How to turn on the second line Xiaomi Mi A3

The modern Xiaomi Mi A3 is a popular device running on a clean Android One operating system. This shell is radically different from the usual MIUI, which often confuses users when first setting up basic functions. In particular, the question of how to properly activate a second SIM card, causes many queries, since the menu here looks different.

Mi A3 owners appreciate the device for its compactness and clean interface, but the lack of the usual tabs "Sim cards and mobile networks" as they are on other Xiaomi phones creates the illusion of complexity. In fact, the process of activating the second line here is even easier and more logical if you know where to look for switches. You do not need to be an expert to understand the basic communication settings.

In this article, we will take a detailed look at each step required to make two numbers work, and we will cover not only the physical installation, but also the software setting of call priorities and mobile Internet, and the right configuration will allow you to save battery power and not miss important calls from any number.

Physical installation SIM-cardboard

The first and most obvious step is to properly install plastic cards into the device. The sim card tray in the Xiaomi Mi A3 is located on the lower end of the case, to the left of the USB Type-C connector. To extract the tray, you need to use a special metal clip that comes with the kit, or a thin needle.

You can't have a second SIM and a memory card at the same time, because they share a single slot, and if you need extra storage, you'll have to give up the second line, and vice versa.

• 📱 Take a paperclip and gently press into the tray hole before clicking.
• 💾 Make sure that both SIM cards are nano-SIM (smallest size).
• 🔌 Place the cards in the tray according to the scheme, the cutout to the outer edge.
• 📥 Insert the tray back into the phone to the end, observing the orientation.

Once the device is turned on, the system should automatically detect new cards. If this does not happen, check if the tray is tightly sitting and if the chips are properly cropped. Sometimes contamination of the contacts can prevent reading, so wipe them with a soft cloth before installing.

Setting Call Priorities and SMS

Unlike multi-menu shells, pure Android groupes your communication settings into a single unit. To manage the second line, go to Settings → Network and Internet → Mobile Network. This is where all the SIM card controls are located, including activity switches and selecting preferred networks.

Here you will see a list of installed cards, usually designated as "SIM 1" and "SIM 2." You can give them clear names, such as "Work" and "Personal", so as not to be confused later on, this is especially useful when you need to quickly understand from which line you are going to make a call.

You can customize your individual settings for each SIM card, and you can choose which will be used by default for voice calls and which will be used for sending. SMS-This flexibility allows you to optimize costs using different operators' rates for different tasks.

⚠️ Note: If you switch a standard SIM card for calls, the next call will be made from it. Be careful when choosing, so as not to waste extra minutes from a number without packages.

Mobile Internet configuration (4G/LTE)

One of the main features of the Android architecture is the ability to use high-speed Internet on only one SIM card at a time. In the Xiaomi Mi A3, this feature is implemented through the choice of "Preferred Network for Data Transfer." The second card will only work in 2G/3G mode for receiving calls and text messages.

To set up, go to the Mobile Network menu and find the data transfer point, and you will be asked to choose one of the active SIM cards, depending on which plan provides better conditions or better coverage in your area.

It's worth noting that when you switch an active SIM card for the Internet, you can have a short-term disconnect, which is normal for the system to behave, because the communication module is reconfigured to work with another base station, which takes from a few seconds to a minute.

If you don't like Internet speed, try manually selecting the type of network. In the Preferred Network Type menu, select 4G (LTE) to ensure maximum speed. However, in areas of uncertain reception, it is better to leave automatic mode that allows the phone to switch to 3G.

Management of costs and traffic limits

Using two numbers requires careful cost control, especially if one of the fares has a limited number of minutes or gigabytes.There is a built-in monitoring tool in pure Android that allows you to track traffic consumption for each SIM card separately.

To activate control, go to Settings → Network and Internet → Data Transfer → Traffic Savings. You can set limits and warnings here, which will help you avoid unexpected charges if you accidentally exceed the limit of the main package.

You should pay special attention to background applications. Some programs can actively consume traffic even when you are not using them. In data settings, you can prevent specific applications from using the mobile network, leaving them access only via Wi-Fi.

Solving problems with the definition of the second SIM card

Sometimes users are faced with a situation where the phone stops seeing the second SIM card after updating or resetting the settings. Most of the time, the problem is a software failure or contamination of contacts. The first thing you try to reboot the device, this solves 90% of the temporary glitches.

If a simple reboot doesn’t work, check the SIM card status in the settings menu. Make sure the switch opposite the card is activated. In Android One, it sometimes happens that after a software update, the settings are reset and the second line needs to be turned on manually.

• 🔄 Perform a full reboot of the smartphone.
• 🧹 Remove the tray and wipe the SIM card contacts with a lastic or alcohol.
• 📲 Change the SIM cards in the tray (SIM 1 in slot 2 and vice versa).
• 🛠 Reset network settings to factory values.

⚠️ Note: If none of the SIM cards are identified in a particular slot, the tray itself or the contact group inside the phone may be damaged.

It is also worth checking whether the SIM card is blocked. PIN-When you turn on your phone, the system will ask for an unlock code, and if you type it incorrectly three times, the card will be blocked. PUK-Be careful when entering numbers so that access is not permanently blocked.

Optimization of autonomy when working with two SIMs

Active operation of two SIM cards, especially in areas of weak signal, significantly affects the battery life of the Xiaomi Mi A3. The phone has to constantly communicate with two different base stations, which increases the power consumption of the radio module.

To extend the life of the battery, you can use the power saving mode, but a more effective method is to turn off the second SIM card in situations where you do not need it, for example, at night or during meetings, you can switch the second number to "Unavailable" mode software.

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If you are in a very bad reception zone, the phone will waste a lot of energy searching for the network, in such cases it is advisable to temporarily turn on air mode or turn off the second SIM card to save charge.

In addition, disabling 4G on the second SIM card (if it is used only for calls) will also help save charge, and in the mobile network settings for the second card, you can force the “2G/3G Only” mode to be set, which will reduce the activity of search algorithms.

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Two active SIM cards in standby mode consume more power than one, and in areas of poor signal, the difference can be up to 20% of autonomy per day.

Frequently Asked Questions (FAQ)