WiFi Calls on Xiaomi: A Complete Guide to VoWiFi

Xiaomi’s current smartphones, which run on the shell of MIUI or HyperOS, have a wide range of features that many users do not even know about. One of these hidden, but extremely useful features is the ability to make voice calls over a wireless Internet connection. In the phone’s settings, this option can be displayed as “Calls over WiFi”, “Wi-Fi Calling” or “VoWiFi”.

The essence of the technology is that voice traffic is transmitted not through standard cell towers, but through a Wi-Fi hotspot. This solution becomes a salvation in places with unstable cellular signal, but a stable Internet: in basements, deep offices or country houses with thick walls.

In this article, we will take a closer look at what this protocol is, how to activate it on Xiaomi and Redmi devices, and the typical problems users face when trying to set up. Understanding how VoWiFi works will help you stay connected in any environment.

What is VoWiFi Technology and How Does It Work?

Voice over Wi-Fi (VoWiFi) technology allows mobile operators to provide voice services over IEEE 802.11 wireless networks. The process is transparent to the user: you dial the same number as you always do, and the interlocutor sees your normal phone number. The only difference is that the signal goes through the router, not through the base station.

Unlike popular messengers like WhatsApp, Telegram or Viber, where calls are made via an Internet account, VoWiFi is integrated directly into the standard smartphone “ringer”, which means that you do not need to have a particular software installed or access to the Internet.

The key advantage is the high quality of sound, often exceeding standard performance. GSM-The protocol uses high-definition codecs to make the conversation more natural, and Xiaomi and other manufacturers have implemented a seamless handover mechanism: if you leave Wi-Fi coverage during a conversation, the call automatically and without interruption switches to the cellular network. 4G/LTE, vice versa.

⚠️ Attention: The quality of communication depends on the speed and stability of your router. If the Internet channel is overloaded with downloading files or streaming videos, the quality of voice calls can drop sharply, there will be delays or a robotic voice.

It is important to understand that the function requires support from your mobile operator. Even if the switch is active on the smartphone menu, without configuring the service on the operator's side, calls will not be made. Most large operators have already implemented this technology, but it often requires activation through a personal account or a private account. USSD-team.

The main differences between VoWiFi and VoLTE messengers

Many users confuse VoWiFi with VoLTE (Voice over LTE), believing that they are the same. Although both technologies are related to packet voice (PS), there are significant differences between them. VoLTE uses a fourth generation (4G) network for voice transmission, while VoWiFi relies solely on a Wi-Fi router.

Let’s look at the key differences in the table to structure understanding:

Another important difference is the charging, which is that when you use VoWiFi, you don't usually charge for the Internet traffic you spend during a conversation, you get the minutes written off according to your basic plan, like a regular call, and this is especially true for those who are roaming, because incoming and outgoing Wi-Fi is often charged as a call from your home network, which saves you a lot of money abroad.

However, it is worth remembering the nuances of roaming. When abroad, VoWiFi activation can be regarded by the operator as being in the home region, even if you are physically in another country, but connected to home Wi-Fi (this works differently through roaming partners).

With instant messengers, the situation is very different: they use their own server to transmit voice and video, without integrating into the phone book as deeply as the native feature of Xiaomi. VoWiFi is a bridge that allows telephony to work where the cellular network is silent.

How to enable WiFi calls on Xiaomi and Redmi

Activation of the function on Xiaomi, Redmi and smartphones POCO It usually does not require complex manipulations if your operator supports the technology and it is already activated. SIM-Interface. MIUI HyperOS may vary slightly depending on the Android version, but the logic remains the same.

First, make sure your smartphone is connected to a Wi-Fi network. Then go to the basic settings of the device. Find the section responsible for SIM cards and mobile networks. In modern versions of the shell, the path most often looks like this: Settings → SIM-maps and mobile networks.

Select the SIM card you want to enable (if there are two) and in the menu that opens, look for Wi-Fi Calls or Wi-Fi Calls. Switch the slider to the active position. If there is no such option explicitly, try searching for it through a global search by settings by typing in "WiFi Calling".

