Teletype (TTY) in Xiaomi Redmi 9A: what is this feature and how to use it

If you've ever looked at the call settings on your Xiaomi Redmi 9A, you might have noticed a mysterious item called "TTY." For most users, this option remains unclear: what it does, why it is needed, and why it is even present in a modern smartphone? In fact, teletype is not an archaic relic, but an important accessibility feature that is still relevant for people with hearing or speech impairments.

In this article, we will discuss in detail what a teletype in a phone is, how it works on Redmi 9A, in which cases it can be useful for a regular user (spoiler: not only for communicating with deaf people), and why it is better not to turn it on unnecessarily, and you will learn how to set up TTY correctly, what modes it supports, and what to do if the function interferes with normal calls.

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

Teletype (TTY, Text Telephone) is a technology that allows real-time text messages to be sent over a phone line, originally designed for people with hearing or speech impairments to communicate by phone, typing messages on a special device. In modern smartphones, including the Xiaomi Redmi 9A, this feature is integrated at the software level.

How does it work? Instead of voice, subscribers exchange text messages that are displayed on the screen, and both people must have TTY support, either built into the phone or through an external device. Redmi 9A teletype is software-based, meaning it doesn't require any additional hardware.

• 📱 For whom it is intended: primarily for the deaf, hard of hearing or people with speech disorders.
• 🔄 How the text is transmitted: over the same telephone channel as the voice, but in a different format (signal modulation).
• ⚡ Exchange rate: 45–60 characters per second (enough for real-time dialogue).
• 🌍 Compatibility: Works with other phones that support TTY, and call centers equipped with appropriate equipment.

Although teletype seems to be an outdated technology, it is still used in emergency services in many countries (for example, in the United States, 911 operators are required to maintain their services). TTY-In Russia, this feature is less common, but its presence in Redmi. 9A International standards of accessibility.

Teletype modes in Xiaomi Redmi 9A

The Xiaomi Redmi 9A has three main teletype modes, each designed for different scenarios, which can be selected in the settings, and it depends on how the feature will work during the call.

It's important to understand that TTY must match both people, otherwise the communication will either fail or not work properly. For example, if you choose TTY Full and the other person is TTY HCO, the text may be distorted or delayed.

⚠️ Attention: When the teletype is on, voice calls may be interrupted or interrupted. TTY, It is recommended to disable this function in the settings.

How to turn on or off the teletype on Xiaomi Redmi 9A

The setup of the teletype on the Redmi 9A takes less than a minute.

1. Open the Phone app (the tube icon on the home screen).
2. Click on the three dots in the upper right corner (menu) and select Settings.
3. Go to the Calls section → Additional → Teletype (TTY).
4. Select the desired mode from the list (Full, HCO, VCO or Recruitment).
5. Confirm the changes and exit the menu.

Once the teletype is activated, the status bar (top bar) will have the corresponding icon, the letter "T" squared, which means that the function is active and will apply to all outgoing calls.

Make sure the regimen TTY coincides with both interlocutors|Check for the T icon in the status bar|Use the keyboard to enter text during a call|Turn it off. TTY after use, if it is not necessary-->

If after turning on the teletype calls stopped working or there were interference, go back to the settings and select TTY Also make sure that your operator tariff does not block special services (some budget rates may limit your service). TTY-linkage).

Teletype problems on Redmi 9A and their solution

While the teletype in the Xiaomi Redmi 9A is stable, users sometimes face difficulties, and here are the most common problems and ways to fix them:

• 📞 Call is not set to mode TTY: Check if the interviewer supports you. TTY (Ask him directly. Make sure you choose the same mode (Full mode, HCO or VCO). Restart your phone and try again.
• 🔊 Interference or noise during TTY-Call: Disable other applications that use a microphone (e.g. voice recorder — TTY Sensitive to bad signal. Switch to another mode. TTY (For example, from full to HCO).
• ⌨️ Do not display the keyboard to enter text: Make sure TTY It's on before the call starts (you can't activate it during the call). Check if third-party software (such as launchers or optimizers) is blocking the keyboard. Update the phone's firmware in older versions. MIUI were display bugs TTY-interface.

⚠️ Note: Some carriers (especially virtual ones, such as Tele2 or Yota) may not support TTY If the calls don't pass, check with your provider.

If the problem persists, try resetting your network settings: go to Settings → SIM-maps and mobile networks → Network resets, which will delete the stored connection settings, but can help restore the teletype.

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Before using TTY, check it with another Xiaomi phone (like a friend) to help you understand if the problem is in your device or in the carrier’s network.

Can I use teletype for normal text messages?

No, teletype is not a substitute for SMS or messengers, it's designed solely for text exchange during a voice call. Here are the key differences:

• ⏱️ TTY It works in real time (like chat) and SMS delay.
• 📶 Requires an active call - without connection, text is not transmitted.
• 💬 No message history – no text is saved after the call is completed.
• 🔒 It only works between TTY-devices (cannot be sent) TTY-phone-mail).

If you need text communication, it is best to use standard tools:

• 📩 SMS — Short messages without the internet.
• 💬 Messengers (WhatsApp, Telegram) – for chats with history and media files.
• 📞 Video calls with subtitles – Google Meet or Zoom has a voice recognition feature.

TTY is not suitable for sending messages to short numbers (for example, 112 or 911) - emergency services in Russia do not support this protocol. SMS (where provided).

Alternatives to Teletype on Xiaomi Redmi 9A

If teletype doesn’t work for you, consider alternative ways to text:

For Redmi 9A users, instant messengers will be the most versatile solution, for example, Telegram has a built-in text-based voice messaging feature that could be useful for people with hearing impairments, to enable it:

1. Open a chat on Telegram.
2. Press and hold the microphone button to record a voice message.
3. After sending, click on the message and select the text of the message (decryption will appear automatically).

Security and privacy when using TTY

Although teletype seems to be a harmless feature, when using it, you should take into account several nuances:

• 🔒 Lack of encryption: TTY-messages are transmitted in an open form over the telephone network, they can be intercepted by attackers (for example, through wiretapping).
• 📡 Metadata Leak: The operator sees what you are using TTY, And it can fix it in the logs.
• 📱 Malware risk: There are viruses on Android that intercept keyboard input, including during the TTY-call-up.

To minimize the risks:

• Do not transmit confidential information (passwords, card data) through TTY.
• Use TTY only with trusted interlocutors.
• Regularly update the Redmi 9A firmware – new versions of MIUI fix vulnerabilities.
• Install an antivirus (such as Avast or Kaspersky) to protect against keyloggers.

⚠️ Note: In some countries (e.g. the United States) operators are required to provide TTY-services are free for people with disabilities. In Russia, such requirements do not exist, so the operator can charge for the service. TTY-Calls as if they're a special service.

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Teletype is convenient for people with hearing/speech impairments, but does not replace instant messengers or SMS. Use it only when necessary and turn it off after use to avoid interference in voice calls.

FAQ: Frequent questions about the teletype in Xiaomi Redmi 9A