emergency services | Mandatory TTY support for hearing-impaired calls | Specialized applications (e.g., "Emergency Call 112") |
| Business (call centers) | Serving clients with disabilities | Chatbots, email support |
Interesting fact: in some countries (for example, in the United States) operators are required to provide free of charge. TTY-There are no such programs in Russia, so smartphones like Redmi 9 with built-in support TTY They are an important tool for accessibility.
⚠️ Note: The teletype mode on Xiaomi Redmi 9 does not replace the Gestures in Call or Real-Time Titles feature. This is a separate technology that requires support at both ends of the line. TTY, Text messages won't reach.
How to enable and configure TTY on Xiaomi Redmi 9: step-by-step instructions
You can activate teletype mode on Redmi 9 in a few steps. Importantly, before setting up, make sure your carrier supports TTY (check this with support).
Instructions:
- Open the Settings app on the main screen.
- Go to the Special Opportunities section (the person in the circle icon).
- Select the item Rumor.
- Tap on Teletype Mode (TTY).
- Turn the switch on in the on position.
- Select one of the modes: TTY Full for full text exchange; TTY HCO if you hear but can’t speak; TTY VCO if you can talk but can’t hear.
After activation, the TTY icon will appear in the status bar. Now when you call, you can type text on the keyboard, and the received messages will be displayed on the screen.
Make sure you're supported. TTY operator|Check balance (some operators charge for a fee) TTY-call-up)|Set up a regime (Full/HCO/VCO) according to the needs|Conduct a test call to the support number TTY-->
⚠️ Note: Xiaomi Redmi 9 with firmware MIUI 12.5 and new mode TTY It may interfere with the Vibration function when you call. TTY Vibration is gone, restart the device or reset the settings of special features.
Common TTY Problems on Redmi 9 and Their Solutions
Redmi 9 users sometimes experience difficulties with TTY, and here are the most common ones and ways to fix them:
| Problem. | Possible cause | Decision |
|---|---|---|
| Impossible to turn on TTY | The operator does not support the technology | Call the operator and clarify the availability of the service |
| Text is not displayed during the call | Incompatibility of modes of interlocutors | Make sure that both devices are set to TTY Full |
| The call is terminated when TTY is activated. | Conflict with other special facilities | Turn off Sound Amplification or Mono Audio in your hearing settings |
| Symbols are displayed incorrectly | Poor communication quality | Try switching to 3G (In Settings → SIM-maps and mobile networks) |
If none of the solutions worked, try resetting your network settings:
→ SIM-maps and mobile networks → Network resetOn Xiaomi Redmi 9 with firmware below MIUI 12.0.3, the TTY mode may not work stable due to an error in the modem module. Update the software via Settings → About Phone → System Update.
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If you use TTY frequently, add the Special Features widget to the home screen for quick access to settings. To do this, click and hold free space on the screen → “Widgets” → find “Special Features”.
TTY Alternatives on Xiaomi Redmi 9: What to use instead of teletype
If TTY is not your favorite or the operator doesn’t support this technology, Redmi 9 has a few alternative ways to text:
- 💬 SMS and MMS — The downside is that there's no real-time exchange.
- 📱 Messengers (WhatsApp, Telegram, Viber) – require the Internet, but support voice messages and video calls with subtitles.
- 🎧 Signal translation applications (e.g. Rogervoice or Ava) – translate speech into text in real time.
- 🆘 Specialized services (e.g., "Emergency Call 112" with text support for hearing-impaired people).
Business applications can be run on solutions like Google Live Transcribe (translating speech into text) or Microsoft Translator (supporting group chats with translation), the main difference being that TTY requires an internet connection, whereas teletype works via a voice channel.
How to turn Live Transcribe on Redmi 9
Security and privacy when using TTY
Like any data technology, TTY has its risks, and here's what to look out for:
- 🔒 Lack of encryption: text messages in TTY They're transmitted openly, like a voice signal, and they can be intercepted by special equipment.
- 📍 Call Localization: The operator sees what you are using TTY, What can be used for targeted advertising or behavior analysis.
- 💰 Additional rates: Some operators charge for TTY-Calls as international communication.
To minimize the risks:
- Use TTY only with trusted interlocutors.
- Do not share confidential information (passwords, card data).
- After the call, clear TTY history in the special features settings.
⚠️ Attention: Xiaomi Redmi 9 firmware MIUI Global history TTY-messages stored in a folder /data/data/com.android.phone/files/tty_logs/. When you reset the phone to factory settings, this data is deleted, but it can be extracted using the help of ADB before discharge.
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The Xiaomi Redmi 9's Teletype Mode (TTY) is not an outdated feature, but an important accessibility tool, indispensable in situations where voice is impossible and the Internet is not available, but modern encrypted messengers are better for everyday communication.