How to turn on the second sim on the Android Xiaomi Redmi

Modern Xiaomi smartphones and the Redmi sub-brand are almost always equipped with a hybrid slot or a full-fledged dual tray, which allows users to use two numbers at the same time. This is especially true for those who share work and personal contacts or want to save on tariffs by combining offers from different operators. However, after buying a device, many owners face a situation where the second slot is not active by default or does not work correctly.

Activating an additional communication module is not a complicated process, but it requires attention to detail, especially when it comes to setting up 4G/LTE networks and traffic distribution. In the shell of MIUI or the new HyperOS, this is a special section where you can flexibly adjust your call and mobile Internet priorities. If you just unpacked your gadget or replaced your SIM card, the correct initial configuration will eliminate problems with the missing network in the future.

In this article, we’ll go into all the steps from the physical installation of the card to the subtle software prioritization, learn how to avoid frequency conflicts and why sometimes the second SIM can’t be detected by the system without manual intervention. Importantly, a hybrid slot means you can use either two SIM cards or one SIM card plus a microSD card, but not all three elements at once.

Physical installation SIM-cardboard

Before you get to software settings, you need to make sure that the physical setup is done correctly.The card tray in Redmi smartphones is usually located on the bottom or side end of the case and is removed using a special clip that comes with the kit. Be careful when extracting, so as not to damage the mechanism or scratch the device body.

Depending on your smartphone, the design of the tray may be different. In budget models, there is often a hybrid version where the second socket is combined with a place for a memory card. Flagship devices are more likely to receive full-fledged dual slots that allow you not to sacrifice memory for the second number. Pay attention to the shape of the chip cutout - it should exactly match the shape of the Nano-SIM card.

When installing, it is important to observe the orientation of the contacts. The chip should be directed down to the contacts of the phone, and the cut corner of the card usually indicates the correct position. If you use adapters or old-format cards, make sure that they do not hang in the socket, as this can lead to poor contact and periodic disappearance of the network.

• 📱 Use the original paperclip from the box so as not to damage the tray extraction sensor.
• 🔍 Check the purity of the SIM card contacts and wipe them with a soft dry cloth before installation.
• 🚫 Do not insert the card by force; if it does not enter easily, check for correct orientation.
• 🔄 After installing the tray, wait for the system to fully load before checking the signal.

⚠️ Warning: Never try to remove or insert a SIM card while the phone is on unless the model supports hot replacement (although most modern Android smartphones allow it, the risk of damaging contacts if handled carelessly remains).

Initial activation via MIUI settings

Once the cards are installed and the device is on, Android must automatically identify new modules. New SIM cards may be notified on the lock screen or at the top of the display. To get started, you need to go to the settings menu and activate both slots, as sometimes one of them can be disabled by software default.

To do this, go to Settings, then select SIM cards and mobile networks, and here you will see a graphical display of both slots. If the card is correctly defined, next to the slot number, the operator name and signal level will appear. If the message "No" is displayed. SIM-maps, check the density of the adjoining card in the tray.

You can also use the same menu to name each SIM card, like "Work" and "Personal", to avoid confusion when making calls, and you can also adjust the color of the indicator in the notification curtain, which visually helps you distinguish which card is the active connection or the call is received, which is especially convenient when using two numbers from the same operator.

Remember that to work both cards simultaneously, the device must support Dual SIM Dual Standby (DSDS) technology, which means that both SIMs are online and ready to take the call, but there can only be one active voice channel. If you are in a conversation on the first line, the second will not be available to incoming ones, although the subscriber will hear the "busy" signal or redirect.

Setting Call Priorities and the Internet

One of the most important tasks is to correctly allocate roles between SIM cards. A smartphone needs to know which card to charge for mobile Internet and which to use for voice calls by default. SIM cards and mobile networks have a section on the "Default for" menu, where preferences for calls, SMS and data are selected.

To transfer data, it is recommended to choose the card with the highest traffic packet or the best 4G coverage in your region. The system allows you to switch the Internet between SIM cards directly from the notification curtain, which is very convenient for roaming or when traveling outside the city. Voice calls can be configured to use the main card, leaving the second for rare calls or only for reception.

The network switching feature during a conversation is particularly noteworthy: if you are talking on the first SIM, and at this point an important call comes to the second, the system may suggest switching, in the settings you can activate the option to take a second call, put the first on hold, or automatically reset the incoming to the second line during a conversation.

⚠️ Note: When using two active SIM cards, mobile internet speed on one of them may decrease as the smartphone antenna divides the resource between the two communication channels. DSDS.

Solving the Problems of Defining a Second SIM

Sometimes users are faced with a situation where the phone sees only one card despite the correct physical setup.The first step in diagnosis should always be to recheck the tray. Make sure the contacts on the SIM card itself are not oxidized and have no mechanical damage. Also try to install the card in the first slot - if it works there, the problem may be in the second slot or its settings.

The second common cause is a software failure in the radio module, in which case the network reset helps. Go to Settings → Connection and Sharing → Reset Wi-Fi, mobile network and Bluetooth. This operation will not delete your personal data, but will return all network settings to factory values, which often eliminates driver conflicts.

If the problem persists, check frequency compatibility. Operators use different frequency bands for 2G, 3G and 4G. If your smartphone purchased in one region does not support operator frequencies in another region, the second SIM may not catch the network or only work in 2G mode. Up-to-date information about the supported frequencies can be found on the manufacturer's official website in the model specifications.

Table of supported network modes

Understanding how your SIM card is running helps diagnose speed or quality issues. Below is a table of the main modes of networking that most modern Xiaomi and Redmi devices support.

In mobile Internet settings, you can choose the preferred network type. It is recommended to leave a value Preferably LTE or 5G/LTE/3G/2G (auto). Forced on only 4G can lead to the fact that in the area of insecure reception you will be left without communication, as the phone will not be able to switch to a more stable 3G.

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If the second SIM is only used to receive SMS from the bank, in the settings of this card you can turn off data transmission and voice calls, leaving only the "Network Only" mode, which will save battery power.

Optimization of two SIM cards

Using two active SIM cards increases the load on the processor and radio module of the smartphone, which can affect battery life.To minimize energy consumption, turn off 5G network search if you are not actively using this standard, or limit the background activity of applications for the second SIM.

Also worth paying attention to is VoLTE (Voice over LTE) feature, which allows voice calls over a 4G network, providing high audio quality and the ability to use the Internet and phone simultaneously. Make sure that your operator supports this technology and the service is activated in the tariff. You can turn on VoLTE in the SIM card settings menu, if the item is hidden - sometimes you need to enter a special operator code.

For owners of older Redmi models, the problem with heating the case during long conversations with two active SIMs may be relevant, in such cases, it is recommended to check in the developer settings or in the engineering menu whether the phone is working in enhanced network search mode, and if necessary, limit the processor frequency or close background applications.

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For maximum stability, make sure both cards are registered on the same standard (e.g., both 4G) if your phone supports Dual 4G VoLTE technology.

Frequently Asked Questions (FAQ)