Modern Xiaomi, Redmi and POCO smartphones offer a wide range of communication capabilities, including technology Voice over Wi-Fi This feature occupies a special place. This allows you to make and receive voice calls over a wireless internet network, bypassing standard cell towers. For residents of densely populated cities or those with thick-walled apartments, this is a real lifesaver, as the cellular signal indoors can be critically weak.
Implementation of technology VoWiFi The integration of MIUI and HyperOS into the user interface has significantly simplified life for users. There's no longer a need to install third-party apps like Skype or Viber to call regular landlines or mobile numbers. System integration It works transparently: you dial the number as usual, and the phone automatically decides which communication channel to use. However, activation isn't always automatic, and manual settings are often required.
In this article, we'll detail the steps to enable this option on various device models. We'll cover not only the standard menus, but also hidden engineering codes that may be required if your telecom operator It doesn't provide settings automatically. We'll also focus on diagnosing potential issues, as even with this feature enabled, problems may still occur due to specific router or data plan features.
VoWiFi Technology: How It Works and Its Benefits
Technology VoWiFi (Voice over Wi-Fi) is the transmission of voice traffic as packet data via the IP protocol. Unlike VoIP apps, which operate in their own isolated ecosystems, VoWiFi is integrated directly into the standard phone module of a smartphone. This means that to the other party, your call appears like a regular mobile call, not an internet call. The audio quality often surpasses standard GSM, thanks to the use of a high-definition codec.
One of the key benefits is battery saving. When a smartphone is in a weak cellular signal area, it begins constantly searching for a tower, which leads to a sharp increase in power consumption. Switching to a stable Wi-Fi channel Allows the communication module to operate in a low-power mode. Furthermore, when roaming, Wi-Fi calls are often charged as domestic calls, which helps avoid hefty international call bills if your operator offers this service.
⚠️ Please note: For VoWiFi to work, your plan must support this service. Some carriers have it enabled by default, while others require you to activate the feature or change your plan. Please check this information in your personal account.
It's important to understand that for the technology to function correctly, support from three components is required: a smartphone, a telecom operator, and a home router. If even one component in the chain doesn't meet the requirements, the function may not activate. Modern devices Xiaomi And Redmi They usually have all the necessary certificates, but software limitations of firmware in different regions may make their own adjustments.
Checking device and operator compatibility
Before you begin setting up your phone, you need to make sure your device and SIM card are ready to handle voice calls over the internet. Not all models, even those released in recent years, have hardware or software support. IMS (IP Multimedia Subsystem), which is the foundation for VoWiFi. This is especially true for devices imported from China without global firmware or older budget models.
The first step should be checking the list of supported operators. Major Russian and international telecom providers have already implemented this technology, but coverage may vary by region. You need to ensure that your tariff plan isn't a backup plan and doesn't limit the amount of multimedia traffic required to establish a connection.
It's also worth paying attention to the operating system version. Xiaomi smartphone owners often use custom firmware or global versions, which may differ from the Chinese originals. Chinese firmware (China ROM) the function may be called differently or be hidden, requiring a change of region to activate. Global versions (Global ROM) usually have a more understandable menu localization.
To quickly check the service status, you can use the following table, which displays typical indicators and their meaning:
| Indicator in the status bar | Meaning | Connection status |
|---|---|---|
| Wi-Fi Call | Function active and ready | Calls will be made via Wi-Fi |
| HD + Wi-Fi icon | VoWiFi is active in the background | When you call, it will switch automatically. |
| Wi-Fi icon only | Data is being transmitted, but no voice. | VoWiFi is not active |
| 4G / LTE / 5G | The cellular network is used | Wi-Fi Calling is turned off |
Basic activation via smartphone settings
The standard way to enable this feature in MIUI or HyperOS is usually found in the SIM card settings menu. The steps are intuitive, but the names of the options may vary slightly depending on the Android version. First, open the main menu and go to Settings. Next, find the item SIM cards and mobile networks.
In the list that opens, select the SIM card for which you want to activate the service. Scroll down to the call settings section. There should be a toggle switch there. Wi-Fi calling (or Wi-Fi Calling). If you see this toggle switch, simply turn it on. The system may ask you to confirm this action, as voice over the internet may incur charges according to your plan.
☑️ Menu inclusion algorithm
In some cases, especially on dual-SIM models, the setting may be located in a separate menu. Try searching for "Wi-Fi" or "Calls" in the settings search. If the standard search doesn't work, the menu may be hidden or misaligned due to regional firmware settings. In this case, changing the region in the settings may help. Additional → Region to a country where the service is known to work (for example, India or Singapore), after which the item may appear.
After turning on the switch, a corresponding icon should appear in the status bar. If the icon appears but calls still fail, try restarting your device. The modem stack (the modem software module) often requires a restart to register with the operator's IMS network.
