Mobile communications have become an integral part of life, but cell tower coverage is far from perfect everywhere. In basements, offices with thick walls, or country houses, the signal can drop out, making important conversations impossible. This is where VoWiFi technology comes in, allowing voice calls over an internet service provider's wireless network.
MTS was one of the first operators to implement this feature in Russia, giving subscribers the ability to stay connected even where standard cellular coverage is unavailable. WiFi calling No additional apps are required, as the technology is built directly into the smartphone's phone book. This means you dial the number as usual, but the connection is made via the internet rather than a GSM or LTE base station.
The main advantage of this option for users is that it's free. The operator doesn't charge extra for the feature itself or for minutes spent on domestic calls. Calls are billed strictly according to your primary plan, as if you were in a strong cellular coverage area. However, to take advantage of this benefit, you need to configure a number of settings on your device.
What is VoWiFi technology and how does it work?
The technology known as Voice over Wi-Fi VoWiFi, or simply VoWiFi, enables voice traffic over IP protocols. Essentially, your smartphone uses your internet connection to transmit your voice digitally. This process is completely transparent to the user: you won't notice the difference, other than the handset icon with a wireless network symbol in the status bar. Unlike messaging apps, connection quality is often higher and more stable thanks to the carrier's traffic prioritization.
It's important to understand that this feature requires support from three components: the carrier itself, your data plan, and, crucially, your smartphone's hardware. MTS provides network support for most modern data plans. Android- smartphones of recent years are also universally equipped with the necessary module, but the function may be hidden by software or require activation.
The principle of operation is that when dialing a number, the phone first checks for cellular network availability. If the signal is weak or absent, but Wi-Fi is active, the device automatically switches the call to the internet channel. This allows you to continue the conversation when entering a building with poor coverage, even if you're already within range of the router.
- 📶 Seamlessness: Switching between WiFi and cellular networks occurs without interrupting the connection (with Handover support).
- 💰 Saving: No roaming charges for incoming calls abroad when connected to WiFi.
- 🔋 Energy efficiency: lower power consumption compared to constantly searching for a cell tower in "dead zone" areas.
⚠️ Please note: Voice quality directly depends on the speed and stability of your internet connection. If your connection is overloaded by downloading large files or watching 4K videos, your voice may be interrupted.
Checking smartphone and tariff compatibility
Before setting up, you need to make sure your device is compatible with MTS VoWiFi. The list of supported models is constantly expanding, but the basic requirement is the presence of an operator certificate in the phone's firmware. This is most often the case for Samsung, Xiaomi, Honor, Huawei, and iPhone. Budget models or parallel-imported devices with Chinese firmware may not have the required software.
The second critical factor is your tariff plan. While most modern MTS plans, both archived and current, support VoWiFi, this feature may be unavailable on some older lines or limited corporate plans. The Voicemail service must also be activated, as VoWiFi technology is closely linked to it in the operator's infrastructure.
The easiest way to check compatibility is to use the official "My MTS" app. The services section often displays the availability of this option for your number. If the app doesn't restrict this feature, but it still doesn't work, the issue lies in your phone settings or operating system version.
List of popular supported models
Samsung Galaxy S10 and later, Note and A series (mid- and high-end). Xiaomi Mi 9 and later, Redmi Note series (not all models). Honor 20 and later, Huawei P30 and later. iPhone 6s and later (with iOS 12 or later).
It's worth noting that even if your phone model is on the supported list, this doesn't guarantee 100% functionality in all regions. The carrier is rolling out equipment in stages, so in some remote areas, the feature may be temporarily unavailable, despite the smartphone's technical readiness.
Step-by-step activation instructions on Android
The process of enabling WiFi calling on devices with the operating system Android The process may vary slightly depending on the manufacturer's operating system (MIUI, OneUI, EMUI). However, the general steps remain the same. First, you need to activate the service with your carrier, and then authorize your phone to use it.
Activation on the MTS side is instant. You can send a USSD command *111*1710# Or use your personal account. After receiving confirmation of service activation, proceed to your smartphone settings. Here, it's important to find the section responsible for your mobile network or SIM cards.
☑️ VoWiFi activation algorithm
In the settings menu, look for "Wi-Fi Calling." It may be in the submenu for a specific SIM card if you have two. Toggle the slider to the on position. If the system prompts you to select a priority, select "Prefer WiFi" or "Wi-Fi Only" to ensure calls connect over the internet even with a weak cellular signal.
| Smartphone brand | Menu path (approximate) | Nuances |
|---|---|---|
| Samsung | Settings -> Connections -> Wi-Fi Calling | May require a reboot after first power-up. |
| Xiaomi / Redmi | Settings -> SIM cards & mobile networks -> Wi-Fi calling | Often hidden if the SIM card is not identified as the primary one |
| Honor / Huawei | Settings -> Mobile Network -> Wi-Fi Calling | The operator's basic settings need to be updated. |
| Realme | Settings -> Mobile network -> SIM card -> Wi-Fi calling | The interface is close to stock Android. |
After turning the slider on, the phone may search for a network for a few seconds. Successful activation is confirmed by the appearance of a special icon at the top of the screen (usually a handset with a WiFi symbol). If the icon appears but calls aren't working, try restarting the device.
