Many subscribers are familiar with the situation where mobile network coverage in an apartment or office is terrible, but they need to make an urgent call. In such cases, technology comes to the rescue. VoWiFi (Voice over Wi-Fi), which allows voice calls over an internet service provider's wireless network. For Xiaomi smartphone owners and MTS users, this feature has become a real lifesaver in areas with weak signal strength, turning their home router into a fully-fledged base station.
In this article, we'll take a detailed look at how to activate and set up Wi-Fi calling on Xiaomi devices so you can use MTS for free without paying extra for extra minutes. You'll learn about the intricacies of MIUI menu settings, pricing details, and solutions to common issues when the feature doesn't work. It's important to understand that Wi-Fi calls are charged according to your MTS plan, meaning they use up your bundled minutes but don't require you to pay for the actual data.
The technology works transparently for the user: you dial the number as usual, but the connection is established via an internet channel. This is especially relevant for modern smartphones. Xiaomi, Redmi And POCO, which are equipped with advanced communication modules. However, for the magic to work, a number of conditions must be met by the device and SIM card.
What is VoWiFi and how does it work on MTS?
Technology VoWiFi Voice over Wi-Fi (Voice over Wi-Fi) transmits voice traffic via IP protocols, using your internet connection, rather than standard cellular radio frequencies. For MTS, this means the signal is transmitted through the operator's internet gateways, bypassing problematic areas of radio coverage in buildings. It's not like messaging apps like WhatsApp or Telegram, which require a special account for the other person—you call any regular number.
The main advantage is connection stability in areas where your phone shows "no network" or only a single bar. If you have a good router at home, the sound quality will be HD, and dropouts will be minimal. Smartphones Xiaomi They support this standard very well, but often hide the switch in deep layers of the menu or activate it automatically if the SIM card supports it.
It's worth noting that switching between Wi-Fi and cellular networks occurs automatically. If you move out of range of the router during a call, the call won't be interrupted but will switch to 4G/LTE (provided VoLTE is supported). This ensures uninterrupted communication under any conditions.
⚠️ Attention: Call quality directly depends on the stability of your internet connection. If your provider is performing maintenance or your speed has dropped, your voice may be interrupted. Always have an alternative method of communication available in case of a network outage.
Checking device and SIM card compatibility
Before you dive into settings, you need to make sure your hardware is physically and software-ready to work with VoWiFi. Not all models Xiaomi This feature is available out of the box, especially older or global versions released for markets where MTS hasn't yet implemented the service. First, check your smartphone model and MIUI firmware version.
The second critical element is the SIM card. If you're using an older SIM card, manufactured many years ago, it may not support modern voice call encryption protocols. In this case, you'll need to replace the SIM card at an MTS store, which is usually free or for a nominal fee. Also, make sure your balance isn't blocked and the "Voice Calls" service is active.
MTS automatically activates VoWiFi for most subscribers, but in rare cases, manual activation is required via your personal account or a USSD command. Check the service status to rule out issues on the operator's end.
☑️ VoWiFi Readiness Check
Step-by-step instructions: enabling Wi-Fi calling on Xiaomi
The process of activating the function on smartphones Xiaomi This may vary depending on the MIUI version and regional firmware. On most modern models, the setting is located in the standard telephony menu. First, open the Phone app (green handset) and go to Settings by tapping the three dots or the gear icon.
In the menu that opens, find a section that may be called "Wi-Fi Calling," "Wi-Fi Calling," or hidden within the "Use Wi-Fi for Calling" section. If you see a toggle, simply turn it on. The system may ask for confirmation or prompt you to enter your emergency services address (E911), which is standard procedure.
If you can't find the setting using the standard method, try using the hidden engineering menu. To do this, enter the code in the Phone app. ##869434##This action should open the VoWiFi debug menu. In the list that appears, find "VoWiFi Carrier Check" and uncheck it if it's checked. Then return to the regular settings and check if the option appears.
⚠️ Attention: The engineering menu is a sensitive tool. Do not change any parameter values you are unsure of, except those specified in the instructions. Incorrect settings may cause the communication module to malfunction.
What if the code is not on the list?
