Modern Xiaomi smartphones offer a wide range of opportunities to improve the quality of voice communication, and one of the key features is VoLTE technology (Voice over). LTE). Many users are faced with a situation where after buying a new device or changing the device. SIM-card HD in the status bar does not appear, and during the conversation the phone is forced to switch to the standard 3G or 2G. This is not only annoying, but it also significantly reduces the sound quality, making the voice of the interlocutor deaf and intermittent. In this article, we will discuss in detail why this happens and how to force the function to activate at the software level.
The problem often lies not in the lack of support from the operator, but in the hidden firmware settings. MIUI Chinese versions of smartphones, which are popular for their price, often have a stripped-down list of supported carriers or a completely hidden engineering interface. USSD-code-in ADB-Understanding the network architecture and modem principles will help you avoid errors and properly configure the device to work in modern fourth-generation networks.
Before you start complex manipulations, you need to make sure that your device is physically capable of supporting this technology. Most models, starting with the Xiaomi Redmi Note 8 and later, have the necessary communication modules. However, software locking can hide this ability from the user. We will look at both standard on-board methods and advanced methods through the engineer's hidden menu, which work even in cases where the operator is not on the official list of compatible.
What is VoLTE and why is it necessary?
Voice over LTE allows voice calls to be transmitted directly over a 4G network, bypassing the need to switch to older communication standards. In the past, when you dialed a number, the phone reset its LTE connection and went into 3G mode, which took time and reduced quality. Now voice is transmitted as a data stream, providing crystal clear sound and instantaneous connection. This is especially important for gamers who play online games while talking, since the connection to the Internet is not interrupted.
In addition to sound quality, using HD Voice saves battery life. Modems don’t have to constantly switch between different frequencies and communication standards, which reduces the load on the processor and radio module. In addition, simultaneous voice and data allow you to use a navigator or messengers without delay during a conversation. For tariff owners with a large amount of traffic, this also means that minutes of conversation can be charged as Internet traffic, although most Russian operators have not yet implemented this massively.
It is important to understand that for the function to work, three conditions must be met: operator support, appropriate support for the function. SIM-map and the ability to customize the smartphone itself. If one of these elements is missing, the icon HD Operators are constantly updating their profiles, so even if the phone didn't work with VoLTE a year ago, after updating the firmware or changing the region, the situation may change.
⚠️ Warning: Enabling VoLTE on some custom firmware or modified devices may cause network instability or signal loss.Before making changes to system settings, make sure you understand the consequences of your actions.
Users often confuse VoLTE with LTE video calls (ViLTE). These are different technologies: the first improves sound quality, the second allows you to transmit video in high resolution without using instant messenger applications. Setting the first option usually does not affect the second, although both are based on the same network infrastructure. If your operator does not support video calls over the network, the video phone icon in the call may not appear, even if the voice HD will work correctly.
Checking the compatibility of the operator and SIM-map
The first step before trying to activate hidden functions should be to check the tariff plan and type. SIM-Older cards issued by more 5-7 years ago, you may not have the necessary profile to work in the network 4G Telecom operators such as MTS, MegaFon, Beeline and Tele2, long ago implemented support technology, but often require manual activation of services in the personal account or through the USSD-request.
You also need to make sure that your region has strong LTE coverage. In unstable reception areas, the phone will constantly try to hold the signal by switching to 3G, which will make VoLTE impossible to work. Check the access point settings (APN), as incorrect Internet settings can block the transmission of voice traffic over LTE. Sometimes it helps to simply create a new access point with factory parameters that can be found on the operator's website.
You can use special codes or carrier applications to verify the status of the service, for example, for some providers, activation occurs automatically when the first call is made from a device that supports the technology, but this does not always work. If you changed your phone and the icon didn’t appear, you may have a network profile on your phone. SIM-The card is outdated and requires updating through the service center or replacing the card with a new one with support USIM.
Below is a table with activation codes for the main operators that are worth trying before climbing the engineering menu:
| Operator. | Activation code. | Status verification code | Commentary |
|---|---|---|---|
| MTS | *111*1771# | *111*177# | Volte service |
| MegaFon | *155*0055# | *155*00# | 4G phone required |
| Beeline | *110*1861# | *110*186# | Activation is free. |
| Tele2 | *155*612# | *155*61# | Works in Moscow and SPb |
If the HD icon does not appear after entering the codes and restarting the phone, we move to the settings of the smartphone itself. In some cases, the operator can block the service at the network level if the IMEI of the device is not listed in the supported database, which often happens with devices imported on gray schemes or Chinese versions.
Standard activation via the settings menu
In global versions of firmware MIUI The path to enable the function is usually standard and does not require additional manipulation. You need to go to the Settings section, select the item. SIM-So here, if you select the SIM card you want, you should see the Use VoLTE switch. If this is the option, but it's inactive (gray), then the phone doesn't see any support from the outside. SIM-card or operator, and you need to go back to the previous step.
