Owners of modern smartphones, in particular the popular Xiaomi Redmi 9T, often notice the appearance of a new icon at the top of the screen next to the signal level indicator. This symbol, usually consisting of the letters VoLTE, can cause confusion among users who have not previously encountered this acronym. The appearance of the icon indicates that the device has moved to voice mode over the fourth generation network, which radically changes the quality of communication.
Voice over LTE technology allows voice calls to be transmitted over high-speed 4G networks, bypassing switching to outdated 2G and 3G standards. For a Redmi 9T owner, this means not just a beautiful picture in the status bar, but a real improvement in the quality of communication, faster connection with the interlocutor and the ability to use the Internet and conversation simultaneously. Understanding this feature will help you maximize the use of your gadget.
In this article, we will discuss in detail what this icon means, why it may not appear even with operator support, and how to properly configure the smartphone. We will look at the technical details of the communication module in the MIUI shell, and provide step-by-step instructions for activating the function for various use cases.
The Technology Essence of VoLTE and Its Advantages
VoLTE stands for Voice over LTE, which literally translates as Voice over LTE. Traditionally, 4G networks were designed solely for data, and voice calls were made over second and third generation networks. When you started calling on a regular smartphone without the support of modern standards, the phone was forced to switch to 3G or 2G mode, which took time and reduced the sound quality.
With the introduction of technology IMS (IP Multimedia Subsystem: The ability to pack voice into IP-packets and transmit it through the channel LTE. On the screen Xiaomi Redmi 9T This is displayed by an appropriate icon, and the main advantage is that there is no delay in connection: the call is set almost instantly, as opposed to a few seconds of waiting when switching between generations of networks.
And voice is HD Voice, which provides crystal clear sound without the typical noise and distortion of analog communication. You can talk and use high-speed Internet at the same time, which is not possible in 3G networks where the communication channel is occupied by voice traffic, this is especially true for navigation while talking or sending files in messengers.
- 🚀 Instant connection with the subscriber without long waiting horns.
- 🎧 High quality sound HD Voice with extended frequency range.
- 🌐 Simultaneous work 4G Internet and voice calls without switching modes.
- 🔋 Reduced power consumption of the communication module due to the absence of constant switching between 2G/3G/4G.
⚠️ Attention: VoLTE communication quality depends on your carrier's network coverage. 4G, The phone can automatically switch to 3G, And the VoLTE icon will disappear.
It is important to note that the function requires support not only from the smartphone, but also from the operator, as well as the availability of the corresponding service in your tariff plan. Xiaomi Redmi 9T fully supports this standard, but the software may hide the possibility of inclusion depending on the region of the firmware.
Why VoLTE icon may not be available on Redmi 9T
Many users are faced with a situation where the operator claims to support the technology, the SIM card is replaced with a new one, and the cherished icon never appears in the status bar. First of all, this may be due to the regional limitations of the MIUI software. In global firmware versions, the VoLTE activation menu is often hidden, since Xiaomi relies on automatic settings by the operator.
The second common reason is the lack of activated service on the mobile operator side, even if your tariff formally supports the service. 4G, Service "Voice calls on the LTE» may be disabled by default or require a separate connection via a personal account or USSD-Without confirmation from the base station, the smartphone will not display the icon.
It is also worth checking the physical condition. SIM-Old cards that were used in the era. 2G/3G, You may not have the necessary profiles to work on fourth-generation networks with support IMS. In this case, the replacement of the SIM card in the cabin of the operator is a prerequisite for the appearance of the VoLTE icon on the Redmi screen. 9T.
- 📱 Hidden settings menu in the global version of firmware MIUI.
- 📡 Non-activated VoLTE service on the mobile operator side.
- 💿 Outdated. SIM-map without profile support USIM.
- 📍 Staying in the area of coverage only 2G or 3G network.
Sometimes the problem is that you don't configure the access point or network preferences correctly, and if you force the "Only" mode on the network type selection menu. 3G» or «2G/3G», activation LTE So VoLTE will become technically impossible, so you need to make sure that you prioritize your settings. 4G.
Instructions for enabling VoLTE through the standard menu
The first and easiest way to activate is to check the standard settings interface. MIUI The switch is available to the user without the need for an engineering menu or third-party applications. First, you need to open the main settings of your Xiaomi Redmi. 9T.
Go to the Connection and Networks section. The path may vary slightly depending on the shell version, but it's usually in the Settings menu. → SIM-Select the SIM card you want to activate if you have two cards on your phone. Find the option called "Use VoLTE" or "Calls on the phone." LTE».
☑️ Checking network settings
If you find a switch, just activate it. Once you turn on the status bar, it should appear that the label is not there, which means that the manufacturer has hidden it for your region, and you will need to use alternative activation methods, which will be discussed below.
