Vo WiFi on the Redmi Note 9: What is this feature and why is it needed on a phone?

Have you ever noticed in your settings Redmi Note 9 mysterious switch Vo WiFi and wondered what it is? This feature appears in the communication menu of many modern smartphones, but not all users understand its purpose and benefits. This is especially relevant for owners of budget-friendly but functional devices from Xiaomi, where the manufacturer often integrates advanced technologies, not always accompanied by detailed explanations.

In fact Vo WiFi (or Voice over WiFi) is a technology that allows you to make calls over a wireless network instead of traditional cellular communications. For Redmi Note 9 with his support WiFi 5 With stable hardware, this feature can be a real lifesaver in areas with poor mobile coverage. But how does it work in practice? When should it be used, and when is it best to disable it? And why does Vo Wi-Fi sometimes suddenly disappear from the settings? You'll find the answers to these questions in our detailed guide.

We'll not only explain the technical aspects of the service, but also provide step-by-step setup instructions, address common errors (for example, when VoIP WiFi doesn't activate despite operator support), and provide recommendations for optimizing your connection. We'll also reveal a few little-known tips that will make your WiFi calls even more stable.

What is Vo WiFi and how does it work on the Redmi Note 9?

Vo WiFi (from English) Voice over WiFi) is a communications standard that allows voice calls to be transmitted over networks Wi-Fi instead of traditional cell towers. The technology is based on the protocol IMS (IP Multimedia Subsystem), which is integrated into modern 4G/5G networks. For Redmi Note 9 This means that when connected to WiFi, the phone can automatically switch voice traffic to the wireless network if the mobile operator signal is weak or absent.

How does this work in practice? Imagine you're in a basement or a densely populated area where cell service is poor but there's reliable WiFi. Instead of interrupting your conversation or switching to messaging apps like WhatsApp, yours Redmi Note 9 Automatically reroutes calls over the internet, maintaining connection quality. At the same time:

• 📞 The subscriber number remains the same (call from your mobile phone, not through a messenger account).
• 🌐 The call is made via WiFi, but is charged as a regular mobile call (if the operator supports the technology).
• 🔄 When leaving the WiFi zone, the call smoothly switches to the cellular network (if available).
• 📶 No need to install additional apps - everything works at the firmware level MIUI.

It is important to understand that Vo WiFi ≠ VoIPThe latter term refers to any calls made via the Internet (for example, via Skype or Zoom), while Vo WiFi is a specific standard integrated into mobile networks. Redmi Note 9 The technology is supported out of the box, but its operation depends on three factors:

1. Hardware support by smartphone (available in all models) Redmi Note 9/9S/9 Pro).
2. Technology support IMS And VoLTE your mobile operator.
3. Firmware settings MIUI (sometimes the function is hidden in the engineering menu).

Differences between VoLTE, VoLTE, and regular calls

Many people are confused Vo WiFi With VoLTE (voice over 4G), although these are two different technologies with a common purpose—improving connection quality. Let's look at the key differences with an example. Redmi Note 9:

The main advantage Vo WiFi before VoLTE — the ability to make calls in places where there's no cell service but Wi-Fi is available. For example, in the subway, underground parking garages, or country houses with poor coverage. Moreover:

• ✅ Advantages of Vo WiFi: Stability in weak signal areas, battery saving, free calls when connected to home WiFi (if your operator doesn't charge for traffic).
• ❌ Cons: Dependence on the quality of the WiFi network, possible delays when switching between WiFi and the cellular network, not all operators support the technology.

On Redmi Note 9 both technologies (Vo WiFi And VoLTE) can work simultaneously. For example, if you start a call over WiFi and then go outside where 4G is available, the phone will automatically switch to VoLTE without losing connection. This is called SRVCC (Single Radio Voice Call Continuity) is another useful standard supported by modern smartphones. Xiaomi.

How to enable VoIP WiFi on Redmi Note 9: step-by-step instructions

Activation Vo WiFi on Redmi Note 9 It takes no more than a minute, but the path to the settings may differ depending on the version MIUIHere are the universal instructions for firmware MIUI 12–14:

1. Open the app "Settings"** (gear icon on the desktop).
2. Go to the section SIM cards and mobile networks.
3. Select your SIM card (if you have two).
4. Tap on the item "WiFi Call"** (or Vo WiFi).
5. Activate the switch to the position "On".
6. Confirm enabling if prompted (sometimes a reboot is required).

• 🔄 Your mobile operator does not support Vo WiFi (check the list below).
• 📱 You have an outdated version MIUI (update firmware via Settings → About phone → System update).
• 🔧 The function is hidden in the engineering menu (we recommend not to access it without experience).

Once enabled, an icon will appear next to the network indicator in the status bar. «Vo WiFi» or «WiFi Call» (Depends on firmware). To check the function, make a test call after disabling mobile data. If the connection is stable, everything is configured correctly.