Modern Xiaomi and Redmi smartphones offer users a wide range of features that often go unnoticed in standard settings. One of these hidden gems is the Dual 4G mode, which dramatically changes the way mobile Internet is used when you have two SIM cards. Many device owners do not even suspect that their phone is able to support high-speed LTE connection on both lines at the same time, not just on one, as was customary in early versions of Android.
Turning this option on avoids situations where when calling a second SIM card, the Internet on the main one drops to EDGE or 3G, making it impossible to use a navigator or messengers. In this article, we will discuss in detail what this technology is, how it affects the autonomy of the device and whether the game is worth a candle in your particular case of using the gadget.
Understanding how radios work will help you set up Mi or POCO correctly for maximum efficiency, and we will look at the technical details, hidden risks, and give clear instructions on how to activate the function through the engineering menu or standard system settings.
The principle of Dual 4G LTE technology
Dual 4G (or Dual VoLTE) technology is based on the ability of the processor and modem of the smartphone to support two active connections of the fourth generation at the same time. In the classic Dual SIM scheme, which has been used for years, one SIM ran in 4G/LTE mode, providing fast Internet, and the second forced to switch to 2G/3G mode to wait for incoming calls, this created inconvenience, especially if the second SIM card did not have Internet charging or 3G coverage in the area was weak.
When Dual 4G mode is activated, the situation changes: both SIM cards are registered on the LTE network. This means that you can receive VoLTE calls to the second number without interrupting the high-speed connection on the first. The smartphone uses DSDS (Dual SIM Dual Standby) technology, where both lines are active, but data is transmitted only through one of them, selected by default, while the second is in LTE call standby mode.
⚠️ Note: To function properly, both SIM cards must support VoLTE technology, and your carrier must provide this service. Without VoLTE, a call to a second SIM card can still reset the network to the Internet. 3G.
It's important to understand that physically transfer data through two SIM cards at the same time in the same second smartphone can not. Dual 4G mode means registering both cards in the LTE network, but active traffic is only through one selected SIM card. The second card just hangs on the 4G network, ready to instantly accept a call or SMS without switching generations of communication.
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The main essence of the technology is the ability to stay on the 4G network on both SIM cards, which provides stable Internet and instant call reception without falling speed to 2G/3G.
The Benefits of Using Two SIM Cards in 4G
The transition to Dual 4G offers tangible benefits for users who are actively using mobile Internet and often communicate over the phone, especially in connection stability. If you use a navigator on a trip and at the same time waiting for an important call to the work number, the enabled mode ensures that the cards do not stop loading at the time of the incoming call.
In addition, the presence of two active LTE-The channels allow for more flexible management of the surface, and in some regions, one operator may have a great tower. 4G, But it's a bad voice connection, and the other one's the other way around. 4G allows you to choose the best provider for the Internet, without losing the ability to receive calls to the second SIM card in high quality.
- 🚀 Stable Internet: Avoids the drop in speed to EDGE incoming calls to the second SIM card, which is critical for online games and video calls.
- 📞 Quality of communication: Using VoLTE technology on both lines provides cleaner sound and faster subscriber connection.
- 🔄 Setting flexibility: The ability to quickly switch the main SIM card for the Internet in the menu without losing registration on the network LTE second.
Another plus is the speed of switching. In older implementations, if a missed call was made, the phone could search for a network for a long time before connecting 4G again. In Dual 4G mode, this process happens almost instantly, since modem is already registered on the high-speed network.
Impact of Dual 4G on battery and heating
The issue of power consumption is one of the most discussed when you include additional functions of the radio module. It is logical to assume that maintaining communication with two towers simultaneously in the 4G standard requires more power than working in 4G + 2G. Indeed, the modem has to constantly monitor the signals of two different base stations, which leads to additional charge consumption.
But the current Snapdragon and MediaTek processors used in Xiaomi smartphones are highly energy efficient, and the difference in autonomy between one 4G and two 4G in a city with a reliable signal can be as low as 3-5% per day, changing in areas of insecure reception, where the phone is constantly searching for the network, in which case battery consumption can increase significantly.
⚠️ Warning: If you are in a low signal area (basement, countryside), turn on Dual 4G on both SIM cards can lead to accelerated battery discharge and noticeable heating of the case in the area of the camera.
Also, consider the heating of the device. When you load data actively and wait for a call on the second line, the temperature can rise. For most users, this remains invisible, but with long gaming sessions with Dual 4G enabled, trottling can occur a little earlier.
