Owners of modern smartphones of the Chinese giant often face incomprehensible settings in the menu of the mobile network, which can significantly affect the quality of communication and data transfer speed. One of these features, which raises many questions, is Dual 4G. Many users do not even realize that this mode can be disabled by default or, conversely, work incorrectly depending on the regional version of the firmware. Understanding the principle of this technology allows you to significantly improve the stability of the connection in areas of uncertain signal reception.
The essence of the technology lies in the ability of the device to support high-speed connection. LTE simultaneously SIM-In the standard use case, when one card is busy with a voice call, the second card is often switched to the next card. 3G or 2G, This causes the Internet connection to break on number two. 4G This eliminates this disadvantage by allowing both modules to stay online regardless of call activity, especially for those who use one number for work and the other for personal communication, but want to stay online on both messenger accounts.
Note that support for this feature depends not only on the software, but also on the hardware platform of your device. Xiaomi, Redmi and Poco smartphones released in recent years, as a rule, are equipped with modems that can handle two LTE streams simultaneously. However, the MIUI or HyperOS software shell can hide this option or limit its operation depending on the operator’s settings. In this article, we will discuss in detail how to activate the mode, what side effects it has, and whether to keep it on all the time.
The Dual SIM Dual Standby Technology
First, you need to understand the basic architecture of the two SIM-Smartphones are the cards. Most of the devices that we have today use circuitry. DSDS (Dual SIM Dual Standby, which means two cards running in standby mode, but physically the radio module is often (one), and it switches quickly between SIM cards, creating the illusion of simultaneous operation. When you’re not using your phone, both cards are registered on the network, but when you’re actively connected, one of them may lose access to high-speed channels.
Dual mode 4G Changes this logic, forcing the modem to allocate resources to maintain the system. LTE-This requires more complex coordination with the operator's base stations, if earlier the first SIM card was called, the second one fell into the same system. 3G, Now the system is trying to save the channel. 4G. This is especially important for modern voice calls. LTE (VoLTE, where the sound quality and speed of dialing directly depend on the presence of the fourth generation network.
⚠️ Attention: Implementation of Dual 4G Snapdragon-based devices often have more stable performance than budget models on MediaTek, where switching can take longer.
Technically, this means that the phone is constantly scanning the frequencies for both cards, which increases the load on the antenna module. In a city with many towers, switching happens unnoticed by the user. However, in rural areas or places with poor coverage, the phone will spend more energy finding the signal for the second card if it is not used to transmit data right now. Understanding this mechanism helps to rationalize settings in different locations.
💡
Use Dual 4G only if your carrier supports VoLTE technology, otherwise you may have trouble getting incoming calls to the second SIM card while you are talking to the first one.
Advantages and Disadvantages of Simultaneous LTE
The feature has obvious advantages, but it also imposes certain limitations on the device’s autonomy. The main advantage is, of course, the constant availability of high-speed Internet on both numbers. You can receive SMS with confirmation codes for the second SIM card instantly without waiting for a network switch, which is critical for banking applications and security systems.
On the other hand, the impact on autonomy cannot be ignored: constantly searching for a network and maintaining two active channels requires additional energy. Although modern processors have learned to efficiently manage power, in a weak signal, battery discharge can occur 10-15% faster. Users who value every percentage of charge at the end of the day should weigh the need for this feature.
- 🚀 Instant access: The second SIM card does not fall into the 2G/3G, Providing fast delivery of push notifications and messages.
- 📶 Stability of VoLTE: Improves the quality of voice calls through the Internet LTE, Both cards are in the high-speed network coverage area.
- 🔋 Battery consumption: A noticeable, though not critical, increase in standby and active use power.
- 🌡️ Heating: In areas of uncertain reception, the smartphone can heat up more because of the intensive operation of the radio module.
Compatibility with operators is another important aspect: not all Russian and foreign providers support the correct operation of two active providers. LTE-In some cases, the dual channels are enabled. 4G This can cause one of the SIM cards to lose the network altogether, so always check if the function is activated. 4G/LTE on both slots in the notification curtain.
How to enable Dual 4G on Xiaomi smartphones
Activating a function usually does not require complex manipulations, however, the path to setting up may vary depending on the shell version. MIUI In most cases, the option is hidden in the settings menu. SIM-If one of the cards is old and doesn't have a chip. LTE, function will not be able to activate.
To start, go to the basic settings of the device, find the partition that is responsible for connection and networking, in newer versions of the firmware, it can simply be called"SIM-This is where all the key parameters of the radio module are concentrated. If you can't see the switch right away, you might need to select a particular SIM card from the list.
