Owners of Xiaomi, Redmi and Poco smartphones often face the need to initially configure the device, where the key stage is activation. SIM-Despite the apparent simplicity of the process, modern shells MIUI HyperOS has its own nuances that can cause difficulties for an untrained user, especially devices imported from other regions or older models that require manual profile adjustments.
Incorrect activation can cause the phone to not see the network, not be able to send MMS or operate 4G/LTE. In this article, we will take a detailed look at all aspects of smartphone interaction with the SIM card, from the physical installation to hidden service menus, you will learn how to properly configure access points and what to do if the device says “No network” or “Only emergency calls".
Physical installation and primary map definition
The first and most obvious step is to install the right system. SIM-Modern Xiaomi smartphones use combined trays or separate Nano-SIM slots. It is important not to confuse the orientation map and make sure that the chip contacts are pointing down, unless otherwise indicated by the pictogram on the tray. After switching on the phone, the system automatically reads IMSI-code and try to register in the operator's network.
If the device does not respond to the installation of the card, you need to check the integrity of the contacts and the tray itself. Sometimes the problem lies in the oxidation of the contacts or mechanical damage to the chip of the SIM card itself. In such cases, it is recommended to wipe the contacts with dry soft cloth or replace the SIM card from the operator with a new one with 4G/5G support.
It is worth noting that some global firmware versions may have restrictions on certain frequencies or operators if the phone is designed for the Chinese market, in which case activation may be successful, but the network will be caught unstable or only in 2G/3G mode.
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Use the original paperclip to extract the tray, so as not to damage the mechanism of the card sensor inside the smartphone.
After the physical installation, Android sends a request to the operator’s network, and if it’s successful, the signal level icons and connection type (H+, 4G, 5G) will appear at the top of the screen, and the absence of these indicators indicates a software failure or account problem.
Service activation through the engineering menu
For deeper diagnosis and forced activation of the SIM card in Xiaomi smartphones, there is a special engineering menu, accessed through a set of combinations of numbers in the Phone application, which is a powerful tool that allows you to switch modems and reset network settings at the system level.
To get into the testing menu, open the dialer and enter the code ##4636##. If the code is entered correctly, the screen will automatically switch to the Testing page. Here we are interested in the Phone Information section. This section is where the key switches for controlling the radio module are located.
Inside the section, you will see a list of installed SIM cards (SIM 1, SIM 2).
- 📱 Switch the preferred network type (e.g., force-exposure) LTE Only or NR/LTE/GSM).
- 🔄 Reset the connection to the base station by selecting the option "Turn off radio" and then "Turn on radio".
- 📡 Check the current status of the signal and running pings.
- ⚙️ Change the settings IMS (IP Multimedia Subsystem for the correct operation of VoLTE.
What is Ping Test on the Engineering Menu?
Using these settings requires caution: Incorrect network mode selection (for example, installing LTE Only on a phone without support for VoLTE from the operator) can lead to a complete loss of voice communication, since in 4G mode only normal calls do not pass.
Configure APN access points for the Internet
A common problem after activating a SIM card is the lack of mobile Internet, even if there is a signal, this is due to incorrect or missing settings of the APN access points (Access Point Name). Without the correct APN, the phone does not know through which gateway to send data to the operator's network.
Usually the settings come automatically in the form of SMS You need to manually prescribe them from the operator when you first register. → SIM-maps and mobile networks → Select a SIM card. → Access points (APN).
In the access point menu, click the "New Access Point" button or the plus in the corner of the screen, and you need to enter data that can be found on your operator's website.
- 🌐 Name: any convenient name (e.g, MTS Internet).
- 🔗 APN: domain name of the access point (for example, Internet.mts.ru).
- 👤 Username and password: often left blank or matched with login.
- 🔢 Type APN: Usually stated default,supl.
