Modern Xiaomi smartphones offer users a wide range of features that make communication more comfortable, and one of the key technologies is VoLTE. Many device owners notice the icon "HD" or "VoLTE" in the status bar, but not everyone understands what exactly lies behind this acronym and why it is needed in the daily operation of the gadget. In fact, it is a voice data standard that allows you to make calls directly through fourth-generation networks, providing a crystal clear sound.
Unlike traditional voice calls, which often reset or slow down to 3G when switching to mobile, the new technology works differently: It uses LTE packet data for voice, which frees up frequencies and allows you to talk and use high-speed Internet simultaneously without delay. For owners of Xiaomi Redmi or Mi, this means being able to watch high-quality videos during an important conversation without losing a second of communication.
The introduction of this feature has become the standard for operators of the “big four”, but on the side of the smartphone sometimes requires manual activation or proper setting of the SIM card. Owners of Chinese versions of firmware or users who change operators may face the lack of the desired icon or the inability to make calls in the area of poor 3G coverage. Understanding the principles of Voice over LTE will help to eliminate these problems and significantly improve the quality of communication.
Technological features and principle of operation
Voice over technology LTE This is a voice traffic transmission in the form of IP-packet-wise LTE, And that technically turns voice calls into messenger calls, but with priority in the operator's network. 2G and 3G, Voice was transmitted over dedicated switching channels, which limited bandwidth and sound quality, and the switch to batch transmission allowed to increase the audio bitrate to 23.85 kbit / s against the standard 12.2 kbit / s in third-generation networks.
The key difference is the use of the AMR-WB (Adaptive Multi-Rate Wideband) codec, which is often labeled as HD Voice. This codec captures the wider frequency range of the human voice, cutting off unnecessary noise and making speech more natural and legible. Xiaomi smartphones equipped with modern Qualcomm or MediaTek modems, hardware support this technology, but its implementation depends on the software and network configuration.
⚠️ Note: VoLTE consumes packet data traffic, but most operators do not charge these megabytes separately if you have a standard tariff with voice minutes.
It's important to note that the technology requires support not only from the phone, but also from the carrier base station, if you're in an area where the coverage is. 4G Unstable, the device can automatically switch to 3G, And the sound quality will become normal, and the critical condition is that the operator has support. IMS (IP Multimedia Subsystem, without which voice transmission is LTE technically impossible.
The main advantages of using HD-calls
The switch to VoLTE gives Xiaomi users a number of tangible benefits that are noticeable in the first minutes of use, primarily the quality of audio communication: the interlocutor can be heard as if he is in the same room, even if there is a noisy street or wind around, the voice becomes voluminous, disappears metallic shades and distortions characteristic of old networks.
The second major advantage is the ability to use voice and data simultaneously. In older networks, when an incoming call was made, the phone reset the 4G connection to 3G, which interrupted file downloads or navigation. With the new technology, the Internet remains at maximum LTE speeds, allowing you to send heavy files in messengers or watch online transactions in parallel with the conversation.
The third aspect is the speed of connection, which reduces the time between the call button and the beeps of the interlocutor to 1-2 seconds, whereas in 3G this process could take up to 7 seconds, which is especially important in emergency situations or if you need to quickly contact a person.
- 📶 High connection speed: Instant dialing and connection to the subscriber.
- 🗣️ Broadband sound: Support for frequencies up to 7000 Hz vs 3400 Hz on conventional networks.
- 🌐 Simultaneous work: Internet 4G Does not fall during conversation.
- 🔋 Energy efficiency: Lower power consumption by a modem when transferring data in a single standard.
💡
For maximum energy saving, make sure that the “Preferred to be 4G/LTE” mode is selected in the mobile network settings, so that the phone does not waste resources on constantly searching for old 2G networks.
Checking the compatibility of the operator and the tariff
Before looking for settings in the smartphone menu, you need to make sure that your mobile operator supports Voice over LTE technology in your region. In Russia, all major operators (MTS, Beeline, MegaFon, Tele2) have long implemented this feature, but it may not be available in some remote areas or on old tariff plans. Often, activation requires replacing the SIM card with a USIM version if your card was released more than 10 years ago.
It's also worth checking if the service is connected to the operator itself. On some tariffs, especially archival or corporate, the function can be disabled by default. USSD-request or use the operator's personal account. Without confirmation from the provider, the phone settings will not work.
