Modern smartphones from the Chinese manufacturer have long ceased to be just devices for calls, becoming powerful multimedia centers, but the basic functionality of communication remains critical for most users. Device owners often face the need to use two numbers at once: one for work contacts and the other for personal calls or more profitable tariff plans of mobile operators. Activation of the second SIM card on Xiaomi smartphones usually occurs automatically when installing the chip, but in some cases requires manual configuration through the interface of the operating system MIUI.
The process of launching the second number can vary depending on the version of the installed firmware and the specific model of your gadget, whether it is a budget Redmi or flagship Xiaomi Mi. Sometimes the system does not recognize the module immediately, requiring a reboot or change the slot settings, and in other situations the user simply does not know where to find the right switch in the menu. Understanding the logic of the communication modules will help to avoid unnecessary calls to the service center and save time for setting up personal space.
In this article, we will take a look at all the stages of connection, from the physical installation of the chip to fine-tuning call priorities and mobile Internet, learn how to correctly allocate tasks between numbers and what to do if the device stubbornly ignores the installed set. SIM-Competent configuration will ensure stable communication and no missed calls from any of your numbers.
Physical installation and primary module recognition
The first and most obvious step is to physically fit the chip into the device tray correctly. Most modern Xiaomi models use a combined tray, where the second slot can work either as a place for a second Nano-SIM SIM card or as a microSD card jack. You need to carefully inspect the tray: if there is space for memory, then installing a second SIM is only possible instead of a memory card, which limits the storage expansion. Carefully remove the tray with a clip, put the chip down with contacts and make sure that it sits tightly in the recess.
Once the tray is put back in the case, the phone usually detects a new communication module on its own. The screen should display a notification of network registration and assignment of a number, which often appears as "SIM 2." If this does not happen within a minute, it is worth checking whether the contacts on the chip itself or in the device slot are dirty. Sometimes it helps to simply wipe the contacts with a soft eraser or dry cloth, which eliminates oxidation that interferes with contact.
In rare cases, especially on older models or after a firmware update, the system may not see the module without a forced reboot.Rebooting the smartphone initiates a rescan of communication ports and often solves the problem with an undetectable number. If the second slot is silent after a reboot, it may be in the default settings it is disabled programmatically, which is a standard security feature of Android for saving energy.
⚠️ Warning: Never try to insert a SIM card into a phone that is off unless the tray supports hot replacement (although it is usually safe in Xiaomi), and never use force when installing to avoid damaging the contacts inside the slot.
Configure activation through the menu SIM-maps and mobile networks
If everything is physically connected correctly, but the second number is not working, you need to go to the software settings. MIUI, But the general logic remains the same across all the brand's devices. Open the Settings app and find a section that might be called "SIM-Maps and mobile networks, or simply "SIM-This is where the control center for both of your phone's communication modules is located.
In the menu that opens, you'll see a list of modules installed. If the second slot is displayed but marked off, just click on the switch next to it to activate. Here you can specify profile names, such as "Work" and "Personal", so you don't get confused about outgoing calls. This is especially useful when you need to quickly choose which number to call a particular contact.
Priority setting is an important aspect: the system allows you to choose which SIM card will be used by default for voice calls and which one for data transfer. Mobile Internet can only work on one card at a time, so choosing a main data provider is critical for stable application operation. You can also turn on the function "Receive calls to another SIM" if one card supports only 2G or is in a low reception zone.
☑️ Verification of activation SIM
Remember that in some regions or on certain firmware versions (especially Global ROM vs. Chinese ROM), item names may vary. If you can't find the right switch, search by settings by typing "SIM" in. This is the fastest way to get to the desired menu, bypassing complex interface directory structures.
Task distribution: Internet, calls and SMS
Once both numbers are successfully activated, the user is faced with the question of how to allocate resources rationally: Two SIM cards are not just two numbers, they are the ability to flexibly manage costs and quality of communication, for example, one card can be used exclusively for cheap mobile Internet, and the second card can only be used for incoming and outgoing calls at tariffs with free minutes on the network.
MIUI has a handy call management section where you can specify a specific SIM card for each contact or leave the option "Always ask." The latter option is often annoying when communicating actively, so it's better to set the main card by default. For SMS, you can also choose your preferred number, which will eliminate the accidental sending of messages from the work number to personal contacts.
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Use the Traffic Limit function for each SIM card separately so that an unexpected megabyte consumption on a secondary number does not lead to a negative balance.
VoLTE (Voice over LTE) is a special feature, and if your carrier and data plan support this technology, you should definitely turn it on for both SIM cards, which will allow you to conduct high-quality conversations simultaneously using fast 4G Internet, without switching to EDGE or 3G during a conversation.
| Parameter | SIM card 1 (Main) | SIM card 2 (Additional) | Recommendation |
|---|---|---|---|
| Mobile Internet | Included (4G/5G) | Off. | Use a card with unlimited traffic |
| Voice calls | By default. | On. | For a card with a free minutes package |
| SMS text message | By default. | On. | For bank confirmation codes |
| Network mode | Preferably 5G/4G | Preferably 4G/3G | To save battery power |
Solving problems with display and registration on the network
It's quite common for a phone to see a SIM card but write "No Network" or "Emergency Calls Only" because of the incompatibility between the carrier's frequencies and the ranges supported by the phone, especially if the device is purchased in the Chinese market. Check the specifications of your Xiaomi model on the official website and compare them to the frequencies of your carrier.
Another common reason is the blocking. SIM-code PIN. If you don't enter the unlock code when you turn on your phone, the card may remain inactive. SIM-If the code is lost, it can be restored through the operator's personal account or by contacting the communication salon with a passport.
What to do if you write "Unknown" SIM-map"?
Sometimes it helps to reset your network settings to factory settings, which will not delete your personal data (photos, contacts), but will return all network settings, including APN access points and Bluetooth settings, to the original state. To do this, go to Connect and Share and select Reset Wi-Fi, Mobile Networks and Bluetooth.
Dual SIM and Dual 4G **
Modern Xiaomi smartphones support Dual 4G technology, which allows both numbers to be on fourth-generation networks at the same time. Previously, when one card received a call, the second switched to 2G, making it unavailable for the Internet. Now, with Dual 4G enabled, both numbers can operate at high speeds, although active Internet traffic still goes through only one of them.
To activate this mode, go to the settings SIM-Maps and find the item "Use the map" 4G second SIM-Once you turn on, you'll see that both of the network's indicators show the icon. 4G or LTE. This significantly improves the quality of communication and the speed of switching between numbers.
Keep in mind that the two modules can be used in 4G mode to increase battery consumption slightly. If you are in a safe reception zone and you are not critical of the top speed on the second number, you can manually switch it to 3G/2G mode to save energy. The balance between performance and autonomy is customized by each user.
Features of working with virtual eSIM on Xiaomi
Xiaomi’s new flagship models are supported by eSIM technology, a built-in SIM card that does not require a physical media. QR-This allows you to have three or more numbers on the same device, switching between them software.
To activate eSIM, make sure your data plan supports this technology. SIM-The card will be "Add a tariff plan" option, and once the code is scanned, the profile will be loaded into the phone's memory, and virtual numbers can be managed as easily as physical numbers, assigning them to the Internet, making calls, or completely disabling them.
⚠️ Note: When you reset your smartphone to factory settings, eSIM profiles can be deleted. Before the reset procedure, be sure to back up your profiles or ask the operator how to restore them.
The use of eSIM is especially relevant for travelers, allowing them to connect local fares without finding a tray and replacing physical chips. However, at the moment, support for this technology in Russia and several other countries may be limited by legislation or lack of offers from operators.