Modern smartphone users are accustomed to the idea of ubiquitous connectivity, but reality often dictates its own set of requirements. Concrete office walls, basements, or remote rural areas often become "dead zones" where mobile networks lose signal. It's in these situations that technology comes to the rescue. Voice over Wi-Fi, which allows you to make voice calls over an Internet connection.
MTS, like other major telecom players, has implemented support for this feature to ensure subscribers remain connected even when there is no cellular network coverage. The key feature of the service is that incoming and outgoing calls via Wi-Fi are charged the same as regular calls according to your tariff plan., without using up mobile data plans. This makes the technology not only convenient but also a cost-effective solution for those who often find themselves in areas with poor reception.
In this article, we'll take a detailed look at how this feature works on MTS, which devices support it, and what to do if it doesn't activate automatically. You'll learn about the setup details on various operating systems and understand how this mode differs from traditional messaging apps.
VoWiFi Technology: How It Works and Its Benefits
Technology Voice over Wi-Fi (or VoWiFi) is a method of transmitting voice traffic over wireless networks rather than standard GSM or LTE cellular channels. For the subscriber, the process is transparent: you dial a number and make a regular call, but technically, the data is transmitted through a router or access point. This is especially relevant for smartphones, which often switch to "emergency calls only" mode when the signal is poor.
The main difference from apps like WhatsApp or Telegram is the integration with a native dialer. You don't need the other person to have any apps installed or an internet connection. You call a regular number, and the operator's network routes your voice packet through the internet to its gateway. MTS Provides high quality sound (HD Voice), which often surpasses the quality in congested 3G networks.
Wi-Fi Calling solves the problem of "blind spots" in buildings with thick walls, where cellular radio waves are attenuated but the Wi-Fi signal penetrates freely. This feature can also be a lifesaver when roaming: while abroad and connected to a hotel's Wi-Fi, you can call Russian numbers at your home region's rates, avoiding international roaming charges.
⚠️ Please note: Connection quality directly depends on the stability and speed of your internet connection. When using congested public networks (such as cafes and airports), call delays or dropped calls may occur.
Operators are implementing this technology not only for customer convenience but also to reduce the load on base stations. By transmitting some traffic through providers' home and office networks, cell towers experience less load, which positively impacts overall network stability in the area.
Requirements for the device and connection conditions
To successfully activate and use Wi-Fi calling, simply having a smartphone with wireless network support is not enough. Your device must be carrier-certified and support the security protocols required to encrypt voice traffic. Most modern flagships and mid-range devices released after 2016 already have built-in support.
In addition to hardware, software is critically important. MTS constantly updates the list of supported models, as this feature requires collaboration with smartphone manufacturers. Your device's firmware must be up-to-date, and the corresponding option must be enabled in your network settings. If you changed your SIM card a long time ago, you may need to replace it with a USIM card that supports new security standards.
It's also important to keep in mind that the service must be available in your region. While VoWiFi works virtually anywhere in the world with internet access, the ability to register on the MTS network via Wi-Fi depends on the operator's settings in your region. The service is already fully active in most major cities and regions.
Below is a table with the basic requirements for connection:
| Parameter | Requirement | Note |
|---|---|---|
| Device | Smartphone with VoWiFi support | iPhone 5c and later, Samsung Galaxy S6 and later, Huawei, Xiaomi, etc. |
| operating system | Current version of iOS / Android | The latest available software version is recommended. |
| SIM card | USIM (4G/5G) | Older SIM cards may not support encryption. |
| Net | Wi-Fi 802.11 a/g/n/ac | Stable connection, public networks with authorization may not work |
How to activate VoWiFi on iPhone (iOS)
For smartphone owners Apple You're the luckiest of all: the setup interface is extremely simplified and unified. Activating the feature doesn't require sending USSD codes or calling support; it's all done in a couple of taps. Make sure your iPhone is updated to the latest available version of iOS, as carrier support is often added with system updates.
The first step is to go to the main settings of the device. Find the section Cellular communications (or Mobile data). If you have a dual-SIM phone, select the SIM card that belongs to MTS. Then click on Wi-Fi callingMove the slider to the active position. The system may request address verification for emergency services—this is a standard procedure required by law.
After turning on, the following message will appear in the status bar (top left or in the "bangs") next to the operator's name: Wi-FiThis indicates that the phone is ready to route calls over the wireless network. If you move out of Wi-Fi range, the call may automatically switch to the cellular network (if Continuity is enabled), but this depends on the quality of LTE coverage in your location.
☑️ iPhone Activation Checklist
In some cases, if the option does not appear immediately, try turning Airplane mode on and off (Airplane mode). This will force the phone to re-register with the network and update its carrier profile. Also, make sure location services are enabled for system services in your privacy settings, as this is required for emergency calls to work.
Setting up Wi-Fi calling on Android
The Android world is more diverse, and the location of settings may differ depending on the manufacturer (Samsung, Xiaomi, Huawei) and shell versions. However, the general algorithm remains similar. The function may be called "Wi-Fi Calling," "Wi-Fi Calling," or "Wi-Fi Calling."
