Redmi’s mobile devices have been the benchmark for reliability in the budget segment for many years, and the Redmi 4X model is no exception. Despite its age, this smartphone continues to be in demand as a second device or device for the elderly, but new owners often have questions about the initial setup of communication. Proper installation of communication modules is the foundation of stable operation of the gadget, which allows you to avoid problems with signal loss or overheating.
Unlike modern models, where the tray can be hidden or have a non-standard shape, Xiaomi Redmi 4X uses a classic and convenient system of accommodation. However, even here there are nuances associated with the type of networks supported and the location of contacts. Understanding the physical design of the slot will help you avoid mechanical damage when you carelessly handle.
In this article, we will take a closer look at how the tray is removed, determine the correct orientation of the chips, and consider software-based traffic prioritization, learn how to correctly allocate roles between two active numbers, and what to do if the device stops seeing the operator after installation.
Anatomy of the tray and installation preparation
Before you start physically interfering with the design of the smartphone, you need to make sure that there is a suitable tool. Complete with the original device always came a special metal clip, but if it is lost, you can use a thin needle or an unbended stationery clip. The main requirement for the tool is its strength and thin profile, so as not to damage the latch mechanism inside the case.
The tray at Redmi 4X It's located on the top end of the device, which is a design feature of the era, and it's a combined design that often causes confusion among users who are first encountering hybrid slots, and there are two distinct spaces inside the metal frame: exclusively SIM-Nano-SIM card, and the second is a hybrid, accepting either a second Nano-SIM or a microSD memory card.
Importantly, using a hybrid slot requires a choice: you can’t use two SIM cards and a memory card at the same time unless you use special adapters, which are not recommended by the manufacturer because of the risk of overheating. To ensure a stable connection, the contacts on the chip must face down to the motherboard, and the beveled angle of the plastic must match the shape of the notch in the tray.
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Always turn off your smartphone before removing the tray, if the device supports hot replacement, this will reduce the risk of software failures in the definition of the operator.
The preparation process takes no more than a minute, but requires care. An improperly inserted tray can cause it to protrude from the body, breaking the tightness and creating a risk of damage when carried in your pocket. Make sure that the frame fits into the groove perfectly across the entire area.
Step-by-step instructions for installing modules
The installation procedure does not require any technical knowledge, but requires attention to detail. First, find a small hole next to the tray on the top edge. Insert the tool perpendicular to the body and press until the characteristic click, after which the tray will slightly extend. Take it with your fingers and completely remove it from the device.
Put the tray on a flat surface and place the cards on it. The Xiaomi Redmi 4X uses the Nano-SIM format, which is the smallest at the moment. If your card is larger (Micro or Mini), you need to carefully trim it along the circuit or contact the communication salon to replace it with the correct format, because using adapters can jam the mechanism.
☑️ Pre-installing check
Once you have the chips in the appropriate recesses, put the tray back into the smartphone. It's important not to confuse the sides here: the tray has only one correct orientation. Don't use excessive force; if the tray doesn't enter easily, flip it over. Bring the frame to the end until it equals the body of the phone.
Turn on the device and wait for the operating system to load MIUI. If it's successful, the signal level indicators for both operators will appear at the top of the screen. PIN-code, if it was previously installed on the map.
Features of the hybrid slot and memory card
One of the key features of the model is its hybrid architecture: the second slot (SIM 2/SD) is designed so that the user can choose between a memory expansion and a second active SIM card, a solution that was motivated by the desire to keep the device thin, but it imposes certain limitations on operation.
If you plan to use a 32, 64 or 128 GB memory card, you will have to abandon the second SIM card. In this case, a microSD is installed in the second socket. If you are more important than a dual SIM card, then you will have to abandon the expansion of internal memory through the slot, relying only on built-in 16, 32 or 64 GB (depending on the modification).
⚠️ Note: Use of memory cards larger than 128 GB in Redmi 4X This can cause system instability or file read failure because the memory controller in the Snapdragon 435 processor has addressability limitations.
