What is VoWiFi in Xiaomi smartphones and how does it work?

Modern Xiaomi smartphone users often face a situation where the signal level of the cellular network drops to critical values, and incoming calls become inaccessible. It is to solve this problem that Voice over Wi-Fi technology, known in the MIUI shell interface or HyperOS as VoWiFi, was developed, which allows voice calls to be transmitted through an Internet connection, rather than through standard cell towers, providing stable communication even in dead areas or inside buildings with thick walls.

Owners of Redmi and Poco devices may notice a Wi-Fi-characterized handset icon in the status bar after activating the option, which means your phone now uses a wireless network for voice communications that often exceeds standard quality. GSM-VoWiFi technology does not require the installation of additional applications, as it is integrated directly into the standard call module.

In this article, we will discuss in detail the principle of operation of the function, the need to use it and the step-by-step switching algorithm on Xiaomi smartphones. You will learn which operators support this standard in Russia and the CIS, as well as what to do if the cherished switch does not appear in the settings menu.

The principle of the technology Voice over Wi-Fi

The fundamental difference between Voice over Wi-Fi and regular messaging (Viber, Telegram, WhatsApp) is the level of integration with the operating system. When you make a VoWiFi call, it looks like a regular incoming call to your phone number. You don't need the other party to have an Internet connection or an installed application — it's at the carrier network level, but traffic is transmitted over the Internet channel.

The data transfer process is packaged in special IP packets (Internet Protocol), which the Xiaomi smartphone sends via the router to the operator's servers. The operator, in turn, routes the call to the general telephone network, which allows you to maintain high audio quality, often in HD Voice format, and instant connection without long waiting horns.

⚠️ Note: The function requires support from your mobile operator. If the service provider has not activated VoWiFi on its side, you will not be able to include the option in the phone menu, even if the smartphone supports it.

It is important to note that switching between Wi-Fi and the cellular network is automatic and unobtrusive to the user. If you leave the range of the router during a conversation, a modern Xiaomi smartphone with VoLTE (Voice over LTE) will smoothly transfer the call to the 4G mobile network without breaking the connection. However, if your old phone or carrier does not support VoLTE, the call can be interrupted when the Wi-Fi signal is lost.

Benefits of Using Wi-Fi Calling on Xiaomi

The main reason for this feature is to improve communication quality in dense urban areas or remote areas. Xiaomi smartphones, with powerful antenna modules, combined with VoWiFi technology provide crystal clear sound. Users note the absence of the characteristic noise, cracking and interruptions that are often encountered when talking over EDGE or 3G networks.

And battery savings are also a big plus: When the phone is in the low-wave zone of the cellular signal, it's constantly increasing the power of the transmitter to look for the tower, which quickly puts the battery down. Switching to Wi-Fi reduces the load on the radio module, allowing the device to last longer, and this is especially true for models with a smaller battery.

International roaming is another important aspect: While abroad, you can receive incoming calls to your number via Wi-Fi for free (or at home region rates), as technically the call is via an Internet channel, not through networks of foreign partners. Outgoing calls can also be charged as local if the operator provides such a service.

• 📶 Stable communication in basements, offices with metal walls and country houses.
• 🔋 Reducing the power consumption of the radio module with a weak signal of the cellular network.
• 🌍 Savings in roaming when receiving incoming calls via the Internet.
• 🎙️ High quality audio through the use of broadband audio codec.

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If you are often in the area of poor reception, turn on the "Flight" mode and leave only Wi-Fi - this will forcibly transfer all calls through the Internet protocol, saving battery power.

Compatibility of operators and tariff plans

Successful VoWiFi activation on Xiaomi smartphones depends not only on the phone itself, but also on the terms of your plan. The largest Big Four operators in Russia and many providers in the CIS have already implemented this technology.

It often happens that technically the phone and the SIM card are ready to work, but the service is not activated in the personal account of the subscriber. MTS, Beeline, Megafon and Tele2 require that there be no debts on the balance sheet, and the tariff itself supports the transfer of votes on the IP. In some cases, it is necessary to send a special USSD-Network-side activation code.

