How to set up 2 SIM cards on Xiaomi Redmi Note 9: the full guide

A modern smartphone is no longer possible without the ability to use multiple numbers at once. Owners of the popular Xiaomi Redmi Note 9 model often face the need to separate personal and work contacts, as well as optimize mobile costs. The dual-sim system allows you to flexibly manage tariffs, choosing the best offers from different operators for calls and mobile Internet. However, the correct initial configuration of the device is key to the stable operation of all communication functions.

The process of activating the second number on board this gadget does not require deep technical knowledge, but it has its own nuances that are important to consider when you first install. A combined tray can confuse an inexperienced user if you do not know the design features. In addition, the MIUI operating system offers a wide range of priority settings that by default may not work as the owner expects. Understanding these mechanisms will avoid signal loss or unforeseen traffic costs.

In this article, we will discuss in detail the physical installation of modules, the software setting of call priorities and the Internet, as well as the typical errors that occur during operation. You will learn how to correctly allocate roles between SIM cards and what hidden functions are available in the SIM management menu.

Physical installation of SIM cards and preparation of tray

The first step towards full-fledged operation of two numbers is the correct physical installation of chips in the device. the Redmi Note 9 model is equipped with a hybrid tray, which means the ability to install either two Nano-SIM SIM cards, or one SIM card and a microSD memory card. It is important to understand that the simultaneous use of two SIM cards and a memory card is impossible, so before starting the procedure you need to decide what is more important for you: memory expansion or the second number.

To extract the tray, use a special paper clip included in the delivery kit, or a thin needle.The extraction hole is located on the bottom end of the smartphone, usually to the left of the USB Type-C charging port. A light tap will cause the tray to slide out. Pay attention to the shape of the cutout: it corresponds to only one correct position of the chip. Don't put excessive effort unless the card enters easily, as this can damage the contact pads or tray mechanism.

⚠️ Warning: Before installing or retrieving SIM cards, it is strongly recommended to turn off the smartphone completely.Although current standards support hot replacement, in rare cases this can lead to a software failure in the communication module or data corruption on the operator's chip.

Once the cards are installed, gently insert the tray back into the case until the characteristic click.Make sure it has entered flatly and does not protrude beyond the frame to keep the design tight.If you use only one SIM card, it is usually recommended to install it in slot 1, although MIUI allows you to flexibly adjust priorities programmatically regardless of physical location.

Initial configuration and activation in MIUI system

Once you turn on your smartphone, the system will automatically detect the communication modules installed, a notification will appear on the screen about new SIM cards, suggesting that you configure them. If this does not happen, you should go to the settings menu manually. The path to the desired section is: Settings → SIM cards and mobile networks. This is where all the main levers of telephony control are concentrated.

In the menu that opens, you'll see a list of installed cards, and the first thing you need to do is activate them by switching the sliders to "On." You can give each card a convenient name, like "Work" or "Personal" to avoid confusion, and you can also choose a network standard, where the preferred 4G network type is the best option for most users, which provides high data rates.

Particular attention should be paid to the configuration of codes. PIN, if you plan to use unauthorized access protection, Enable the request PIN-If the card is new and does not have a pin, this step can be skipped, but the installation of protection is recommended for storing important contacts.

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Use the "Pseudonym" feature in SIM card settings to give them vivid names and colors, which will help you visually distinguish them in the call log and when sending messages, especially if you have similar contact names in the phone book.

Setting Call Priorities and Mobile Internet

The key to making two numbers comfortable is to distribute tasks between them correctly. The SIM and mobile menus have a section called Default for Calls and Default for Mobile Internet, and you can choose one specific card for all activities, or you can set the system up to ask you every time you make a call.

For mobile Internet, it is recommended to choose a card with the most favorable tariff plan for traffic. The system allows you to assign one card to the main data transfer, while the second one will be used only for voice communication and the second one will be used for the mobile network. SMS-This prevents expensive traffic from the main card from being accidentally consumed if you forget to switch the access point.

An important feature is the ability to select a SIM card for each particular contact. When dialing a number or sending a message, the system can suggest choosing which card to take action from if the global settings do not set a strict priority, and you can configure a permanent selection for favorite contacts, so that important work calls always leave the desired number without further questions.

• 📞 Voice calls: Set a priority card or Always Ask mode for flexibility.
• 🌐 Mobile Internet: Choose a card with unlimited traffic or a large package of gigabytes.
• 💬 SMS-Messages: Assign a primary map for outgoing messages by default.
• 🔄 Switching: Use a desktop widget to quickly change your Internet map.

Managing the schedule and modes of operation of SIM cards

MIUI provides advanced tools to manage SIM card activity depending on the time of day, the On/Off Schedule allows you to automatically deactivate one card at night or on weekends, which is especially useful for those who want to completely disconnect from work calls after the end of the day.

You can set up your schedule in the same SIM management menu, you set the start and end times, and you also select the days of the week when the rule will apply. For example, a working SIM card can automatically turn off at 19:00 and turn on at 9:00 in the morning, which helps not only to maintain work-life balance, but also save battery life, since the communication module will not search the network in the background.

In addition to time constraints, there is a Do Not Disturb mode that can be flexibly configured for each SIM card separately, in which incoming calls can be blocked or switched to silent mode, while important contacts from a select list can be reached, such selectivity allows you to remain available for emergencies, ignoring the usual information noise.

⚠️ Note: When setting up to automatically turn off the SIM card, make sure you have missed call notifications from the operator on. Otherwise, while the card is off as scheduled, you will not know about attempts to contact you and the subscriber will hear a standard unavailability message.

Solving typical definition and signal problems

Despite the fact that the process is fine, users may encounter situations where one of the SIM cards is not detected or loses the signal. Often the problem lies in the oxidation of the contacts or the loose fit of the card in the tray. Try to remove the tray, wipe the contacts of the SIM card with a soft dry cloth and install it again, making sure that the position is correct.

If the physical contact is fine but the network is not catching, check the network type settings. Sometimes the automatic choice of 4G/3G/2G mode is not working correctly in areas of uncertain reception. In such cases, forced switching to 3G Only or 4G Only mode through the engineering menu or standard settings helps, and you should also make sure that the SIM card is not blocked by the operator and there are funds in the account.

Failures in operation can be caused by software errors of the shell itself. MIUI. In this case, the effective solution is to reset the network settings, which will not delete your personal data, photos or applications, but will return all network settings, including access point settings. APN And Bluetooth, to factory values. → Connection and sharing → Reset Wi-Fi, mobile network and Bluetooth.

Optimizing battery consumption with two SIM cards

Using two active SIM cards inevitably leads to increased energy consumption compared to one communication module. Two radio modules constantly communicate with base stations, register on the network and exchange service data. To minimize the impact on the autonomy of the device, it is recommended to turn off the second SIM card if it is not used for a long time, for example, on vacation or during sleep.

Reducing energy consumption also helps limit the background activity of applications using the mobile Internet. In the battery settings, you can view in detail which programs are most charged and limit their operation in the background. In addition, using the power saving mode automatically optimizes the operation of network modules, disabling synchronization and reducing the frequency of network surveys.

Another important factor is coverage. If you are in a place where the signal of one of the SIM cards is very weak, the phone begins to increase the transmitter power to maintain the connection, which leads to rapid discharge and heating of the case. In such situations, it is advisable to temporarily switch the problem card to 2G only for calls or completely disable it before leaving the bad reception zone.

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The most effective way to save battery on two SIM cards is to turn off an unused card through the notification curtain or settings, and avoid areas with a critically weak signal where the phone is running at power limit.