Modern smartphones like the Xiaomi Mi 9 are equipped with combined trays, which requires care when installing memory cards and communication modules. Mishandling the retrieval mechanism can damage the case or the tray itself, so it is important to follow a certain sequence of actions. Owners often have difficulty determining the correct orientation of the chip or choosing a slot for the main SIM card.
In this article, we will discuss in detail the process of installing a SIM card in your Xiaomi Mi 9. We will consider not only the physical installation, but also the software configuration that is necessary for the correct operation of two numbers at the same time.
Before you start manipulating, make sure the device is turned off or in flight mode, although current standards allow hot replacement. However, to avoid any software conflicts when you first start, you better use caution. Let's move on to preparing the necessary tools and studying the design of the tray.
Preparation for installation and study of tray design
The first step is to find a complete paper clip, which usually comes in a box with the device. If the original key is lost, you can use a thin needle or a special device to extract, but you can categorically not use thick objects like pins or knives. The latch mechanism in the Mi 9 is quite sensitive, and excessive force can block it forever.
⚠️ Warning: Do not attempt to insert a paper clip into the microphone hole next to the tray, which will cause permanent damage to the microphone and loss of warranty.
The tray in Xiaomi Mi 9 has a specific shape and is located on the lower end of the case, to the right of the USB Type-C port. It is designed to install two nano-SIM cards, while there is no separate slot for a microSD card in this model.
Visually, the tray is a metal frame with a plastic base, where the contacts are located on one side. The frame often has a small bevel in one of the corners that corresponds to the shape of the SIM card itself. Understanding this geometry will help avoid errors when stacking the chip.
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Before installation, wipe the SIM card contacts with a soft dry cloth to remove fatty traces and dust that can impair the connection.
Step-by-step extraction and installation process SIM-map
The physical installation process takes only a few seconds, if done confidently and without jerking. First, find a small circular hole at the end of the tray and insert a clip perpendicular to the phone body. Press until the characteristic click appears and the tray is easily extended outwards.
After removing the tray, place it on a flat surface and place a nano-SIM SIM card. Note that the chip should look up and the cut angle matches the shape of the tray. In Xiaomi Mi 9, both slots support the nano-SIM standard, so the card size should be minimal.
☑️ Pre-installing check
Carefully insert the tray back into the case, keeping track of its orientation. The tray only enters in one position, so don't make any effort if you feel resistance. Once the frame is fully immersed in the case, you can turn the phone on and go to the software setup of the network.
Features of Dual SIM in Xiaomi Mi 9
Xiaomi Mi 9 supports two SIM cards simultaneously in standby mode, allowing different call and internet plans. MIUI provides flexible settings for traffic and voice management, allowing you to prioritize each card separately, especially for separating work and personal contacts.
When you first activate two cards, the system will prompt you to select the main SIM card for mobile Internet and for voice calls by default. You can change these settings at any time through the SIM card management menu, where switching is also available. 4G-cards without rebooting the device.
Technical limitations of Dual SIM
It is important to note that when you are actively talking on one line, an incoming call to the second line can come in standby or reset, depending on the operator’s settings. To fully use two numbers in 4G, your carrier needs VoLTE support.
Set up network and priorities in MIUI
After you physically install the cards, make sure they are correctly defined by the operating system, go to the settings section where the connected networks are displayed. If the SIM card is not visible, check the density of the contacts in the tray.
Settings menu → SIM-You will find detailed options for each slot, where you can turn on or off a particular card, change its name (for example, "Work" or "Home") and select the color of the indicator for easy identification in the notification curtain.
| Parameter | Description | Recommended value |
|---|---|---|
| Mobile Internet | Selection of a data transfer card | Map with unlimited traffic |
| Default calls | The main map for outgoing | Cheap minutes map |
| SMS default | Message map | Main number |
| 4G card | High-speed network slot | Operator SIM card 1 |
To access advanced settings, such as selecting your preferred network type, use the Settings menu. SIM-map → The preferred network type. You can force the device to switch to mode. 4G/3G/2G (vehicle or select only 4G, If the coverage in your area is stable.
Solution: if the SIM card is not determined
Sometimes after installation, users are faced with a message"SIM-No card found or No service. The first thing you should do is reboot the device, as this helps the modem re-initiate the network search. If the problem persists, check the cleanliness of the contacts on the map itself and in the smartphone tray.
Make sure the SIM card is intact and has the correct nano-SIM format. If you cropped the card yourself or used an adapter, this can cause bad contact, and it is also worth checking whether the card is active by calling it from another phone.
⚠️ Note: If the phone says, "Unlocking is required." PUK-"code," don't try to guess the code. Three wrong attempts will lead to a lockdown of the SIM card.
In rare cases, the problem may be a software firmware failure. Try resetting the network settings to factory values through the Settings menu → Advanced Settings → Restore and Reset → Resetting Wi-Fi, mobile Internet and Bluetooth settings. This action will not delete your personal data, but will return the network settings to their original state.
Security and card retrieval
While modern smartphones support hot SIM card replacement, it is better to retrieve them after the device is turned off or flight mode activation.This prevents possible failure of the radio module and loss of data on the contact card. In the Xiaomi Mi 9, the extraction mechanism is safe, but requires accuracy.
To extract, use the squeezing again, pressing the tray hole. After the frame appears, gently pull it with your fingers. If the tray is stuck, do not use sharp objects to pick through the crevices, it is better to slightly tap the phone with your rib on the soft surface.
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Regular cleaning of contacts of the tray of the SIM card from oxidation with an alcohol napkin prolongs the life of the radio module and improves the quality of communication.
Store your SIM cards in a special plastic holder to protect them from static electricity and mechanical damage. Losing or breaking the card may require a visit to the operator's cabin to restore the number, which takes time.