Using the engineering menu to activate
If the switch isn't available in the standard menu, you can try activating the function through Android's engineering menu. This method is riskier and requires caution, as changing incorrect settings can lead to unstable connection. To access the menu, enter the code in your phone book. ##86583##The message "VoWiFi Carrier check was DISABLED" or "ENABLED" should appear on the screen. Clicking this button toggles the check status.
There is also a code to force it to turn on: ##869434##After entering this combination of characters, the system should report successful activation of the hidden VoWiFi menu. Afterward, reboot your smartphone and check your SIM card settings again—the required switch should appear there. This method doesn't work on all models, as Xiaomi often blocks access to these codes in global firmware versions.
⚠️ Warning: Changing the engineering menu may cause your phone to lose network connectivity or cause battery drain. If the connection is lost after making these changes, reset your network settings or hard reset your device.
For advanced users, there is the option of using ADB commands. By connecting your smartphone to a computer with ADB installed Android Debug Bridge, you can enter a command to change the global parameter:
adb shell settings put global volte_wfc_enabled 1This command forces the VoWiFi support flag to be enabled in the system settings. However, if the service itself isn't provisioned (enabled) by the carrier or firmware, the command may not produce any visible results. Using third-party apps from the Play Market, such as "Force LTE Only," can also help access hidden menus, but their effectiveness varies from model to model.
Router setup and network settings
Voice call quality directly depends on the stability of your home internet connection. Not only speed but also latency (ping) are critical for VoWiFi. If your router is overloaded with dozens of connected devices, torrents, and 4K streams, voice packets may lose priority, leading to interruptions. It's recommended to configure QoS (Quality of Service) on the router, giving priority to smartphone traffic.
Frequency range also matters. The 2.4 GHz band has a longer range, but is often congested with neighboring networks and household appliances, causing interference. For calls, it's better to use the 5 GHz band, which offers higher throughput and lower latency. Make sure your smartphone Xiaomi connected specifically to the 5 GHz network, if available.
It's also worth checking your DHCP settings. A static IP address for your smartphone can ensure a more stable connection, eliminating potential address conflicts or lengthy address acquisition processes when reconnecting. You can reserve an address based on the device's MAC address in your router settings, ensuring a consistent network identifier.
Diagnosing and solving common problems
Even after proper setup, users may encounter a situation where the VoWiFi icon is lit, but calls fail or are immediately dropped. Often, the problem stems from a network mode conflict. If the phone attempts to simultaneously support 4G/5G and Wi-Fi Calling, but the cellular signal is too weak to maintain the control channel, a network failure may occur. In such cases, temporarily switching to "3G/2G only" mode or enabling airplane mode and then enabling Wi-Fi only can help.
Another common issue is incompatible encryption protocols. Some corporate networks or public Wi-Fi networks with web-based authentication (Captive Portal) block ports required for voice traffic. A home network should use standard WPA2/WPA3 encryption. If you have a complex corporate certificate, VoWiFi may not work without a special security profile configuration.
What to do if the icon appears and disappears?
This may indicate an unstable Wi-Fi signal. Try moving closer to the router. Also, check if the router has a limit on the number of connected devices or a data cap. Sometimes disabling the "Data Saver" feature in the Phone app settings helps.
The table below lists the main symptoms and methods for their elimination:
| Symptom | Possible cause | Solution |
|---|---|---|
| The icon is there, but calls don't go through. | Ports blocked by your ISP | Check your tariff, contact your operator |
| The sound is interrupted and robotic. | High ping, packet loss | Switch to 5 GHz, configure QoS |
| The function is not included in the menu. | Lack of IMS support | Check the model, change the region, update the software |
| The phone does not switch from LTE | Strong cellular network signal | Turn on airplane mode, then Wi-Fi |
Frequently Asked Questions (FAQ)
Do Wi-Fi calls affect mobile data usage?
No, voice calls over VoWiFi don't use your mobile data plan. They use the Wi-Fi channel. However, if the Wi-Fi connection is interrupted during a call, the phone may switch to the mobile network (if Handover is enabled), and the minute will then be charged at your mobile operator's rate.
Is it possible to use VoWiFi while roaming for free?
This depends entirely on your carrier's terms and conditions. Many carriers consider Wi-Fi calls while roaming to be "at home" calls, meaning they are free (incoming and outgoing calls to numbers in your home country). However, some may charge standard roaming rates. Be sure to check the terms and conditions before your trip.
Why did the VoWiFi feature disappear after a firmware update?
Updating MIUI or HyperOS may reset your network settings, or the new firmware version may temporarily remove the list of supported carriers for your region. Try resetting your network settings (Settings → Connection and sharing → Reset Wi-Fi, mobile networks, and Bluetooth) or change the region in the phone settings.
Does VoWiFi work if mobile data is disabled?
Yes, VoWiFi technology works independently of mobile data (3G/4G/5G). Furthermore, to save battery and data, you can completely disable mobile data, leaving only voice calls and Wi-Fi enabled. The call will still go through.