⚠️ Warning: Once the function is enabled, it may be necessary to restart the device or briefly break the connection to register with the network IMS operator.
In some cases, when the switch is turned on, the icon does not appear immediately. Try turning on and off "Flight Mode" or rebooting your smartphone, which will force the communication module to re-register on the network and request an up-to-date list of available services at the base station.
Activation through engineering menu and hidden codes
If the standard path failed, you can use the Android engineering menu, which is hidden from the average user. On Xiaomi smartphones, access to it is often through special codes in the Phone app. However, starting with newer versions of Android, direct access to the engineering menu through the code # #4636## can be blocked or redirected to the standard test menu.
For Redmi. 9T The code ##86583## is current. Entering this combination in the dialer number should cause a pop-up notification “VoLTE Carrier check was disabled” or “enabled.” This does not include the function itself, but removes the software lock of the operator check, then in the standard settings menu (Settings). → SIM-Maps and mobile networks may appear previously hidden switch.
##86583##Another useful diagnostic code is ##4636##. If it runs on your version of the software, select Phone Information. There may be a "VoLTE provisioned flag" option, which is forced to tell the network that the device is ready to work with voice over LTE. However, this method is not guaranteed to work on all MIUI builds due to Google's security limitations.
- 🔢 Code #86583## removes operator check lock.
- 🔢 Code #4636## opens the test menu (if not blocked).
- ⚙️ Search for the flag “VoLTE provisioned” in the testing menu.
- 🔄 Reboot after making changes to hidden settings.
What do I do if the codes don't work?
Be careful when changing the settings in the engineering menu, carelessly changing the parameters of the radio module can cause the phone to stop seeing the network at all, in which case a reset of the network settings or a complete reset of the device will help.
Comparison of voice technologies in Xiaomi networks
To better understand the value of VoLTE, it’s useful to compare it to other technologies that Xiaomi Redmi 9T uses for voice communications, with its main competitors being CSFB (Circuit Switched Fallback) and VoWiFi (Voice over Wi-Fi), each with its own features and use cases.
CSFB is a mechanism where a phone rolls back from a 4G network to 2G or 3G when it is called in or out. This leads to a delay in the connection and the inability to use fast Internet during a conversation. VoLTE eliminates this disadvantage by leaving the device on an LTE network. VoWiFi, in turn, allows you to call over Wi-Fi, which is ideal for rooms with a poor cellular signal, but requires a wireless network.
| Characteristics | VoLTE (4G) | CSFB (3G/2G) | VoWiFi |
|---|---|---|---|
| Sound quality | HD (High) | SD (Standard) | HD (depending on the Internet) |
| Connection speed | 1-2 seconds | 3-5 seconds | 2-4 seconds |
| Internet during a call | It's running on 4G. | Falls to 2G/3G | It works over Wi-Fi. |
| Battery consumption | Low. | High (switching) | Medium. |
For a Redmi 9T owner, the optimal scenario is a combination of VoLTE and VoWiFi. If the operator supports both technologies, the phone will prioritize using VoLTE in the tower coverage area, providing mobility, and automatically switching to VoWiFi in buildings with poor signal but good Wi-Fi.
💡
For maximum battery savings in areas of weak 4G signal, it is better to temporarily turn off VoLTE so that the phone does not constantly try to hold an unstable LTE connection, consuming battery life.
Solving problems and troubleshooting
Even when set up correctly, there can be situations where the VoLTE icon disappears or the connection is unstable. SIM-If both cards are set to work in the 4G, The phone modem has only one radio channel. LTE (As is typical for many budget and medium-sized models, the second card will work in the mode of the system. 2G/3G. In this case, the VoLTE icon can only be displayed for one active SIM card.
Also worth checking for system updates. Xiaomi regularly releases security patches and improvements for modems. Go to Settings → About Phone → MIUI version and check for updates. Sometimes the problem is solved by simply resetting the network settings. To do this, go to Settings → Connection and Sharing → Reset Wi-Fi, mobile networks and Bluetooth.
⚠️ Note: Resetting network settings will remove stored Wi-Fi passwords and Bluetooth pairs, so make sure to remember the data to connect to important networks.
If nothing works, your carrier may not have certified this phone model to work with VoLTE in your area. APN (access points) to the operator's standard values or to contact technical support with a request to update the service profile on the SIM-map.
- 🔄 Check for firmware updates MIUI.
- 🗑️ Resetting network settings to factory parameters.
- 📝 Checking the correctness of filling the fields APN.
- 📞 Contacting the operator to check the profile SIM-map.
💡
If the VoLTE icon is missing after the firmware update, it is likely that the device certificates in the system have changed. Try re-entering the activation code or temporarily changing the region of the phone in the settings.