Modern smartphones, particularly the popular Xiaomi Redmi Note series, are originally designed to work with two SIM cards, which allows users to flexibly manage personal and work calls. However, it often happens that after buying a new device or updating the MIUI or HyperOS operating system, the second line does not activate automatically, requiring manual intervention in settings. Users may face a situation where the slot is physically present, but the software system ignores the installed card, leaving the owner without communication through the second operator.
Turning on the second line is not just mechanically installing plastic in the tray, but also the correct software configuration that affects the quality of signal reception and mobile Internet speed. In this article, we will discuss in detail how to activate Dual SIM mode, what priority settings should be set and what to do if the phone stopped seeing the second SIM card after a reset or update.
It’s worth noting that the menu interface may vary slightly depending on the firmware version installed on your Redmi Note, but the logic of action remains the same across the manufacturer’s ecosystem. We’ll look at both the standard menu activation methods and the deeper customizations that may be required in specific cases. Understanding these processes will help you unlock your device’s full potential.
Physical installation of SIM card and tray check
The first and most obvious step before software manipulation is to physically fit the SIM card into the appropriate slot. Many Xiaomi Redmi Note models feature a combined tray where one of the locations can be reserved for a microSD card, which often causes confusion among inexperienced users. It's important to make sure you're using the exact slot that's designed for a second SIM card, not for memory expansion, unless your phone supports simultaneous installation of two SIMs and a memory card.
To remove the tray, you need to use a special paper clip that comes with the kit, or a thin needle, gently pressing the hole next to the edge of the case. Be extremely careful not to make excessive efforts to not damage the mechanism or the tray itself, as repairing these elements may require disassembling the device. Make sure that the golden contacts on the SIM card are pointing down and the card fits tightly to the plastic base of the tray.
How do you determine the type of tray?
After putting the tray back in your phone, take your time to check the settings right away, give the system a few seconds to survey the hardware. If you use old Nano-SIM-cut SIM cards, make sure they don't have thickenings or uneven edges that can prevent close contact. In some cases, poor contact is the reason the second line doesn't appear on the list of available networks.
Activation of the second SIM card in the MIUI settings
After a successful physical installation, you need to switch to software activation, as by default the second slot can be disabled for energy saving or due to previous user settings. To do this, open the Settings app on the home screen and find the SIM Cards and mobile networks section, which is usually located at the top of the menu or inside the Connections and Sharing category. In the window that opens, you will see a graphical display of installed SIM cards, where the second line can be marked as “Not Installed” or have a switch off.
Click on the second SIM card image to deploy the additional control menu and make sure the Use SIM card switch is in the active position.If the switch is off, the system ignores the card in the slot, even if it is physically installed correctly. Once turned on, the phone may require a reboot or reconnect to the operator's network on its own, which will take 10 to 30 seconds.
☑️ Verification of second line activation
In the same menu, it is recommended to specify clear names for each SIM card, for example, "Work" and "Personal", so as not to get confused when making calls. Also, it configures the preferred network type, where for the second line it often makes sense to choose Preferably 4G, if the operator supports voice calls over LTE (VoLTE), which provides better communication quality. Remember that for the correct operation of both cards, they must be registered on the network, as evidenced by the corresponding signal level icons in the status bar.
Setting Call Priorities and the Internet
When both SIM cards are activated, it is critical to properly distribute roles between them to avoid a situation where the Internet is not working or the call is made from the wrong number from which you were supposed to. In the section SIM cards and mobile networks there is a block "By default", where you can choose a card for mobile Internet, voice calls and SMS-Usually, the card with the highest traffic packet is chosen for the Internet, and the card with the most contacts calls is chosen for calls.
One of the most useful features in Xiaomi is the ability to ask questions at every action, which allows you to flexibly manage your device in different situations. For example, you can set the "Always Ask" option to make calls, then when dialing, the system will ask you to choose which SIM card to make a call from, which is especially convenient if you use one line for local calls and another for long-distance communication or roaming.
| Setup parameter | Description of function | Recommended value |
|---|---|---|
| Mobile Internet | Map through which data traffic is carried | Card with unlimited tariff |
| Default calls | Automatic Selection for Outgoing SIMs | Always ask (for control) |
| SMS default | Map for sending text messages | Main number |
| VoLTE | High quality voice through 4G | Included for both cards |
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Use the two SIM cards widget on your desktop to quickly switch settings, allowing you to change Internet priority or turn off one of the cards directly from the home screen without going into the deep settings menu.
