Modern Xiaomi smartphones offer many features to improve communication quality, and one of the most popular is Voice over Wi-Fi (VoWiFi), an option that allows you to make and receive voice calls using a wireless Internet connection instead of a standard cellular network, especially for residents of private homes, office buildings with thick walls or remote areas where the signal of the cellular operator is weak or absent.
Many users face a situation where the Wi-Fi Calling switch is either missing or not activated in the phone’s settings, even if there is a supported tariff, the problem lies not only in the hardware, but also in software restrictions, regional settings and configuration. SIM-In this article, we will discuss in detail how to properly activate VoWiFi on Xiaomi devices with a shell. MIUI HyperOS and also consider hidden methods of enabling the function.
Before you start technical manipulation, you need to make sure that your mobile operator does support this technology in your area. Even if the phone is perfectly configured, without the appropriate service on the provider’s side, the function will not work. In addition, it is important that data roaming is included in the system settings, as this is often a prerequisite for registering a device in the IMS network.
Compatibility check and device preparation
The first step before activating VoWiFi should be to thoroughly check your hardware and data plan. Not all Xiaomi, Redmi and POCO models support this feature at the hardware level, although most devices released after 2018 already have the necessary modules.
Make sure your device has the latest firmware. Xiaomi engineers often add support for new carriers and fix IMS protocol errors in security updates. Go to Settings → About your phone and check for updates. If you’re using a global firmware version and the carrier only works with the Chinese version (or vice versa), the feature can be hidden software.
It is also necessary to check the status SIM-Some of the old ones are old. SIM-The cards you’ve been using for years may not support the modern encryption standards required for Voice over Wi-Fi. If the feature is gray or inactive after all the settings in the phone’s menu, it makes sense to contact the salon to replace the SIM card with a new one with support. 4G/LTE.
⚠️ Attention: Before replacement SIM-The cards must be saved all contacts stored in the SIM memory, as they will be lost when replaced. Modern smartphones offer to save contacts to a Google or Mi Cloud account.
The region of the device is an important nuance: If you bought a phone that was intended for the Chinese market but you use global firmware (or have reflashed it), the list of available carriers for VoWiFi may be trimmed, in which case standard on-boarding methods may not work, and you will need to use an engineering menu or third-party apps to activate hidden flags.
Basic configuration through the system menu
The easiest and safest way to enable Wi-Fi calls is to use the standard MIUI or HyperOS interface, which is suitable for most users whose carriers officially support the technology. To start, open the standard Phone application, which is installed by default on the system.
In the upper right corner of the screen, click on the menu icon (three dots or gear) and select Settings. In the list that opens, look for Accounts for Calls or Wi-Fi Calls. If your operator and region match, you will see a switch. Activate it, and the phone will try to register with the IMS network via a wireless connection.
The alternative path is in the general settings of the system. → SIM-Maps and mobile networks. Choose active networks. SIM-If you have two cards, the settings menu for a particular SIM card should include the option Use Wi-Fi for calls, and enable this option prioritizes wireless connection when there is a weak signal from the cell tower.
☑️ Checklist for VoWiFi activation
Once the function is enabled, an icon must appear in the status bar, which can look like a handset with a Wi-Fi symbol or be signed VoWiFi. If the icon appears but there is no 4G/LTE indicator next to it, this means that calls will now be exclusively over the Internet, which is especially useful in the dead zone of cellular communication.
Use of the Engineering Menu to Activate
If the standard switches are missing or not working, you can try activating VoWiFi through the Xiaomi engineering menu. This method requires caution, since changing the wrong settings can affect the operation of the radio module. To enter the menu, open the Phone app and type the combination ##4636##.
From the menu that opens, select Phone Information, and look for the section related to IMS settings. Look for Set Preferred Network Type or specific switches that contain the words VoWiFi, IMS, or WFC. Make sure the boxes are ticked against the relevant items.
In some versions of MIUI shells, access to the full engineering menu is limited, which may require installing a dedicated activator application, such as Activity Launcher, through which you can run the hidden system component com.android.settings with a specific action to open the full test menu.
