How to set up a second line on a Xiaomi phone

Modern Xiaomi smartphones have long ceased to be just bells, becoming powerful multimedia centers, but their basic communication function remains critical for millions of users. SIM-Cards at the same time - it is not just a convenience, but often an urgent need for those who share work and personal contacts or seek to save on tariffs of different operators. Owners of Redmi and Poco devices often face questions about how to correctly distribute roles between SIMs, so as not to lose important calls and enjoy fast Internet without constantly switching manually.

The process of activating and configuring the second slot on Miui or HyperOS smartphones usually does not cause difficulties, but there are a number of hidden nuances, ignoring which can lead to unstable operation of the communication module. In this article, we will discuss in detail the algorithm of actions that will allow you to correctly adjust the priorities of calls, the Internet and SMS, and also explain why in some cases the second slot can only work in 2G mode. Understanding these mechanisms will help to avoid common errors and ensure stable communication in any conditions.

Before you go to software settings, you need to make sure that the physical correctness of the installation of the cards, since the software interface only manages the hardware already connected. Incorrectly installing the chip in the tray is the most common reason why the phone does not "see" the second SIM, and no menu settings will help here. Next, we will look at each step in detail, starting with the hardware and ending with fine calibrating network parameters for specific use cases.

Physical installation SIM-cardboard

The first and most important step is to physically fit the card properly into the device slot, as even minimal skewing or contamination of contacts can result in a lack of signal. SIM-Xiaomi smartphones usually have a combined card: one slot is designed for a microSD memory card, and the other two are for nano.-SIM, or all three slots are combined depending on the model.Before removing the tray with a clip, it is strongly recommended to completely turn off the smartphone to avoid potential short circuit or software errors of the chip reading.

Notice the shape of the cutout in the tray — it strictly corresponds to the size of the nano-SIM, and trying to insert the card force or in the wrong position is unacceptable. Golden contacts on the card itself should look down, and the bevelled corner of the chip should match the schematic image on the tray or the case of the smartphone. If you use adapters with a micro-SIM or standard SIM, make sure that they are not too thick and do not interfere with the tight fit of the tray in the case.

Once the tray is installed and the phone is turned on, the system will automatically try to identify new maps and suggest basic settings, but it will require a manual configuration to work properly. Often users forget to remove the protective film from the tray itself if it was there, or do not fully push the mechanism, which leads to poor contact. Make sure that the tray snaps with a characteristic, barely audible click, and the gap between it and the frame of the case is minimal.

⚠️ Warning: Never try to insert a microSD card into a slot designed solely for the purpose of SIM-cards, and vice versa, if the design of the tray does not provide for this - this can lead to a breakdown of the reading mechanism.

In some budget models, Redmi tray can be hybrid, where the second slot is split between the second SIM and memory card, which means that you can not use two SIM cards and flash memory at the same time. In this case, you will have to choose which is more important for you: memory expansion or second number, or use cloud services and online storage instead of a physical card. Check the specification of your particular model on the official website or in the instructions to know exactly the type of tray.

Primary activation and operator selection

After successfully physically connecting the cards and turning on the smartphone, the Android system with the MIUI shell usually immediately reacts with the appearance of two signal icons at the top of the screen. If the icon of the second SIM does not appear, you need to check whether the slot itself is activated in the software, since sometimes by default the second port can be disabled to save resources or to avoid conflicts.

Click on the gear icon to enter Settings, then search for the SIM card and mobile network section (in some firmware versions it may be simply called Two). SIM-In the menu that opens, you will see a graphical display of both cards: you can give them individual names, such as "Work" and "Home", so as not to get confused when making calls. Also on this menu is a switch that allows you to temporarily disable one of the SIM cards without physical extraction, which can be useful in roaming or areas of poor coverage.

An important aspect of initial setup is assigning the correct network types to each card, especially if one of them is solely for data transfer.The system can automatically identify the operator, but in rare cases manual selection of the network profile is required, especially for virtual operators or corporate tariffs. If the automatic selection did not work, you can use the manual network search function, although in most cases it is enough to simply restart the device after installing the card.

Setting Challenge Priorities and the Internet

The central element of dual SIM management in Xiaomi is the default settings block, which dictates to the system which line to use for various actions. In the SIM card and mobile menus, you will find three main items: Calls, Internet and SMS, where you can choose your preferred SIM card for each setting or leave the option "Always ask". The choice of the "Always ask" option for calls is convenient for those who often change plans or want to control costs in real time.

