In today's world, voice communication is no longer simply the transmission of sound through cellular base stations. With the advancement of data transmission technologies, it has become possible to make calls over an internet connection, which is especially important in areas with poor cellular coverage. This technology, known as Voice over Wi-Fi VoWiFi, or VoWiFi, allows a smartphone to use a home or public Wi-Fi router to route voice calls. This solution is ideal for those who frequently experience connection drops in basements, offices with thick walls, or country houses.
The main advantage of this method is its transparency for the user. You don't need to install additional apps, remember new numbers, or ask your caller to do the same. Calls are made through your smartphone's standard dialer, and are billed according to your basic minute plan. If you have unlimited calls to numbers in your region, they will also be free over Wi-Fi within that limit. All you need is a stable internet connection.
However, despite the simplicity of the concept, the process of activating the feature may vary depending on the device model, operating system version, and specific carrier terms. In this article, we'll cover the technical aspects of the technology in detail, provide step-by-step instructions for Android and iOS, and answer questions about security and data savings while roaming.
β οΈ Please note: VoWiFi service terms are subject to change by telecom operators. Before setting up, be sure to check your tariff plans and feature availability in your operator's personal account or on the official website.
How VoWiFi technology works and how it differs from instant messaging apps
VoWiFi (Voice over Wi-Fi) technology operates on the same principles as VoIP (Voice over IP), but it differs fundamentally from popular messaging apps like WhatsApp, Telegram, or Viber. When you make a call via a messaging app, the call goes through the servers of a specific app, requires the other person to have that app installed, and often has less stable connection quality when switching between networks. VoWiFi, on the other hand, is integrated directly into the core of the smartphone's operating system and the operator's network.
When this feature is enabled, your phone creates a secure tunnel to the carrier's gateway via the Wi-Fi internet connection. To the network, this appears as a regular data stream, but the carrier recognizes it as voice traffic and routes it to the public switched telephone network (PSTN). This means you can call landlines and mobile numbers, even if the other person doesn't have internet access or a smartphone. Encryption protocolsThe rules used in this case are often even stricter than those used in regular cellular communications, ensuring a high level of confidentiality of the conversation.
Another important feature is seamless handover. Modern smartphones support handover technology, which allows you to switch from Wi-Fi to a mobile network (LTE/5G) and back during a call without interrupting the connection. This is critical if you move out of range of your router during an important conversation. The sound quality is typically superior to standard HD Voice, as home internet bandwidth is typically more stable than overloaded base stations.
- πΆ Stability: The sound does not disappear in buildings with thick walls, where the cellular signal does not reach.
- π Safety: Traffic is encrypted between the phone and the operator's gateway, protecting it from eavesdropping on open networks.
- π Seamlessness: Automatically switch between Wi-Fi and mobile networks without dropping the call.
- π° Pricing: The package of minutes from the main tariff is used, not the Internet traffic (although Wi-Fi traffic is used).
Checking smartphone and SIM card compatibility
Before setting up, you need to make sure your equipment supports VoWiFi technology. Not all smartphone models, even modern ones, have software or hardware support for this protocol, depending on the region of sale. Furthermore, the SIM card must be a new model that supports IMS (IP Multimedia Subsystem) profiles. If your SIM card is more than 5-7 years old, it will likely need to be replaced at a carrier store, which is often free.
For devices based on Android The list of supported models is extensive and includes flagship lines from Samsung, Google Pixel, Xiaomi, OnePlus, and others. However, even if a phone model supports the technology, it must be certified by your carrier. In some cases, the feature may be blocked by software on "gray" versions of smartphones intended for other markets.
Users iPhone are in a better position because Apple implements VoWiFi support centrally. Starting with the iPhone 5c and later (provided you're running the latest version of iOS), the technology is supported by virtually all major carriers worldwide. The only requirement is the "Wi-Fi Calling" setting in the menu, which appears automatically when you insert a compatible SIM card.
How to check IMS support on Android?
On some Android devices, you can enter ##4636## in the dialer, go to "Phone Information," and check the "IMS Status." If it says "Registered," then support is available. However, this method doesn't work on all models and firmware versions.
It's also important to note that the router doesn't require any special configuration for this feature to work, but it must provide a stable ping. If your Wi-Fi suffers from high latency or packet loss, call quality will be poor, even if your phone is fully compatible.
How to enable Wi-Fi calling on Android
On Android devices, the setup process may vary slightly depending on the manufacturer's operating system (MIUI, OneUI, ColorOS, etc.). However, the steps remain the same. First, make sure Wi-Fi is enabled and the phone is connected to a network. Then, go to the device's main settings.
In most cases, the desired option is located under "Connections," "SIM cards and mobile networks," or "Wi-Fi and Internet." You'll need to find an option that may be called "Wi-Fi calling," "Wi-Fi calling," or "Wi-Fi calling." After activating the slider, the system may ask you to confirm your emergency services address (this is a regulatory requirement for calling emergency services even without a SIM card, although this requirement is relaxed in some regions).
Settings β Connections β Wi-Fi Calling β Turn onIf you can't find a setting using the standard search methods, try using the settings search. Enter "Wi-Fi" or "Calling" in the search bar, and the system will highlight the appropriate section. Once enabled, a corresponding icon should appear in the status bar (at the top of the screen), often a phone handset with a Wi-Fi symbol next to it.
