Wi-Fi Calling: What it is and how to set up internet calls

Modern smartphone users often encounter situations where a room, whether an office or an apartment, has virtually no cellular signal, yet the Wi-Fi network is stable and fast. It's precisely for such situations that the technology was developed. Wi-Fi Calling, which allows you to make voice calls and send SMS messages over the internet, bypassing traditional cell phone towers. This isn't just a messaging app, but a full-fledged integration of telephony into IP networks, running natively on the device's system software.

Unlike traditional apps like WhatsApp or Telegram, here Wi-Fi Calling uses your regular phone number, and the person on the other end of the line won't even know that you're in an area with poor cellular coverage. The key advantage of this technology is the transparency of the process: you don't need to ask your interlocutor to install a special app or register for a new service. Everything happens automatically as soon as the smartphone detects an available Wi-Fi network and the absence or weakness of the cellular network signal.

The introduction of this feature has been a real lifesaver for subscribers living in buildings with thick walls or in remote areas where carriers can't provide stable coverage. Understanding how this mechanism works will help you avoid missing important calls and significantly save battery life, as searching for a network in weak signal conditions is one of the most energy-consuming processes for a smartphone.

How the technology works and how it differs from VoIP

Technology VoWiFi Voice over Wi-Fi (Voice over Wi-Fi) is the transmission of voice traffic over IP network protocols. When you activate this feature, your smartphone creates a secure tunnel to your carrier's server. It's important to understand that the call doesn't go through Google, Apple, or third-party servers, but is routed directly through your mobile carrier's infrastructure.

The main difference from classic VoIP services such as Skype or Viber is the integration with the operating system's phone book and call log. VoWiFi No separate account is required, as authentication occurs via the SIM card or eSIM profile. Your carrier treats this traffic as a regular voice call, allowing it to be charged according to your current plan, even when roaming.

⚠️ Please note: Audio quality directly depends on your internet bandwidth. If multiple devices are downloading large files simultaneously on the same network, voice quality may be interrupted.

Technically, voice transmission is encoded into digital packets and sent over the internet. If you're out of Wi-Fi range during a call but have Wi-Fi support, VoLTE (Voice over LTE) and the appropriate configuration with your operator, a call can be seamlessly transferred to the cellular network without interrupting the connection. However, switching back from the cellular network to Wi-Fi during a call is not supported by all devices and operators.

Technical details of coding

Audio is transmitted using high-resolution codecs such as AMR-WB, providing HD voice quality superior to that of a traditional GSM network.

Advantages and disadvantages of using

Switching to wireless calling has its obvious advantages, but it also comes with certain limitations that should be considered when setting it up. The main advantage is the ability to stay connected in areas where your phone would previously simply display "No Service."

Besides, saving battery power It becomes noticeable because the cellular module doesn't have to constantly operate at maximum power while searching for a base station signal. This is especially true for older smartphones or devices with worn-out batteries.

• 📶 Coating: Possibility to make calls from basements, deep rooms and buildings with shielding.
• 🌍 Roaming: In many countries, incoming and outgoing calls over Wi-Fi are charged as local calls, even if you are abroad.
• 🔋 Energy efficiency: Reducing the power consumption of the radio module when the cellular network signal is weak.
• 🔒 Safety: Traffic is encrypted between the device and the operator's server, which protects against eavesdropping on open networks.

However, there are some downsides. Firstly, the feature is entirely dependent on the quality of your internet connection. Secondly, not all operators support this service, and even those that do, it may be a paid service or require an additional option. It's also worth keeping in mind that when calling emergency services (112, 102), your location may not be determined accurately, as geolocation is based on the router's IP address, not the cell tower.

Device compatibility and operator requirements

For this feature to work, three conditions must be met: your smartphone supports the technology, your carrier has the appropriate service, and your plan is configured correctly. Most modern flagship models released after 2016 already have a built-in module for working with this feature. VoWiFi.

Carriers are gradually rolling out this service, but the list of supported devices may be limited. It's often the case that on iPhones, the feature works out of the box on all carriers, while on Android, specific device certification is required for each specific carrier. This is due to the specifics of the firmware and software.

Below is a table showing approximate compatibility of popular brands and operators (relevance may change):

If your device isn't on the certified list, it doesn't always mean the feature won't work. On Android, hidden settings can often be activated through the engineering menu or special codes, but this requires caution. On iOS, the list of supported carriers is updated with each new version. iOS, so it is recommended to keep the system up to date.

