Modern Xiaomi smartphones offer many features that are often hidden from the eyes of the average user. One such feature is VoWiFi technology, which allows you to make voice calls over a wireless network, bypassing a traditional cellular operator. This solution is especially relevant for residents of apartment buildings, office centers or country areas where the signal level of cellular communication is poor, but there is stable Internet access.
Activating this option can dramatically change the quality of communication. You no longer have to run out on the balcony or raise your phone to the window to hear someone. Internet calls provide clean sound and stable connection if the router is running correctly. However, the process of enabling this feature on Redmi and Poco devices may vary depending on the firmware and region of use.
In this article, we will discuss all the details of the configuration. We will discuss the activation methods for different versions of the MIUI and HyperOS shell, and also discuss issues related to charging from operators. VoWiFi is only available with the support of your mobile operator and the availability of the corresponding service in the tariff plan. Not all cellular providers automatically provide this access, so it is important to check the terms of your contract before setting up.
What is VoWiFi Technology and How Does It Work?
VoWiFi (Voice over Wi-Fi) is a voice-over-IP protocol, similar to the way that data is transmitted when you browse a website. Unlike regular messaging apps like Telegram or WhatsApp, it uses the standard phone book interface, you dial the phone book in the usual way, and the system itself redirects the call over the wireless network if the cell tower signal is weak or absent.
The main advantage is that the process is transparent to the user. You don't have to convince the person to install an additional application or search for it in the messenger's contact list. The sound quality when using HD Voice over Wi-Fi often exceeds the quality of conventional cellular communication, since the channel has a higher bandwidth. Xiaomi smartphones can automatically switch between Wi-Fi and LTE/3G during a conversation without breaking the connection if you leave the coverage area of the router.
It’s important to understand the difference between VoWiFi and VoLTE. If VoLTE uses a fourth-generation (4G) network to transmit voice, VoWiFi relies solely on a Wi-Fi hotspot, making it indispensable in basements, thick-walled buildings, or remote areas where cell towers simply don’t finish but have fiber optic internet.
- 📶 High quality sound due to a wide data channel.
- 🏠 The ideal solution for rooms with poor cellular network coverage.
- 🔄 Seamless switching between Wi-Fi and mobile network during a conversation.
- 💰 Savings in minutes of the tariff plan (depending on the operator’s conditions).
⚠️ Note: When using VoWiFi abroad, there are special roaming rules, check with the operator whether calls over Wi-Fi will be charged as international, even if you are on a home network.
Verification of device and operator compatibility
Before you start looking for a coveted switch in your settings, you need to make sure that your hardware and SIM card support this technology. Not all Xiaomi models, especially those released a few years ago, have hardware support for the necessary encryption protocols.
Operators also play a key role. Even if the phone has all the settings, without network-side support, the feature will not work. Large providers are gradually implementing this option, but often it is only available for subscribers with certain rates or for new SIM cards. You may need to replace the old SIM card with a new one with USIM-enabled applications.
The best way to check compatibility is to start with your carrier’s official website, which usually publishes lists of supported devices. If your Redmi Note or Xiaomi Mi model is not on the list, it doesn’t always mean that the feature won’t work, but the likelihood of successful activation decreases.
There is also a nuance with regional firmware versions. Global versions (Global) often have a wider list of supported carriers compared to Chinese versions (China ROM) that are flashed into the global language. If you own the Chinese version of a smartphone, you may need to additional customize via an engineering menu or change region.
Standard activation through smartphone settings
Most modern Xiaomi models with the current version of MIUI or HyperOS feature is enabled by standard means. the path to setup may vary slightly depending on the version of the shell, but the logic remains the same. Usually the switch is in the SIM menu or in advanced call settings.
To start, open the standard Phone app or go to the general settings of the device. Find the partition responsible for connection and networking. If you have a dual-sim device, the settings can be applied individually to each SIM card. This is important to consider if you plan to use VoWiFi only on one of them, for example, on the one where the network catches worse.
☑️ Checklist before inclusion
The sequence of actions is as follows:
- Go to the smartphone settings.
- Select a point. SIM-maps and mobile networks.
- Click on the name of the desired operator.
- Find the Wi-Fi Calling or Wi-Fi Calling switch.
- Activate the slider and confirm the action if necessary.
If you activate a status bar next to the Wi-Fi signal level with a wireless phone icon or a Wi-Fi sign, it's a success. Now, when calling in or out, the phone will prioritize using a wireless connection. Some versions of the menu firmware may call you Additional settings inside the SIM card menu.
⚠️ Warning: If the status bar icon doesn't appear after the function is turned on, try restarting the device. Sometimes the system takes time to log into the operator's network through the new protocol.
