Modern Xiaomi and Redmi smartphones have long ceased to be just devices for calls, turning into powerful multimedia centers, where the presence of two active numbers becomes necessary. Users often combine personal communication with work issues or use different tariff plans to save on calls and the Internet, which requires competent equipment configuration. Owners of popular models POCO and Black Shark also face the need to share communication flows without buying a second gadget.
The process of activating the second slot on devices with a MIUI shell or a new HyperOS is usually automated, but sometimes requires manual intervention to correctly operate mobile data. System algorithms can by default turn off one of the cards in the absence of a signal or try to redirect traffic to a less priority channel. Understanding the logic of the communication modules will avoid losing important calls and ensure stable access to the network.
In this guide, we will take a detailed look at all the stages of connection, from the physical installation of the chip to the fine-tuning of the program call priorities. You will learn how to correctly allocate roles between numbers and what hidden functions are available in the control menu. SIM-We will focus on solving common problems when the device does not see the second module or does not switch between networks.
Physical installation and primary definition of modules
The first step is always to properly install the card in the tray, as even a minimal skew can lead to no contact with current tracks. Most modern Xiaomi models use a combined tray where the second slot shares space with the microSD card, which requires careful installation. You need to use the original paper clip or a special key to not damage the pull-out mechanism.
After removing the tray, notice its shape: often one of the slots has a specific cutout or beveled angle indicating the correct position of the chip. If you insert the card incorrectly, it simply will not enter the groove until the end, and the forced pressure can break the contacts inside the smartphone. Carefully place the chip in the designated place, making sure that it lies flat and does not stagger.
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Installation SIM-wipe the golden contacts with dry soft cloth to remove oxidation and fatty traces that can worsen the signal.
Once the tray is returned to the housing, the device must vibrate and display a notification of registration in the network of the new operator. If this does not happen, check the integrity of the tray and the absence of dust inside the connector, as small villi often cause poor contact. In some cases, a complete restart of the system is required to initialize new equipment.
⚠️ Warning: Never try to insert the tray backside or force, this is guaranteed to break the motherboard and expensive repairs.
Basic activation through the settings menu
After a successful physical installation, you need to go to the software menu to manage communication parameters. On all current firmware versions, the path to settings is standardized, although the item names may vary slightly depending on the regional version. Open the Settings app and find the section SIM-maps and mobile networks, which are usually located at the top of the list or in the group of "Wireless Networks".
In the menu that opens, you'll see a graphical display of the installed modules where you can control their status. To activate the second number, you need to click on the corresponding icon and switch the switch to the On position. The system immediately starts searching for available cell towers and registers the device in the operator's network.
☑️ Verification of activation of the second SIM
You can also specify a name for each card to avoid confusion with outgoing calls, and select a color label for visual distinction, which is especially useful when viewing a call log, where the numbers of different operators will be highlighted in different colors, and it is recommended to immediately check whether the signal level display option for both active slots is included.
| Parameter | Description of function | Recommended value |
|---|---|---|
| Name. SIM-map | User name for identification | Working/Personal |
| Type of network | Preferred communication standard | Preferably 5G/LTE |
| Data roaming | Data transfer in networks of other operators | Turned off (for savings) |
| Voice calls | Selecting a default card for calls | Always ask |
| Mobile Internet | Data map | Main (with a large package) |
Setting Challenge Priorities and the Internet
The key to comfortable use of two numbers is the competent distribution of tasks between them, so as not to waste expensive traffic from the main card. SIM-There's a separate default block that assigns the main card for voice and mobile Internet, and it's logical to assign a SIM card to the Internet with unlimited rates, and for calls, one where a minute of conversation is cheaper.
The system allows you to flexibly adjust the behavior of the smartphone when outgoing calls: you can choose a permanent card or the “Always ask” mode, the latter option is preferred for those who often call different contacts, since it prevents accidental calls from the wrong number and gives full control over costs.
Incoming calls don't require settings, because the phone will receive calls to both numbers at the same time if they are active, but you should pay attention to the Smart Calls feature, which allows you to redirect calls to the second SIM if the first one is not on the network or it is busy, this ensures continuity of communication in all conditions.
⚠️ Note: When using navigation or video, make sure that the card with the Internet has a stable signal, otherwise the system may try to switch to the Internet.EDGE/3G, break-up.
Managing Contacts and Call Logs
Working with two numbers involves organizing contacts to understand which phone you are calling a particular person from. The standard Contacts and Phone app has a convenient tagging system that shows which number was used to contact the subscriber last time. When dialing, the system automatically substitutes the icon of the selected SIM next to the name.
If you want to force a card change for a particular contact, click on his name in the list and select the default option for calls. After that, all calls to this subscriber will go from the selected SIM without unnecessary questions and confirmations, this eliminates the risk of confusing numbers in a hurry.
Call log is also adapted to work with two lines: next to each number, a small number 1 or 2 is displayed, or a color label, which allows you to instantly know who called you and which line, which is especially important if the numbers are used for different areas of activity.
Synchronization of contacts
Solving the Problems of Defining a Second SIM
Sometimes users are faced with a situation where the phone stops seeing the second SIM card, although physically it is installed correctly. The first thing to do is to eliminate the software failure of the communication module by resetting the network settings. To do this, go to Settings → Connection and Sharing → Reset Wi-Fi, mobile networks and Bluetooth and confirm the action.
If the reset didn't work, check the SIM card itself on another device, as the chip may have malfunctioned or demagnetized. It's also worth trying to replace the tray or clean the contacts with alcohol if there is a suspicion of oxidation. In rare cases, the problem lies in the incompatibility of the operator's frequencies and the supported ranges of a particular smartphone model.
In situations where the second card is detected but not caught (writes "No Network" or "Emergency Calls Only"), try manually selecting the operator. Go to the mobile network settings, turn off automatic selection and wait for the list of available providers to appear, then select your own.
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A common cause of problems is an outdated firmware version, so always check for system updates in the About Phone section.
Features of working in modem and Hotspot
When using a Xiaomi smartphone as a Wi-Fi hotspot, it is important to consider which SIM card is chosen for data transfer. Internet distribution is possible only from the card that is assigned to the main mobile traffic at the moment. Switching between SIMs in active distribution mode can lead to a short-term connection break for connected customers.
Newer versions of MIUI have introduced a traffic restriction feature for the access point, which allows you to control the consumption of megabytes if you distribute the Internet from a limited rate, and you can set the limit in the section of the access point settings, specifying the limit amount of data or uptime.
It is worth remembering that when using hotspots, the device can heat up more than usual, especially if you use a 4G/5G network. In such cases, the system can automatically limit the speed or turn off the second SIM card to stabilize the operation of the radio module.