Modern smartphones like the Xiaomi Redmi 9 have become so functional that we often forget about basic mechanical actions when setting them up. However, it is the right connection of the communication module that is the foundation for the entire device. If you just bought this device or decided to replace the carrier, you need to know the intricacies of working with the hybrid tray used in this model, errors at this stage can lead to malfunctioning of the mobile Internet or even damage to contacts.
In this article, we will discuss the process of physical installation of the card, pay special attention to the support of NFC technology, which in some versions of this model caused questions from users, and set the priorities of the network. It is important to understand that Redmi 9 is a budget segment, where design solutions are aimed at reducing the cost of production, but not at the expense of basic functionality. We will consider how to correctly organize the space in the slot if you need to use two SIM cards and a memory card at the same time.
Before you start tray manipulation, make sure your device is turned off or in flight mode, although modern standards allow hot replacement. However, to prevent software failures in IMEI code recognition, it is better to be safe. In the following sections, you will find a step-by-step algorithm of actions, a format compatibility table and answers to frequent questions that will help avoid the typical mistakes of beginners when working with the MIUI ecosystem.
Preparation of the workplace and necessary tools
You need a comfortable environment before you pick up your smartphone. You need a well-lit space with a flat surface so that small parts like the paper clip or the SIM card itself don't get lost. The main tool to remove the tray is a special metal clip that comes with the device. If the original key is lost, you can use a regular stationery clip, straightening one of the ends, or a thin needle point, but you should be extremely careful not to scratch the case.
The second important element of the training is itself SIM-Today's networks use the Nano-SIM format, which is the smallest of the existing standards. If your card is larger (Micro or Mini), you need to gently break the perforated parts along the circuit or contact the operator’s salon for replacement with a Nano format. Using cards of the wrong size or self-cut scissors can lead to a tray getting stuck or damage to the contact area inside the phone.
You should also prepare a soft cloth or microfiber to wipe your contacts. Even a microscopic speck of dust or a fat fingerprint on the gold contacts of the card can cause unstable signals or periodic communication breaks. Wipe the card chip with light movements, trying not to touch the contact group with your fingers. Make sure that your hands are dry and clean, since static electricity can theoretically harm electronics, although modern devices have protection.
- 🔍 Special paper clip for extracting the tray (or a thin needle).
- 📱 Nano-SIM map with activated tariff plan.
- 🧼 Microfiber wipe to clean contacts.
- 💡 Good lighting for visual control of the process.
Anatomy of the tray and physical installation SIM-map
The Xiaomi Redmi 9 model uses a hybrid slot located on the lower end of the case to the left of the USB Type-C charging connector. This means that the second slot can be used either for a second SIM card or for a microSD memory card, but not simultaneously. The tray has a specific shape with notches corresponding to the size of the cards. To extract it, insert the tool into a small circular hole next to the tray and press before clicking, after which the tray will be pushed out.
Notice the shape of the notches: the SIM card has a cut angle that should match the shape of the tray. In Redmi 9, the tray is often designed so that the cards are mounted in the same plane or at different levels depending on the revision of the board, but always with contacts down. Don't put too much effort into installing. If the card doesn't lie flat, flip it or check the orientation of the cut. Incorrect installation can lead to breakage of contacts inside the phone.
⚠️ Warning: Never try to force a tray into your phone, if it doesn't come in smoothly, you're either misdirecting your cards or you're putting the tray upside down. Forced pressure will cause mechanical damage to the motherboard.
Once the cards are installed in your cells, carefully move the tray back into the case. It should enter tightly and without gaps. Make sure that the rubber seal (if visible around the tray perimeter) is not hushed, as it provides protection against dust and splash, although this model does not have full IP moisture protection. Once the device is turned on, the system must automatically determine the new SIM card.
☑️ Installation verification SIM
Features of the NFC module in Redmi 9
One of the key issues for many users is the availability and operation of the NFC (Near Field Communication) module in Redmi 9. The situation here is ambiguous and depends on the regional version of the device. Global versions designed for Europe and Russia are most often equipped with a full-fledged NFC chip that allows you to pay for purchases through Google Pay (or its counterparts, given current restrictions) and quickly pair devices. However, in some Asian versions, this module may be physically absent, despite the presence of appropriate marking on the box in some lots.