Xiaomi owners should take into account that some carriers require IMEI devices to be included in the whitelist of supported phones. Although this requirement has been a thing of the past in recent years, this may still be true on old firmware or regional operators.
| Operator. | Support for VoLTE | Need for activation | Features |
|---|---|---|---|
| MTS | Yes. | Automatically / Through the application | 4G coverage required |
| Beeline | Yes. | Automatically. | Works on most tariffs |
| Megaphone | Yes. | Automatically. | Priority HD-sound |
| Tele2 | Yes. | Automatically. | Depends on the region. |
What if the operator declares support, but the icon does not appear?
How to enable VoLTE on Xiaomi smartphones
Activation of the function on Xiaomi and Redmi devices usually occurs automatically after installing the supported carrier's SIM card. However, if the "HD" or "VoLTE" icon does not appear in the status bar, you need to check the settings manually. The path to the menu may vary slightly depending on the version of the MIUI shell or HyperOS, but the overall logic remains the same.
To start, open the Settings app and go to the section"SIM-Maps and mobile networks. Here you need to select the SIM card you want to activate the function for (if there are two of them). In the menu that opens, find the "Use VoLTE" or "Calls through" switch. LTE" If there's no switch, the system automatically detects the network's capabilities.
In some cases, especially on global firmware with Russian carriers, the menu may be hidden. Then it is worth trying to enter the engineering code in the phone app. The command set ##86583# (or #868583##) often forcibly turns on or off the hidden VoLTE Carrier Check menu. Once the code is entered, you should see the message "VoLTE Carrier check was disabled" (which means unblocking the check).
☑️ Activation checklist
Once the switch is turned on, restart the device. If the operator supports the technology and the SIM card is activated, a corresponding icon will appear at the top of the screen next to the 4G network indicator. If the icon appears but the calls do not pass, try turning off and re-energizing the flight mode for re-registration on the network.
⚠️ Note: On dual-symbol models, the function can only work on one SIM card at a time, usually on the one that is configured as the main one for data transfer. 3G/2G during conversation.
Solving common problems and errors
Despite the automation of processes, Xiaomi users often face situations where VoLTE stops working or does not turn on at all. One of the most common reasons is the incompatibility of the regional version of the firmware with the settings of local operators. For example, the Chinese version of the smartphone (CN ROM) may not have profiles for Russian or European operators, which requires manual editing of configuration files or flashing.
Another common problem is the failure to update network settings. After a major MIUI update, the old network settings may conflict with the new modem algorithms, in which case resetting the network settings to factory values helps, which will remove stored Wi-Fi passwords and Bluetooth settings, but return the network modules to their original state.
If the icon goes missing in certain places, it may indicate that there is insufficient LTE coverage by voice services in a given location. The base station may provide fast Internet but no available resources for voice packets. In such cases, the phone is forced to switch to 3G to ensure stable communication, and the HD icon disappears.
- 🔄 Reset: Reset network settings in the menu" Advanced settings".
- 📲 Software Update: Check for system updates in the menu About Phone".
- 📡 Slot change: Move the SIM card to another slot, as priority may be given to the first one.
- 🏭 Reset to factory: In extreme cases, a complete reset of the device (Factory Reset).
💡
If after all the manipulations and checks the operator does not appear icon, most likely, your specific tariff plan does not include the service HD-calls or SIM card is physically outdated.
The impact of technology on autonomy and traffic
There is a common myth that using Voice over LTE puts the battery down much faster. In practice, the opposite is true: since the phone does not need to constantly switch between 4G and 3G standards during incoming and outgoing calls, the power consumption of the radio module is reduced.
As for Internet traffic, voice calls over LTE do consume data. A minute of HD-quality conversation weighs between 0.5 and 1.5 MB depending on the codec used and the activity of the interlocutor. However, as mentioned earlier, operators usually do not write off this traffic from the main package, but charge minutes at normal voice rates.
However, when roaming is used, the situation can be radically different.In international roaming, voice transmission through the Internet is a very important issue. LTE This can be considered as data traffic use, which will lead to significant costs. Therefore, it is recommended to disable the Settings function before traveling abroad. → SIM-map → Roaming data or specifically disabling VoLTE in the network menu.