VoLTE in Xiaomi Redmi 9: why you need, how to configure and what to do if it does not work

Did you buy a Xiaomi Redmi 9 and stumble upon a mysterious VoLTE option in your settings? Or did the operator send an SMS asking you to connect this feature, but you don't understand why you need it? This article will look at Voice over LTE (voice over 4G) technology for your smartphone, from theory to practice.

Many users mistakenly think that VoLTE is just “enhanced calls.” In fact, it’s a full-fledged revolution in mobile communications that changes the principles of voice transmission. If before calls were made over outdated 2G/3G networks, VoLTE sends them over the 4G- channel, like normal data in instant messengers. For Redmi 9 with its modest hardware, this means not only better communication quality, but also battery life savings.

But there are nuances: not all carriers support VoLTE, and in some regions the feature can malfunction. Next, we will tell you how to check support on your Redmi 9, turn on VoLTE manually and what to do if your smartphone “can’t see” the 4G network during a call.

What is VoLTE and why is it needed in Xiaomi Redmi 9?

VoLTE (Voice over LTE) is a fourth-generation (4G) voice technology. Unlike traditional calls that use 2G or 3G, VoLTE encodes the voice into a digital data packet and sends it over the same channel as Internet traffic. For Xiaomi Redmi 9, this means:

• 📞 Sound quality in HD is a sampling rate of up to 16 kHz (vs. 8 kHz in 2G), which makes the voice of the interlocutor more natural, without noise and distortion.
• ⚡ Instant connection – The call setup time is reduced from 5-7 seconds to 1-2 seconds (as in instant messengers).
• 🔋 Battery savings – The smartphone doesn’t need to switch between 4G and 3G/2G during a conversation, which reduces the load on the modem.
• 🌐 Parallel Internet operation – you can talk and use the mobile Internet at the same time (in 3G/2G when you call, the connection is cut off).

In practice, the difference is noticeable from the first call, for example, if you call via VoLTE with Redmi 9 to another smartphone with technology (not even Xiaomi), the interlocutor will hear your voice as if you are sitting next to each other — without the characteristic “underwater” effect of old networks.

But there’s a downside: if your region has a weak 4G signal, VoLTE can perform worse than regular calls, because voice data packets require a stable connection, and if you have a weak signal, the call can be interrupted or switch to 3G automatically (if the carrier supports such a fallback).

Does Xiaomi Redmi 9 support VoLTE technology?

Xiaomi Redmi 9 (model M2004J19C for the global market) officially supports VoLTE at the hardware level. The smartphone has a modem Qualcomm Snapdragon 662, which is certified for voice over 4G. However, there are several key points:

• 📱 Firmware: VoLTE only works on official versions of MIUI (global/stable or EEA).
• 📡 Operator: The technology must be activated on the mobile operator side. In Russia, VoLTE is supported by Beeline, MegaFon, MTS and Tele2, but the coverage is not the same everywhere.
• 🌍 Region: In some countries (e.g. India, Indonesia), VoLTE on Redmi 9 may be disabled by default due to local regulatory requirements.

To make sure your Redmi 9 is VoLTE compatible, check the following options:

1. Open Settings → About Phone → MIUI version. Make sure you have official firmware installed (e.g. MIUI Global 12.5.3 or later).
2. Check the device model in Settings → About Phone → Model. All Redmi 9 modifications are suitable for VoLTE, including Redmi 9 Prime and Redmi 9 Power.
3. Make sure your SIM- card supports 4G (nano-SIM). Older Micro-SIM cards or without LTE support can block VoLTE.

If you bought Xiaomi Redmi 9 in China (model) M2004J19G), VoLTE may not work in Russia due to differences in frequency ranges. MIUI.

How to enable VoLTE on Xiaomi Redmi 9: step-by-step instructions

If your carrier and smartphone support VoLTE, you just need to activate the function in the settings. Redmi 9 does this in a few steps:

1. Open Settings and go to the section SIM-maps and mobile networks.
2. Choose yours. SIM-card (if two of them).
3. Tap on Network Type (or Preferred Network Type in some versions of MIUI).
4. In the options list, select 4G (preferably)/3G/2G or LTE/3G/2G (auto).
5. Go back and find the VoLTE option (can be called Voice over LTE or Improved Calls).
6. Reboot your smartphone so that the changes take effect.

When you turn on the network indicator, you'll see the word VoLTE or HD in the status bar (some carriers don't have it), and if you don't, try making a test call -- if the connection is instant and the sound is cleaner, the function works.