When the notification curtain is turned on, the appropriate icon should appear in the status bar, usually an icon of a phone handset with a Wi-Fi symbol or the inscription "Wi-Fi Call", and the presence of this indicator confirms that the phone is ready to make and receive calls over the Internet.

In some cases, especially on global versions of firmware with Russian SIM cards, the menu may be hidden, then you may need to enter special code in the engineering menu or use the application for hidden settings, but this is already an advanced level that requires caution.

Why VoWiFi is not working: the main reasons and solutions

It's quite common for users to see a switch, but the icon doesn't appear in the status bar, or calls get disrupted. The first and most common reason is a lack of support from a carrier or a specific one. SIM-map.

Even if the operator claims support, the service may not be connected to your number. USSD-A command specific to your carrier (e.g. *111# or via the operator's app) and find the "Wi-Fi Calls" service management there. SIM-The card is not worth the old settings, replace it with USIM, if she's very old.

The second set of problems is related to smartphone software: on global versions of MIUI for Russia and CIS, VoWiFi support is not implemented for all operators; the firmware may not know that you need to activate this protocol for your particular provider.

⚠️ Warning: Do not try blindly (at random) to edit system files or use third-party applications to activate hidden menus if you are not sure of your actions.This can lead to incorrect operation of the communication module and constant restarts of the smartphone.

The third reason is router configuration conflicts: some encryption protocols or NAT settings on the router can block the passage of voice packets. Try rebooting the router or temporarily changing the DNS to public ones (for example, Google DNS 8.8.8.8) to eliminate routing problems.

Set network and roaming priorities

An important aspect of using the technology is to set priorities correctly: a smartphone needs to know when to use Wi-Fi for calls and when to switch to a cellular network. Xiaomi’s settings usually have a Network Preference option inside the Wi-Fi call menu.

There are two main modes of operation:

• 📶 Prefer Wi-Fi: The phone will try to hold a call on Wi-Fi even when the signal is weak, if Wi-Fi is available. This saves battery power in areas of poor reception of cell towers.
• 📶 Prefer a mobile network: A phone will only use Wi-Fi if the cellular signal is completely absent.

As mentioned earlier, VoWiFi is a great way to save money when traveling. If you are in a hotel abroad, turn on flight mode, then activate Wi-Fi and wait for the VoWiFi icon to appear, in which case incoming calls can be free (depending on the tariff), and outgoing calls can be charged as calls from home.

However, be careful with background processes.If you turn off the mobile network completely, some apps may stop receiving push notifications as they depend on Google Play Services channels that may be trying to use mobile internet.

The Impact of VoWiFi on Autonomy and Security

The battery impact is a common concern for smartphone owners, and logic tells them that the constant search for the network and the operation of the Wi-Fi module should be loaded, but in reality, the opposite is true: in a bad cell signal (1-2 division), the phone constantly increases the transmitter power, trying to "shoot" to the tower. This is a huge energy consumption.

Using stable Wi-Fi to transmit voice in such a situation significantly reduces the load on the modem and processor. Smartphone less warms up and the battery discharges more slowly, so in offices or homes with poor cellular coverage, turning on VoWiFi prolongs the life of the device.

As for security, VoWiFi uses the same encryption standards as modern LTE networks. Voice traffic is encrypted between your phone and the operator gateway (IMS). Even if you are on a Wi-Fi network (cafe, airport), your conversations are protected from listening at the protocol level, unlike calls through open messengers without encryption.

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If you are often in places with a bad signal (basement, cottage, shopping center), add Wi-Fi network to the list of trusted in the security settings so that the phone automatically turns on VoWiFi when connecting.

However, public Wi-Fi networks may have port and protocol restrictions (SIP ALGs), which sometimes interfere with the connection, in which case the function may simply not activate and the phone will switch to normal cellular communication or give an error.

Frequently Asked Questions (FAQ)

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VoWiFi on Xiaomi is not just a “call over the Internet”, but a full replacement of cellular communication in areas of poor reception, providing high sound quality and battery saving without losing number.