Owning a Xiaomi smartphone often involves using two SIM-However, there are situations when there is an urgent need to quickly deactivate one of the slots, for example, if a bad signal in a particular area or to save battery power. Users are looking for ways to turn off the second line so they don’t take out the physical card every time.
The MIUI or HyperOS shell interface provides multiple layers of access to control communication modules. Standard settings make it easy to switch active SIMs, but sometimes require deeper immersion into the system. In this article, we will break down all available methods, from simple switches to engineering menus.
Incorrect network settings can cause the phone to stop picking up the signal at all or to constantly search for the network, consuming energy. So it is important to understand the difference between a temporary shutdown and a complete lock of the slot. We will look at safe algorithms of actions that will not harm the software of your device.
Standard SIM card management through settings
The easiest and safest way to deactivate the second line is to use the built-in interface of the system. In modern versions of Android based on MIUI, this process is as simple as possible for user convenience. You do not need third-party applications or root rights.
To start, open the Settings menu and find the section. SIM-Maps and mobile networks, and you can see both slots if you have cards on them, and you can manage each one independently, so you can have the flexibility to prioritize.
Click on the icon of the second SIM card to see the detailed menu. At the top of the screen is usually a switch Use Use. SIM-If you put it in an inactive state, you completely shut down the communication module for this slot.
⚠️ Note: After disabling the SIM card through settings, incoming calls and SMS This number will not be available.
If the switch doesn't respond or the interface freezes, try restarting the device. Often, the software failure of the communication module is solved by a simple restart of the system, after which the control returns.
Using flight mode to temporarily lock
Sometimes you don't have to turn off a particular SIM card, but the entire radio module of a smartphone, which is true in airplanes, hospitals, or places with extremely unstable surfaces, where the phone is constantly trying to catch a signal, and flight mode is a radical but effective method.
To activate this mode, lower the notification curtain and tap the aircraft icon. All wireless interfaces, including Wi-Fi, Bluetooth and mobile communications, will be immediately deactivated, ensuring that none of the lines will consume power.
However, if your goal is to keep one line active and the other off, this method is not suitable in its pure form, in which case you can use a trick: turn on the flight mode, then manually activate Wi-Fi and, if the firmware version allows, only turn on one SIM card through the settings, previously disabling the second.
Some Xiaomi models have an extended flight mode menu. Press the power button to trigger the shutdown menu, and select the aircraft icon. This gives access to more subtle settings if supported by a particular version of the shell.
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Use the Flight Mode widget on your desktop for quick access if the standard curtain is occupied by other controls.
Setting priorities and switching data
Often, users confuse a complete disconnection of a line with a prioritization switch, and if your goal is to make the Internet work only through one card and calls are received to another, you don't have to turn off the second line completely.
On the menu. SIM-There's a default settings section for maps and mobile networks, and you can choose a voice map and a mobile map, which allows you to optimize your costs by using a tariff with cheap minutes to call, and a high-traffic map for the web.
Smart Data Switching is also available, and if the main card for the Internet loses its signal, the system will automatically switch to the second card, which is useful for travel, but can lead to unexpected costs if the second card does not have an unlimited tariff.
- 📱 Open the SIM card settings and select “Mobile Internet».
- 📞 Install your preferred card for Voice Calls».
- 📉 Turn off the Smart Switch option if you want to tightly control your expenses.
☑️ Checking network settings
Engineering menus and hidden codes
For advanced users who don't have enough standard settings, there's an engineering menu, a hidden part of the system that's designed to be used for testing by engineers, where you can force certain frequency bands or even specific slots at the driver level to be disabled.
To enter the engineering menu, open the Phone app and dial ##4636##. If the code works, the Test menu will open. Select Phone Information. This can show the status of each SIM card.
In some versions of Xiaomi firmware, this code does not open the full menu, but requires additional password or activation through ADB. If the standard code does not work, you can try the code ##3646633##, which leads to EngineerMode.
⚠️ Warning: Changing the settings in the engineering menu without understanding their function can cause signal loss or unstable phone performance.
Inside the EngineerMode menu, go to the Telephony -> World Mode tab. Here you can try selecting a mode for only one SIM card, although the functionality depends heavily on the processor model (MediaTek or Qualcomm).
What do I do if the codes don't work?
Comparison of methods of disconnecting the second line
The choice of method depends on your ultimate goal, and if you just want to save energy, one method will do, if you avoid calling, another. Below is a table that helps you determine the best solution for your situation.
| Method | Difficulty | Efficiency | Risks. |
|---|---|---|---|
| Through MIUI settings | Low. | Tall. | Absent. |
| Flight mode | Low. | Full (both lines) | You can't leave one active. |
| Engineering menu | Tall. | Maximum | Possible malfunctions |
| Physical extraction | Medium | 100% | Wearing the tray |
As you can see from the table, software disabling through standard settings is the most balanced option for most users. It's safe and reversible in one click.
Engineering methods should be considered only in extreme cases, when standard tools do not help solve the problem with a “glutching” SIM card.
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The standard MIUI settings provide 99% of the functionality needed to manage SIM cards without risk to the system.
Frequent problems and their solution
Xiaomi users sometimes face a situation where a second SIM card disappears from the list or appears as "No Service" even if it is enabled.This can be due to a frequency range conflict or a software glitch.
Try resetting your network settings. Go to Settings -> Connection and Sharing -> Reset Wi-Fi, mobile networks and Bluetooth. This action will return all network settings to factory values, but will not delete your personal data.
Another reason could be that the old-style SIM card is incompatible with the new slot: Make sure the card is cropped properly and sits tightly in the tray. Poor contact is often perceived by the system as lacking a card.
- 🔄 Reboot your smartphone after any changes to your network settings.
- 💾 Make a backup of contacts before resetting network settings.
- 🔍 Check if the SIM card is blocked by the operator.
If the problem persists after all the manipulations, the SIM card tray itself or the device's antenna module may have malfunctioned, in which case a diagnosis at the service center will be required.