How to switch SIM card on Xiaomi phone: full guide

Owners of Xiaomi, Redmi and POCO smartphones often face the need to quickly change the active SIM card, especially if the device supports two numbers at once. The MIUI shell or the new HyperOS offers flexible management tools, but they are not always obvious to the user at first glance.

Changing your SIM card can be required in a variety of situations, from simply switching to faster internet to solving coverage issues in a particular location. Sometimes the system itself offers to choose a card for a call, but for constant use it is more convenient to configure strict rules for routing traffic. SIM-mapping on Xiaomi devices.

It's important to understand that physical card swaps and programmatic prioritization are different processes, albeit interrelated. If you just installed a new SIM card in a tray, it needs time to register online, and it needs the right access point settings. Let's figure out how to manage this process as efficiently as possible.

Basic setting SIM-maps in the control menu

The first step for any user is to learn the standard map management menu, and that's where the basic parameters of the communication modules are set. To get into this section, you have to open Settings and find the item. SIM-maps and mobile networks. Depending on the firmware version, the path may be slightly different, but the logic remains the same.

In the window that opens, you'll see a list of all the cards installed, and you can set the names for each number to keep things from getting confused, like "Work" and "Personal." This is especially useful when you need to quickly understand which card is coming from, and you can also set the priority for default voice calls.

The situation is a little more complicated for the Internet, because it allows you to choose one card as the primary card for data transfer, and if you want to switch the mobile Internet to another SIM card, just tap the appropriate item in the list and select the desired number, the changes take effect instantly, without rebooting the device.

It's worth noting that when you activate the Internet on one card, the second automatically goes to standby or 2G/3G if VoLTE is not enabled. This helps save battery life. Remember to check if you have activated Smart Switch Mode, which can change priorities on its own when a bad signal is triggered.

Physical replacement and installation of a new SIM card

If the software settings don't help or the SIM card is physically out of order, it will need to be replaced. In modern Xiaomi models, the card tray is usually combined or hybrid. Before removing the tray, it is advisable to turn off the device, although the Hot-swap standard allows you to do this on the go, but with the risk of data loss or damage to contacts.

Use only the original paper clip or the special key included in the kit. Inserting foreign objects can damage the mechanism of the card presence sensor. After removing the tray, note the location of the contacts: the golden part should look down, and the bevelled corner of the card should match the shape of the tray.

Once the phone is installed and turned on, the system must automatically identify the new card. If this does not happen, check if the card is tight in the tray. Sometimes it helps to clean the contacts with a smooth sweep. If the phone says "No SIM", try installing the card in another slot, as one of them may be software locked by the operator or have a physical defect.

⚠️ Warning: Never insert a SIM card into your phone until the tray is fully removed.Attempting to push the card into a slot without a tray is guaranteed to cause the reader to break and costly repairs.

Switching between 4G, 5G and 3G to improve communication

Often, by switching a SIM card, users mean changing the network type to improve communication quality. In areas of unstable coverage, 5G or 4G can perform worse than the good old 3G. On Xiaomi phones, this is solved through the network type selection menu.

Go to the settings of a particular SIM card and find the preferred network type. Here you can force the module to LTE Only or, conversely, to 3G preferably, this helps to "re-register" the SIM card to the nearest tower if the current one is overloaded.

To access the hidden engineering menu, where you can configure the radio module in more detail, you can use a special code.

##4636##

From the menu that opens, select Phone Information. From the Set Preferred Network Type section, you can select a specific standard. Be careful: choosing the wrong setting can temporarily leave the phone without communication.

Configure Access Points (APN) for a new SIM card

When switching a SIM card or changing the operator, there is often a situation where the Internet is not working, although the balance is positive.The reason is because of the APN hotspot settings. On Xiaomi, they may not automatically update when the card is first installed.

To fix this, go to Settings. → SIM-maps and mobile networks → select the desired card → Access points (APN). Click the New Access Point button or reset to factory settings if the list is empty or contains erroneous data.

Once you enter the data, be sure to save the profile and select it by ticking or radio buttoning. Without this step, the new parameters will not apply. If the Internet does not work immediately, turn on and off the REM flight to restart the radio module.

Using scenarios and automation

MIUI is famous for its automation tool, which allows you to switch SIM cards or change their settings on a schedule, which is useful if you need to have a corporate card take calls during work hours and a personal one in the evening.

Open the Security → Auto Run app (or find the Scripts app). Create a new script by adding the Time or Location condition. Select Settings → Mobile Network → Call Map as the action.

💡

Use Do Not Disturb mode in conjunction with SIM switching. Set your phone so that the second SIM card is switched to Emergency Calls Only at night so that you do not disturb advertising calls.

You can also create a scenario to save traffic, such as when connected to a home Wi-Fi, a phone can automatically turn off mobile internet on a second SIM card, leaving only the basic one active for important notifications, a subtle but useful setup for advanced users.

Solving problems with the definition of the second SIM card

A common problem with two-sym Xiaomi is that one card works and the other card is displayed as “Unknown” or constantly searching for the network, often due to a conflict of communication standards or an outdated version of basic radio communication.

Try swapping slots. Sometimes the first slot is prioritized for 4G/5G, and if you put a more modern card in there and the old one in the second, the conflict can disappear. Also check if the flight mode for the second slot is turned on in quick settings.

⚠️ Note: If the phone stopped seeing the SIM card after falling or getting moisture, do not try to heat the hair dryer or put in rice.

In rare cases, network resets help. Go to Settings → Connection and Sharing → Reset Wi-Fi, mobile networks and Bluetooth. This action will remove stored Wi-Fi passwords, but often solves software glitches with logging into the network.

💡

If none of the software settings worked, the problem may be the physical wear and tear of the SIM card itself. Contact the operator's salon for a free replacement with a new one with support for modern standards.

Frequently Asked Questions (FAQ)