How to turn on VoWiFi on Xiaomi Mi 9T Pro: a complete guide to checking compatibility

What is VoWiFi and why is it needed on Xiaomi Mi 9T Pro?

VoWiFi (Voice over Wi-Fi) technology allows you to make calls over a wireless network instead of traditional cellular communication. This is especially true for owners of Xiaomi Mi 9T Pro (also known as Redmi K20 Pro), where the quality of communication in rooms with poor coverage leaves much to be desired. With active VoWiFi, your smartphone automatically switches to Wi-Fi for voice calls if the mobile network signal is weak – for example, in basements, elevators or country houses with thick walls.

The main advantages of the technology for the Mi 9T Pro:

  • 📶 Stable communication in areas with poor coverage 4G/3G
  • 🔋 Battery savings – the phone doesn’t waste energy searching for the network
  • 🎧 Cleaner sound thanks to digital voice transmission (codecs) HD Voice)
  • 🌍 International calls at home operator rates (if roaming is supported)

However, there are nuances: not all operators in Russia and the CIS support VoWiFi, and Mi 9T Pro requires the right firmware.

📊 Your mobile operator?
MTS
Beeline
MegaFon
Tele2.
Yota
Other

Verify VoWiFi support on Xiaomi Mi 9T Pro

Before setting up, make sure your device and SIM-The map supports the technology. 9T Pro (Raphael) VoWiFi only works under three conditions:

  1. Version. MIUI not less than 12.0.3 (for global firmware) or 12.5+ (You can check the version in Settings. → The phone. → Version. MIUI.
  2. The operator must support VoWiFi. In Russia for 2026, the function is officially provided: 📡 MTS (for subscribers with tariffs "Ultra" and "SuperMTS") 📡 Beeline (on the tariffs "It's simple" and "Unlimited") 📡 MegaFon (for corporate clients and owners only")

SIM-map

nano-SIM

VoLTE

To check for VoLTE support (and thus VoWiFi support), do:

  1. Open the Settings. → SIM-maps and mobile networks.
  2. Choose yours. SIM-Map and find the VoLTE Calls item.
  3. If the switch is active, your SIM is ready for VoWiFi. If you don't have an option, contact your carrier to change the card.
How to find out the model of your Mi 9T Pro?
Open the Settings. → The phone. → Model, if indicated. M1903F10I or M1903F11I — This is a global version (raphael). The Chinese version (raphaelin) will require firmware with support for Google services.

Step-by-step: how to turn on VoWiFi

If all conditions are met, follow this instruction. On the Xiaomi Mi 9T Pro, the path to VoWiFi settings may vary depending on the version of MIUI - in some firmware, the option is hidden in the engineering menu.

Method 1: Using standard settings (MIUI 12.5+)

  1. Open the Settings. → SIM-maps and mobile networks.
  2. Choose yours. SIM-card (if there are several).
  3. Slip on VoWiFi calls (or Wi-Fi Calling on English firmware).
  4. Activate the switch and confirm the address for emergency calls (usually automatically substitute your home address).
  5. Restart your phone – VoWiFi or Wi-Fi Calling will appear in the status bar.

Method 2: Engineering menu (for older versions of MIUI)

If the option is not in the standard settings, try activating it through the engineering menu:

  1. Open the Phone app and dial ##4636##.
  2. Select your phone information (Phone Information).
  3. Scroll down to Wi-Fi Calling and set the Enabled value.
  4. Go back to the basic settings and check for the appearance of the VoWiFi item.

💡

If after activation of VoWiFi mobile Internet disappeared, check APN-settings at the operator. Some configurations conflict with IMS-profile.

⚠️ Attention: On Xiaomi Mi 9T Pro with custom firmware (such as LineageOS or Pixel Experience) VoWiFi may not work smoothly due to the lack of certified software. IMS-For full support, it is recommended to use an official MIUI.

