VoLTE in Xiaomi Redmi 9: a detailed guide to technology, configuration and problem solving

Have you ever noticed that while talking on the phone, the Internet suddenly slows down or disappears? With the Xiaomi Redmi 9, this may be due to the lack of support for VoLTE, a technology that allows you to talk and use mobile Internet at the same time. But what is it in practice, why are operators actively implementing it, and how to check if it works on your device?

In this article, we will analyze VoLTE from the technical and user side: from the principles of operation to the step-by-step configuration on Redmi 9. You will learn which operators in Russia support the technology, how to enable it manually, and what to do if the icon is installed. HD Or VoLTE doesn't appear in the status bar, and we'll also uncover myths about the impact of VoLTE on battery life and communication quality.

Spoiler: If your Redmi 9 is bought from an official store, chances are VoLTE is already out of the box supported, SIM-Maps and network settings you should know about.

What is VoLTE and why is it important for Redmi 9?

VoLTE (Voice over LTE) — This is a voice transmission technology over the network. 4G LTE, Not through outdated standards. 2G or 3G. The main difference: when a normal call the phone “switches” to a slower network, and with VoLTE connection remains in the mobile phone. 4G, giver:

• 📞 Fast connection – the call rises in 1-2 seconds (versus 3-5 seconds in a single day) 3G).
• 🎙️ Pure sound – wide bandwidth (up to 24 kHz) removes noise and echoes.
• 🌐 Internet while talking – you can talk and check your email, watch maps or stream music at the same time.
• 🔋 Battery savings – no need to constantly switch between networks.

On Xiaomi Redmi 9 (model) M2003J15SC) VoLTE is supported hardware, but it requires work:

1. SIM-VoLTE-enabled card (check with the operator).
2. Active VoLTE service in the tariff (free of charge for most operators).
3. The phone's settings are right.

No VoLTE when you call Redmi 9 will fall on 3G, This is a problem that slows down the Internet and impairs the quality of communication, especially in low-cost areas. 2G/3G.

How to check if your Redmi 9 VoLTE is supported

Before you set up VoLTE, make sure your device is compatible. Redmi 9 has two ways to check:

Method 1: Viewing characteristics in settings

Go to Settings. → The phone. → All the characteristics. In the "Network" section, look for the lines:

• VoLTE or HD-Calls – if there is support.
• LTE The voice is also a sign of compatibility.

Method 2: Checking through the Engineering Menu

Enter the code in the "Phone" application:

##4636##

Select Phone Information and see the VoLTE provisioned line:

• ✅ Yes – VoLTE is supported.
• ❌ No – no support (maybe you need firmware).

Also check whether your operator supports VoLTE. In Russia, the technology is actively used:

⚠️ Attention: If you are using SIM-card over 5 years old, most likely it does not support VoLTE. USIM (free-for-free).

Step-by-step: how to turn on VoLTE on Xiaomi Redmi 9

If the check shows that VoLTE is supported, follow this instruction. on Redmi 9 with firmware MIUI 12.5 and the newer path to settings may be different – use the search in the settings on the request “VoLTE».

Step 1: Activate in the settings SIM-map

1. Open Settings. → SIM-maps and mobile networks.

2. Choose yours. SIM-card (if two of them).

3. tap by Network Type and select 4G (preferably).

4. Go back and turn on the VoLTE call switch (or Improved calls).

Step 2: Check in the Engineering Menu (optional)

If, after the icon is turned on, HD or VoLTE did not appear in the status bar:

1. Enter the code ##4636##.
2. Go to Phone Information → Settings.
3. Enable VoLTE provisioned (if any).
4. Reboot the phone.

If after all the manipulations VoLTE did not work, the problem may be:

• 📱 Firmware, update. MIUI last-minute.
• 📶 Coverage – VoLTE only works in the area of operation 4G LTE.
• 💳 SIM-map - replace it with USIM operator.

💡

If after turning on VoLTE mobile Internet disappeared, try to manually select the operator network in the settings (Settings) → Mobile network → Network operators).

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

In addition to VoLTE, Redmi 9 may have other voice technologies, and let's see how they differ.

