Modern smartphones Xiaomi They are equipped with powerful communication modules, but in dense urban areas or in country houses, the cellular signal often weakens. In such situations, technology comes to the rescue. Voice over WiFi, allowing voice calls over an internet connection without loss of quality. This solution is especially relevant for subscribers facing coverage dead spots in basements, offices with thick walls, or remote areas.
Enabling this feature on devices with the shell MIUI or HyperOS This doesn't always happen automatically, as support depends on the combination of carrier, phone model, and regional settings. The user may need to not only activate the switch in the menu but also check the compatibility of the tariff plan. The key condition for stable operation is the availability of VoWiFi service from the operator and the correct device firmware.
In this article, we'll detail the steps for enabling wireless calling, explore common errors, and troubleshoot them. You'll learn how to properly configure network priority and which router settings affect voice quality. A thorough understanding of these processes will ensure you never miss important calls, even if your cellular network indicator shows no signal.
How VoWiFi technology works on Xiaomi smartphones
Technology Voice over WiFi (often referred to as VoWiFi) is the transmission of voice traffic in the form of packet data over the Internet Protocol (IP). Unlike traditional messaging apps such as Viber or Telegram, a native phone number is used here. To the other party, your call appears as a regular mobile call, and is charged according to your carrier's primary plan.
Smartphones Xiaomi use the built-in module IMS (IP Multimedia Subsystem) for voice routing. When the cell tower signal strength drops below a certain threshold, the system automatically switches the call to an available Wi-Fi network. This process should be seamless to the user, but in reality, it often requires manual network configuration or even changing the region in the phone's system settings.
⚠️ Please note: Connection quality directly depends on the stability of your internet connection and router settings. If your router aggressively filters traffic or uses outdated encryption standards, this feature may not activate.
It's important to understand that not all operators support this feature on all equipment models. The operator must have the technical capability to authorize the device in its IMS network. Typically, the list of supported models is updated by telecom operators, but in the case of Xiaomi It is often required that the phone firmware contains the corresponding operator configuration files.
Checking service support by operator and tariff
Before delving into your smartphone settings, you need to make sure your SIM card and data plan are ready to work with VoWiFiMany of the "big four" operators have already implemented this service, but it may not be activated by default or may require activation through your personal account. Without confirmation from the provider, any phone operations will be useless.
This can be verified through the subscriber's personal account or via a special USSD command. Some providers call this service "Wi-Fi Calling." It's also worth checking that your balance is sufficient, although the service itself is often not billed separately but included in your minute package.
- 📱 Go to your telecom operator's app and find the section with communication services.
- 🔍 Look for an option called "VoWiFi", "Wi-Fi Calling" or something similar.
- ✅ Activate the service if it is disabled and wait for SMS confirmation.
- 💳 Make sure your plan isn't an archived one, as support may be limited for older plans.
After activating the service on the operator's side, it is recommended to reboot the smartphone. This will allow the device Xiaomi Re-register with the network and receive updated settings profiles. If the phone icon with the Wi-Fi symbol doesn't appear after rebooting, proceed to manual device setup.
Step-by-step activation of Wi-Fi calling in MIUI and HyperOS
Shell interface MIUI and new HyperOS The process may vary slightly depending on the Android version and regional firmware (Global, EEA, China). However, the activation logic remains the same. You need to find the hidden or explicit switches that control your preferred network type.
The standard activation path is as follows: open "Settings" and go to "SIM cards and mobile networks." Select the SIM card for which you want to enable the feature. In the menu that opens, find the "Use Wi-Fi for calls" or "Wi-Fi calling" option. If you don't see this option, try switching the network type to "Wi-Fi Calling" mode. LTE preferred.
☑️ VoWiFi Activation Checklist
In some cases, especially on global firmware versions, the menu item may be hidden. In this case, try entering the code in the dialing field. ##869434##This engineering code is designed to check the VoWiFi Carrier status. If the message "VoWiFi Carrier check was successful" appears after entering the code, the phone is technically ready, and all you need to do is wait for the carrier to configure it.
If standard methods don't help, you can try changing your phone's region. It's often the case that the "Advanced" -> "Region" settings are set to a location where the carrier hasn't certified the feature. Changing the region to a country where the service is known to work (for example, India or Indonesia for testing) may unlock the hidden menu, but this is a temporary solution.
⚠️ Please note: Changing the region in your smartphone settings may affect the operation of some system apps, the frequency of ad updates in the system, and the availability of certain features (such as themes or stickers).
Setting up network priority and data roaming
Setting the priority is critical. Smartphone Xiaomi The phone must understand when to switch to Wi-Fi and when to stay on the cellular network. Incorrect settings can result in the phone "clinging" to a weak 2G/3G signal instead of a stable Wi-Fi, or, conversely, dropping calls when leaving the router's coverage area.