In the newer versions of the HyperOS shell, the logic may have changed. Sometimes the switch is hidden inside the Preferred Network Type menu. Try selecting Preferred LTE or 5G/LTE/3G/2G (auto) mode. Then an additional switch may appear under the list. It's also worth checking whether flight mode or power saving are on, which can block the operation of additional communication modules to save charge.
☑️ Checklist of standard activation
If the switch is not completely off, it means that the firmware does not contain a configuration file for your region or operator, in which case the standard methods will not work, users of global versions sometimes decide to change the region in the phone settings to the country where the operator officially cooperates with Xiaomi (for example, India or Indonesia), but this method works unstable and can disrupt the work of other services.
⚠️ Warning: Changing your phone’s settings may lead to ads in system applications and changes to the list of preinstalled programs.
Use of the Engineering Menu to Activate
The most effective way for advanced users to log in to the engineering menu, which is a hidden part of the system, designed for testing equipment by plant engineers, where you can force VoLTE support on any operator. The modem settings menu often uses the code ##4636##. If the code doesn’t work, you may have a call blocker or a specific version of dialer on your device that intercepts the device. USSD-request.
Once in the Testing menu, select Phone information. Scroll down to Set Preferred Network Type. Here you need to select an option that contains the IMS or VoLTE marking, for example, LTE/TD-SCDMA/WCDMA/GSM (IMS). After selecting this item, an HD icon should appear in the status bar. If the icon is not present, try making several test calls or turning on and off flight mode.
In some cases, especially on Chinese firmware, activation is required through a special Carrier menu. To do this, in the same engineering menu (4636), you need to find the tab associated with the SIM card and enable the option VoLTE Provisioned. SIM-The card is ready to work in high quality, ignoring the operator’s check.
Alternative codes and login methods can vary depending on the Android version and the processor model (Snapdragon or MediaTek). For MediaTek processors, code ##3646633## sometimes works, which opens the full engineering menu with the Hardware Testing and Telephony tabs.
If the settings fly off after the reboot, you will need to repeat the procedure or use deeper methods of modifying the system, such as obtaining root rights, which is not recommended for ordinary users for security reasons.
Activation through ADB-team
If the phone menu is blocked or does not give the necessary options, you can use debugging on the phone. USB. This method requires a computer and a driver installed. ADB. You need to turn on the developer mode on the phone (click seven times on the build number in About Phone), then activate Debugging by USB. Connecting your phone to your PC, open the command line and enter the command to check the status: adb shell settings get global. volte_feature_disabled.
If the team returns 1, It means that the function is forced to shut down by the system. To enable it, use the command: adb shell settings put global. volte_feature_disabled 0. Once the command is complete, you need to restart the smartphone, which works at the level of global Android settings and is often more effective than manipulating the interface.
adb shell settings put global carrier_volte_available 1
adb shell settings put global carrier_vt_available 1You can also try to prescribe commands to force carrier availability, enter the two commands above in sequence, tell the system that the operator supports VoLTE and video calls, even if they are not in the database, and after doing this, the phone may require re-registration on the network.
Using ADB gives you more control, but it requires care. One typo in a command can lead to unexpected behavior of the system, so copy the commands accurately.
Solving Frequent Problems and Errors
Users often complain that the icon HD It appears, but during a conversation the phone still falls into the 3G. This may indicate that the operator base station in your area does not support voice transmission through the network. LTE It's a low-loading problem, and it could be a problem with the wrong work. IMS-In this case, cleaning the application cache helps. IMS Service or reset network settings to factory.
Another common mistake is the conflict between the two. SIM-If both cards are set to 4G, The phone may not be able to handle both voice and data simultaneously on both slots. Try to turn off the second SIM card temporarily and check VoLTE on the main one. If the problem disappears, then the device modem does not support Dual mode. 4G VoLTE and one of the cards will have to be transferred to mode 3G/2G call-only.
- 📶 Weak signal: VoLTE requires a stable signal LTE. If the signal level is lower -110 dBm, the phone can be forced to switch to 3G linkage.
- 📱 Firmware Version: Make sure you have the current version installed MIUI. Old builds could have bugs that were fixed in security updates.
- 🔋 Energy saving: Aggressive battery settings can turn off VoLTE background processes.Add phone to exceptions or select performance mode.
If nothing works, it’s possible that your device is simply not certified to work with VoLTE on your carrier’s networks, and this is common with devices purchased on AliExpress labeled Global Version (but not Global ROM), in which case only flashing from the official website to the global version or changing the carrier to a more loyal to “grey” devices helps.
Understanding this principle allows you not to waste time on useless actions, but immediately look for a way to replace the region or firmware.