βοΈ VoWiFi Activation Checklist for Android
Please note that on some custom firmware versions or on phones purchased in countries where carriers don't support VoWiFi, this menu item may be hidden. In such cases, activation is only possible through the engineering menu or specialized apps, but this requires a high level of skill and may result in unstable device operation.
β οΈ Note: On some Xiaomi and Huawei models, this feature may be hidden in global firmware versions. Try changing the device's region in settings to a country where your carrier officially supports VoWiFi (e.g., the UK or India) to unlock the menu.
iPhone Setup: Enable Wi-Fi Calling in iOS
The setup process is as unified as possible within the Apple ecosystem. If your carrier supports the technology, the menu item will appear automatically after inserting the SIM card and connecting to the internet. To get started, open the Settings app and go to the Phone section.
Find "Wi-Fi Calling" in the list of options. Tap it and toggle "Wi-Fi Calling on This iPhone." You'll receive a warning that your emergency phone number may be shared with your carrier. Confirm. You can then select "Add Wi-Fi Calling to Other Devices" if you want to receive calls on your iPad or Mac using the same number.
- π Open
Settingson the main screen. - π Go to the section
Telephone. - π‘ Select an item
Wi-Fi calling. - β Activate the switch and confirm the address.
A unique feature of iOS is the ability to customize network preferences. You can choose which network to prioritize: "Prefer Wi-Fi" or "Prefer Cellular." The former will force the phone to use Wi-Fi for calls even when the cellular signal is weak, which is useful for saving battery life in areas with poor reception.
Once configured, "Wi-Fi" will appear in the status bar next to the carrier's name. This indicates that the phone is ready to make and receive internet calls. If the icon disappears, the Wi-Fi connection has been lost or the channel quality has dropped below the required threshold.
Pricing and calls in roaming
One of the most frequently asked questions concerns the cost of these calls. It's important to understand the difference between calls in your home region and while roaming. When you're in your home country (in the region where your SIM card is registered), Wi-Fi calls are charged just like regular voice calls. They use up your plan's minutes. If you have unlimited minutes, Wi-Fi calls are also free as part of your plan.
The situation changes dramatically when you are abroad. This a key feature of the technology for travelersIf you're roaming but connected to Wi-Fi and calling numbers in your home country (home region), your operator often treats it as an incoming or local call, avoiding international roaming charges. You don't pay for roaming partner minutes, as your voice traffic doesn't go through their base stations but rather over the internet directly to your operator's gateway.
However, if you're roaming and calling a number in your host country or a third country via Wi-Fi, your carrier's standard international calling rates may apply. It's also worth remembering that while voice data isn't consumed, using Wi-Fi requires internet access. If you use paid Wi-Fi at a hotel or airport, you pay for network access, but not for call minutes.
| Scenario | Caller | Where is the call? | Tariffs |
|---|---|---|---|
| Home region | Russia | RF number | According to the tariff (minutes of the package) |
| Roaming (abroad) | Russia | Russian Federation number (via Wi-Fi) | Feel at home (often for free) |
| Roaming (abroad) | Russia | Local number of the host country | International operator tariff |
| Any region | Russia | Emergency services (112, 911) | Free (address required) |
Troubleshooting: Why VoWiFi Isn't Working
Despite its apparent simplicity, users often encounter a situation where the feature doesn't activate or the icon doesn't appear. The first and most common cause is a lack of carrier support for your specific plan option. Some older or corporate plans may not include VoWiFi service by default.
The second cause could be a block at the router level. Some providers or corporate network settings block ports and protocols required to establish a secure connection to the operator's IMS core. The problem could also lie in the DNS servers. Try changing the DNS in your router or phone settings to a public one (for example, from Google or Cloudflare) to eliminate routing errors.
If the icon is lit, but calls are dropped or the voice is choppy, the problem is with the connection quality. VoWiFi is sensitive to jitter and packet loss. Even with high download speeds (100 Mbps), unstable ping can make calls impossible. In this case, rebooting the router or switching to the 5 GHz frequency, which is less noisy, will help.
What should I do if the Wi-Fi Calling setting is missing after updating iOS?
Sometimes after updating the operating system, the carrier profile may reset or become outdated. Try removing the SIM card and reinserting it. If it's an eSIM, try deleting the carrier profile and adding it again using a QR code or the carrier's app. Also, check that "Data Saver" mode isn't enabled for cellular data, as this can interfere with network priority.
Is it possible to make calls via Wi-Fi if the cellular network is completely turned off?
Yes, you can. Moreover, in Airplane Mode with Wi-Fi enabled, VoWiFi calls will also work if the phone has registered with the carrier's network via the internet. This is ideal for use on airplanes (if the onboard Wi-Fi allows it) or in bunkers without a signal.
Does VoWiFi affect internet speed?
Voice traffic uses very little bandwidth (usually up to 100 kbps), so it doesn't noticeably impact page or video loading speeds. However, if the bandwidth is very low (less than 1 Mbps), voice may be prioritized, slowing down other traffic.
Does VoWiFi work if the router distributes Internet from a mobile phone?
Technically yes, but it's pointless. You'll waste mobile data on voice calls that could otherwise be routed through the cellular network. Furthermore, some carriers may block their own traffic from being rerouted through tethering. Use this method only in emergency situations.
Do I need to pay for the connection service?
In most cases, connecting and using the service is free. Operators are interested in reducing the load on their base stations, so they encourage users to switch to Wi-Fi where possible. Just check if this option is available in your personal account.