Keep in mind that the list of supported models and carriers is constantly updated: if your Xiaomi phone is purchased in China (Global) ROM), It may not be identified by the operator's network as a compatible device, and the VoWiFi icon will not appear, in which case it helps to flash to the global version (Global Stable) or edit the system file. carrier_policy.xml, root-rights.

How to turn on VoWiFi on Xiaomi and Redmi smartphones

The process of activating the function on the shells MIUI 12, 13, 14 and the new HyperOS is quite simple and unified. However, the location of the switches may vary slightly depending on the version of Android and regional firmware. Before you start, make sure that your smartphone is connected to a wireless Wi-Fi network.

The first step is to go to the main settings of the system. SIM-Maps and mobile networks (or "Connect and Sharing" in the newer versions). Select the SIM card you want to enable the feature for if there are two. Next, look for "Use Wi-Fi for calls" or "Wi-Fi Calls".

If you can't find the option in the standard way, you can search by settings. Type the word "Wi-Fi" or "VoWiFi" into the top search box. The system will suggest you go to the menu you want, and make sure you have VoLTE enabled, as they often work together.

⚠️ Note: After the function is turned on, the corresponding icon (Wi-Fi tube) should appear in the status bar. If the icon is not there and the menu says "Unavailable", then your operator does not support the technology in your region or on your SIM card.

In some cases, especially on Chinese firmware, the menu may be hidden, so you can try typing the engineering code ##86583## into the dialer, and you'll see a message saying "VoLTE carrier check was DISABLED," which will force you to access the VoLTE and VoWiFi settings in the menu, and re-entering the code will bring it back.

Priority setting of networks and modes of operation

In advanced settings, Xiaomi allows you to choose the preferred network mode for making calls. This is important for those who want to tightly control which channel the conversation will go through. There are usually three options available: “Prefer to mobile network”, “Prefer to Wi-Fi network” and “Wi-Fi only”.

Prefer Wi-Fi is optimal for most scenarios, in which case the phone will attempt to make a call over the Internet if it is available and has sufficient speed. If Wi-Fi is weak or disabled, the device will automatically switch to LTE/4G. This provides a balance between quality and availability.

Wi-Fi Only is useful in situations where cellular communication is available but it is very bad (constantly disrupted), or when you are roaming and want to avoid accidental connections to local towers. In this mode, if Wi-Fi goes missing, the call will be interrupted and the phone will not try to use GSM.

Remember that when you are in active Do Not Disturb mode or in Game Turbo mode, the system can block network switching to maintain connection stability. If you notice that calls are not going through during the game, check the settings of the game accelerator.

Solution and troubleshooting

Despite the technology's fine-tuning, Xiaomi users may experience problems using Voice over Wi-Fi. The most common is the absence of an icon in the status bar. This does not always mean that the feature is not working. In some versions of MIUI, the icon is only displayed when an active call is made or when an incoming call is made.

If calls break or sound is interrupted, the problem may be in the router. VoWiFi technology is sensitive to firewall and port settings. Make sure the router is not locked. SIP-Protocols or restrictions by type of traffic (NAT). Also check if the Wi-Fi channel is overloaded with neighbouring networks.

• 🔄 Rebooting the modem and smartphone – the first action in case of failures.
• 📡 Checking firmware updates MIUI/HyperOS.
• 📱 Reset network settings in the "Connection and Sharing" menu".
• 🔒 Shutdown VPN — Virtual networks often block voice traffic.

⚠️ Attention: Use VPN-VoWiFi calls are not recommended. VPN-The tunnel may conflict with the operator's protocols, causing delays or a complete break in the connection.

In rare cases, replacing a SIM card with a new one with support for USIM (4G/5G) helps. Old 3G SIM cards may not work properly with modern voice protocols, even if the phone supports them.

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The quality of VoWiFi communication depends on the stability of your home router and the distance to it. For best results, use the 5 GHz band.

Frequently Asked Questions (FAQ)