How to enable Wi-Fi Calling on Android

Activating this feature on Android devices may vary depending on the manufacturer and operating system version. Typically, you can access the settings from the phone's main settings menu. Before you begin, make sure your smartphone is connected to Wi-Fi.

On most devices, you'll need to go to the SIM card or mobile network settings. There, you'll find a toggle for Wi-Fi calling. If you don't see it right away, you may need to enable advanced settings.

Let's look at a step-by-step algorithm for the standard Android interface:

1. Open Settings on your device.
2. Go to the section Connections or Network and Internet.
3. Find the item Mobile network or SIM cards.
4. Look for the option Wi-Fi calling (Wi-Fi Calling) and activate the slider.
5. In some cases, you may be required to enter or confirm your emergency address (E911).

On Samsung smartphones the path may look like this: Settings → Connections → Wi-Fi CallingOn Xiaomi devices, you often need to go into the app Telephone, click on the three dots in the corner, select Settings and find the item Calls via Wi-FiIf after turning on the Wi-Fi connection, a handset or the words "Wi-Fi Call" appear in the status bar next to the Wi-Fi icon, then everything is configured correctly.

⚠️ Note: Menu interfaces may differ depending on the operating system (MIUI, OneUI, ColorOS). If you can't find the item, search for "Wi-Fi" in the settings.

Setting up the feature on iPhone (iOS)

Apple smartphone owners are fortunate to have a more unified approach. If your carrier supports the technology and you're within its coverage area (or roaming), setup takes literally seconds. The feature on iPhones is very stable and rarely requires user intervention after initial activation.

To enable it, you need to open the application. Settings and scroll down to the item TelephoneIn the menu that opens, select the option Wi-Fi callingToggle the switch to the active position. The system may ask you to confirm your action, warning you that the operator may receive your location data for emergency services.

After activation, the following message will appear in the status bar next to the operator's name: Wi-FiThis means the phone is ready to route calls over the internet. It's important to note that on the iPhone, you can configure this feature to only route calls over Wi-Fi or to prefer the cellular network when available.

In the section Other devices Within the Wi-Fi calling menu, you can enable receiving calls on your iPad, Mac, or iPod touch. This is incredibly convenient, as it allows you to answer calls from your primary number even if your iPhone is in another room or out of battery, as long as the devices are connected to the same Apple ID network and the internet.

What to do if the inscription does not appear?

Make sure Airplane Mode is on, then turn it off. Also, check if Screen Time is restricting changes to cellular data settings.

Troubleshooting and Common Errors

Even with proper configuration, users may encounter problems. Sometimes the icon Wi-Fi Call If the service doesn't appear, or calls are dropped, the first step is to check the service status with your carrier. Sometimes you need to send a special USSD request or enable the option in your personal account.

Network conflicts are a common issue. If you have both mobile data and Wi-Fi enabled, your phone may try to switch between them, causing disconnects. We recommend prioritizing Wi-Fi for voice calls in the developer options (for advanced users) or in the standard network settings.

• 🔄 Reboot: A simple but effective method: Restart your router and smartphone.
• 📡 Router frequency: Try switching from 5 GHz to 2.4 GHz or vice versa, sometimes this solves the stability problem.
• 🔒 Port blocking: In corporate Wi-Fi networks, ports for VoIP may be closed by the administrator.
• 📱 Software update: An outdated version of iOS or Android may not have the required security certificates.

Roaming is also a factor to consider. If you're abroad, make sure data roaming is enabled in your cellular network settings, even if you plan to make calls over Wi-Fi. This is necessary to authenticate with your carrier's international partner network.

Does Wi-Fi Calling affect internet speed?

Voice traffic uses very little (around 64-128 kbps for HD audio). For the average user, this isn't noticeable. However, if the bandwidth is very low (less than 1 Mbps), problems with both download speed and audio quality may arise.

Are minutes charged for Wi-Fi calls?

Yes, you're billed according to your main plan. If you have unlimited minutes, they're not used up. If your minutes are used up, you'll be charged per minute, not per data plan.

Is it possible to use Wi-Fi Calling without a SIM card?

No, for initial activation and operation of the technology, you must have a valid SIM card or eSIM card with the carrier's service. Without a SIM card, the phone will not be able to log in to the IMS network.

Does the function work if the router is turned off?

Obviously not. Wi-Fi Calling requires an active connection to a Wi-Fi access point, which in turn must have access to the global internet.

Why does the call drop when I leave the house?

This happens if seamless handover between Wi-Fi and LTE isn't configured, or the cellular signal at the point of connection is too weak to receive the call. The phone attempts to switch, fails to find a stable network, and drops the connection.