Indoor connectivity issues aren't just an annoyance; they're a real obstacle to business and personal communications. Mobile operators are constantly improving technologies to ensure uninterrupted voice access even in areas where cell tower signals can't penetrate thick walls or concrete floors. Voice over Wi-Fi (VoWiFi) allows you to use the Internet channel to transmit high-quality voice, replacing the traditional GSM signal.
This feature has become especially important for MTS subscribers, as network coverage, although extensive, is not always ideal inside buildings with complex architecture. VoWiFi It works on most modern smartphones, but requires proper configuration on both the device and the SIM card. In this article, we'll cover in detail how to activate the service, which phones support the technology, and what to do if Wi-Fi calls aren't working.
The main advantage of this method is its transparency for the user. You don't need to open separate apps like Skype or WhatsApp to make a call. The phone number remains the same, you're charged according to your primary plan, and the connection quality depends on the speed of your home or office internet.
What is VoWiFi and how does it work with MTS?
Technology Voice over Wi-Fi This technology transfers voice traffic over IP protocols, similar to how instant messaging apps work, but at the carrier's system level. When you're within range of a wireless network and the corresponding option is enabled on your device, your smartphone automatically switches voice traffic from the cell tower to the router. This allows you to make and receive calls in areas where GSM/3G/4G signal strength is critically low or completely absent.
MTS uses standard security protocols to ensure conversation encryption. It's important to understand that connection quality directly depends on the stability of your internet connection. If download speeds drop below minimum values, your phone may attempt to switch back to the cellular network, if available, or terminate the connection.
MTS is actively developing infrastructure to support VoWiFi, and the service is currently available to the vast majority of subscribers with modern plans. However, there are technical nuances that may prevent connection. For example, using corporate networks with strict restrictions or public Wi-Fi hotspots that require browser authentication may block the service.
⚠️ Please note: This service may not work on some routers with AP Isolation enabled or specific firewall settings that block SIP traffic.
The cost per minute of a Wi-Fi call is the same as the rate per minute for your plan in your home region. If you're roaming internationally but connected to Wi-Fi, calls to Russian numbers will be charged as incoming or outgoing calls in your home region (depending on your plan), allowing you to save significantly on calls abroad.
Checking device and SIM card compatibility
Before you begin setting up, you need to make sure that your equipment physically and software supports working with the technology. Voice over Wi-FiNot all smartphones, even those released several years ago, have the necessary module or firmware to support MTS standards. This primarily applies to devices intended for markets in other countries where the operator does not offer this service.
The list of compatible models is constantly expanding. Currently, flagship and mid-range series from Apple, Samsung, Xiaomi, as well as devices of brands Honor And RealmeFor older phone models, even if they run Android or iOS, the function may not be available due to the lack of necessary drivers in the firmware.
The second important aspect is the SIM card itself. If you're using a SIM card that was issued many years ago and has been repeatedly swapped between phones (especially if it's been manually cut), network identification conflicts may occur. In such cases, it's recommended to replace the SIM card with a new one at a mobile phone store, keeping your phone number.
It's also worth checking your operating system version. For stable operation VoWiFi On Android, version 10 or higher is recommended, although on some models, the feature is available on earlier versions. On iOS, the requirements are similar: it's recommended to use the latest version of the operating system, as Apple regularly updates carrier lists and settings profiles.
Requires activation in the operator menu
You may need to reset your network settings.
Often it is necessary to reflash to the global version
Support depends on the region of purchase.
| Brand | Series with support | Minimum OS | Nuances |
|---|---|---|---|
| Apple | iPhone 6 and newer | iOS 13+ | |
| Samsung | Galaxy S, A, Note | Android 9+ | |
| Xiaomi | Mi, Redmi, Poco | Android 10+ | |
| Honor | Series 9, 10, Magic | Android 9+ |
How to find out the exact phone model?
To find the exact model, go to Settings → About phone (or General → About device). The full model code is listed there, for example, SM-G991B. You can use this code to check the specifications on the manufacturer's website.
Activating the service via your personal account and USSD
The first step in the setup process is activating the service with your carrier. Even if your phone is fully compatible, Wi-Fi calls won't work without permission from the MTS network. The fastest way to check the status and activate the service is using USSD commands or the mobile app.
To activate via the phone menu, dial the command *111*379# and press the call button. The system will automatically check the connection and activate the service. Alternatively, use the MTS Russia app. In the services section or by searching for the app, find the "Wi-Fi Calling" option and toggle the switch to the on position.
If automatic methods don't work, you can use your personal account on the operator's website. The required switch is located in the "Services" -> "All Services" -> "Communications" section (or a similar section, as the interface may change). Sometimes the service may be disabled by default on new plans, so manual activation is required.
☑️ Pre-activation check
⚠️ Note: After activating the service via USSD or the app, it is recommended to completely reboot your smartphone. Without a reboot, the network profile may not update, and the feature will not work.
