What is a teletype in Xiaomi smartphones and why you need it
If you've ever looked at the call settings on Xiaomi, you've noticed the mysterious Teletype (TTY) feature, which raises a lot of questions: what does it do, who needs it, and why isn't everyone activated? In fact, teletype is not just an archaic relic of the past, but an important tool for people with hearing or speech impairments.
Teletype (TTY, Teletypewriter is a technology that allows you to send text messages over a phone line in real time, POCO X5 Mi 11) this function is integrated for compatibility with special TTY-It's a device that connects to a phone via cable or Bluetooth, and it allows deaf or hard of hearing users to communicate on the phone by typing messages instead of voice.
But why is this option hidden in the menu and disabled by default? The fact is that Xiaomi teletype only works when you connect an external one. TTY-modem or compatible accessory. Without it, the function remains inactive, but it is in the firmware MIUI It's going to be a way to get the standards of accessibility backed up, and then we're going to go through how that works in practice and who really needs it.
How does teletype work in modern phones
Xiaomi's teletype system is based on converting text characters into audio signals that are transmitted over a phone line.
- 📱 The user prints a message on the keyboard TTY-device or in a special application.
- 🔄 Smartphone converts text into tonal signals (similar to fax).
- 📡 The operator's network transmits signals to the other end of the line.
- 🖥️ The recipient sees the text on his TTY-terminal or in a supported application.
It's important to understand that to make a teletype work, both people have to use TTY-compatible devices. If you turn this on Xiaomi, but the subscriber on the other end of the wire doesn't support TTY, the connection just won't set up.
- ⚡ Teletype does not replace SMS Messengers are a separate protocol for voice calls.
- 🌍 This function is only available in countries where operators support TTY (In Russia and the CIS, this is rare).
- 🔌 To connect externally TTY-modem may be required USB-OTG adaptor.
Where to find teletype settings in Xiaomi
The MIUI teletype setup takes a couple of minutes, but the path to the menu may vary depending on the firmware version. Here is a universal guide for most models (Redmi, POCO, Mi):
- Open the phone application (green handset).
- Press three points (⋮) in the upper right corner and select "Settings».
- Go to Calls → Additional settings (or Special features in older versions).
- Find the "Teletype (TTY)" item and tap it.
In this menu you will see several modes:
| TTY mode | Description | When to use |
|---|---|---|
| TTY Off | The function is disabled (standard call mode). | For regular voice calls. |
| TTY Full | Full-fledged teletype mode (text only). | If both parties are using TTY-device. |
| TTY HCO | Mode for people with hearing impairments (text + voice). | If you can hear, but you can't talk. |
| TTY VCO | Mode for people with speech disorders (voice + text). | If you can talk but you can't hear. |
Once you select the mode, the smartphone can request a reboot. Don't ignore this requirement - without restarting, the settings will not apply.
Make sure the operator supports TTY|
Connect compatible TTY-device if necessary)|
Choose the right regimen (Full/HCO/VCO)|
Reboot your phone after the changes-->
Problems and mistakes when working with teletype
Despite the ease of customization, Xiaomi users sometimes have difficulty with teletype, and here are the most common problems and solutions:
⚠️ Note: If after activation TTY Calls have stopped, check if your operator supports this protocol. In Russia, most mobile networks (MTS, Beeline, Tele2) do not provide TTY-services.
- 🔕 No sound in front of you. TTY-ring → Make sure that the external is connected. TTY-modem or compatible software. Xiaomi's built-in speaker does not play TTY-signal!
- ❌ Mistake «TTY unsupported» → Update the firmware MIUI In the old builds (below) MIUI 12) the function may not have worked correctly.
- 📵 The call is interrupted when switching to TTY → Try changing the mode from Full to Full. HCO/VCO Or shut down the function altogether.
Another common mistake is trying to use teletype to send SMS. These are fundamentally different technologies: TTY only works during a voice call, and SMS is a separate data channel. If you need text messages, you should use standard messengers (WhatsApp, Telegram) or services for the deaf (for example, Rogers Video Relay Service).
What if TTY doesn’t work after the MIUI update?
Xiaomi Teletype Alternatives: What to Use Instead of TTY
If teletype is not suitable for you (for example, due to lack of operator support), consider alternative ways of texting:
- 💬 Subtitled video calls → Apps like Google Meet or Zoom support automatic speech-to-text decryption.
- 📱 Specialized messengers → Glide or Marco Polo lets you send text-transcripted video messages.
- 🎧 Devices for the hearing-impaired → Modern hearing aids (for example, Phonak Marvel) synchronize with smartphones via Bluetooth and display the text of calls on the screen.
Xiaomi users are particularly interested in the option with built-in call transcription function available in MIUI 14+:
- Open Settings → Special Opportunities → Hearing.
- Activate the “Transcription of Calls” option.
- The next call will display the text of what the interlocutor says (works only in English and Chinese).
This method does not require TTY-devices and works through the cloud services Xiaomi, but keep in mind that the quality of recognition depends on the speed of the Internet and the clarity of speech of the interlocutor.
💡
If you need text calls often, install InnoCaption (available for Android), which is free for hearing-impaired users and supports Russian.
Security and privacy when using TTY
Xiaomi's use of teletype raises questions about data protection, unlike encrypted messengers, TTY-The messages are transmitted in plain form through the networks of operators:
- 🔍 Technically possible to audition — TTY-Signals can be intercepted using special equipment.
- 📜 The operator may store logs in some countries (e.g. the United States) TTY-Calls are archived for emergency services.
- 🚫 No end-to-end encryption – unlike Signal or WhatsApp, text is transmitted without protection.
If privacy is critical, avoid transferring sensitive information (passwords, financial data) through TTY.
- 🔐 Encrypted messengers → Signal, Session.
- 📧 Post with PGP-encryption → ProtonMail.
- 🌐 VPN upon TTY-call-up → It won't protect the protocol itself, but it will hide yours. IP operator.
⚠️ Note: In some regions (e.g. the EU), operators are required to provide TTY-services for emergency calls (112), however, in Russia, such a duty is not - when calling the Ministry of Emergency Situations or the police teletype will not work.