Modern Xiaomi smartphones and its sub-brand Redmi are almost always equipped with a hybrid slot that allows you to use two SIM cards at the same time. However, many users face confusion when trying to change the priority card for calls or mobile Internet. The standard procedure may seem unclear due to the features of the shell MIUI or HyperOS.
In this article, we will discuss how to correctly and quickly switch the SIM on your device without restarting the gadget or retrieving the tray. You will learn how to configure individual profiles for voice and data communication, and learn about hidden network management functions.
Competent settings allow you to significantly save battery power and control communication costs. Below is a step-by-step instruction that is relevant for most current models, including the Redmi Note series and the flagship Xiaomi Mi.
Basic management settings in MIUI
You first need to go to the SIM control center. Unlike stock Android, Xiaomi's interface takes these settings into a separate, easily accessible block. Open the main menu and find the Settings app. At the top of the screen, just below the search bar, usually the item Two is displayed. SIM-maps and mobile networks.
If you don't have fast access, search by settings or go to Connect and Sharing, which shows the status of both cards, you'll see switches to activate or deactivate each SIM separately, and that's where the initial prioritization is set.
⚠️ Note: If you just inserted a new SIM, wait until the registration process is completed before you change settings.
The interface may vary depending on the firmware version. In older versions of MIUI, settings were scattered, now they are aggregated for convenience. The main thing is not to confuse the slots, especially if you have a memory card installed in the second slot.
How to change SIM card for calls and SMS
The most common task is to change the number from which the outgoing call will be made. The system allows you to set one default card or request a choice every time. SIM-Maps and mobile networks and find the Calls section.
Here you will be given three options: you can choose a specific SIM (e.g. SIM 1 or SIM 2) for all outgoing calls, and the alternative is a mode where the phone will ask before each dial.
- 📞 Always. SIM 1: Ideal for the main work number so that there are no random calls from a personal SIM.
- 💬 Always. SIM 2: It is useful if you switch to a new operator with a more favorable tariff for minutes.
- ❓ Always ask: The best choice for those who often balance personal and business conversations.
And there's also the SMS setting, which is just below the same menu, and the logic is the same as the call setting, and you choose which card will send the default message, which is critical if one of the SMS cards doesn't have an SMS packet on it or you run out of money.
☑️ Checking call settings
Switching the mobile Internet between SIM cards
Unlike calls, mobile Internet can only work through a single SIM card at any given time. Switching to a 4G/5G hotspot requires a separate action. In the SIM management menu, find the Internet or Mobile Internet.
Click on the current selected map and the system will offer a list of available options. After switching, the speed indicator (4G, H+, 5G) will move to the icon of the new selected SIM.
There's a useful feature called Intelligent Data Switching, which, if activated, will use the second SIM card's Internet if the main signal is lost or there are connection problems, but this can lead to unplanned traffic consumption.
| Parameter | SIM 1 (Main) | SIM 2 (Additional) | Mode of work |
|---|---|---|---|
| Type of network | 5G / 4G LTE | 4G LTE / 3G | Automatic. |
| Data roaming | Off. | On (option) | Hand-held |
| Access Point (APN) | auto.apn | internet.mts.ru | Automatic. |
| Traffic limit | Not installed. | 10GB | Hand-held |
When you change your SIM for the Internet, the system may request confirmation to reconfigure the APN hotspot. Accept this action, otherwise the mobile Internet will not work. The old settings may conflict with the new operator profile.
What is APN and why should I change it?
Using a quick menu to change the SIM card
You don't have to go deep every time. The MIUI shell offers a handy widget for quick switching. Swipe down from top to bottom to open the Notification Curtain. Some firmware versions have a separate SIM card switch.
If there is no standard widget, you can add it through the control button editing menu. Click on three dots or the pencil icon in the corner of the curtain, find the SIM switch element and drag it to the active area, which will change the priority of calls in one click.
There's also a blind dialing method. If you try to make a call from the contact book, if you have the "Always Ask" option in your settings, the phone will prompt you to select a SIM card with a pop-up window, which is the fastest way to make a one-time call from another number.
⚠️ Warning: Quickly switching over the curtain may not work if one of the SIM cards is blocked PIN-code or is in a network outage. Unlock the card before using the widget.
The convenience of a quick menu is particularly noticeable when you use two carriers with different coverage, for example, you are in an area where one operator catches poorly and the other one is great, and a quick switch allows you to instantly restore communication without much searching the menu.
Problems with the definition of the second SIM card
Sometimes users are faced with a situation where the phone sees only one SIM, even though two are inserted. First of all, check the physical position of the cards in the tray. Make sure they lie flat and are trimmed according to the nano-SIM standard. Incorrect pruning is a common cause of poor contact.
The second step is software verification. Go to Settings → About Phone → General information and see the IMEI status. If the second slot is "Unknown" or the field is empty, the problem may be a software failure of the radio module.
- 🔄 Reboot: a banal but effective method. Turn off the phone completely and turn it on in 10 seconds.
- 🔧 Reset Network Settings: Go to Settings → Connections → Reset Wi-Fi, mobile networks and Bluetooth.
- 📱 Check tray: Remove the tray and wipe the SIM card contacts with dry soft cloth.
If nothing works, try swapping the SIM cards, if the problem has moved with the card, it means that the SIM itself is defective or it does not support the frequencies of your phone, and if the problem remains in the same slot, it may be the tray itself or the motherboard that is damaged.
💡
Use the SIM card adapter only as a last resort. Cheap plastic adapters are often incorrectly thick, resulting in a tray getting stuck or a reader breaking down.
Tricks of 4G and 5G setup on two SIM cards
Many modern Xiaomi smartphones support Dual 4G (or Dual VoLTE) mode, which means that both SIM cards can run on fourth-generation networks simultaneously.However, when one card is busy talking, the second can temporarily switch to 3G or 2G if the feature is not configured correctly.
To activate advanced modes, log in to the engineering menu or use hidden codes. Enter the dialer code ##4636##. In the menu that opens, select Phone Information, where you can force the preferred network type for each slot separately.
However, be careful with manual settings. If you set LTE Only, you may lose the ability to receive regular voice calls if your carrier does not support VoLTE technology, in which case incoming calls will simply not pass.
The optimal setup for most users is to leave the network type in LTE mode. The system will choose the best communication standard available. Manual intervention is required only in areas of uncertain reception, when the phone "storms" between 3G and 4G, quickly landing the battery.
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For stable performance of two SIM cards on 4G/5G networks, make sure that both operators have VoLTE enabled and this feature is enabled in the phone settings.