Many smartphone users Apple People notice a mysterious message appearing on their screen during calls, especially in areas with poor cell phone coverage. This message reads "Wi-Fi Calling" or includes the carrier's logo with the word "Wi-Fi," and many wonder: what is this and what is it for? On the Internet MTS, as with other major operators, this function is called VoWiFi (Voice over Wi-Fi) and is a technology for transmitting voice via the Internet protocol, bypassing standard GSM/3G/4G channels.
The essence of the technology is that your iPhone uses any available wireless connection to establish a voice or video connection. This is not just an app like WhatsApp or Telegram, but full integration at the operator level. Calls are charged according to your basic plan, with minutes deducted from your package, and incoming calls remain free, just like with a regular call. The main advantage is the ability to talk in areas with Wi-Fi coverage but no mobile network, such as basements, thick-walled buildings, or remote summer cottages.
How does VoWiFi technology work on the MTS network?
Technology VoWiFi works on the basis of the standard IMS, which allows you to transmit voice packets over the Internet. When you make a call, iPhone Automatically detects the cellular network signal quality. If the signal is weak or absent, but a stable Wi-Fi connection is available, the phone switches to voice over the internet. This process is seamless for the user, without the need to launch separate apps or enter additional codes.
MTS is actively implementing this feature, as it reduces the load on base stations and improves connection quality in densely populated areas. It's important to understand that for the service to work, the phone must support the standard. VoWiFi and be configured correctly. The carrier uses secure tunnels to transmit data, so your conversations remain private. The sound quality often surpasses that of a regular cellular connection, maintaining the same HD Voice.
Technical details of VoWiFi operation
When using VoWiFi, your phone creates a secure connection to MTS gateways. Traffic is encrypted, and specific ports may be used to pass through corporate firewalls. If your router blocks UDP ports 5060 or 5061, the feature may not work.
It is worth noting that the function works even in roaming, if your operator has the appropriate agreements, but in the case of MTS It's best to check the pricing terms in advance. When switching between Wi-Fi and cellular data during a call, modern iPhone support technology eSRVCC, allowing you to continue your connection. However, this depends on the operator's coverage in your area.
Device and SIM card requirements
To use the Wi-Fi Calling service, your smartphone must meet certain technical requirements. These primarily concern the following models: iPhone, starting with version 5c and newer, although full support in Russia appeared later. Operating system iOS must be updated to the current version, as older firmware may not contain the necessary settings profiles for Russian operators.
The second important element is SIM card. It must be replaced with a card of the format USIM (These are usually cards issued in the last 5-7 years). Older SIM cards may not support the required authentication protocols. Additionally, the service itself must be activated on the number with the operator. MTS, although it often connects automatically the first time you try to use it.
- 📱 Smartphone iPhone 5c or later with support for iOS 13 and above.
- 📡 Active USIM card MTS operator with 4G/LTE support.
- 🔐 Enable the "Wi-Fi Calling" service in your account or via USSD command.
- 🌐 Stable network connection Wi-Fi with open ports for voice traffic.
It's also important to have data roaming enabled in your phone settings, even if you're in your home region. This is a system requirement. Apple For the VoWiFi function to work correctly, as the phone must be able to transmit service data to the operator via the internet. Without this, activation may fail, and the "MTS Wi-Fi" message will not appear.
Step-by-step instructions for enabling it on iPhone
Setting the function on iPhone it happens quite simply, because MTS provides automatic settings that load upon first connection. However, if automatic activation doesn't occur, you'll need to check the settings manually. First, make sure your phone is connected to Wi-Fi and "Data Roaming" is enabled in your cellular settings.
Next, you need to go to the main device settings. The path to the required menu may vary slightly depending on the version. iOS, but the general logic remains the same. Find the section responsible for cellular communications and select your SIM card. MTS (if there are several). This is where the switch that activates internet calls is located.
☑️ VoWiFi Enablement Algorithm
After turning on the switch iPhone may send a service SMS to confirm the service. Make sure you have sufficient funds in your account or have a plan that allows sending such messages, although they are usually free. If the feature doesn't work after enabling it, try restarting your device or temporarily turning Airplane Mode on and off.
⚠️ Attention: This feature may not work on some corporate Wi-Fi networks with strict firewalls. If you see the message "Wi-Fi calling is not available on this network," try switching to your home network or mobile hotspot.
Tariff and roaming features
One of the most frequently asked questions from users concerns the cost of such calls. MTS Calls over Wi-Fi are charged the same as regular voice calls over a standard channel. This means minutes are charged from your basic package, and if your package is exhausted, the per-minute rate is based on your plan. There is no separate charge for using the technology. VoWiFi not provided.