To check whether NFC is available and working, go to your smartphone settings. Search for settings, type "NFC" or find the appropriate switch in the notification curtain. If the switch is there and it is activated, then the module is present. For contactless payment, the antenna in Redmi 9 is usually located at the top of the back cover, closer to the camera.
Why can't NFC work?
It is important to note that the work NFC closely related to the correct work SIM-card if you use operator services such as SIM-Toolkit or payment via mobile operator. Make sure your SIM card supports the necessary communication protocols. In rare cases, replacing the SIM card with a new one from the operator solves problems with displaying menus NFC-service.
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For better NFC performance, remove the case with metal inserts or a magnetic cover, as they can block the signal of the antenna located under the back panel.
Set Network and Internet Priorities
After the physical installation of two SIM cards, the user faces the issue of traffic and call management. In the MIUI shell installed on Redmi 9, a flexible dual-SIM management system is implemented. By default, the Internet works only on one of the cards, while the second is available only for voice calls and SMS. You can switch the main card for the Internet directly from the notification curtain or through the settings menu.
For fine-tuning, go to the Settings section. → SIM-Maps and mobile networks. Here you can assign which card will be used by default for calls, SMS It is also recommended to enable the function "Receive calls to both". SIM", If you use one card for the Internet (for example, a tariff with a lot of traffic), and the second only for calls, make sure that the mobile network settings for the second card do not include data roaming to avoid unnecessary costs.
| Parameter | Recommended value | Description |
|---|---|---|
| Type of network | 4G is preferred | It provides maximum speed by switching to 3G/2G only when there is no LTE coverage. |
| Data roaming | Off. | Protects against accidental traffic flow abroad or in border signal zones. |
| APN | Automatically. | Access points are usually loaded by themselves, but can be manually configured for specific operators. |
| VoLTE | Included. | It allows you to conduct high-quality conversations at the same time using the Internet. |
Special attention should be paid to setting up APN access points. In most cases, Redmi 9 automatically reads the operator's settings. However, if the Internet does not work, although there is a signal, you may need to manually prescribe APN. This data can be found on your carrier's website. Incorrect APN settings are a common reason why the phone shows "4G", but the pages in the browser do not load.
Diagnostics of network definition problems
When the phone doesn't see the SIM card ("No SIM" or "Put SIM"), it can occur even when installed correctly. The first step should always be to reboot the device. This is a trivial action that helps to reset the errors in the radio module. If the reboot did not help, try to remove the tray, wipe the contacts of the SIM card with a wipe or an alcohol wipe and install the card again, slightly shifting its position.
If the problem persists, check the SIM card itself on another device, which will prevent the chip from malfunctioning, and check if the card is locked by the operator. → Status SIM-The cards can be seen if they are read. IMSI If the field is empty or contains zeros, the problem is hardware, either in the tray or in the phone itself.
⚠️ Note: If the phone says "Unlocking is required" SIM-map PUK-In no case do not enter the wrong codes more 3-5 Ten wrong attempts will lead to complete blocking and destruction of the card, which can only be restored by re-releasing from the operator.
In rare cases, the problem lies in software firmware failure. Updating to the latest available version via Settings → About Phone → The MIUI version can fix errors in modem drivers. You can also try resetting your network settings, but remember that this will remove saved Wi-Fi passwords and Bluetooth pairs.
Using a memory card together with SIM
As mentioned earlier, the Redmi 9 tray is hybrid. If you want to expand your device memory with a microSD card, you have to sacrifice a second SIM card. This is a physical limitation of design. When you install the memory card, make sure it is formatted in the FAT32 or exFAT file system, or the phone may suggest formatting it, which will result in the deletion of all data.
Once the memory card is installed, the system may suggest using it as internal storage. In the case of the Redmi 9 and its Helio G80 processor, using the card as internal memory can slightly slow down the interface, since the write speed on cheap memory cards is often lower than that of the built-in flash module, and it is recommended to use the card as a portable storage for photos, videos and music.
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The hybrid slot requires a choice: either two SIM cards for work and communication, or one SIM card and a large amount of memory for multimedia. USB-cardreader.