Make sure that:

Smartphone supports VoLTE|SIM-map activated for 4G-voice|Settings are on mode. 4G|The operator provides VoLTE in your region|A test call was made to check the quality-->

If VoLTE is not available in the settings, try the following:

• 🔄 Update. MIUI Up to the latest version through Settings → The phone. → Updating the system.
• 📋 Reset network settings: Settings → SIM-maps and mobile networks → Network reset.
• 📱 Reinstall SIM- card (remove and paste back).
• 📞 Call the carrier and request VoLTE activation for your number (sometimes manual connection is required).

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If VoLTE calls start to stop after you turn on, try disabling the feature and using standard 3G mode. Perhaps in your region the 4G signal is not stable enough for voice transmission.

Why VoLTE doesn’t work on Xiaomi Redmi 9: common problems

Even if you set up VoLTE correctly, the feature may not work, and here are the main reasons and ways to fix them:

One of the most insidious problems is the conflict with two SIM- cards. If the Redmi 9 has two cards installed, VoLTE can only work on one of them (usually the one in the SIM1 slot).

1. Go to Settings. → SIM-maps and mobile networks.
2. Select the SIM- card on which you want to activate VoLTE.
3. Make sure that it has 4G mode and VoLTE option enabled.
4. Try calling – if the second SIM VoLTE doesn’t work, it’s OK (hardware restriction).

⚠️ Warning: If you use Redmi 9 with firmware for another region (e.g. Indian on a European smartphone), VoLTE may not work properly, requiring a change of region in settings or a complete flashing.

VoLTE vs ViLTE vs VoWiFi: What’s the difference and what’s best for Redmi 9

In addition to VoLTE, in the settings of Xiaomi Redmi 9 you can find other similar options: ViLTE and VoWiFi.

• 📶 VoLTE – Voice over 4G (requires mobile network coverage).
• 📞 ViLTE (Video over LTE) — video calls over 4G (like VoLTE, but for video) — Redmi 9 supports, but only works between subscribers of the same operator.
• 📶 VoWiFi (Voice over Wi-Fi) — Wi-Fi calls are useful if there is no 4G signal in the room, but there is Internet.

For Redmi 9, the best option is to use VoLTE + VoWiFi.

• Maximum quality of communication in the 4G coverage area.
• Automatic switching to Wi-Fi when the signal is weak (for example, in the basement or outside the city).
• Battery savings, as the smartphone does not have to constantly search for the network.

To enable VoWiFi on Redmi 9:

1. Go to Settings. → SIM-maps and mobile networks.
2. Choose. SIM-map.
3. Activate the option of Wi-Fi (or VoWiFi) calls.
4. Confirm the address for emergency calls (required for service 112).

⚠️ Warning: Some carriers (e.g., "Tele2") may block VoWiFi for prepaid rates.

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VoWiFi is a great addition to VoLTE, but it doesn’t replace it. 4G- will always be a priority, and Wi-Fi is only used when there is no signal.

How to check internet speed during a VoLTE call

One of the key benefits of VoLTE is that it can use the Internet while you're talking, but how do you know if you're cutting your speed?

1. Make a call via VoLTE (make sure there is a VoLTE or HD indicator in the status bar).
2. Without completing the call, open your browser and run a speed test (for example, on Speedtest.net).
3. Compare the results with the usual mode (no call).

Normal performance for Redmi 9 during VoLTE call:

• Download speed: at least 50% of the maximum (if you have 50 Mbit / s without a call, then during a conversation it should be at least 25 Mbit / s).
• Ping: up to 100 ms (if higher, voice delays are possible).

If the speed drops by more than 50%, it can mean:

• 📉 The operator limits the bandwidth for VoLTE (a common practice in "virtual" operators).
• 📡 The network is overloaded (peak hours).
• 🔋 The smartphone overheats and the trottlit modem (check the temperature in Settings → About Phone → Battery status).

Tip: If you need Internet during a call often (for example, for a navigator), turn on modem mode in the settings and distribute the Internet to the second device. This will reduce the load on the Redmi 9.

VoLTE and battery: how technology affects the autonomy of the Redmi 9

Many users are worried that VoLTE is increasing battery consumption, but it really depends on the conditions:

• ⚡ Charge savings occur when:
• 🔋 An increase in flow is possible if:

To assess the impact of VoLTE on Redmi 9 autonomy, do a test:

1. Charge your smartphone to 100%.
2. Turn off VoLTE and use your phone as normal (calls, internet) for 2-3 hours.
3. Write down the discharge percentage.
4. Turn on VoLTE and repeat the test with the same actions.
5. Compare the results.

According to user tests, VoLTE reduces battery consumption by 5-10% in stable 4G environments due to no switching between networks, but if the signal is weak, the difference can be negative.

⚠️ Warning: If your phone gets too hot during calls after turning on VoLTE, turn off the function and check your power saving settings.

FAQ: Frequent questions about VoLTE on Xiaomi Redmi 9