If nothing happens after entering the code or the menu doesn't open, your firmware doesn't support hidden operator commands. In this case, try changing the region in your phone settings (for example, to India or Russia), reboot, and try again.
Setting up the engineering menu and hidden parameters
Sometimes the standard switch is not enough and deeper customization is required through the engineering menu. MIUIIt can be accessed not only through codes, but also through the Engineering Menu app (if installed) or through the About Phone settings by repeatedly tapping the build number. However, for VoWiFi, entering the USSD code in the dialer usually works.
In some firmware versions for Redmi And POCO after entering the code ##869434## A notification appears that says "VoWiFi Carrier Check disabled." This means carrier verification is disabled, and the phone will allow Wi-Fi calling even if the carrier hasn't formally transferred the settings profile. After this, be sure to reboot the device.
If you have a dual-SIM device, you need to configure the settings for each SIM card separately, selecting the desired one in the call settings menu. Make sure the "Prefer Wi-Fi" or "Wi-Fi Only" priority is selected for the MTS SIM card if you are in an area with poor cellular coverage.
Please remember that interfaces are subject to change. Carriers and phone manufacturers are constantly updating software, so the location of menu items may shift. If you don't find an exact match, look for synonyms or related sections in the menu.
Comparing VoWiFi and messaging calls
Many users confuse VoWiFi technology with the calling features of Viber, WhatsApp, or Telegram. While the data transfer principle is similar (over the internet), the user experience is radically different. VoWiFi is integrated into the phone's default dialer, doesn't require the other person to install additional apps, and works with any numbers, including short service numbers.
Below is a table to help you understand the differences and choose the appropriate communication method for a particular situation.
| Characteristic | VoWiFi (MTS) | Messengers (WhatsApp, Viber) |
|---|---|---|
| The other person needs internet access. | No | Yes (required) |
| Tariffs | At the MTS tariff (minutes) | Free (traffic consumption) |
| Caller ID | It works (Caller ID) | Only if the number is in contacts |
| Sound quality | High (HD Voice) | Depends on the application |
| Working in roaming | Like at home (no roaming) | Free (via Wi-Fi) |
Using VoWiFi is especially beneficial when roaming. While abroad, you can connect to hotel Wi-Fi and call Russian numbers at your home region's rates, avoiding international roaming charges. The only requirement is that "Prefer Wi-Fi" mode be enabled in your phone's settings.
Typical problems and solutions
Even with proper setup, issues may still occur. Most often, users encounter a problem where the handset icon with the Wi-Fi symbol doesn't appear in the status bar. This may mean the phone is unable to register with the carrier's server. Try turning Airplane Mode on and off or restarting the phone.
Another common problem is dropped calls due to poor internet connection. If your router is overloaded or the Wi-Fi signal is weak in a distant room, the connection quality will drop. In this case, the phone may try to switch to the mobile network, but if the signal there is also poor, the call will be dropped. The solution is to move closer to the router or use a Wi-Fi repeater.
It's also worth checking whether your antivirus or firewall software is blocking ports required for SIP protocols on your router, although this rarely happens on home routers. Make sure your phone's date and time are set automatically, as time desynchronization can prevent you from logging into your carrier's network.
Frequently Asked Questions (FAQ)
Do you charge for Wi-Fi calls when roaming?
If you're abroad and connected to Wi-Fi, calls to Russian numbers will be charged as if you were in Russia (according to your MTS plan). No roaming surcharge applies, but make sure "Prefer Wi-Fi" is selected in your settings.
Does making calls over Wi-Fi use up mobile data?
No, traffic is transmitted via your home or public Wi-Fi connection. However, the call itself uses up minutes from your MTS plan. If you run out of minutes, per-minute billing will begin.
Why isn't VoWiFi working on my Xiaomi?
Possible causes: outdated firmware version, model incompatibility with MTS networks in your region, old SIM card, or unavailable service from your carrier. Try updating the firmware and checking the SIM card.
Is it possible to make calls via Wi-Fi if your mobile connection is completely disconnected?
Yes, you can. If you enable Airplane Mode and then activate only Wi-Fi, VoWiFi calls will work, provided the phone has registered with the carrier's network via the internet.