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If you notice that the phone is quickly discharged in Dual 4G mode, try temporarily disabling one of the SIM cards or switching the second to 2G/3G Only mode via the engineering menu if the second operator does not need 4G coverage.
How to enable Dual 4G on Xiaomi smartphones
Activation of the function on Xiaomi, Redmi and POCO devices can be done in two main ways: In newer versions of the MIUI shell and HyperOS, the switch is often hidden in the standard menu, but in some regions or older versions of Android, the use of engineering code is required.
The first and easiest way is through the standard settings, you have to go to the SIM management section, and there's often a switch that allows you to use 4G for the second SIM card, and if you don't have one, then we'll go to a more sophisticated but effective method.
The second method involves the introduction of a special USSD-This opens a hidden developer menu where you can force the desired option to activate.
- 📱 Open the phone application (caller).
- 🔢 Dial the code ##4636##.
- 🛠 Select "Phone Information 1" (or 2, depending on the slot).
- 🔍 Find the option “Configure your preferred network type” and select LTE/TD-SCDMA/UMTS/GSM mark-up LTE.
☑️ Check before activating Dual 4G
Once you do the steps, restart your smartphone. If done correctly, the status bar should have 4G or HD icons next to both SIM cards (which stands for VoLTE). In some cases, the ##4636## can be blocked by the operator or firmware, then you will need to use third-party applications like Force LTE Only from the Play Market that emulate this input.
Comparison of network modes in MIUI
To better understand the difference, it’s worth comparing different network configurations. Users are often confused in terms, not understanding how “4G preferably” mode differs from the real Dual 4G. Below is a table showing the key differences.
| Parameter | Single 4G (Standard) | Dual 4G (Activated) | 4G Only (Engineering) |
|---|---|---|---|
| SIM card 1 | 4G/LTE | 4G/LTE | Only 4G. |
| SIM card 2 | 2G/3G | 4G/LTE (VoLTE) | Only 4G. |
| Internet when calling on SIM 2 | Interrupted or dropped to 3G | It's stable. | It works (if there is a VoLTE). |
| Battery consumption | Low/Mediocre | Medium/High | High (network search) |
The 4G Only mode mentioned in the table is an extreme.It makes the phone ignore 2G and 3G towers.It's useful in places where 4G is available, but the phone clings to weak 2G, however, on trips you risk being left without communication at all, as LTE coverage is not ubiquitous.
Dual 4G with VoLTE support is the best option for everyday use, providing a balance between speed and coverage. Standard mode without Dual 4G is now considered obsolete, as 2G and 3G networks are gradually being phased out by operators around the world.
Possible problems and ways to solve them
Despite the obvious advantages, the introduction of Dual 4G can face a number of technical problems, the most common of which is the absence of an HD or VoLTE icon even after all settings are turned on. This often indicates that the operator has not certified your device to work with voice over LTE, or the firmware does not have a corresponding config file.
Another problem is the periodic network loss on one of the SIM cards, which can occur due to a frequency conflict if both operators use close ranges and the smartphone’s antenna system can’t cope with signal isolation, in which case manual network selection or temporary disconnection of one of the cards helps.
What to do if the Internet is lost after the Dual 4G is turned on?
And users may also find that the second SIM card shows 4G, but the Internet is not working through it, which is a standard behavior for the DSDS architecture: data is transmitted only through one, the "main" SIM card, and in order for the Internet to go through the second one, you need to change the priority of data transfer in the settings.
⚠️ Warning: Do not try to activate the mode "4G Only" through the engineering menu as a permanent solution, which can result in a complete loss of communication in the elevator, subway or outside the city, where the coverage is covered. LTE absent.
Support for functions in different Xiaomi models
Not all Xiaomi devices support Dual 4G at the hardware or software level. Generally, this feature is available on all smartphones released after 2018 and running Android 9 and higher. The flagship Mi series, Mi Mix and modern Xiaomi 13/14 support technology out of the box.
In the low-end segment, such as the Redmi Note or Redmi A series, implementations may depend on the regional version of the firmware. Global ROMs are more likely to have this feature in the standard menu, while Chinese firmware (CN ROM) may require additional manipulation.
You can check the support by looking at the specifications of the modem of your device (Cat6, Cat12, Cat18 It is almost guaranteed to work with two active LTE-Problems can only occur on very old or ultra-budget models with stripped-down modems.