Modern mobile standards dictate their terms, and the presence of a VoLTE icon in the status bar of a smartphone becomes a sign of a quality connection. Owners of flagship devices such as the Xiaomi Mi 9 often face a situation where the voice call function over 4G is not activated automatically, this can be due to firmware features, operator settings or hidden system parameters.
Activating this technology allows you to talk on the phone and use high-speed Internet simultaneously without switching to 3G or 2G. The sound quality when using HD Voice is much higher, and the connection is established almost instantly. In this article, we will discuss in detail all ways to enable the function, including hidden menus and system codes.
Before you start complex manipulations, you should make sure that your SIM-The map and the data plan support voice transmission in fourth-generation networks, sometimes the problem is not the phone, but the lack of service from the mobile provider.
Checking operator support and basic settings
The first thing to do is make sure your mobile operator is providing VoLTE services in your region of residence. Even if the Xiaomi Mi 9 is technically ready to go, without network support, the feature will remain inactive. Most major operators have already implemented this technology, but it may require a connection through the Internet. USSD-team-room.
Go to the standard settings menu of your device. You need to find the section responsible for work. SIM-maps and mobile network. Shell interface MIUI It may differ depending on the Android version, but the logic remains the same.
Make sure you select 4G/LTE mode as your preferred mode in your settings. If the phone is forced to switch to 3G during a call, then VoLTE is not working. Also check if flight mode or power saving is on, which may limit modem functions.
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Before changing the network settings, it is recommended to restart the device after installation SIM-card so that the phone correctly reads the operator profile.
In some cases, manual re-registration helps, so you can temporarily turn on the flight mode for 10-15 seconds, and then turn it off, which will force the communication module to re-enter the operator's network and update the available services.
Activation through the standard MIUI menu
In most cases, if the operator supports the technology, the switch appears automatically. However, on global versions of Xiaomi firmware, this item is sometimes hidden by default. SIM-map.
Go to the Settings section, then select SIM-Maps and mobile networks. Choose active networks. SIM-The map you want to enable the function for. In the list that opens, look for Use VoLTE or Network Calls. LTE.
If the switch is present, just activate it. Then the status bar next to the signal level should show the corresponding inscription or icon. If there is no item, this means that the system has not determined support by the operator or activation through the engineering menu is required.
It's worth noting that on dual-symbol devices, the setting is customized for each card, so you can only use VoLTE on one SIM while the second one is running normally, which is useful if only one of the carriers is providing service in your area.
Use of the Engineering Menu to Activate
If the standard path fails, you'll have to use a hidden engineering menu, which is a powerful tool to diagnose and adjust hidden modem parameters, and be careful when you change values, because incorrect settings can disrupt communication.
Open the Phone app and enter a special code ##4636##. If the code is entered correctly, the testing menu will open. Select Phone Information. This displays detailed network status and signal information.
In the settings list, find the VoLTE Provisioned or Turn on VoLTE switch. Activate it. Once the icon is turned on, you may not see it instantly — try making a test call or restarting the device.
☑️ Check before entering the engineering menu
In some versions of MIUI, access to this menu may be restricted, and if the code is not working or the menu is empty, you may need superuser rights or use third-party applications to open hidden system activities.
Change of region and type of firmware
Often, the lack of VoLTE on the Xiaomi Mi 9 is due to the region selected in the system settings. Some operators only work with certain regional configurations.
Go to Settings → Additional → Region. Try to choose a country where your operator officially operates, such as Russia, Ukraine or Kazakhstan. After changing region, the phone may need to restart.
Global Stable versions usually have stricter restrictions than Chinese ROMs or Indian ones, and Chinese firmware often has more functionality, but may not have Russian or Google services out of the box.
Risks of flashing the device
If you use custom firmware, make sure that the modem configuration files work correctly, and sometimes enthusiasts delete files they think are unnecessary, which leads to the loss of VoLTE functionality.
Comparison of network modes
Understanding the difference between network modes will help you better control your smartphone behavior, and here is a table showing the differences between standard calls and VoLTE.
| Parameter | Regular Call (CSFB) | VoLTE (HD Voice) |
|---|---|---|
| Connection speed | 2-5 seconds | Instantly (< 1 sec) |
| Sound quality | Standard (narrowband) | High (broadband) |
| Internet access | Network drops to 3G/2G | It runs on 4G/LTE. |
| Battery consumption | Above (module switching) | Below (stable mode) |
As you can see from the table, the benefits of the technology are clear, especially in areas of insecure reception, where the phone is constantly "jumping" between communication standards, and a stable 4G signal allows for clearer voice transmission.
However, it is worth remembering that VoLTE consumes traffic. Although operators often do not charge minutes of conversation as Internet traffic, technically, data is transmitted through IP packets.
Possible problems and solutions
Even after all the instructions are done, there may be nuances, such as a VoLTE icon, but calls are disrupted or the voice of the interlocutor is interrupted, which may indicate a coverage problem or an overload of the operator's tower.
In some cases, resetting network settings helps. Go to Settings → Connection and Sharing → Reset Wi-Fi, mobile networks and Bluetooth. This action will delete stored Wi-Fi passwords, but update network configurations.
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Resetting your network settings is a secure procedure that does not delete your personal data (photos, contacts), but requires re-entering passwords from Wi-Fi.
If nothing helps, maybe your Xiaomi Mi 9 has hardware limitations for the frequencies of a specific operator in your region.Check the model specifications and compare them to the frequencies used by your provider.