Configuration via the engineering menu and hidden codes
In some cases, the standard settings path doesn't produce the desired result because the carrier or phone manufacturer has hidden the option. For these situations, there are hidden menus and codes that allow you to force activation. VoWiFiHowever, using these methods requires caution, as incorrectly changing the parameters may disrupt the operation of the communication module.
One of the common methods for many Android smartphones is using a code ##86943# (or variations like ##86943##). Entering this combination into the dialer may open the hidden Carrier Configuration menu. Here, you can try changing the region or carrier profile to one where VoWiFi is known to work (for example, select MTS Russia if you have MTS Ukraine or a general profile).
##86943#Another method for advanced users is to use the Activity Launcher app. It allows you to find hidden activities in the system. Find an activity with the word "WifiCalling" or "ImsService" and try launching it. This may open a hidden settings menu that isn't visible in the regular interface.
⚠️ Warning: Changing settings in the engineering menu is at your own risk. Record the original parameter values so you can restore everything as it was in the event of a connection failure.
If neither codes nor hidden menus help, it's possible that your firmware truly does have carrier support disabled. In this case, the only legal solution is to wait for a software update from the manufacturer or change the phone's region (this requires unlocking the bootloader, which is difficult and risky).
Troubleshooting connection issues and errors
Even after following all the instructions, users may encounter situations where the feature doesn't work. One of the most common issues is the absence of the VoWiFi icon in the status bar. This may mean the phone is connected to WiFi but is unable to establish a tunnel connection to MTS servers. Check to see if your router has port blocking or a strict firewall.
Another common situation is when calls are made, but the other person can't hear you, or the connection drops. This is a classic sign of insufficient bandwidth or high ping. Try switching to the 5 GHz frequency if your router and phone support it. The 2.4 GHz frequency is often overloaded by neighboring networks, causing interference.
It's also worth checking your date and time settings. If your phone's time is out of sync, security certificates won't be verified, and the connection to your carrier's IMS server will be lost. Set up automatic time synchronization via the network.
- 🔄 Reset network settings: In Android settings, find "Reset network settings" (not data!) and perform it. This will clear the DNS cache and reset APN settings.
- 📱 Profile update: In the SIM card settings, find the "Update operator profile" button.
- 🛑 Disabling VPN: An active VPN tunnel often blocks VoWiFi voice traffic, try disabling it.
If all else fails, the problem may be with your home internet provider. Some providers use NAT technologies, which don't support VoIP protocols. In this case, the only solution is to call your internet provider's technical support or use mobile internet (shared via a hotspot, if your plan allows it).
Pricing and important nuances of use
Many users are wary of hidden fees when activating new features. In the case of MTS VoWiFi, calls to Russian numbers are charged the same as regular voice calls. If you have unlimited minutes, they will be charged according to your plan. If you pay per minute, you'll be charged according to your plan. There's no double billing for "internet calls."
Using VoWiFi while roaming is especially interesting. While abroad, you can connect to a local Wi-Fi network and call Russian numbers at the rates of your home region (or roaming rates, if different), avoiding incoming and outgoing calls on the foreign network. However, registering with the IMS network will still require a short-term cellular signal (at least for SMS), or activating the service before leaving.
Operators recommend relying on traditional cellular service in critical situations if it is available, as determining a subscriber's location via WiFi is less accurate.
It's also worth keeping in mind that micro-pauses may occur when switching between WiFi and mobile data during a call (handover). Not all carriers and phone models support seamless handover, so when leaving WiFi range, the connection may be interrupted for a second before switching to LTE.
Why did the VoWiFi icon disappear after updating Android?
Carrier configuration files are often reset after a major OS update. Go to your SIM card settings and try re-enabling the VoWiFi slider. If that doesn't help, remove and re-add the SIM card or reset your network settings.
Is it possible to make calls via WiFi if there is no cellular network coverage at all (airplane mode)?
Yes, this is possible. Turn on Airplane Mode, then activate WiFi separately. If the service is configured correctly, your phone will register with the operator's network via the internet, and you'll be able to make calls. The network icon may appear as "MTS Wi-Fi" or simply a handset icon.
Does VoWiFi work on dual SIM phones?
Yes, but this feature can typically only be activated for one SIM card, the one that's set as the default for voice calls. The second SIM card will work as usual or over 2G/3G/4G if a call is made to it.
How much traffic does one hour of conversation use?
VoWiFi technology is very energy-efficient. One hour of high-quality talk time uses approximately 1-2 MB of data. This is negligible, but significant if you're on a limited, hourly plan (though such plans are rare these days).