Xiaomi’s current smartphones have many hidden features that most users don’t even know about, including teletype (TTY) mode, which is designed for people with hearing or speech impairments, which allows real-time text messaging via voice calls, turning a phone conversation into a chat.
Although the feature has been around since the 1960s, in the age of messengers, it remains relevant for specific scenarios: emergency calls, public service, or areas with poor Internet. TTY-How to activate it on different models (Redmi Note 12, POCO X5, Mi 11 et al., and why it can be useful even for those who do not have hearing problems.
Important: the feature is not available in all countries and may not be available on some MIUI firmware. If your Xiaomi does not have TTY in its settings, this is not a breakdown, but a feature of the regional version of the software.
What is Teletype Mode (TTY) and How Does It Work?
TTY (Teletypewriter) is a text communication technology originally developed for teletypes (printing telegraph machines). In the context of Xiaomi smartphones, it allows:
- 📞 Convert voice calls to real-time text chat
- 🔄 Exchange messages with subscribers who are also enabled TTY
- 🆘 Use emergency services (in some countries, such as the United States, 911 operators support the use of emergency services) TTY)
- 📶 Work without the Internet - the transmission goes through the voice channel of the cellular network
Technically, the mode uses acoustic coupling (communication via speaker/microphone) or digital protocols (for example, Baudot at 45.45 bp). Xiaomi implements a software emulation of TTY, so no additional equipment is required - only a compatible operator tariff.
⚠️ Note: In Russia, most mobile operators (MTS, Beeline, MegaFon, Tele2) do not support TTY-This feature will only work when roaming in developed countries. TTY-network (USA, Canada, Australia) or when calling special numbers of civil services.
Who's it meant for? TTY-Xiaomi
The main categories of users who will need this function:
- 🦻 People with hearing or speech impairments (deaf, hard of hearing, dumb)
- 🏥 Patients after operations on the vocal cords
- 🚨 Emergency services in areas without internet
- 🌍 Travellers in countries where TTY public-services
- 🔧 Technical experts testing equipment compatibility
Interestingly, Xiaomi has TTY integrated at the MIUI level, while many Android smartphones from other brands (such as Samsung) have it implemented through a separate app, which makes it easier to set up but limits flexibility.
How to turn on the teletype mode on Xiaomi: step-by-step instructions
The activation algorithm depends on the version of MIUI and the model of the smartphone, below is a universal instruction for most devices (Redmi, POCO, Mi):
- Open Settings → Special Opportunities
- Select Hearing (or Sound and Vibration → Special features on older versions)
- Find the Teletype Mode (TTY) and tap it.
- Turn on the slider and select one of the modes: TTY Full - text input / output TTY HCO - text input, voice output TTY VCO - voice input, text output
Confirm the changes and restart the smartphone (recommended)
Ensure support from the operator|Check the balance (SMS-tariffification)|Choose the right regimen (Full/HCO/VCO)|Testing with another TTY-device-->
⚠️ Note: On some models (POCO F3, Redmi 9A) point TTY It may not be in the standard settings:
- Update MIUI to the latest version
- Install regional firmware (e.g. MIUI Global instead of MIUI Russia)
- Use the Engineering Mode (Engineering Menu) using the code ##4636###
On the flagship models (Xiaomi 13 Ultra, Mix Fold 3) implemented an expanded version of TTY with support for Unicode (emoji, Cyrillic), while on budget smartphones available only ASCII.
💡
To check for TTY support on your model, type ##4889## in the dialer. If the modem test menu appears, the feature is available.
TTY’s future: Why Xiaomi is keeping its technology obsolete
In the age of 5G and artificial intelligence, it may seem odd that Xiaomi continues to support the technology 60 years ago.
- In the United States (FCC Section 255) and the EU (EU Directive 2019/882), manufacturers are required to ensure accessibility for people with disabilities.
- Emergency scenarios: TTY works when the Internet is disconnected or messengers are blocked (for example, during natural disasters).
- Backward compatibility: Many government agencies (police, hospitals) still use the system. TTY-terminal.
MIUI 15 (2026) is expected to integrate TTY with an AI translator that converts text to speech and back in real time, making it useful not only for people with disabilities, but also for international calls.