How to call over Wi-Fi on Xiaomi: a complete guide to VoWiFi

Today’s Xiaomi and Redmi smartphones have powerful connectivity, but even these can’t always break through the thick walls of panel houses or provide a stable signal in remote areas, and it’s at these moments that VoWiFi technology, which allows voice calls over the Internet, comes to the rescue, ideal for rooms with poor cellular coverage but an affordable wireless hotspot.

Many users mistakenly believe that third-party messengers like Viber or Telegram are necessary for calls over the Internet, but modern operators of the “big four” have long implemented native support for this feature. Wi-Fi Calling on Xiaomi devices is enabled at the system level, which allows you to receive regular calls even in air mode, if the corresponding module is activated. In this article, we will discuss in detail how to activate this option, which operators support the technology and how to eliminate typical connection errors.

Before you start setting up, you need to make sure that your equipment and plan meet the minimum requirements. VoWiFi technology only works if you have carrier support and compatibility. SIM-So the first step is always to check the relevance of your service provider. MIUI HyperOS and also touch on the issues of security and sound quality.

What is VoWiFi Technology and How Does It Work for Xiaomi?

VoWiFi stands for Voice over Wi-Fi, which literally means voice over Wi-Fi. Unlike popular instant messengers that use their own servers to transmit audio, this technology is integrated directly into the infrastructure of the cellular operator. For the subscriber, this means that incoming calls are displayed as regular calls from a phone number, not as Internet messages, and the charging is according to your main tariff plan.

The principle of operation is that the Xiaomi smartphone creates a secure tunnel to the operator's gateway through an Internet channel. The voice signal is digitized, packaged and transmitted via IPSec protocols, providing a high level of encryption of the conversation, which is especially important for business negotiations, where the confidentiality of information transmitted over open networks is important.

The key advantage is seamless switching between networks. If you started a conversation from a secure Wi-Fi reception area, and then you went outside where the wireless signal disappeared, but the cell tower signal appeared, the call will not be interrupted. HyperOS will automatically switch the data stream to an LTE/4G or 3G mobile network without resetting, which is critical for continuity of communication.

⚠️ Attention: Sound quality is directly dependent on the stability of the Internet connection. When using congested public Wi-Fi networks in shopping centers or airports, audio delays or robotic sound may be possible.

To work properly, the smartphone must constantly communicate with the operator’s servers to register the location, even if you are not talking at the moment, this ensures instant delivery of incoming calls, eliminating the situation when the subscriber is beeping and the call is not yet displayed on the smartphone screen.

Checking the compatibility of the operator and SIM-map

The first and most important step is to verify the support of your mobile operator. In Russia, leading providers such as MTS, MegaFon, Beeline and other providers. Tele2, They have already deployed infrastructure for VoWiFi, but activation conditions may vary. USSD-command, while others activate it automatically when they first try to call.

You also need to consider your age and type of yours. SIM-Older cards issued by more 5-7 years ago, you may not have the necessary authentication protocols to work over Internet channels. SIM-cards for a new in the salon, which is usually done free of charge or for a nominal fee.

Below is a table with the current status of the technology support by major operators:

Operator.	Status of support	Do you need activation?	Features
MTS	Supported	Automatically.	Works on most tariffs
MegaFon	Supported	Through the app	Requires a profile update
Beeline	Supported	Automatically.	Available for postpaid rates
Tele2	Supported	Through the USSD	May require setting up an APN

It is important to understand that even if the carrier claims support, a specific Xiaomi model must be certified to work on the provider’s network. Global versions of smartphones usually have a full list of profiles, while the Chinese versions (CN Version) may require additional software customization or a change of region.

📊 Does your operator support calls over Wi-Fi?

Yeah, it works great.

Yeah, but we need to adjust.

No, the operator doesn't support it.

I don't know, I haven't.

Step-by-step: enable VoWiFi in MIUI and HyperOS settings

The activation process on Xiaomi smartphones is quite standardized, but the location of menu items may vary slightly depending on the version of the shell. In current versions of HyperOS, the interface has become more logical, and the necessary switches are brought to the upper level of communication settings.

To start, open the main settings menu for your device, find the wireless connection section, depending on the location, it can be called the "Special" section «SIM-Maps and mobile networks, or simply Mobile Network, and that's where all the parameters that you have for the communication module are.

Next, perform the following actions:

📱 Go to the Settings menu and select the item SIM-maps and mobile networks.
📶 Click on your operator’s name or select the one you want. SIM-card, if two are installed.
🔌 Find a switch called Wi-Fi Calling or Wi-Fi Calling and activate it.
✅ Accept the warning system that your location may be transferred to the operator for emergency services.

☑️ Checklist of VoWiFi activation

Check for Wi-Fi network: Make sure that Wi-Fi is on and Internet is available: Go to settings SIM-maps:Find the point Calls over Wi-Fi:Activate the switch:Wait for the tube icon in the status bar

Done: 0 / 1

When the switch is turned on, the status bar should have a corresponding indicator, usually a phone icon with a Wi-Fi sign or a wave sign tube, and if the icon appears but there is an exclamation mark next to it, it means that the phone is connected to the network, but registration on the operator's server has not yet been successful.

In some cases, especially on Chinese firmware versions, the menu item may be hidden. to display it, you may need to change the region in settings (Settings → Additional → Region) to a country where the service works exactly, such as India or Indonesia, after which the phone needs to restart.

