Owners of flagship devices often wonder about the functionality of communication modules, and the Xiaomi Mi 8 model was no exception.This smartphone, released in 2018, is still a popular choice thanks to its screen and performance, but the nuances of working with the device are not the only one. SIM-Many users are confused about the specifications, not knowing whether you can use two cards at the same time or have to choose between a second SIM and a memory card.
In this article we will analyze the architecture of the tray, the features of the network 4G two active numbers and answer the main question: how much SIM-The maps actually support this machine in various modifications, and understanding these nuances will help to avoid physical damage to the tray and problems with the operator's network definition.
It is worth noting that the configuration of the slots may differ depending on the regional version of the device. Global version and Chinese version (CN) may have differences in marking and even in the physical design of the tray, although the software part of them is identical.
Tray design and number of slots
The answer to the question of the number of SIM cards lies in the design of the tray, which is extracted using a paper clip. Xiaomi Mi 8 model uses a combined slot, but its implementation has its own features. Physically, the tray is designed to install two nano-SIM cards. This is the standard size for modern smartphones, and the use of adapters or self-cutting larger cards is strongly discouraged.
It's important to understand that there's no microSD card slot in this model, and engineers have decided to move away from expandable memory in favor of a thinner case and larger internal battery. SIM-cards, and use one of them for a flash drive will not work under any conditions.
⚠️ Note: Do not try to insert a microSD card into a slot SIM-Contacts are arranged differently and this may result in short circuit or damage to the power controller.
The location of the contacts in the tray is designed to ensure reliable contact even when you are actively using your smartphone. However, if you use cropped SIM cards, there is a risk of them getting stuck. The Nano-SIM should lie in the tray smoothly, without dangling from side to side.
Network modes and Dual SIM
The smartphone supports Dual SIM Dual Standby (DSDS) technology, which means that both SIM cards can be in active standby mode at the same time, you can receive calls and SMS on either of the two numbers without manually switching in settings. However, when one line is busy talking, the second will not be available for incoming calls unless the operator switches calls.
In terms of mobile data, the situation is this: 4G Internet (LTE) only works on one of the cards that is selected as the main card in the settings. The second card at this point goes into 2G or 3G mode for voice communication, which is standard behavior for most devices based on Qualcomm processors of the period, including the Snapdragon 845 installed in the Mi 8.
To switch the priority of the Internet, you don't have to reboot the device, just go to the settings menu and select the card you want, and the system allows you to flexibly customize use cases, for example, assign one card only for calls, and the second card exclusively for mobile traffic.
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Use it. SIM-One operator card for both positions if you are roaming, this will help to avoid problems with registration in the network, as some foreign operators do not work well in pairs with other providers in Dual mode. SIM.
Instructions for the correct installation of SIM
The card installation process requires care, as the tray is quite miniaturized. Before the procedure, you need to completely turn off the smartphone. Although modern devices support hot replacement, in the case of the Xiaomi Mi 8 and its specific antenna system, it is better to be safe to avoid network failures.
Take a paper clip from the delivery kit and tap on the round tray hole on the bottom of the device. The tray will come out. Notice the diagram that's been knocked out on the tray itself or drawn on the box, showing which slot matches SIM 1, and which one is SIM 2.
☑️ Proper installation SIM-map
Place the cards in the appropriate grooves. Make sure the golden contacts look down and the cut corner of the card matches the shape of the tray. After installation, carefully insert the tray back into the case. It should enter smoothly, without undue effort. If the tray does not enter, check the orientation of the cards.
Once the device is turned on, the system automatically recognizes new cards, and if that doesn't happen, check if they're sitting tight, sometimes it helps to wipe the SIM contacts with a soft wipe or an alcohol wipe to remove oxides.
Technical Specifications and 4G Support
Xiaomi Mi 8 is equipped with Qualcomm Snapdragon X20 modem, which provides high data download speeds. The smartphone supports frequency aggregation, which allows you to achieve theoretical speeds up to 1 Gbps. However, the real speed depends on the support of ranges by your carrier.
When you use two SIM cards, the main one (designated for data) is 4G LTE, and the second one is 2G/3G. If you pull one of the cards, the freed slot can support 4G, but in Dual SIM mode, priority is always given to one line for high-speed Internet. This is a hardware limitation, not a software one.
| Parameter | SIM 1 (Main) | SIM 2 (Second) |
|---|---|---|
| Type of network | 4G / 3G / 2G | 3G / 2G |
| Voice calls | Supported | Supported |
| Internet | Main source | Only if the SIM 1 is off |
| VoLTE | Supported | Depends on the operator. |
It is important to note that VoLTE (Voice over LTE) technology is supported. If your carrier provides this service, you will be able to talk in high quality while staying on the 4G network even while you are talking. On the Xiaomi Mi 8, this feature is often hidden in the engineering menu or activated automatically after the operator profile update.
How to activate VoLTE on Xiaomi Mi 8?
Setting priorities in MIUI
The MIUI shell provides a user-friendly interface for managing two numbers, and once you install the cards, the system will suggest you configure their use, and you can assign profile names like "Work" and "Personal" to avoid confusion in notifications.
Settings menu -> SIM-You can set the default card for outbound calls, and you can always ask if you want to choose a number before every call, and you can use it if you make frequent calls to different contacts from different numbers.
Special attention should be paid to the traffic consumption settings, you can limit the background data transfer for the second SIM card or completely deny it access to the Internet, leaving only voice functions, which will help save battery power and avoid the accidental waste of megabytes.
Access to advanced settings sometimes requires you to enter the code in the dial field, for example, code ##4636## opens the testing menu, where you can see the signal level in dBm for each of the SIM cards separately, which is useful information for diagnosing coverage problems.
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Proper prioritization in MIUI saves up to 15% of battery life, preventing a second SIM card from constantly searching for a network in low-cost areas.
Possible problems and solutions
Users may experience a situation where the smartphone sees only one SIM card, most often due to a weak landing of the tray or contamination of contacts, and the problem may lie in the SIM card itself, if it is old and was cropped poorly.
Another common problem is the lack of internet on the second card. As mentioned earlier, in Dual SIM mode, the second card works on 2G/3G networks. If the operator has already disabled 2G networks in your region, the second SIM card may be displayed as “No network” or work unstable.
⚠️ Warning: If the phone stops seeing both SIM cards after falling or getting moisture, don't try drying it with a hair dryer.
In rare cases, network settings are required to be reset, and this will not delete your personal data, but will return all connection settings to factory values. You can do this under Settings -> Advanced Settings -> Reset and Reset -> Reset your Wi-Fi, mobile Internet and Bluetooth settings.
If software methods don’t work, the tray itself or the antenna plume may be damaged, and in such cases, a diagnosis is required at an authorized service center. Self-disassembly of the Xiaomi Mi 8 is difficult due to the glass back cover and requires special tools.