How to set up 2 lines on the phone Xiaomi Redmi 9

The modern smartphone has long ceased to be just a device for calls, becoming a digital life management center, where you often need to separate personal and work communication. Xiaomi Redmi 9, one of the most popular budget-friendly models, offers users an excellent opportunity to use two SIM cards at once, which eliminates the need to carry two devices. However, many owners face the nuances of the initial setting, when one of the lines is not activated after physical installation of the modules or the Internet works incorrectly.

The MIUI network configuration process has its own features that can confuse an inexperienced user who is used to “clean” Android. Properly setting call and access point priorities can save battery life and avoid missing important calls. In this article, we will take a detailed look at each step necessary to fully work both SIM cards on your device.

Physical installation and primary activation of modules

Before you go to the software settings in the menu, you need to make sure that the physical installation of SIM cards is correct, since errors at this stage are most common. The SIM card tray in Redmi 9 is located on the lower end of the case and has a combined design that allows you to install two Nano-SIM format modules or one card and a microSD memory card.

To remove the tray, use a special paper clip included in the delivery, or a thin needle, gently pressing into the hole next to the socket. Attention: do not use excessive force so as not to damage the mechanism. Make sure that the golden contacts of the SIM card are pointing down, and the cut corner matches the shape of the tray. Once the tray is installed, the device automatically goes into the waiting mode for registration in the network.

⚠️ Warning: If the phone was turned on while installing the SIM card, be sure to restart the device.Without a reboot, the system may not see the new communication modules, and the second line will remain inactive.

Once the smartphone is turned on, MIUI will automatically detect two SIM cards and offer basic setup, including naming and choosing a preferred network for data transfer. If this does not happen, or if you want to change the settings, you need to go to manual control mode. Often users forget that slots can have different frequency support characteristics, so for maximum Internet speed, it is better to install the main SIM card in the first slot.

Basic SIM card settings in the MIUI menu

The main management of mobile networks in Xiaomi Redmi 9 is concentrated in the settings section, which is easy to find through the search bar or in the general list of parameters. To start configuration, go to Settings path → SIM-And that's where you see both of your lines, which are marked as SIM 1 and SIM 2, and switch between them to make changes.

The first thing to do is to give clear names to each SIM card, like Work and Personal, so you don't get confused when making outgoing calls. The same menu contains an activation switch: if the second line doesn't work, make sure that the slider opposite the corresponding slot is put into the active position.

Special attention should be paid to data setup, as Redmi 9 can only work on the Internet at the same time through one SIM card. Choose the one that provides a more profitable plan or has better coverage in your area of stay.

• 📱 Network name: for quick identification of operator.
• 🌐 Mobile Internet: Selecting a Priority SIM Card for Data Transfer.
• 📞 Default calls: SIM card setup for outbound calls or Always Ask mode choice».
• 💬 SMS Default: Assigning a number to send text messages.

Call and message management

Once you have a basic activation, it is important to adjust the logic of your smartphone’s incoming and outgoing calls so that there is no confusion. In the Call Settings section, you can activate the Always Ask function if you want to choose which SIM card to call from on a particular occasion, which is especially convenient when you need to urgently contact a colleague from a personal number or vice versa.

For incoming calls, MIUI provides a convenient visual indication: the lock screen will display the icon of the SIM card that the call is coming to, which allows you to instantly know where to respond without looking at the status bar. In addition, you can configure different tunes for each line, which is an effective way to identify the caller without having to look at the screen.

In the Messages app, you can also set the default SIM card to send an SMS. If you send a message without explicitly selecting the number, it will leave the card that is set as the main one in the settings. However, in a dialogue with a particular contact, the system remembers your choice and next time will suggest sending a message from the same line as before.

⚠️ Warning: If the second SIM card is disabled in the settings, all incoming calls to this number will be unavailable, and the caller will hear the signal "Subscriber is unavailable." Make sure that the activation slider is not accidentally shot down.

Configure the Internet and APN access points

The most common problem with using two SIM cards on Redmi 9 is the lack of Internet on one of them or unstable data, the fact that the second SIM card in standby mode can not transmit data while the first one is active. For proper operation, you need to properly configure the access point (APN), Especially if the operator’s automatic settings are not applied.

To check or create a new access point, go to the Settings menu. → SIM-maps and mobile networks → Select a SIM card. → Access points (APN). There should be a list of profiles; if the Internet is not working, try to select a different profile or create a new one by entering data received from your carrier. APN to the factory, by pressing the corresponding button in the menu.

Also worth checking is whether the traffic saving mode or background data restriction for certain applications is enabled. Xiaomi has a powerful built-in firewall that can block network access for individual programs even when the Internet is active. Make sure that browsers and instant messengers have permission to use Wi-Fi and mobile network.

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If the internet is slow, try switching the “Preferred Network Type” to 4G Only (LTE only) mode via the engineering menu, but note that in areas without 4G coverage, communication can disappear completely.

Solving problems with the definition of the second SIM card

There are situations when after updating the firmware or resetting the settings Xiaomi Redmi 9 stops seeing the second SIM card. First of all, you need to eliminate software failure by completely restarting the device. If this does not help, try to remove the tray and check the contacts of the SIM card for oxidation or contamination, rubbing them with soft cloth.

Often the problem is that your old SIM card is incompatible with modern network standards, and if your SIM card is many years old, it may not support the required frequencies or have a damaged contact structure. In this case, the only solution is to replace the SIM card from the operator with a new one with support. 4G/LTE, What is usually done for free in the salon.

It is also worth checking whether the SIM card is blocked. PIN-When you turn on the phone, the system will request an unlock code, and if it is not entered, the second line will remain in the "No network" state. PUK-code in case of multiple incorrect input PIN, Not to block the module completely.

• 🔄 Reboot: completely switching off and turning on the smartphone.
• 🧹 Contact cleaning: removing dust and oxides from the SIM card.
• 📶 Resetting network settings: returning mobile parameters to factory.
• 🛠️ SIM card replacement: installation of a new module from the operator.

⚠️ Warning: Do not attempt to cut a larger Nano-SIM SIM card yourself without using a special conductor. A damaged chip or misaligned contacts can short-circuit and cause the phone tray to fail.

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In 90% of cases, the problem with determining the second SIM card is solved either by replacing the old communication module with a new one, or by correctly resetting the network settings in the phone menu.

Optimizing the two SIM cards to save energy

Using two active SIM cards inevitably leads to increased battery consumption, since the Redmi 9 radio module is forced to constantly communicate with two base stations at the same time. To minimize this effect, it is recommended to turn off the second SIM card at night or in areas where there is no coverage of the network of one of the operators, preventing constant search for the signal.

In the battery settings, you can activate Ultra-Energy Saving mode, which limits the background activity of applications and reduces the frequency of network updates, and it is also useful to disable automatic application updates over the mobile network, leaving this feature only for Wi-Fi, which will significantly reduce the load on the processor and modem.

Another effective way to save money is to turn off unused communication features like NFC or Bluetooth when they are not needed.In regions with unstable 4G coverage, it is worth forcing the phone to switch to 3G/2G mode if high Internet speeds are not required, as constant jumps between communication standards put a lot of battery on the ground.