Set network priorities and modes of operation

MIUI provides flexible tools to manage smartphone behavior when both Wi-Fi and cellular are present, which is important because in some scenarios, the user may prefer mobile to call even if the wireless network is active, for example, to save roaming traffic or for quality reasons.

The Wi-Fi call settings menu often provides additional priority options. You can choose Prefer Wi-Fi mode, where the phone will always try to make a call over the Internet if it is available. Alternatively, Prefer a mobile network, where Wi-Fi is only used as a backup channel in the absence of a cellular signal.

Also worth paying attention to setting up "Data Roaming." VoWiFi operation abroad often requires that mobile internet be turned on to transmit service signals, even if the conversation itself is via Wi-Fi. Without this, the phone may not register with the partner operator's network.

The Impact of Power Saving Mode on VoWiFi

In energy-saving mode, the system can limit background activity of the Wi-Fi module, resulting in a VoWiFi tunnel rupturing. If you notice that calls stopped coming when Wi-Fi was turned on, check your battery settings and add your phone to the exclusion list or use No Limits mode».> Special attention should be paid to the function in Do Not Disturb mode. Make sure that exclusion rules allow incoming calls from contacts, even if you use a Wi-Fi channel. IP-protocols if they are classified by the system as Internet calls, although technically it is common GSM-Typical connection problems and errors Addressed Despite the debugging of the technology, users may encounter situations where the function does not work. One of the most common problems is the mismatch of the access point settings. APN. The operator may require specific parameters to pass voice traffic, and standard settings can block this type of data. If the VoWiFi icon does not appear or burns with an error, try resetting the network settings. This action will return all mobile and Wi-Fi settings to factory values, which often eliminates configuration conflicts. → Connection and sharing → Resetting Wi-Fi, mobile networks and Bluetooth. Another reason could be the use of static IP-In order for tunneling to work properly, the operator often needs to provide a dynamic address through the DHCP. Check your Wi-Fi network settings on your smartphone and make sure that in the section IP-settings selected value «DHCP», not "Static». ⚠️ Note: When using corporate Wi-Fi networks with authorization through the web page (Captive Portal), calls will not work. The phone must be fully logged in before the conversation begins. In case the problem persists, it makes sense to check for system updates. Xiaomi engineers regularly release patches that add profiles to new operators and fix errors in the modem. → About phone and click on system version to check for updates.VoWiFi impact on communication quality and battery consumption Sound quality when using VoWiFi is usually higher than when calling through a regular call 2G/3G, Thanks to the use of high resolution codecs (HD However, if the Internet channel is unstable or has a high ping, there may be artifacts, echoes or delays in conversation that are absent from classical telephony. On the one hand, the smartphone does not need to spend energy searching for a cell tower signal in a dead zone, which saves charge. On the other hand, the constant operation of the Wi-Fi module in active mode and traffic encryption can increase battery consumption by 5-10% per day of active use. To minimize the impact on autonomy, it is recommended to use 5 GHz Wi-Fi frequency if the router and smartphone are close to each other. This range is less busy and provides more stable data transfer with less latency, which reduces the time of the radio module in active use. Remove the security case during long-term Wi-Fi conference calls for better heat sink.Security and privacy conversations The security issue when using VoWiFi is often a concern, especially when connecting to public networks. However, as mentioned earlier, the connection between your Xiaomi and the carrier gateway is protected by encryption protocols. Even if you are in a cafe with open Wi-Fi, it will be extremely difficult to intercept the contents of the conversation to an attacker. The operator sees yours. IP-address and fact of use of VoWiFi, but does not see the contents of the packages. For increased privacy, it is not recommended to use questionable free Wi-Fi networks for important negotiations, relying only on the operator's encryption. In HyperOS privacy settings, you can restrict applications’ access to location data, but for emergency services to work (E911/112) Geolocation is mandatory over Wi-Fi, and the system will ask for permission when you first turn on the feature, and it is not recommended to reject it if you plan to use the phone in areas without cellular coverage. 💡VoWiFi is a secure and modern communication standard that uses the same encryption protocols as online banking, making your conversations secure from being eavesdropped on public networks. Remember that when calling emergency services via Wi-Fi, the operator can only determine your location at the hotspot address, not at the hotspot address. GPS-In critical situations, always try to give the dispatcher your exact address verbally. Can I call you via Wi-Fi if I SIM-Is the card blocked or not? Yes, this is one of the main advantages of the technology. If you don't have a cellular signal (for example, in a basement or a remote village), but you have Wi-Fi, you can make and receive calls. SIM-The card must be active and not blocked by the operator for non-payment (unless the operator provides a call service on credit or via Wi-Fi with zero balance, which is rare). Minutes are spent from your main package of minutes of the tariff plan, as in a regular call. The only exception is international roaming: If you are overseas and make Wi-Fi calls to your home network, this is usually considered normal in/out roaming, but the rules need to be clarified with the specific operator. Why does the Wi-Fi Calling icon go missing during a call? This can happen if the Wi-Fi signal quality dropped dramatically below the threshold needed to maintain a voice channel and the phone tried to switch to a mobile network but couldn't. DHCP-Is VoWiFi working on two-sim Xiaomi? Yes, the technology supports two-sim SIM-You can set the priority for each card separately, or you can allow Wi-Fi to be used for calls only from the main SIM card, leaving the second one for mobile Internet. Do you need mobile Internet to work with VoWiFi? For the conversation process, mobile Internet is not needed, only Wi-Fi is enough. For initial registration on the network and sending SMS-In the mode of "Air Message" with Wi-Fi enabled, calls also work if the operator supports such a configuration.