How to turn off VoWiFi and return to normal calls

If VoWiFi causes inconvenience (e.g., quickly drains the battery or impairs communication quality), it can be deactivated by:

  1. Go to Settings. → SIM-maps and mobile networks.
  2. Choose yours. SIM-map.
  3. Turn off the VoWiFi call switch.
  4. Confirm the disconnection – the icon in the status bar will disappear.

You can also temporarily disable the function through the notification panel:

  1. Swipe down from the top edge of the screen to open the curtain.
  2. Hold your finger on the VoWiFi (or Wi-Fi Calling) icon.
  3. In the window that opens, turn off the option.

⚠️ Attention: On some firmware MIUI Turning off VoWiFi through the notification curtain is not working correctly - the function can turn on again after restarting. SIM-map.

Alternative ways to call via Wi-Fi

If your carrier does not support VoWiFi or the feature is unstable, consider alternatives:

1. VoIP Call Applications

  • 📞 Google Voice – Free calls to the US/Canada, paid international.
  • 📞 Zoiper - Supports SIP-multi-provider accounts.
  • 📞 WhatsApp/Telegram — Calls via messengers (but it is required that the subscriber also used the application).

2. SIP settings through the standard "Phone" application

MIUI allow SIP-direct-account:

  1. Open Phone → Three Dots (menu) → Settings → Calls → SIP accounts.
  2. Add data from your VoIP provider (such as Sipnet or Mango Telecom).
  3. Save settings and use SIP for outgoing calls.

3. Use of eSIM with VoWiFi support

Some virtual operators (such as Tinkoff Mobile or SberMobail) offer eSIMs with VoWiFi support.

  1. Set an eSIM profile through the operator’s application.
  2. In the settings SIM-Select eSIM as the primary for calls.
  3. Activate VoWiFi – usually the option appears automatically.

💡

For business users, Microsoft Teams will be a service that integrates telephony, which allows you to call city numbers over Wi-Fi, saving history in Outlook.

FAQ: Frequent VoWiFi questions on Xiaomi Mi 9T Pro

My carrier supports VoWiFi, but the option is not in the settings. What do I do?
Your firmware probably doesn't contain IMS-profiles for the operator. Solutions: Update MIUI Up to the latest version through Settings → Update system. Install Carrier Services from Google Play and update it. Reset network settings (Settings) → System system → Reset → If nothing helps, try reflashing your phone to the global version. MIUI (for example, MIUI EU).
VoWiFi works, but the person can't hear me. What's the problem?
It's a typical codec or microphone problem: 🎤 Microphone – test it in a dictaphone. 🔊 Sound settings – turn off noise cancellation in Settings → Sound. → Improvement of sound. 📡 Wi-Fi router – some models (e.g. TP-Link Archer) C6) block UDP-If you have a problem, contact the operator, if you need an update, you may need to update. IMS-profile.
Can I use VoWiFi abroad?
Yes, but with reservations: 🌎 Roaming – VoWiFi only works if your carrier supports Wi-Fi roaming (for example, MTS in EU countries). 💰 Tariffing – calls via VoWiFi in roaming can be charged as international (check with the operator). 🔒 Blocking – some countries (e.g. China, UAE) block VoIP traffic at the provider level. VPN (For example, ProtonVPN or local SIM-card with VoLTE support.
How to check if the call is via VoWiFi, not the network?
There are a few signs: 📱 Icon in the status bar – VoWiFi or Wi-Fi Calling icon next to signal level. 📶 Lack of network indicator – if you have 0 sticks of coverage, but the call passes, then Wi-Fi is used. 🔍 Call logs – some firmware in the call history displays a "Wi-Fi" tag. You can also temporarily turn off the mobile network (Settings) → SIM-map → Mobile network → Disable) and try calling – if the connection is established, it means VoWiFi is used.
Portrait of VoWiFi for balance or traffic?
No, VoWiFi doesn't consume: 💳 Money from the balance - calls are charged as usual (at the operator's tariff). 📡 Mobile traffic - only Wi-Fi is used. However, outgoing VoWiFi calls can consume up to 1MB/minute of your Wi-Fi traffic (depending on the codec). 4G (VoLTE is consuming ~0.5 MB/minute of mobile traffic.