Why the Internet goes missing on Xiaomi Redmi

The situation when during a phone conversation on a Xiaomi or Redmi smartphone, mobile Internet stops working, is familiar to many users: you open the messenger or try to look at the navigator, and instead of downloading data, you see only the E or 3G icon, although before the call, LTE worked confidently. This is not a device breakdown and not a SIM card failure, but a feature of mobile networks that owners of various models face, from budget Redmi 9A to flagship versions.

The main reason is how your carrier and your phone model handle voice calls. In the old communication standards, voice and data were transmitted over different channels, and the phone could not physically talk and pump traffic at high speeds at the same time. Modern technology allows this, but they often require manual tuning or support from the operator to activate them.

In this article, we will take a closer look at the technical reasons behind the speed drop, explain what VoLTE technology is and why it is critical to a smartphone experience, and learn how to configure network settings properly in the MIUI or HyperOS menu to stay online even during lengthy conversations.

Technical reasons for switching to 2G and 3G

The fundamental problem lies in the architecture of previous generations of networks: 2G (GSM) and 3G (UMTS) standards were originally designed so that voice calls took up the entire dedicated channel, and when you started a conversation, the phone forced to switch to frequencies designed only for voice, cutting off the data channel, which is why the indicator on the screen changed from 4G to H+ or E.

With the advent of fourth-generation LTE networks, this was supposed to change, as this technology was originally designed for packet data transmission. However, in order for voice to also be transmitted over LTE, VoLTE (Voice over LTE) technology is required. If this feature is not activated, the phone performs the CSFB (Circuit Switched Fallback) procedure when calling or out - it temporarily rolls back to a 3G or 2G network to make a call, interrupting the Internet connection.

On Xiaomi and Redmi smartphones, this behavior can be exacerbated by software firmware restrictions or region settings. Sometimes the phone “does not see” the carrier’s VoLTE support and automatically selects an older, supposedly more stable communication protocol, which causes WhatsApp video calling or map downloading to the navigator to be interrupted at the most inopportune moment.

⚠️ Warning: Forced switching to "Only" mode 4G" Without VoLTE enabled, you may stop accepting regular voice calls because the network will not be able to find a channel for voice.

Role of VoLTE technology in stabilizing communications

VoLTE technology is a key element for voice and the internet to work together, allowing voice streaming to be transmitted like normal data over an LTE network without requiring a switch to lower frequencies. For Xiaomi users, this means higher HD-voice, faster connectivity, and the internet continues to work at full speed.

But having VoLTE on your smartphone is only half the success, and the other half depends on your carrier and your phone. SIM-The operator must support this technology in your area, and the tariff plan must allow its use. SIM-Cards you received years ago may not work properly with new protocols, and replacing them in the salon solves the problem instantly.

On Redmi and Poco devices, VoLTE activation often occurs automatically when a compatible carrier SIM card is installed. If an HD or VoLTE icon does not appear in the status bar, it may be hidden in the engineering menu or disabled in the system settings. Without activating this option, the phone will use the rollback method described above, which causes the Internet to disappear.

Network setting and VoLTE enabled on Xiaomi

The first step in solving the problem should be to check the basic settings of the smartphone. Xiaomi owners need to make sure that the menu selected the right type of network. SIM-You can click on the SIM card that you're using to access the Internet and find the type of network.

If you select "3G Only" or "2G/3G", you can forget about high-speed Internet during the conversation. Also in the same menu should be a switch Use VoLTE. If you have one, make sure it is activated. On some global firmware, this item may be hidden if the system believes that your operator does not support the technology.

If the standard methods fail to enable the function, you can try to activate the hidden engineering menu. To do this, dial the code # # # #86583#. After entering the command, a VoLTE Carrier check was disabled (or enabled) pop-up message should appear, which means that the software locks the operator checker.

The impact of two SIM-mapping the speed of the Internet

The use of two SIM cards in Redmi and Xiaomi smartphones makes its own adjustments to the communication module. Most budget and medium-sized models are equipped with modules that can not simultaneously support two LTE channels. This means that if one SIM card is busy with voice calls, the second can temporarily lose connection or significantly reduce speed, especially if both cards are in the zone of uncertain reception.

The problem is compounded when the Internet is configured on one SIM card and the call is sent to another, in which case the phone has to switch the radio module between the frequencies of different operators, causing delays and connection breaks. Even with VoLTE on both cards, the physical architecture of the antennas may not be able to handle two high-density data streams simultaneously.

To minimize problems, it is recommended in the settings SIM-Make sure that the mobile Internet site selects the SIM card that has the most stable coverage. 4G. It is also worth checking your data roaming settings if you are on a trip, as in roaming mode, network priorities may change.

Firmware problems and reset network settings

Sometimes the reason is not the hardware, but the software failure of the Android operating system or the MIUI shell. Errors in the radio module (RIL) can lead to incorrect switching between cell towers. If after the system update the problem appeared suddenly, most likely, the network configuration files are lost.

The safest way to fix this is to reset your network settings. This action will not delete your personal photos or contacts, but will return all your Wi-Fi, Bluetooth and mobile settings to factory values. To do this, go to Settings → Connection and Sharing → Reset Wi-Fi, mobile networks and Bluetooth. Once rebooted, the phone will re-register on the carrier’s network.

In more complex cases, especially on custom firmware or after flashing from Chinese to global, modem flashing may be required. This is a complex procedure that requires a computer and Mi Flash. The average user is better off limiting himself to resetting or waiting for a software update from the manufacturer in which engineers will fix communication errors.

When is the fault of the operator

External factors cannot be ruled out. Even a perfectly configured Xiaomi won’t be able to keep the internet on a call if your carrier’s nearest base station is overloaded or under repair. During peak hours, when network load is high, voice traffic is always given priority, and data channels can be artificially restricted or cut off.

Also worth considering is coverage. In buildings with thick walls or in basements, the LTE signal can be weak. The phone, trying to hold the call, will cling to any available signal, often switching to 2G, which punches walls better but does not have enough bandwidth for the Internet, in which case the loss of the Internet is the normal behavior of the device to maintain the quality of communication.

To diagnose the problem, try making a call in different locations, if you have a downtown Internet connection and you lose it in a residential area or in a suburban area, it's the operator's infrastructure, and you can only change your service provider or use Wi-Fi to transfer data.

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Use Wi-Fi calling if supported by your carrier, which allows you to make calls over your home Wi-Fi without affecting your mobile network at all, ensuring a stable 4G/5G Internet in parallel with the conversation.

Additional optimization methods

There are lesser-known methods that can help in specific cases. For example, changing APNs can sometimes stabilize the connection. Go to your mobile network settings, select an access point, and make sure that the APN type field spells out default,supl,mms. The absence of a supl parameter can affect the operation of GPS and support services, indirectly affecting stability.

Another nuance is energy saving: Aggressive MIUI algorithms can limit the background activity of applications during a call to save charge. Go to the battery settings and set the No Limits mode for important applications (navigator, messengers) to prevent the data module from falling asleep while the screen is off during a call.

If nothing works, the radical but effective method is to completely reset the device. Be sure to back up your data to the Mi Cloud or your computer before doing so. Clean installation without user debris often works wonders with a radio module, making it run normally.

⚠️ Note: Before performing a full reset, make sure you remember the password from your Mi and Google account, otherwise activation of the phone after the reset will not be possible.

Frequently Asked Questions (FAQ)

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The main condition for a stable Internet when calling is the joint support of VoLTE technology by your smartphone, SIM card and operator in a particular region.