Dual 4G LTE technology on Xiaomi Redmi smartphones

Xiaomi Redmi smartphones are no longer just budget phones, they have become powerful multimedia centers where the stability of the Internet connection is critical. Many users stumble upon the settings menu item Dual 4G LTE, but not everyone understands its real purpose and impact on the device.

In fact, this technology allows both of them to SIM-And the first thing you do is you use one SIM to make calls, and the second one is forced to switch to the fourth generation. 2G or 3G. Now Xiaomi offers more advanced traffic management, which is especially important in the conditions of unstable coverage or when using VoLTE actively.

In this article, we will discuss in detail how this function works, whether it should be kept on all the time and what nuances exist when configuring two SIM cards on devices with a MIUI or HyperOS shell.

The principle of two SIM-mapping 4G

The traditional architecture of mobile modems has long limited users, so while one card was running in high-speed LTE, the other card was forced to "watch" on second- or third-generation networks, which created an inconvenience: if the main SIM received a voice call, the Internet on the second card could completely disappear or slow down.

Dual SIM Dual Standby (DSDSDS) technology with 4G support for both slots is a game changer.The smartphone constantly supports communication channels with two base stations at once.This does not mean that data is swinging from two sims at once (although in some scenarios this is possible), but both cards are ready for instant call reception or SMS without switching modes.

⚠️ Note: Simultaneous active data transfer through both SIM-map-mode 4G+4G It's only possible with the operator's support for VoLTE technology and the appropriate modem setting. In standard mode, one card is the main one for traffic, and the second one is in standby mode. 4G.

It’s important to understand that implementing this feature is not just firmware-dependent, but also hardware-dependent. The Snapdragon and MediaTek processors used in Redmi have built-in modems capable of handling two LTE streams. However, if you’re using very old models released before 2018, a hardware limitation may not allow this mode to be activated, even if a menu item is present.

Advantages and Disadvantages of Using Dual 4G

The inclusion of this feature brings tangible benefits for those who actively use the mobile Internet, the main advantage is stability. If the main operator loses the LTE signal, the smartphone will not frantically try to rebuild the network on the second card, maintaining the overall balance of connections, and it is critical for the work of messengers tied to a particular number.

Let’s look at the main pros and cons in more detail:

• 🚀 Instant Call Acceptance: The second SIM does not go into “unavailability” during a conversation on the first one, if both operators support VoLTE.
• 📡 Stable Internet: When switching between towers, connection speeds remain more predictable.
• 💬 The work of messengers: WhatsApp or Telegram, tied to the second SIM, is always online, as it does not fall into the Internet. 2G.
• 🔋 Battery consumption: Constant monitoring of two networks 4G It can lead to faster battery discharge in areas with poor coating.

On the other hand, there are nuances: In some regions where 4G coverage is fragmented, the phone may switch between communication standards more often in an attempt to hold two networks, which puts a strain on the radio module, and it’s worth considering that not all Big Four carrier plans are equally friendly to staying in LTE permanently without voice calls.

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If you notice that your smartphone starts to run out faster after you turn on Dual 4G, try turning it off at night or in places where you know for sure about poor network coverage.

Instructions for activation of the mode on Xiaomi Redmi

The process of enabling the function is quite simple, but the path to settings may vary slightly depending on the shell version. MIUI Or HyperOS. Usually, all the controls you need are in the mobile network section. SIM-maps are installed and determined by the system.

To activate, perform the following actions:

1. Open the Settings app on your device.
2. Find the section SIM-maps and mobile networks.
3. Click on the SIM card you want to set up as your primary internet setting, or select the general setting if it is available.
4. Find Preferred Network Type and make sure you choose Preferred 4G (LTE).
5. Go back and find the switch to use. 4G second SIM-Cards (or similar Dual cards) 4G).

Once the slider is turned on, the smartphone can lose the network for a few seconds, which is normal behavior, because it re-registers on the networks of both operators. If the item is missing, it is possible that your current version of the firmware hides it, and you will need to activate it through an engineering menu or codes.

The role of VoLTE in the work of two SIM cards

You can't talk about Dual 4G without mentioning Voice over LTE. It's a key element that allows voice calls to pass through a fourth-generation network without resetting the connection to 3G. For owners of two sims, this is critical: without VoLTE when you call the first card, the second will inevitably fall off LTE.

In Xiaomi smartphones, VoLTE support is often on by default for many carriers, but sometimes requires manual activation. If you see an HD or VoLTE icon in the status bar next to the network indicator, then the technology works. Otherwise, even with Dual 4G enabled in the settings, real work can be done according to the old standards.

⚠️ Warning: Make sure your mobile operator supports VoLTE in your area.Even if the phone is configured correctly, without carrier support, the feature will not work.

You can check status by calling someone and seeing if the 4G/LTE icon is still active during a conversation, and if the icon changes to H+ or E, then the 3G switch is still happening, and the full Dual 4G is not functioning.

Impact on the autonomy and heating of the device

Any additional activity of the radio module affects battery life. The two active 4G networks require more frequent exchange of signals with base stations to maintain registration. In ideal conditions, when the signal is excellent, the power difference between the conventional mode and the Dual 4G is almost invisible.

But things are changing in the areas of insecurity, where the phone has to constantly increase the power of the transmitter and scan the air more often to avoid losing one of the networks, which can lead to noticeable heating of the case in the area of the camera and increased battery consumption, if you are on a trip away from civilization, it may make sense to turn off the second SIM or put it in 3G mode.

Users also note that when you actively use navigation and music streaming on two SIMs at the same time (if the tariffs allow), the phone can work slightly hotter than usual, which is the standard behavior for modern compact devices with powerful hardware.

Problem Solving and No Item in the Menu

It is often the case that a user wants to enable Dual 4G, but the corresponding switch simply does not exist in the interface.This may be due to regional firmware restrictions (e.g. Global ROM vs China ROM) or the specifics of the specific operator whose SIM card is installed in the slot.

In some cases, network resets help. Go to Settings → Connection and Sharing → Reset Wi-Fi, mobile network and Bluetooth. After you reboot, check the menu again. It's also worth checking if the item is hidden in the engineering menu.

Engineering code for verification (not working on all models):


In the app "Phone" dial: ##4636##




Select "Phone Information."




You can try to set the preferred type of network manually.

If that doesn’t work, your modem may not support two devices simultaneously. LTE-channels, despite marketing claims, in which case it is left to put up with switching to the 3G second-card.

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The absence of a Dual 4G switch in the menu most often means either a hardware modem restriction or a lock by the carrier, rather than a system error.