Many subscribers are familiar with the situation where indoor Wi-Fi coverage is excellent, but the mobile network is completely unavailable or intermittent. Under these conditions, traditional voice calls become impossible, and you risk missing an important conversation or being unable to contact the other party. VoWiFi technology offers a solution to this problem, transmitting voice traffic over the internet rather than through the cellular operator's base stations.
Operator MTS actively implements and supports the Voice over WiFi function, which is available for most modern smartphones based on AndroidThis isn't just a simple in-app call like in messaging apps, but a fully-fledged system call integrated into the standard dialing system. To the other party, your call will appear as a regular one, and you'll be charged according to your primary plan, which is often more cost-effective and convenient than using third-party services.
In this article, we'll cover in detail how to activate this option, the hardware requirements, and what to do if the desired button doesn't appear in the menu. You'll learn how to properly configure your router and phone to ensure a stable connection and high-quality audio during calls.
What is VoWiFi technology and how does it work?
Technology Voice over WiFi (often referred to as Wi-Fi Calling) is a solution that allows a mobile phone to use a wireless network to transmit voice calls and SMS messages. Unlike popular messaging apps, which use the data channel of a specific app, VoWiFi operates at the operating system level and IMS (IP Multimedia Subsystem) protocols. This means you don't need to open a separate program or ask your caller to install special software.
The operating principle is that the voice signal is digitized and transmitted via the Internet channel to the operator's gateway. MTS, where it is converted into a standard telephone signal and forwarded further into the network. If you call another subscriber who also has Wi-Fi Calling enabled, the conversation can take place entirely over internet channels, bypassing cell towers. The audio quality is often higher than on a standard 2G/3G network and comparable to HD voice on LTE.
The main advantage is coverage. If you're in a basement, a country house with thick walls, or a remote area where the cellular signal is weak or nonexistent, but there's a stable Wi-Fi connection, you'll be able to receive and make calls. Your phone will automatically switch to Wi-Fi Calling when it detects that the cellular network is unavailable or its signal is too weak to provide a reliable connection.
⚠️ Attention: A stable internet connection is critical for the technology to work. If the router is overloaded or the bandwidth is limited, call quality may drop sharply, leading to delays or a robotic voice.
It's important to understand the difference between VoWiFi and regular calls made via internet apps. With VoWiFi, your real phone number is used, calls appear in your standard call history, and you can use additional carrier services such as call forwarding or call waiting. Furthermore, this technology uses significantly less battery power than constantly using 3G/4G in poor coverage areas, as the Wi-Fi module is more energy-efficient in such scenarios.
Checking device and tariff compatibility
Before setting up, make sure your hardware and data plan support this feature. Not all smartphones, even modern ones, have software support for this feature for Russian carriers. This primarily applies to devices shipped to other regions or through gray market importers.
List of supported models Android is constantly expanding. Currently, stable operation is guaranteed on most flagship and mid-range models from Samsung, Xiaomi, Honor, Huawei And Google PixelHowever, having the technical capability in the hardware is only half the battle. Operator MTS must see your device in its database of compatible models in order to send the necessary settings profiles.
You should also check the status of your SIM card. VoWiFi is free to connect and use (data isn't billed separately; minutes are included in your plan), but it must be active with your carrier. Older SIM cards, issued many years ago, may require replacement with a new one that supports 4G/LTE, as the technology relies on the IMS infrastructure.
To quickly check whether your phone sees the option to enable the function, you can use the engineering menu or a special code, although in the latest versions Android Access to these options is often blocked by manufacturers. A more reliable method is to try activating them through the settings menu. If the option isn't there even after all the checks, it's possible your specific model isn't yet certified by the operator.
Activating the service on the MTS operator's side
The first step in the setup process is activating the service on the network side. Even if everything is configured correctly on the phone, the feature won't work without permission from the operator. MTS There are several ways to enable this option, and the choice depends on how you prefer to manage your services.
The fastest way is to use a USSD command. This is a universal method that works on any phone, even without internet access (though you will need internet access later to use the service itself). Open the Phone app and enter the activation command. After entering the code and pressing the call button, you will receive an SMS notification that the service has been successfully activated.