In some cases, especially on corporate plans or plans with special terms, activation may not be possible. In this case, you should contact the operator's support team via chat or hotline. The operator will check whether your contract type blocks the use of the technology. Voice over Wi-Fi.
Setting up iPhone for Wi-Fi calling
For smartphone owners Apple You're luckier than most: setup usually happens semi-automatically. After you've activated the service on MTS, all you need to do is perform a few simple steps in your iOS settings. The system will automatically pull the necessary parameters from your carrier.
Go to the menu Settings, then select the item Cellular communications. Find the section Wi-Fi calling and turn on the switch Wi-Fi Calling on This iPhoneIf this option is missing, make sure you have the latest version of iOS installed and that the MTS SIM card is selected as the primary voice card (if you use two SIM cards).
Sometimes the system may ask you to confirm your address for emergency services. This is a standard procedure required by communications regulators. Please enter a current address, even if you plan to use your phone elsewhere. This doesn't affect your ability to call regular numbers, but it is critical for online emergency services (112, 102, etc.).
If after enabling the option the icon Wi-Fi If the "Enable LTE" icon doesn't appear next to the carrier name in the status bar, try toggling Airplane Mode on and off. This will force the device to re-register with the network. Also, make sure "Enable LTE (or 4G)" is enabled for your MTS number in the cellular settings, as VoWiFi is often tied to LTE technology.
Instructions for Android: Samsung, Xiaomi, and others
On the platform Android The setup process may vary depending on the smartphone manufacturer and the OS version. The logic is similar, but the menu names may vary. The main task is to find the switch that controls Wi-Fi Calling.
On smartphones Samsung the path usually looks like this: Settings -> Connections -> Wi-Fi callingHere you need to activate the function. In some firmware versions, this option may be located directly in the main settings menu or in the notification shade (after editing the buttons).
For devices Xiaomi, Redmi And Poco the algorithm is as follows: Settings -> SIM cards and mobile networks -> select MTS SIM card -> Use Wi-Fi for callsIf this option isn't present, your firmware version may not be certified for VoWiFi in your region. In this case, changing the region in your phone settings (for example, to India or Germany) may help, but this may affect the operation of other system apps.
Hidden Android Settings
On some Android phones, the hidden settings menu can be accessed by dialing the code ##4636## on the phone (##4636##). There you can find the "Phone Information" section and force VoWiFi to be enabled or disabled, but this should be done with caution.
On phones of other brands (Honor, Realme, Oppo) Look for the "Mobile Network" or "Two-Pocket Mode" section. The switch is often located directly in the SIM card management menu. If you can't find the option, use the settings search: enter "Wi-Fi" or "Calls" in the search bar.
⚠️ Note: On dual-SIM phones, the setting must be checked for each SIM card separately. It often happens that the function is enabled on the primary SIM card, but not on the secondary one.
Troubleshooting and Common Errors
Even with the correct settings, situations may arise when the icon VoWiFi The phone doesn't appear, or calls are dropped. One of the most common causes is an unstable internet connection. If the router is overloaded or the provider is experiencing problems, the phone may consider the connection unsuitable for voice calls and switch to GSM, even if the signal is weak.
Another common issue is an IP address or DNS conflict. Try changing your router's DNS servers to Google's public ones (8.8.8.8) or Cloudflare (1.1.1.1). This often solves the problem when the phone is connected to Wi-Fi, but the Internet is not working for the operator's system services.
It's also worth paying attention to the power saving mode. Aggressive power saving algorithms on Android can block background service operation. Voice over Wi-FiAdd your phone service or the Phone app to the Low Power Mode exceptions.
In rare cases, the problem lies with your antivirus or router firewall, which blocks ports used for voice traffic. Try temporarily disabling traffic filtering on your router to test this hypothesis. If calls continue to work after this, you'll need to configure exclusion rules for the MTS infrastructure IP addresses.
Questions and Answers (FAQ)
Do you charge for calls over Wi-Fi?
You'll be charged according to your main plan. If you have free minutes enabled, they will be used. If you're roaming, Wi-Fi calls to Russian numbers are charged at the same rate as in your home region, which is a significant discount compared to standard roaming rates.
Can the other person hear the difference in quality?
With a good internet connection, the sound quality is significantly better than on a standard cellular network (HD Voice). The other person will hear you clearly, without the typical noise or interruptions. If the internet is poor, the quality may deteriorate, or the call may be dropped.
Is it possible to make calls via Wi-Fi if the SIM card is blocked?
No. To authenticate with the operator's network and place a call, the SIM card must be active. If the number is blocked due to non-payment or lost, the technology will not work, even with internet access.
Does VoWiFi work if I turn off my mobile internet?
Yes, mobile internet (3G/4G) is not required for Wi-Fi calling; a wireless network is sufficient. However, a mobile network may be required briefly for initial registration with the operator's IMS network.
Why did the Wi-Fi handset icon disappear during a call?
This means the phone has automatically switched to the cellular network. This happens if the Wi-Fi signal becomes too weak or unstable. Handover technology (transferring a call between networks) doesn't work perfectly on all phone models.