⚠️ Warning: Do not change the settings you are not 100% sure about. Resetting the radio module may lead to temporary loss of communication or inability to identify the network.
After you make changes to the engineering menu, be sure to restart the device. Only after the full cycle of on and off, the new settings will apply to the radio module. If the VoWiFi icon does not appear after the reboot, try turning on and off flight mode to initiate re-registration on the network.
What to do if the engineering menu is not opened?
Setup through hidden codes and applications
For advanced users who don’t have standard methods, there are alternative ways to activate calls over Wi-Fi. USSD-codes or hidden menus that may only be available for specific models or regions, but the most effective method is often to use configuration files or helper apps.
There are specialized applications such as IMS Settings or Force LTE Only (in 4G mode) that allow you to force IMS support. Once you install such an application, you need to give it the necessary permissions and find the VoWiFi Config item. Here you can try changing the status of the function from "Disabled" to "Enabled".
Also worth looking at is the Xiaomi.eu app or custom firmware forums. Often, global firmware has configuration files (XML) cut out for specific operators. Enthusiasts create patches that add those files to the system. Installing such a patch through Recovery can instantly solve the problem of missing a menu item.
If your phone is under warranty, it can lead to loss of warranty, so consider the risks and benefits before you start.
Comparison of VoLTE and VoWiFi technologies
Often users confuse the two technologies or don't understand the difference between them. Both protocols are designed to improve communication quality, but use different data channels. Understanding the differences will help you to properly configure your smartphone for maximum comfort.
VoLTE (Voice over LTE) transmits voice traffic over fourth-generation (4G) networks, which delivers high-quality audio (HD Voice) and allows you to simultaneously use the Internet at high speed while talking. VoWiFi (Voice over Wi-Fi) uses any available wireless Wi-Fi connection to transmit voice, which is critical where there is no cellular coverage.
| Parameter | VoLTE | VoWiFi |
|---|---|---|
| Transmission channel | 4G/LTE cellular network | Wireless Wi-Fi network |
| Dependence on the tower | High (BTS signal needed) | Low (only router needed) |
| Sound quality | HD (high) | Depends on the speed of the Internet |
| Traffic consumption | Normally not charged. | Wi-Fi traffic is consumed |
| Priority | Highest (if there is a signal) | Secondary (if there is no LTE) |
Under ideal conditions, a Xiaomi smartphone should automatically switch between these modes. For example, when entering a building with a bad signal, the phone switches to VoWiFi, and when going outside, back to VoLTE. Seamless switching (without breaking the connection) requires that both functions be activated in the settings.
💡
Tip: For stable operation of both technologies, turn on the settings SIM-The card item "Always use" 4G/LTE" (If available, this will prevent the network from falling into 3G/2G during conversation.
Solving Typical Problems and Errors
Despite the correct setup, users may encounter a situation where Wi-Fi calls are not working. The most common mistake is that the icon appears but calls fail or are reset. This is often due to data roaming settings. Even if you are at home, system roaming of data must be enabled to work with the IMS protocol.
Another problem is conflict. IP-address DNS. If your router uses non-standard settings DNS, Your phone may not be able to find the operator's registration server. Try changing the Wi-Fi settings on your phone. DNS Public by Google (8.8.8.8) or Cloudflare (1.1.1.1).This often solves the problem of "is" but doesn't work".
It’s also worth checking if antivirus or the built-in MIUI Security firewall blocks the connection for system services. In rare cases, resetting network settings helps. Go to Settings → Connection and Sharing → Reset Wi-Fi, mobile networks and Bluetooth. Note that this action will remove saved passwords from Wi-Fi networks.
⚠️ Note: If you reset your network settings, you will lose all saved Wi-Fi passwords and a pair of Bluetooth devices. Make sure you know the passwords from the main networks before performing this operation.
If nothing helps, there may be a problem on the operator's side. Some providers require manual activation of the service through a personal account or a private account. USSD-Check the status of the service "Vifay calling" or "Internet calls" in the application of your mobile operator.
💡
Successful activation of VoWiFi on Xiaomi depends on three factors: operator support, correct settings. SIM-maps (data roaming) and the relevance of phone firmware.