☑️ The Dual Incorporation Algorithm 4G
Once the switch is turned on, the system can perform a short-term re-registration on the network, the screen can go out for a second, and the network icons disappear and reappear. This is normal behavior, indicating a restructuring of the radio module. If the 4G icon did not appear on the second card, try to remove and insert the SIM cards again, making sure that they are located correctly in the tray.
In some regional firmware versions (such as Chinese or Indian), this option may be enabled by default and not have a switch. Global ROMs often hide it to save battery by default. If the standard way to enable the feature fails, you can use the engineering menu, but this requires caution.
Hidden settings and engineering menu
For advanced users who have not found the standard switch, there is access to a hidden test menu, which allows you to force the mode to activate even if the manufacturer has hidden this option in the interface. However, using the engineering menu carries risks: incorrect change of parameters can lead to unstable operation of the communication module.
To get to the menu, open the Phone app and dial the combination ##4636##. If the code doesn't work, it's possible that your shell version is blocking access to it. From the menu that opens, select Phone Information 1 (or 2, depending on the slot).
Select LTE/TD-SCDMA/GSM (or similar to LTE prefix)Choosing LTE-enabled mode for both slots is actually the inclusion of Dual 4G. However, you can also find specific settings in this menu, such as switching between Single LTE and Dual LTE modes. Beware: changing the settings in the "Radio Band" section without understanding the frequencies of your operator can completely deprive the phone of communication.
⚠️ Note: Do not change the settings in the engineering menu unless you are sure of your actions. Resetting the radio module through the normal interface after that may be impossible, you will need a complete reset of the device (Hard Reset).
Also worth mentioning is the existence of third-party apps from the Play Market that allow you to manage these settings through a GUI, which work as a shell for ADB system commands or use root rights. Using these gates is less secure than embedded tools, since you transfer control of network settings to a third-party developer.
What if the #4636## code doesn’t work?
The effect of the regime on the speed and stability of communication
Many users mistakenly believe that Dual 4G doubles the speed of the Internet. It is not. The mode only affects the availability of the network for the second SIM card, but does not add up the data channels. The download and return rate remains the same as when using a single card, unless you use special channel aggregators that are not implemented in Xiaomi smartphones for user scenarios.
However, ping stability in online gaming can improve: When the second SIM card does not “jump” between 3G and 4G, the background processes on that number do not create micro-latency switching, especially in messengers, where messages can arrive late if the network recovers long after falling in 2G.
| Parameter | Normal mode (Single 4G) | Dual 4G mode |
|---|---|---|
| Status of the 2nd SIM when calling | 3G / 2G / E | 4G / LTE |
| Delivery of SMS codes | Possible delay | Instant. |
| Battery consumption | Standard. | Increased by 5-10% |
| Heating the hull | Normal. | Possible in weak signal areas |
It is important to consider the load on the base station: in crowded networks (concerts, stadiums), the attempt of the phone to keep two active stations is not necessary. LTE-The connection may cause more frequent communication breaks than when working in mixed mode. 4G maintain a common connection.
💡
Dual 4G does not increase the maximum internet speed, but it ensures that the second SIM card is always online and ready to take a call or message over LTE.
Typical problems and ways to solve them
Despite the usefulness of the feature, users often encounter implementation bugs. The most common problem is that after you turn on Dual 4G, one of the SIM cards stops seeing the network or shows the status of "No Service". This often happens when using SIM cards from different carriers, especially if one of them uses rare bands that the phone can not simultaneously process for two cards.
Another common complaint is that the phone may try to use the Internet channel for voice call (VoLTE), but if there is no support from the operator or the APN is not set up correctly, the call simply will not pass, in which case the temporary shutdown of the function or switching the network type in the settings of a particular SIM card helps.
- 🔄 Reset Network Settings: Go to Settings → Connection and sharing → Resetting Wi-Fi, mobile networks and Bluetooth.This often solves registration issues.
- 📱 Verification SIM-Cards: Make sure the SIM card is no older 5-7 Older cards may not support simultaneous operation in the LTE.
- 🌐 Update of profile: For some operators (e.g, Tele2 or Yota) requires an up-to-date settings profile that can be updated through the operator’s application.
If the problem persists, try swapping the SIM cards in the tray. Sometimes the first slot takes priority in getting a 4G resource, and the reshuffle can change the behavior of the system. It is also worth checking for system updates, since Xiaomi regularly releases patches that fix the modems.