To set up the Internet, you need to choose the SIM card that has the highest traffic volume or the best speed in your region.It is worth considering that in most Xiaomi smartphones, only one SIM card can work in 4G/5G mode, while the second one automatically goes to 2G or 3G mode for voice communication. This is a technical limitation of communication modules, and switching both cards simultaneously to 4G mode is impossible without the use of third-party, often unstable firmware modifications.

If you change locations frequently, it makes sense to set up automatic Internet switching to a better-coated map, although this is difficult to do with regular MIUI facilities. Instead, many users resort to using switching apps that change priorities based on geolocation or Wi-Fi connectivity. However, for basic use, it is enough to install a map with unlimited Internet in slot 1 and configure it as the main one for data transfer.

SMS settings are worth special attention, as confirmation codes from banks and services often come to the card that is associated with the account. It is recommended to install the main SIM card for SMS to avoid missing important notifications, even if you call mainly from the second number. In the settings menu, you can also activate the "Use for 4G calls" function if your operator supports VoLTE technology, which will significantly improve the quality of voice communication.

Managing 2G, 3G and 4G network modes

Deep network modes allow you to optimize the smartphone in conditions of weak signal or specific operator requirements. By default, the system itself chooses the optimal communication standard, but the user can forcibly limit the operation of the SIM card to a certain range, for example, leaving the second SIM only in 2G mode for maximum battery power savings. To access these settings, you need to go to Settings → SIM cards and mobile networks → select the desired SIM card → Preferred network type.

In the list that opens, you will see options like “Preferred LTE”, “3G Only” or “2G Only”. Choosing “2G Only” mode for the second SIM, which is used only for incoming calls, can significantly increase the battery life of the device, since the module will not constantly search for 4G towers. However, it is worth remembering that in some regions operators are gradually turning off 2G networks, so this card may become unavailable for receiving calls in the future.

Sometimes, the phone gets stuck in 3G or 2G, not wanting to switch to 4G, even if the coverage is excellent, and this helps reset network settings or briefly turn on flight mode, which causes the modem to re-register online and choose the best available standard. Also check whether VoLTE is activated in the SIM card settings, as it allows you to conduct voice conversations simultaneously using high-speed Internet.

Solution: No network or weak signal

One of the most common problems when using two SIM cards on Xiaomi is the periodic loss of network on one of the slots or the complete absence of a signal. Often the cause is incompatibility of the operator’s frequency ranges and the capabilities of the modephone, especially if the phone is bought in China (Chinese version) and used in Europe or Russia. In such cases, the phone may simply “not see” the frequencies on which the second operator works, and no menu settings will help – you will need to flash it on a global version or use external antennas.

If the problem occurs suddenly on a previously working device, the first thing you need to do is reset your network settings. This action will not delete your personal data, photos or contacts, but will return all connection parameters to factory values, eliminating possible software conflicts. To do this, go to Settings → Connection and Sharing → Reset Wi-Fi, mobile networks and Bluetooth and confirm the operation.

⚠️ Note: After resetting your network settings, you will have to re-enter passwords from all saved Wi-Fi networks and re-interface with Bluetooth devices, as this data will be deleted.

Another cause of problems may be the physical wear of the tray SIM-maps or contact oxidation, which is especially true for devices that are used in high humidity or dust conditions, visually inspect the contacts on the map and on the phone, if necessary, wipe them with dry soft cloth. If the problem persists after all manipulations, try to move the SIM cards in places: if the problem "move" along with the card, then it is in it or in the operator, if it remains on the same slot - the phone is faulty.

Additional functions and optimization

MIUI offers a number of advanced features for dual-SIM users that can make life much easier. For example, Smart Numbers allows you to assign certain SIM cards to specific contacts, eliminating the need to select a line before each call. To set this up, open the Contacts app, select the number you want, click Change, and in the Default SIM card field, specify your preferred operator.

Also worth mentioning is the background limit feature for the second SIM card if it is rarely used, which helps save battery power by preventing the second card from constantly searching the network in the background when you are in the area of poor reception. In the SIM card and mobile network menu, you can find a "Take calls to the second SIM" switch, which allows you to completely block incoming to the second number, leaving only the Internet active.

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Use desktop widgets for quick switching of SIM cards: add the SIM Settings widget for instant access to line management without diving deep into the menu.

For business users, the conversation recording feature, which works independently for each SIM card, will be relevant, and you can set up automatic call recording from a specific number or from all incoming/outgoing calls, which is sometimes critical for documenting agreements. Recording settings are located in the Phone application → menu (three dots) → Call recording.

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Competent distribution of roles between SIM cards (one for voice, the other for the Internet) prolongs the life of the battery and speeds up the smartphone.

Frequently Asked Questions (FAQ)