Modern mobile communication standards require not only high data transfer speeds but also a stable voice connection anywhere. Often, in offices, shopping centers, or country houses, the cellular signal is too weak to make calls, even though the wireless network works perfectly. Voice over Wi-Fi (or VoWiFi) solves this problem by transmitting voice traffic over the Internet rather than through the operator's base stations.
MTS is actively implementing this feature, allowing subscribers to make and receive calls within a wireless network coverage area, even in the absence of a cellular signal. This isn't just an alternative communication method, but a complete replacement for traditional voice calls, using your phone number and your primary carrier's pricing plan. In this article, we'll detail how to set up and activate this service on various devices.
It's worth noting that connection quality in this case directly depends on the speed and stability of your internet connection. If the router is overloaded or the channel is narrow, voice quality may be interrupted, so before starting setup, make sure your router handles the load. It's also important that your device supports the standard IMS (IP Multimedia Subsystem), which is necessary for the technology to operate.
What is VoWiFi and how does it work?
VoWiFi technology is a method for transmitting voice calls and multimedia messages over IP. Unlike popular messaging apps, which require a separate app and a contact, MTS Wi-Fi calling is integrated into your smartphone's standard dialer interface. For the subscriber, the process is no different from a regular call, but technically, the signal travels a completely different path.
Key Features The technology works by automatically switching. If you start a conversation while within range of your home network and then go outside where there's cellular service, the call won't be interrupted. The MTS system automatically transfers the session from the Wi-Fi channel to the LTE or 3G network without losing connection. This ensures uninterrupted communication under any conditions.
⚠️ Note: For this feature to work correctly, the SIP protocol or ports used for voice traffic must not be blocked in the router settings. In some corporate networks, access to these ports may be restricted by the administrator.
It's important to understand the difference between Wi-Fi calls and app calls. With MTS's native feature, you don't use up your mobile data plan (traffic goes through the operator's gateways), and the person you're calling sees your regular number. This is especially important for business subscribers who need to maintain a single number for their clients, regardless of the coverage quality in the building.
Technical details of the protocol
The VoWiFi protocol uses encryption, making conversations more secure from eavesdropping than unencrypted 2G/3G signals. However, the level of security also depends on your home Wi-Fi network settings (WPA2/WPA3 is recommended).
Checking device and tariff compatibility
Before setting it up, make sure your hardware and data plan support this option. Not all smartphones, even modern ones, have built-in VoWiFi support for Russian carriers, as this requires certification and firmware updates at the manufacturer level. Furthermore, the service must be available in your region.
First, check the list of supported devices. These are typically flagship models from leading brands released within the last three to four years. If your phone was officially purchased in Russia, it's likely supported. For devices imported from other countries (so-called "gray" imports), the feature may be hidden or require manual activation through the engineering menu.
- 📱 Apple smartphones: iPhone 6 and newer (subject to updating to the latest version of iOS).
- 🤖 Android devices: Flagship lines from Samsung Galaxy, Huawei, Xiaomi, OnePlus, and others.
- 💳 Tariff plans: The service is available on most archived and current MTS tariffs, but may not be available on some corporate or specialized SIM cards.
It is also worth considering that for the function to work, the phone must have original firmwareIf you've reflashed your device or installed custom versions of Android, VoWiFi may not work properly. In such cases, it's recommended to restore the firmware to its stock version.
Activation of the service on the operator's side
Even if your phone is technically ready, the service must be enabled in your subscriber profile on the MTS network. By default, it's often enabled automatically on new plans, but manual activation may be required on older plans. This can be accomplished in several ways, without visiting a mobile phone store.
The fastest way is to use a USSD command. By entering a short code on your phone's keypad, you send a request to the operator's server. You'll then receive an SMS notification about successful connection or an error message if the service is already active or unavailable for your number.
*111*1036#An alternative option is to use the "My MTS" mobile app. In the services section or in the app search, enter "Wi-Fi Calling" and tap the connect button. This is a convenient option, as the app interface is visual and clear, and the service status is displayed in real time.
⚠️ Note: After activating the service with your carrier, changes may take several minutes to several hours to take effect. If the feature doesn't work immediately after you issue the command, try restarting your smartphone.
Setting up VoWiFi on Android smartphones
On Android devices, the enabling process may vary depending on the model and manufacturer's operating system version. Typically, the setting is located in the mobile network section. If you can't find it immediately, search for "Wi-Fi Calling" in the settings.