An alternative and more informative method is through your personal account. This can be the "My MTS" mobile app or the web version on the operator's website. There's often a VoWiFi toggle switch in the services or plan settings section. The advantage of this method is that you can immediately see the service status and disable it at any time if problems arise.
Please note that activation may take some time, typically from a few seconds to 15 minutes. Don't panic if the Wi-Fi calling indicator doesn't appear during this time. Also, make sure your main account balance is sufficient. While the service itself is free, some plan terms may require a positive balance to activate features.
Setting up an Android phone for WiFi calling
Once the service is activated on the side MTS, you need to properly configure the smartphone itself. The menu interface may differ depending on the version. Android and manufacturer shells (MIUI, OneUI, EMUI), but the logic of actions remains similar.
On most modern devices, this setting is located in the cellular section. You need to go to the settings menu and find the item related to SIM cards or mobile network. This is where you'll find the switch that allows the phone to use the wireless channel for voice calls.
☑️ Android Setup Checklist
Let's take a closer look at the setup paths for popular brands, as the item names can be confusing:
- 📱 Samsung: Settings → Connections → Wi-Fi Calling (switch to "On"). You can also find it by searching for "Wi-Fi" in Settings.
- 📱 Xiaomi / Redmi / POCO: Settings → SIM cards & mobile networks → Wi-Fi calling. Make sure "Prefer Wi-Fi" or "Mobile network & Wi-Fi" is selected.
- 📱 Honor / Huawei: Settings → Wireless & networks → Mobile networks → Wi-Fi calling. In some EMUI versions, you may need to enable "Allow Wi-Fi calling."
- 📱 Pure Android (Pixel, Motorola): Settings → Network & Internet → Mobile networks → Preferred network type → Wi-Fi calling.
Once the switch is enabled, a corresponding icon should appear in the status bar (at the top of the screen). This icon varies depending on the manufacturer: it might be a phone handset with a Wi-Fi symbol, the words "Wi-Fi Call," or simply a Wi-Fi icon next to the cellular signal strength indicator. When this icon appears, it means the phone is ready to make internet calls.
⚠️ Attention: On some Xiaomi and Huawei models, this option may be hidden. If you can't find the switch, try tapping the three dots (menu) in the Phone app → Settings → Calling accounts and selecting the MTS SIM card.
Choosing your network priority is crucial. VoWiFi settings often offer three options: "Prefer Mobile Network," "Prefer Wi-Fi," and "Wi-Fi Only." For most users, the optimal setting is "Prefer Wi-Fi" or "Mobile Network and Wi-Fi." This setting ensures that if the cellular signal is strong, the phone will use it, and if it weakens, it will seamlessly switch to Wi-Fi.
Router requirements and connection quality
Voice call quality directly depends on your home network settings. VoWiFi technology is sensitive to latency (ping) and jitter (ping instability). Even if your download speed is high (for example, 50 Mbps), if your ping fluctuates, your voice will be interrupted.
For stable operation, it's recommended that your router support at least 802.11n (Wi-Fi 4), and ideally 802.11ac (Wi-Fi 5) or 802.11ax (Wi-Fi 6). Older devices using the 2.4 GHz frequency can be overloaded by neighboring networks and household appliances, causing packet loss, which is critical for voice.
Particular attention should be paid to the router settings. Protocol SIP ALG (Application Layer Gateway) often conflicts with VoIP traffic. Although VoIP uses its own secure tunnels, in some cases disabling SIP ALG in the router settings (WAN or NAT section) helps resolve connection issues or one-way audio.
| Network parameter | Recommended value | Impact on call |
|---|---|---|
| Ping (Latency) | Less than 50 ms | Delay in response from the interlocutor |
| Jitter | Less than 20 ms | Robotic voice, interruptions |
| Packet loss | 0% | The disappearance of words, silence |
| Frequency range | 5 GHz (preferred) | Stability and freedom from interference |
If you're using a mesh system or repeaters, make sure that switching between nodes occurs correctly. Sometimes, when a phone switches from one access point to another, a call may be dropped because the IP address may change, and a VoWiFi session requires a stable IP address. In such cases, it's best to force the phone to connect to the main router during important calls.