Redmi 9 can be enabled by default CSFB (Circuit Switched Fallback is when the phone falls on the phone when it rings. 3G. To disable it in favor of VoLTE:

1. Enter the phone application ##4636##.
2. Select Phone Information → Settings.
3. Change the Preferred Network Type to Preferred Network Type LTE only.

⚠️ Attention: If you choose LTE The phone will not be able to call in areas without 4G (For example, in the subway or outback. LTE/WCDMA/GSM auto.

VoWiFi (wi-fi calls) on Redmi 9 is supported, but requires separate activation:

1. Go to Settings. → SIM-map → Additionally. → Wi-Fi calls.
2. Turn on the switch.
3. Confirm the address for emergency calls (if required).

Problems with VoLTE on Redmi 9: causes and solutions

Even if VoLTE is on, it can be unstable, and here are the typical problems and ways to fix them:

Problem 1: The VoLTE sign appears and disappears

Reasons:

• 📶 Weak signal. 4G — phone-to-phone 3G.
• 🔄 Frequent change of towers – the operator does not have time to authorize VoLTE.
• 📱 Energy conservation — MIUI Can disable VoLTE to save battery.

Solution: Turn off the power saving mode for the Phone application (Settings) → Battery → Energy saving applications).

Problem 2: Calls are broken or not connected

This may be related to:

• 🔧 Wrong settings. APN.
• 📡 Dual-SIM conflict (if you use two) SIM-map).
• 🛠️ Software failure.

Decision:

1. Reset network settings: Settings → SIM-map → Resetting mobile network settings.
2. If you use two SIM-Try to leave only one card.
3. Update the firmware to the latest version.

Problem 3: No sound when VoLTE calls

Sometimes, after activation of VoLTE, the sound disappears or becomes quiet.

• 🔊 Conflict with sound settings (e.g., enabled) HD Audio in call settings).
• 🎧 Problems with the speaker or microphone.
• 📞 Failure in the Phone app».

Solution: Go to Settings → Sound. → Call quality and turn off HD-If it doesn't work, clear the phone app cache. → Annexes → Phone. → Warehouse → Clear the cache).

💡

If after turning on VoLTE mobile Internet disappeared, check if the mode "Only" is activated. LTE» In the engineering menu, return the settings to LTE/WCDMA/GSM auto.

VoLTE and battery: is it true that the technology is faster to land the battery

One of the common myths is that VoLTE increases battery consumption.

• ✅ VoLTE saves charge as it does not require switching between 4G and 3G.
• ⚠️ But if the signal 4G The phone spends more energy searching for it.
• 🔋 The difference in battery consumption between VoLTE and CSFB 5-10% in favor of VoLTE.

To minimize battery consumption when using VoLTE:

1. Turn off automatic network search (Settings) → Mobile network → Network search engine).
2. In the weaker areas 4G switch over 3G manually.
3. Use the power saving mode, but add the Phone app to the exceptions.

To check the battery consumption:

1. Go to Settings → Battery → Battery Use.
2. Look at how much energy the phone and the mobile network spend.
3. Compare the results before and after the VoLTE switch on.

⚠️ Note: If the phone becomes very warm after activation of VoLTE, this may indicate a hardware problem (for example, a faulty modem.

VoLTE on custom firmware: what you need to know

If you use unofficial firmware on Redmi 9 (like LineageOS, Pixel Experience or HavocOS), VoLTE may not work properly or at all.

• 📱 Lack of proprietary drivers for modem.
• 🔧 Wrong settings IMS (IP Multimedia Subsystem).
• 📡 Incompatibility with the operator.

To make VoLTE work on custom firmware:

1. Make sure the firmware supports IMS (Check out the developer forum).
2. Set the right ones. APN-settings for your operator.
3. In the engineering menu (#4636##) include:

Reboot the phone.

If VoLTE never worked, go back to the official firmware MIUI or use the VoLTE fix patch (available on forums such as XDA Developers).

💡

Before installing custom firmware, make a backup EFS-section (contains) IMEI And the modem settings, which can be lost, can cause the network to be out of service!

FAQ: Frequent questions about VoLTE on Xiaomi Redmi 9