Use of the Engineering Menu to Activate
In situations where the standard switch is missing or inactive, users often resort to using the engineering menu, a hidden part of the system designed for testing equipment by developers, accessed on Xiaomi through a special code in the Phone application.
Dial the combination ##869434## or ##86583#. Depending on the model and version of the software, one of the codes should run the hidden menu. In the list that opens, find the item associated with VoWiFi Carrier Check. If there is a tick or switch is active, try turning it off or re-enable it. Sometimes you need to uncheck the operator checkpoint to unlock manual control.
Codes for entering the engineering menu:
#869434## - VoWiFi status check
#86583## - Operator Check Switch
#4636## - Testing menu (Phone Information section)Another way is to use the testing menu with code ##4636##. Go to Phone Information. scroll down for Turn off VoWiFi provision or similar. Manipulations here require caution. Incorrect settings of the radio module can lead to temporary network loss.
What do I do if the codes don't work?
Once you make changes to the engineering menu, be sure to restart your smartphone. Often, after a reboot, a previously hidden VoWiFi switch appears in the standard settings menu. If the switch appears but does not work, your operator may be blocking this feature at the network level for devices without official certification.
Setup for different regions and firmware
Xiaomi’s policy is to adapt the software to local carriers, so the list of supported carriers on global firmware may be wider than on Chinese ones, or vice versa. If you purchased a device designed for the Chinese market and use it with a European or Russian carrier, the feature may be hidden.
Changing your region in your smartphone settings sometimes helps unlock the option. Go to Settings → Additional → Region and select a country where VoWiFi is widely available and supported by your carrier (such as India, Singapore or European countries).
For custom firmware or unlocked bootloaders, there are deeper interventions (carrier_config) This allows you to add any operator to the list of supported, but it requires root rights and knowledge of the Android file system, which is not recommended for ordinary users because of the risk of losing the warranty and the stability.>
| Type of firmware | Probability of work | Action required | Risks. |
|---|---|---|---|
| Global (Global) | Tall. | Standard Including in Settings | Minimum |
| China (Chinese) | Medium | Change of region, engineering menu | Absence of some (frequency) |
| EU (European) | Tall. | Standard incorporation | Minimum |
| Custom (Castom) | Depends on the picker. | Config editing, root | High (instability) |
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Changing the region to India or Singapore will often unlock hidden connectivity features on Xiaomi’s global firmware, as VoWiFi has been very active in these countries.
Comparison of VoWiFi and calls via messengers
Many people ask themselves, why do you need VoWiFi when you have WhatsApp, Viber or Telegram? The answer lies in versatility and reliability. Messengers require that the person you are talking to also have an app installed, the Internet and it is online. VoWiFi allows you to call any number, including city and mobile, regardless of what phone the person has or whether he has Internet.
In addition, carriers often charge minutes of conversation over VoWiFi according to your main tariff. If you have unlimited minutes, then calls over Wi-Fi will be free (within the home network), while in roaming, Wi-Fi calls can be significantly cheaper than those coming through the cellular network, since technically you are on the operator’s home network, even if you are physically in another country.
- 📞 Availability: Calls to any number, not just users of the app.
- 💸 Tariffing: Minutes are subtracted from the operator’s packet, not from messenger traffic.
- 🔋 Energy efficiency: Lower battery consumption compared to constant background messengers.
- 📶 Priority: Automatic network switching without a call reset.
However, instant messengers are winning in video and multimedia communication during conversation. VoWiFi is focused primarily on high-quality voice communication. For business negotiations or emergency calls, where reliability and the ability to dial an emergency number are important (if the operator supports E911/112 via Wi-Fi), the technology from Xiaomi and operators is a more professional solution.
Problem Solving and Troubleshooting
Despite the technology, users may encounter difficulties. The most common problem is that the VoWiFi icon appears, but calls fail or are reset. This may indicate a router problem. Make sure your router does not block the ports needed to access the router. SIP-protocols and that the function is included NAT.
Another common situation: the feature worked, but after updating the firmware MIUI disappeared. Security updates can reset the carrier config settings. In this case, re-activation through the engineering menu or resetting network settings helps. Remember that resetting the network will delete the saved Wi-Fi passwords, so it is better to write them down in advance.
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If VoWiFi is unstable, try dividing the 2.4 GHz and 5 GHz frequencies in your router settings, giving them different names. Connect your phone to a 5 GHz network for less call delay.
It is also worth checking the date and time settings. Time mismatch on the smartphone and on the network can lead to authorization errors in the operator's network, which blocks the ability to make calls over Wi-Fi. Set up automatic time synchronization over the network.
⚠️ Note: When using two SIM cards, activating VoWiFi on one of them may temporarily turn off the second SIM card if the phone does not support Dual mode. SIM Dual Standby (DSDS) You can also use VoWiFi at the same time, and you can keep track of the second SIM while you're talking.