The "SIM cards and mobile networks" menu often includes a "Network preference" option. For VoWiFi to work properly, it is recommended to select this mode. 4G preferred or 5G preferred. Technology VoLTE (Voice over LTE) is often a prerequisite for VoWiFi to work, as they use the same IMS substructure.
It's also worth paying attention to your data roaming settings. If you're abroad, Wi-Fi calls may be free (both incoming and outgoing calls to your home country), but only if the data roaming settings are set to the correct limits. Make sure the "Data Roaming" option is enabled if your carrier requires it to register with a partner's IMS network.
Default, ims| Setting parameter | Recommended value | Impact on work |
|---|---|---|
| Network type | 4G/LTE preferred | Provides the basis for IMS and VoWiFi |
| data roaming | Enabled (for registration) | Required for authorization in partner networks |
| APN addresses | Critical for voice traffic | |
| Saving traffic | Disabled for system services | Prevents blocking of signal packets |
What is an APN and why is it needed?
APN (Access Point Name) is the access point's settings. For VoWiFi to work, your operator's APN profile must contain "ims" in the "APN Type" field (separated by a comma with any other values). Without this setting, the phone will not be able to use voice over the internet.
Problems with connection quality and their solutions
Even after successful activation, users may experience issues such as choppy audio, echo, delayed call initiation, or unexpected call drops. Most often, the problem lies not with the phone itself, but with the wireless network. Voice traffic is sensitive to latency (ping) and jitter.
If you are using a dual-band router, make sure your phone is connected to the network. 5 GHzThis band is less congested with neighboring networks and provides more stable packet transmission in real time. The 2.4 GHz band is often overcrowded, leading to packet loss and degraded audio quality.
- 📶 Check your Wi-Fi signal strength: for calls, it's best to have at least two to three bars.
- 🚫 Disable VPN services and ad blockers during calls, as they can block your carrier's ports.
- 🔄 Restart your router if the problem occurs on all devices in your home.
- 📱 Check if your phone is in "Data Saver" mode, which may limit background data transfer for telephony.
Another common issue is a conflict with the Wi-Fi Assistant feature or similar algorithms. Xiaomi, which switch your phone to mobile data if Wi-Fi download speeds seem "slow," ignoring the connection stability needed for voice. Try disabling automatic switching to mobile data in your Wi-Fi settings.
Specifics of working with two SIM cards
Smartphone owners Xiaomi Dual SIM cards are often used, and this poses a challenge: VoWiFi technology typically only works for one, primary card, or requires individual configuration for each. The Android system doesn't always correctly handle the simultaneous registration of two numbers on IMS networks from different operators via a single Wi-Fi channel.
In the "SIM cards and mobile networks" settings, you need to access the menu for each SIM card separately. If you want to receive calls to the second number via Wi-Fi, make sure "Use Wi-Fi for calls" is also enabled for it. However, if one card is roaming and the other is not, your home network may be prioritized.
When an incoming call comes in on a SIM card not assigned as the default data card, the phone may attempt to switch the data channel. This may cause a brief connection interruption or a delay in establishing a connection. It is recommended to assign the SIM card used for most calls or the one with the most reliable carrier in the given location as the data card.
⚠️ Please note: When the second SIM card is active in 2G/3G mode (for example, for receiving SMS), calls via Wi-Fi on the main card may work unstably due to the peculiarities of the communication module, which cannot simultaneously support voice in LTE/Wi-Fi and standby in 2G.
Frequently Asked Questions (FAQ)
Do carriers charge extra for Wi-Fi calls?
Typically, operators don't charge a separate fee for VoWiFi technology itself. Minutes are deducted from your basic plan, just like a regular call. However, if you're abroad, the rules may differ: some operators charge such calls as if they were made from within their home network (which is advantageous), while others may consider them roaming calls. Always check with your provider for details.
Why does the VoWiFi icon appear and disappear?
This may indicate an unstable internet connection or intermittent loss of registration with the operator's IMS network. Aggressive power saving may also be the cause. MIUI, which is killing the background phone process. Try adding the Phone app to the battery exceptions.
Is it possible to make calls via Wi-Fi if the SIM card is blocked or there is no signal?
Yes, this is one of the main advantages of this technology. If the SIM card doesn't detect the network (for example, in a bunker), but the phone is connected to Wi-Fi and the initial authorization has been completed, emergency calls and sometimes regular calls (depending on the carrier) will work. However, at least a short signal from a cell tower is usually required for initial network registration.
Does VoWiFi work on custom ROMs (LineageOS, Pixel Experience)?
On custom firmware, VoWiFi functionality is often disrupted or completely absent, as it requires proprietary files and certificates from the manufacturer (Xiaomi), which are difficult to integrate into third-party operating systems. For stable call functionality, it's best to stick with the stock app.