How to activate the second SIM card on Xiaomi: setup and management

Owners of modern smartphones often face the need to use several numbers to separate personal and work contacts. In Xiaomi and Redmi devices, the implementation of the Dual SIM function is performed at a high level, but the process of initial activation can have its nuances.

Activation of the second slot does not always occur automatically after installing the card. MIUI or HyperOS requires manual check of network settings to ensure a stable connection without breakage. Ignoring this stage can lead to the phone only working in 2G mode or not seeing the operator at all.

In this guide, we’ll take you through all the steps of connecting, from physical installation to fine-tuning data priorities, how to avoid typical errors and why a second SIM card might not work in certain modes, and make the most of your smartphone’s capabilities.

Physical Attitude and Primary Definition

The first and most obvious step is to properly install the card in the tray.Modern Xiaomi models most often use a combined tray where the second slot can share with the microSD memory card. It is important to make sure you are using a standard Nano-SIM size, as cropped cards may not be in contact with the connector properly.

After removing the tray with a paper clip, carefully examine the contacts. They should not be oxides or dust. Put the card in the appropriate slot, observing the shape of the cutout. Usually the layout is drawn on the tray itself or on the protective film of the smartphone. If you use a hybrid slot, make sure that the memory card does not block the contacts of the SIM card.

Once the device is turned on, the system must make a distinctive sound or display a notification of registration on the network. If this does not happen, check if the card is tightly ground. Sometimes it requires a slight pressure on the tray when closing, but without undue effort to not damage the mechanism.

• 📱 Make sure the phone is turned off before installing or replacing the SIM card to avoid short circuits.
• 🔍 Wipe the golden contacts of the SIM card with a soft dry cloth if it has been lying for a long time without using it.
• 📐 Use the original paper clip or special key so as not to damage the tray extraction mechanism.

It is worth noting that in some budget models, the second slot can only support 2G/3G networks, while the first one works with 4G/5G. This is a technical limitation of a particular communication module, not a software bug. If you are critically important to high-speed Internet on the second card, specify the specifications of your model in the official description.

Setting Call Priorities and the Internet

Once a physical connection is successful, you need to set up the logical operation of the numbers, and in the MIUI shell, a separate menu section is responsible for this, where you can flexibly manage traffic and voice flows, and by default, the system can assign one of the cards to the main for all operations, which is not always convenient.

To access the settings go to Settings → SIM-You'll see a list of active cards here, and if you click on the one you want, you can set the behavior in detail, for example, for a work SIM, you should turn off the data transmission, leaving only the voice and the voice. SMS, Not to waste the main tariff traffic.

Pay special attention to the item "Use mobile Internet" here you select the map through which you will access the network. If you switch between operators often, it is convenient to add a SIM card management widget to the desktop for quick access.

⚠️ Note: When the Traffic Saving or Flight Mode function is enabled, the second SIM card can be temporarily disabled by the system to save battery power, even if it is active in the settings.

There is also a mobile internet password for each SIM card separately, which is a useful option if children use the phone or if you want to prevent accidental roaming costs, and a password is requested when you try to activate data transfer through your chosen profile.

Solving problems with the definition of the second SIM card

It's not common for a phone to see only one card out of two, but it requires careful attention. Most often, the problem is a software failure of the communication module or a conflict of network settings. First, try rebooting the device, which allows the module to re-enter the operator's network.

If the reboot didn't work, check the network type settings. → SIM-maps and mobile networks → Choose a network to make sure that there is no limit to 5G or 4G, If your operator in the area is mixed, sometimes manual selection solves the invisibility problem".

In rare cases, network settings may need to be reset.This action will return the connection settings to factory values, but will not delete your personal files or contacts.The path to function: Settings → Connection and Sharing → Reset Wi-Fi, mobile networks and Bluetooth.

• 🔄 Perform a “soft reset” of the network through the settings menu before making a complete device reset.
• 📡 Check if the data roaming service is active if you are located abroad or in a region with coverage from another operator.
• 🧪 Test the second SIM card in the first slot to rule out physical malfunction of the card itself or the second connector.

If none of these methods worked, it might be the firmware problem. Make sure you have the current version of MIUI installed. Developers often release patches that fix the modem errors of specific operators.

Using VoLTE and 5G on two SIM cards

VoLTE (Voice over LTE) technology allows voice calls over fourth-generation networks, providing high sound quality and fast dialing. On Xiaomi smartphones, Dual VoLTE support is implemented at the level of most modern processors, but requires activation.

To enable, go to the settings of each SIM card and find the "Use VoLTE" switch. If the operator supports this function, an HD or VoLTE icon will appear next to the signal indicator. It is important to understand that when calling via VoLTE, the Internet does not switch to 3G, remaining in 4G/5G.

The 5G situation is a bit more complicated. While many Xiaomi models technically support two cards on fifth-generation networks, in practice, the Dual SIM Dual Standby (DSDS) scheme is often implemented, which means that both cards are on the network, but active high-speed traffic or call only goes through one of them at a particular time.

When you talk actively on the second SIM card, the first one can temporarily go to standby or 2G/3G, if the Dual 4G/5G Standby function is not enabled. This is normal behavior to save the resources of the antenna module. You can check the support status in the specifications of the processor of your smartphone.

Table of comparison of SIM modes of operation

To better understand how SIM cards behave in different use cases, we have prepared a comparison table that will help you choose the optimal configuration depending on your needs for speed and stability of communication.

As you can see from the table, using two active cards increases the battery load. If you're in a hot spot, the phone will constantly search for the network, which will further speed up the discharge. In such situations, it's helpful to temporarily turn off an unused SIM card through the software menu without physically removing it.

FAQ: Frequently Asked Questions

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To quickly change the active SIM card for calls, add the Two SIM card widget to your desktop, which allows you to switch the priority number in one click without going into the deep menu settings.

Properly configuring a second SIM card on Xiaomi opens up new opportunities for communication management. Following these guidelines will ensure stable communication and efficient use of your smartphone resources. Remember to check periodically for system updates, as they often contain improvements to the modem.

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The main secret of stable operation of two SIM cards is timely firmware update and proper configuration of APN for each operator separately.