There are adapters that allow you to install a memory card on top of the SIM card, but their use is highly undesirable, such designs often lead to poor contact, overheating in the slot area and, as a result, to a rapid discharge of the battery or even the failure of the power controller.
Can I use two SIMs and a memory card at the same time?
Set up network and priorities in MIUI
Once the phone is physically installed and turned on, the system will offer basic setup, but for optimal performance in unstable coverage or with different communication quality tariffs, it is recommended to manually adjust priorities. To do this, go to the Settings menu, then select the item SIM-maps and mobile networks.
In this section, you'll see a list of installed cards, and you can specify a name for each card (e.g., "Work", "Home", "Internet"), which will make it easier to identify when making calls, and it's also where you set up which card will be used for mobile Internet by default, and which card will be used only for calls and SMS.
You should pay special attention to network type settings. For each slot, you can choose the preferred type: GSM only, WCDMA preferred or LTE preferred. If you are in the zone of confident 4G reception, make sure that you choose the LTE-enabled mode to get the maximum data rate.
Remember that in some versions of the firmware, only one slot can support fourth-generation (4G) networks at high speeds, while the second will work in 2G/3G mode. When you switch the Internet to a second card, the first one can temporarily lose access to the high-speed channel.
Technical characteristics of network support
Understanding the technical limitations of the modem installed in the Redmi 4X will help avoid frustrations with Internet speed.The smartphone is based on the Qualcomm Snapdragon 435 platform, which is equipped with an X6 LTE modem. This modem supports frequency aggregation, but has limitations on maximum download speeds and recoil.
The device supports the main frequencies used by Russian and European operators: FDD-LTE Band 1, 3, 5, 7, 8 and TD-LTE Band 38, 39, 40.This means that in most settlements the phone will work on 4G networks. However, if your operator uses specific frequencies (for example, Band 20, popular in rural Europe), reception may be limited to 3G only.
| Parameter | SIM 1 slot | SIM 2 slot |
|---|---|---|
| Map format | Nano-SIM | Nano-SIM |
| Support for 4G LTE support | Yes (main) | Yeah (on switching) |
| Mode of operation of the second card | 2G/3G (when SIM 1 in 4G) | 2G/3G (when SIM 2 in 4G) |
| VoLTE | Depends on the operator. | Depends on the operator. |
It is worth noting that when you actively talk on the first SIM card in 2G/3G mode, the Internet on the second card may not work or work extremely slowly if VoLTE (Voice over LTE) is not enabled.
Diagnostics and solution of definition problems
Sometimes users are faced with a situation when after installing the smartphone says “No”. SIM-The first step in diagnosis should always be a software reboot, if that didn't work, try removing the tray and wipe the SIM contacts with a soft wipe or alcohol wipe to remove oxides or fatty traces.
A common problem is that the card is not tightly attached in the tray due to inaccurate trimming, and if the card dangles, the contact will disappear at the slightest vibration, in which case you can carefully put a small piece of paper between the card and the plastic tray (not on the contacts!) to fix its position, but it is better to replace the card in the cabin.
⚠️ Warning: If the smartphone gets too hot at the top after installing a new SIM card, remove it immediately.This may indicate a short circuit inside the card chip, which is dangerous for the phone's motherboard.
It’s also worth checking the settings in the engineering menu, although it’s better for the average user not to go there unnecessarily. Make sure that the mobile network settings don’t have a “Only 2G” restriction if you’re in 4G coverage. Resetting network settings to factory values (Settings –> Advanced –> Reset Wi-Fi, mobile networks and Bluetooth) often resolves software conflicts.
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90% of problems with definition SIM-maps 4X solved by pure card trimming to the size of Nano-SIM and clearing gold contacts from oxidation.
If none of these methods worked, the tray itself or the antenna module inside the device may have failed, and this requires a diagnosis at a service center, as self-repairing antenna plumes requires special equipment and skills.