Also worth paying attention to the VoLTE (Voice over LTE) setting, which allows you to talk simultaneously using high-speed Internet. If your operator supports this technology, turn it on for both SIM cards in the appropriate submenu so that when you talk on the first line, the Internet does not switch to 2G/3G mode. This ensures stable operation of the navigator and messengers during the phone conversation.
Solving problems with the definition of the second SIM card
Despite the correct installation and settings, users may face a situation where the second line is not determined or constantly loses the network. One of the common reasons is the use of non-standard cropped SIM cards, when the geometry of the chip is broken or the thickness of the plastic interferes with the tight fit. In such cases, it is recommended to contact the operator’s salon to replace the card with a new Nano-SIM format, which often solves the problem instantly.
⚠️ Warning: If the phone sees a SIM card but says "No Network Access" or "Emergency Calls Only", check if the card is blocked by the operator due to long non-use or lack of payments. 5G", If you do not have this standard in your area.
Another cause of failures can be software errors that are solved by resetting network settings. Go to Settings → Connection and Sharing → Reset Wi-Fi, mobile network and Bluetooth and confirm the action. This procedure will not delete your personal files or contacts, but return all network settings to factory values, which often eliminates software conflicts that interfere with the second line.
In rare cases, the problem may lie in the hardware, such as oxidation of contacts inside the slot or damage to the antenna plume after a fall. If the shift of SIM cards between slots shows that the problem persists precisely behind the particular slot (regardless of the card inserted), this may indicate a malfunction of the connector itself. In this situation, self-repair is not recommended, it is better to contact an authorized service center.
Features of Dual SIM in 5G and 4G mode
With the development of networks of the fifth generation owners of modern Redmi Note have the opportunity to use high-speed Internet, but the mode of operation of two SIM cards in networks 5G In most current implementations of Qualcomm and MediaTek chipsets used in Xiaomi, when activated, the technical limitations are limited. 5G On one SIM card, the second can often only work in mode. 2G/3G/4G, not 5G. This is due to the architecture of the radio module, which can not always support two active fifth-generation connections at the same time.
For users who are critical to having a stable Internet connection on both lines, it is important to understand the difference between DSDS (Dual SIM Dual Standby) and DSDA (Dual SIM Dual Active). Most Xiaomi smartphones are DSDS, which means that both cards are active and ready to take the call, but only one card is fully exchanged at a particular time. When an incoming call to the second line, the first is put on hold or reset if the call wait function is not used.
To maximize speed, set the 5G/4G/3G/2G (Auto) value in the Preferred Network Type menu, allowing the phone to choose the best signal available for itself. However, if you are in a zone of uncertain 5G reception, the phone can constantly switch between standards, consuming battery power. In such cases, experienced users recommend manually switching the priority SIM card to 4G/LTE, leaving the second in auto mode, which provides a balance between speed and autonomy.
Optimization of autonomy with two active lines
Using two active SIM cards inevitably leads to increased battery consumption, as the radio module has to constantly communicate with two base stations, possibly at different frequencies. To minimize the impact of the second line on the life of the Xiaomi Redmi Note on a single charge, you should use the built-in optimization tools. First of all, turn off the second SIM card for the night or during periods when you are in the zone of confident Wi-Fi and calls are not required.
Also effective is to limit background activity for applications using the second SIM card’s mobile network. Go to the battery settings and check which apps consume the most power in the background, and limit their access to mobile internet by leaving only Wi-Fi available. The MIUI’s power saving feature also has presets (templates) that can automatically turn off the second SIM card when a certain percentage of charge is reached, such as 20%.
⚠️ Warning: Do not use third-party accelerators and cleaners from unverified sources to manage SIM cards. These may conflict with Android system services, causing battery drain and unstable communication, instead of helping to help.
Also, if you're in a room with a bad signal, the phone starts to increase the transmitter power to search for the network, which is especially noticeable with two active SIM cards. In such situations, it is advisable to put the phone in flight mode and turn on only Wi-Fi, or manually select the network of a particular operator if you know that it provides the best coverage in a given location, this will save charge and reduce the heating of the device case.