On smartphones Samsung the path usually looks like this: open the application Telephone, click on the three dots in the corner of the menu and select Settings. Find the item Wi-Fi calling and activate it. On some models, the path may go through Settings → Connections → Wi-Fi CallingOnce enabled, a corresponding icon will appear in the top status bar.
Devices Xiaomi And Huawei This option is often hidden deeper. Try going to Settings → Mobile Network → Wi-Fi CallingIf you can't find this option, use the settings search: enter "Wi-Fi" or "VoWiFi" in the search bar. If the search doesn't return any results, your firmware may not be certified by MTS to support this feature.
⚠️ Note: On some Chinese smartphones (Meizu, ZTE, and some Xiaomi models), this feature may be blocked at the firmware level for the Russian region. In this case, only flashing the firmware to the global version (Global ROM) can help, but this is a complex procedure that requires skill.
Please remember that for proper operation on Android the function must also be enabled. VoLTE (Voice over LTE). These two technologies often work together, and without active VoLTE, switching between Wi-Fi and cellular networks can result in connection interruptions.
What should I do if the option is not available in the settings?
If you're sure your phone supports the technology but don't see the option in the menu, try resetting your network settings. Go to Settings → System → Reset → Reset Wi-Fi, mobile data, and Bluetooth. This won't delete your personal data, but it will return your network settings to factory defaults.
Tariffs and features of use in roaming
One of the most frequently asked questions concerns the cost of such calls. MTS positions this service as a free option. This means that there is a fee for simply using the technology. Voice over Wi-Fi There is no separate fee. Call minutes are deducted from your main plan, just as if you were calling through a regular cell tower.
Using this service abroad is especially useful. If you're roaming internationally and connected to Wi-Fi, you can call Russian numbers at the rates of your home region (or according to the terms of your tariff option). This allows you to avoid incoming and outgoing roaming charges. However, if you call a number in your host country while roaming, special rates may apply.
It's important to distinguish between Wi-Fi calls and messaging apps. In the former case, you pay the carrier's voice rates, while in the latter, you use your internet data. If you have unlimited Wi-Fi, the difference isn't noticeable, but when using mobile data (if your Wi-Fi connection suddenly goes down), messaging apps can be more cost-effective, unless you have unlimited minutes.
It's also worth keeping in mind that traffic used for calls isn't usually billed separately, but technically it goes through data channels. Make sure you don't have background data restrictions for system processes if you want to ensure consistent incoming calls.
Troubleshooting and diagnostics
Despite the technology's robustness, users may encounter difficulties. The most common issue is that the VoWiFi icon doesn't appear, even though everything seems to be configured correctly. First, check that the internet connection itself is working. If webpages don't load, calls won't work either.
The second common cause is a network conflict. Some routers have security or client isolation settings that block specific ports required for the SIP protocol (which VoWiFi is based on). Try rebooting the router or connecting to a different Wi-Fi network to test.
If you've changed your phone but still have the same SIM card, it may be the issue. Contact a mobile phone store to replace it with a USIM card. A simple restart with the battery removed (if possible) or a complete reset of network settings may also help.
⚠️ Please note: Operators reserve the right to change the list of supported devices and service terms. Technical requirements may be updated without prior notice. Always check the current list on the official website or in the "My MTS" app.
In rare cases, the problem lies with the operator's base stations or gateways. If all else fails, it's worth calling technical support (from a different phone) and checking if there's any maintenance work happening in your area.
Comparing VoWiFi with Alternative Communication Methods
Users often confuse Wi-Fi calling from their carrier with IP telephony. Understanding the difference helps choose the right tool for a specific situation. VoWiFi is a "white hat" technology integrated into GSM/LTE standards, while messaging apps are overlay applications.
The main advantage of VoWiFi is the quality and reliability of the connection with regular numbers. You don't need to worry about whether the other person has internet access or WhatsApp. You simply dial the number. Furthermore, operators prioritize voice traffic, so even with slow internet speeds, the sound remains clear.
On the other hand, messaging apps offer more features: video calls, groups, and file transfers. But for simple voice communication, especially in poor cellular coverage, the smartphone's native Wi-Fi feature remains the king of reliability.
Do I need to pay for the VoWiFi connection service itself?
No, connecting and using this feature is free. You only pay for the minutes of the call, as per your plan, just like for a regular call.
Does VoWiFi work if I have an ad blocker on my phone?
Aggressive blockers or DNS filters can block SIP ports required for connection. If calls aren't going through, try temporarily disabling the blocker.
Is it possible to call emergency numbers (112) via Wi-Fi?
Technically, this is possible, but the system may not be able to determine your exact location, as the Wi-Fi IP address isn't always geo-located. In emergency situations, it's best to use a regular cellular network, even if the signal is weak.
Why does the Wi-Fi Calling icon disappear during a call?
This can happen if the Wi-Fi signal quality drops below the threshold, and the phone automatically switches to LTE/3G. If there is no cellular network, the call will be disconnected.
Does VoWiFi affect battery life?
In standby mode, power consumption may be slightly higher, as the phone is constantly scanning for networks. However, during a call, power consumption is comparable to normal mode, and sometimes even lower, as the Wi-Fi module finds it easier to maintain a connection via a nearby router than to secure a signal from a distant tower.