☑️ Checking settings APN
Once saved, make sure to select the access point you created (the green checkmark should be displayed) and restart the device, a critical step, as changes only take effect after the radio module restarts.
Solving problems with registration on the network
A phone that writes “No Network” or searches endlessly for a network can be caused by software conflicts or IMEI lockdowns, and it’s worth checking if the phone is locked by the operator, especially if it’s bought from hand or brought from abroad.
You can use special online services over IMEI to check the lock status, and you should try resetting the network settings to factory settings, which will return all modem parameters to their original state, removing possible configuration conflicts.
The table below shows the main symptoms and possible solutions:
| Symptoms. | Possible cause | Decision |
|---|---|---|
| Always "No net" | The wrong firmware region | Changing the region in settings or reflashing |
| Only 2G/3G | Lack of LTE in settings | Selecting "Preferred LTE" mode in the SIM menu |
| They don't come. SMS | Overflowing. SIM-memory | Clearing of messages SIM-map |
| Incoming don't pass | Redirects are on. | Disabling redirection via USSD code |
If simple methods don’t work, you may need to reset all your phone settings to factory settings.Be sure to back up important data before doing so, as all the information will be deleted.
Mi Account and phone number binding
Xiaomi’s ecosystem is closely linked to the Mi Account, and when a new device is activated or reset, the system can request confirmation of the phone number to which the account is registered, a security measure designed to protect user data in the event of a device being stolen.
The activation process requires a stable Internet connection. If the SIM card is not activated for data transfer, use Wi-Fi. Enter the phone number in an international format and wait for the SMS with the confirmation code.
It is important to understand the difference between activating a SIM card from an operator and activating a Xiaomi account: the first gives access to the network, the second gives access to cloud services, device search and contact synchronization. Without a confirmed number, some MIUI functions may be limited.
⚠️ Warning: Never enter the Mi Account confirmation code on third-party sites.The code should only come in the official Security app or in the phone's settings menu.
If you change your phone number, be sure to update your Mi Account profile through your website or other trusted device so you don’t lose access to your account the next time you activate your smartphone.
Specificity of activation for different regions
Global (Global) and Chinese (CN) versions of Xiaomi firmware have differences in modem software. Chinese versions may not support some LTE frequencies used in Europe or Russia, leading to unstable Internet performance even with proper APN setup.
Chinese firmware may also lack automatic configuration of access points for foreign operators, and users of such devices often have to manually prescribe APN settings, as the database of operators in the system is limited to the region of China.
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For stable operation in Russia and the CIS, it is recommended to use smartphones with global firmware (Global ROM), where local frequencies and operators are already taken into account.
It’s also worth considering that some Google services may not work properly on Chinese versions without additional installation of Google Play services (GMS).Although this does not directly affect SIM activation, it can prevent applications that depend on the network from working.
If you purchased a device from China, check the manufacturer's supported bands list and compare them to your carrier's frequencies, for example, missing the 20th band (Band 20) can make it harder to receive signals in the countryside.
Frequent errors and methods of their elimination
One of the most common mistakes is the message "SIM-The card is not installed, although it's physically inserted, and this could indicate software driver failure or contact contamination, try removing the card, wipe the chip, and insert it again with a slight swaying of the tray.
Another common problem is that you can't make a call when you have a signal, check if you have activated the "Block Inbox" or "Black List" function, and make sure that you have funds on your balance and the fare has not expired.
- 🔋 Restart your device in Safe Mode to eliminate the impact of third-party apps.
- 📲 Update the basic modem firmware through the system update menu.
- 🛠 Reset your network settings via the Recovery Mode menu).
⚠️ Warning: If the phone starts to warm up in the antenna area after installing the SIM card, immediately remove the card.This may indicate a short circuit or a malfunction of the power controller.
In cases where software methods do not work, there is a high probability of hardware malfunction, it can be a damaged antenna module, a plume or the smartphone board itself, in such situations, diagnostics are required in an authorized service center.