The roaming situation deserves special attention. While abroad, you can make and receive calls via Wi-Fi while in a hotel or cafe. In this case, the "Like at Home" roaming rates or special options apply. The main advantage is that incoming calls to a Russian number are processed via Wi-Fi Abroad, they are often free, since technically you are not using the channels of a foreign operator, but are “tunneled” to the MTS network via the Internet.
However, there's an important caveat: if you move out of range while using Wi-Fi, your phone will attempt to switch to the cellular network. This can lead to a sharp increase in roaming costs, as local carrier rates will apply. Therefore, it's recommended to exercise particular caution when using this feature abroad.
| Parameter | Regular call (GSM/4G) | Wi-Fi Calling (VoWiFi) |
|---|---|---|
| Tariffing for minutes | At the operator's rate | At the operator's rate |
| Traffic consumption | Doesn't consume internet | Consumes minimal traffic (not charged) |
| Sound quality | Depends on the tower | HD, depends on Wi-Fi speed |
| Working in roaming | Roaming rates | "Like Home" Tariffs / Roaming |
Diagnosing and resolving connection problems
Despite the ease of setup, users may encounter issues where the feature doesn't activate or calls are dropped. Most often, the problem stems from an unstable internet connection. VoWiFi A stable channel with low latency (ping) is required. If the Wi-Fi network is overloaded or the signal is weak, iPhone may refuse to use it for calls.
Another common reason is the lack of operator profile updates. MTS periodically updates network settings, and if your phone hasn't been updated in a while or the settings have been reset, the feature may not work. Check for updates in the Basics → About this device, scrolling down to the "Operator" item.
It's also worth checking whether your router is set to "Guest Network" mode, which isolates clients or blocks certain ports. Some antivirus programs and parental control systems may block voice traffic, deeming it suspicious. In this case, temporarily disabling filtering or creating a separate profile for your phone may help.
⚠️ Attention: If you use a VPN on your phone, VoWiFi may not work. A VPN encrypts all traffic and changes your IP address, preventing your carrier from correctly identifying your device within their VoWiFi network. Disable your VPN before making calls.
How is VoWiFi different from instant messaging apps?
Many people confuse technology VoWiFi with calls through Viber, WhatsApp or FaceTimeThe fundamental difference lies in the level of integration. Calls via messengers require the other person to have the app installed, have internet access, and be online. MTS Wi-Fi They work like regular calls: you dial a number in a standard dialer and connect with any subscriber, even if they have a push-button phone without internet.
In addition, when calling through VoWiFi Your real phone number is identified, not your social media account. This is important for business correspondence and identification. The person you're talking to sees your number, not a random string of numbers or a profile name. Your call history is also saved in the phone's standard log, which is convenient for record-keeping.
Another difference is the connection priority. iPhone can intelligently switch between networks. If you're talking over Wi-Fi and leave the house, the phone will try to transfer the call to the cellular network without interruption (if the carrier supports it). eSRVCC). In messengers, if the internet connection is lost, the call will simply be dropped.
Why doesn't switching to a cellular network work?
Seamless handover only works one way or doesn't work at all, depending on the phone model and carrier support. In most cases, leaving a Wi-Fi zone will simply disconnect the call, and you'll have to redo the call.
Frequently Asked Questions (FAQ)
Do you charge for Wi-Fi calls when roaming?
Rates depend on your plan. If you have the "Unlimited Roaming" or similar option enabled, calls will be free or charged at a special rate. If roaming is billed separately, a Wi-Fi call will cost the same as a regular call from that country, unless otherwise specified in the "Like Home" plan terms.
MTS Often, Wi-Fi calls from abroad are treated the same as calls from within Russia, but this condition should be verified in the current version of your plan.
Why does the "MTS Wi-Fi" message appear and disappear?
This can happen due to fluctuations in Wi-Fi or cellular signal strength. If the Wi-Fi signal becomes too weak, iPhone Automatically switches to the cellular network to ensure a stable connection, and the message disappears. A temporary loss of connection to the operator's servers could also be the cause.
Is it possible to make calls via Wi-Fi if the SIM card is blocked?
No, for the function to work VoWiFi An active SIM card with a positive balance (or authorized credit) is required. The phone must be authorized in the operator's network. However, emergency numbers (112, 101, 102, 103, 104) may be available even without a SIM card if the device supports Emergency Call over Wi-Fi, but this depends on the specific model and region.
Does this feature affect internet speed?
Voice traffic has high priority but takes up little space (approximately 64-128 kbps). On high-speed modern Wi-Fi, you won't notice any impact on page or video loading. However, on very slow links (< 1 Mbps), internet quality may degrade during a call.
How to turn off Wi-Fi calling on iPhone?
To disable, go to Settings → Cellular → Wi-Fi Calling and toggle the switch to the "Off" position. You can also disable the feature through the "My MTS" app in the services section, but disabling it locally on your phone is a more reliable way to prevent use of this communication channel.