What to do if the router is old?
If your router doesn't support 5 GHz or is constantly losing packets, consider upgrading to a new model. You don't need an expensive gaming router for calls; a modern entry-level device with AC support is sufficient.
Diagnosis and solution of typical problems
Even with proper configuration, there may be situations where the feature doesn't work. The most common issue is that the VoWiFi icon doesn't appear in the status bar. In this case, first check if VoWiFi is enabled. airplane modeOn some smartphones (especially Samsung), to activate VoWiFi in areas with no cellular coverage, you need to enable airplane mode and then enable Wi-Fi only. This will cause the phone to think there's no cellular network and force Wi-Fi to make calls.
Another common issue is resetting network settings. If you recently updated the firmware or performed a factory reset, your carrier profile may have been deleted. Try removing the SIM card and reinserting it, or use the "Reset network settings" feature (not data!) in the Android menu. This will restore the default APN and IMS settings.
Problems may be related to your VPN. If you have a VPN enabled, your VoIP traffic may be blocked or rerouted through other countries, which your carrier will perceive as a violation of the terms or simply a technical routing issue. Be sure to disable your VPN before making a call.
⚠️ Attention: Interface settings and terms of service are subject to change. Up-to-date information on supported models and commands can always be found in the operator's official app or on the support website.
If all else fails, it's worth checking whether your SIM card is set to block data services, although this is rarely necessary for VoWiFi. You should also contact support. MTSso that they can check if they see your IMSI number in the list of subscribers who have access to the Voice over WiFi service.
Comparison with alternative communication methods
Users often ask: why use VoWiFi when you have WhatsApp, Telegram, or Viber? The answer lies in its convenience and versatility. Messengers require the other person to have the app installed, have an internet connection, and be online. VoWiFi, on the other hand, allows you to call any number (landlines, mobile phones from other carriers), even if the person on the other end of the line has a push-button phone without internet access.
In addition, the quality of voice encoding in networks MTS Often outperforms messaging codecs, which heavily compress audio to save data. VoWiFi uses high-definition codecs (HD Voice), making conversations more natural. Battery life is also an important factor: a system call consumes less battery than a running video calling app.
However, the technology has its limitations. For example, emergency services (112) may not locate you via Wi-Fi with the same accuracy as via GPS/base stations, although modern systems are gradually learning to transmit router coordinates. Also, when roaming abroad, using VoWiFi may be charged as an incoming/outgoing call from the SIM card's country of registration unless a special data plan is activated, so be careful when traveling.
FAQ: Frequently Asked Questions
Is there an extra charge for Wi-Fi minutes?
No, you're charged according to your base plan. Minutes are deducted from the bundles included in your plan or charged as a standard outgoing call minute. No internet traffic is consumed.
Is it possible to make calls via MTS Wi-Fi if the SIM card is blocked?
No, the SIM card must be active to register with the IMS network and activate the service. However, if you have an active SIM card from another operator in slot 2, and the MTS SIM card in slot 1 is blocked or has no network coverage, you will still be able to receive calls to the MTS number via Wi-Fi if your phone supports the "Calls from another device" feature or similar switching mechanisms, but the standard scenario requires an active SIM card.
Why does the Wi-Fi Call icon disappear during a call?
This can happen if the Wi-Fi signal quality has dropped sharply and the phone has tried to switch to the cellular network (if one is available), or if the router has lost its internet connection. It can also occur if the Wi-Fi module overheats.
Does VoWiFi work if I turn off my mobile internet (data transfer)?
Yes, it works. VoWiFi doesn't require mobile data (3G/4G) to be enabled; it only requires an active Wi-Fi connection. However, the SIM card itself must be registered with the carrier's network (show at least one SIM card or be in "Calls Only" mode) to complete IMS authorization.
Will call forwarding work if the phone is only connected via Wi-Fi?
Yes, call forwarding is configured on the carrier's network. If you don't pick up or are busy, the call will be forwarded according to your settings, regardless of the channel (Wi-Fi or base station) the call is received through.