For most Samsung models, the process is as follows: go to the Settings menu, select "Connections," then "Wi-Fi Calling," and toggle the slider to "On." In some cases, you may be asked to enter the emergency number's address, which is a standard security requirement.
On Xiaomi, Redmi, and Poco smartphones, the process may be slightly different. The setting is often hidden in the "SIM cards and mobile networks" menu. Here, select your active MTS SIM card and find the "Wi-Fi calling" toggle. If you don't see this option, your version of MIUI or HyperOS may not support the feature for your carrier.
☑️ Android Setup Checklist
Setting network priority is important. The function menu often offers a choice of operating mode: "Prefer mobile network" or "Prefer Wi-Fi." To resolve connection issues indoors, it's best to choose the latter, forcing the phone to use the available internet connection.
Instructions for iPhone (iOS) owners
Apple smartphone owners are fortunate to have a unified settings interface, which is the same for all models starting with the iPhone 6. However, for the control center to appear in the menu, the carrier must "allow" it through a settings profile, which is loaded when the SIM card is first activated or when updating carrier settings.
To enable the feature, go to Settings → CellularIf you have two SIM cards, select the one with MTS. Next, find "Wi-Fi Calling" and enable it. After turning on the slider, the system may ask you to confirm your address for emergency services—this is mandatory.
| Parameter | Description | Recommended value |
|---|---|---|
| Service status | On/Off | Included |
| Preferred network | Selecting a priority channel | Wi-Fi |
| Other devices | Adding devices with the same Apple ID | As desired |
| Emergency service address | Location for the 112 service | Current address |
If you've updated iOS but the option doesn't appear, try resetting your network settings. Go to General → Transfer or reset iPhone → Reset → Reset network settingsThis won't delete your data, but it will reset your network settings to factory defaults, which often helps it pick up new carrier profiles.
Diagnostics and problem solving
Despite the simplicity of setup, users may encounter difficulties. Most often, the problem is that the phone doesn't detect a supported network or fails to register with the IMS server. In such cases, instead of the handset icon with the Wi-Fi symbol, the screen may display a regular network or an "R" (roaming) icon, even when you're at home.
One common cause is the use of older routers that incorrectly process data packets or have outdated firmware. The problem can also be caused by antivirus software on the router or smartphone itself, which blocks voice traffic, deeming it suspicious.
- 🔄 Reboot: Simply turning your smartphone off and on helps in 70% of cases.
- 📶 Signal check: Make sure that the Wi-Fi signal strength in the location where the phone is located is sufficient (at least 2 bars).
- 🔒 Blocks: Check if VoIP is blocked in your router settings or in your parental control app.
⚠️ Please note: If you are roaming abroad, VoWiFi may be charged as incoming/outgoing calls in your home region, but there may be data transfer fees. Always check roaming terms before traveling.
In some cases, manually registering with the network can help. Go to your mobile network settings, select "Search for networks," wait for the list to appear, and manually select MTS. After registering, the network may prompt you to update its settings, which will resolve the issue.
Why do Wi-Fi calls drop?
Connection interruptions are most often caused by an unstable internet connection. If the router is overloaded (due to someone downloading torrents or watching 4K video), there may not be enough bandwidth for voice packets. A weak Wi-Fi signal in a distant room could also be the cause.
Do you charge for calls over Wi-Fi?
Calls are billed according to your MTS base plan. Minutes are deducted from the bundles included in the plan. If you run out of minutes, the standard per-minute rate for your region applies. Your internet traffic is not consumed.
Is it possible to use VoWiFi without a SIM card?
No, the technology requires an active MTS SIM card registered on the network. The technology uses subscriber identification via the SIM card for authorization on the operator's servers.
Does the function work if the phone is in sleep mode?
Yes, modern smartphones support standby mode for VoWiFi. However, some Android models can aggressively conserve battery power and disable background data for calls. It's a good idea to add the phone app to the exceptions list in the battery settings.
How do I know if a call is being made via Wi-Fi?
When a connection is established or during a call, a special icon should appear at the top of the screen (in the status bar). On iPhone, this is a handset with the word "Wi-Fi" on it; on Android, it's a handset with a Wi-Fi symbol or the word "VoWiFi."