Owners of the legendary Xiaomi Redmi Note 3 smartphone, released in the mid-2010s, still actively use the device due to its reliability and metal body. However, the issue of compatibility with modern carriers remains relevant, especially when you first set up the device or replace a lost card. Many users are confused in formats, as in recent years, communication standards and the size of plastic media have undergone significant changes.
To work properly, the model requires Nano-SIM cards. This is the smallest standard in use today, and trying to insert a larger Micro-SIM or standard SIM without special trimming can lead to mechanical tray jamming or damage to the contact group inside the phone. It is important to understand that the device supports modern LTE standards, but requires the correct configuration.
In this article, we will take a closer look at the technical details of working with SIM cards in Redmi Note 3, look at the differences between the Pro and Standard versions, and provide a step-by-step guide to safe installation. You will learn how to activate two numbers at the same time and what to do if the phone does not see the network after changing the operator.
Technical characteristics of the SIM slot in Redmi Note 3
Xiaomi Redmi Note 3 is equipped with a hybrid slot, which is an important technical solution for the budget segment of the time.This means that the physical space inside the case is limited, and the user has to choose between using a second SIM card or microSD memory card. The tray is designed in the form of a retractable frame that is located on the bottom of the device, next to the USB connector and speaker.
There are two slots for Nano-SIM cards inside the tray. However, depending on the processor modification (MediaTek or Qualcomm Snapdragon), the logic of these slots may differ. The MediaTek Helio X10 version (regular) and the Snapdragon 650 (Pro) version have different 4G network support circuitry. Both use Dual SIM Dual Standby technology, which allows both numbers to stay online at the same time, but only one of them can receive data at a particular time.
⚠️ Note: The SIM card tray in Redmi Note 3 is retractable and has no mechanical fixation in the closed position.When extracting, use only the original clip or a thin point so as not to damage the spring mechanism inside the body.
Particular attention should be paid to contact areas. Since the phone is not new, the contacts inside the slot may have oxidized or become contaminated. Before installing a new card, it is recommended to gently blow the slot with compressed air. Using cards with a damaged chip or unusual thickness (for example, if the card was cut with scissors without calibration) can lead to short circuits.
Differences between Pro and Standard versions when working with the network
When buying or configuring a used device, it is critical to understand what kind of modification is in your hands, as LTE frequency support and Internet speed depend on it. The Redmi Note 3 Pro version on the Snapdragon 650 processor has a more modern modem that supports frequency aggregation and a wider range of 4G bands. This means that in this model, data transfer speeds will be higher, and coverage is stable in low signal conditions.
The MediaTek-based model (often labeled as Redmi Note 3 SE or simply Standard) also supports 4G, but it already has a list of compatible frequencies. In some regions of Russia and CIS countries, this can lead to the fact that the phone will catch the network only in 3G or even 2G mode if the operator uses specific frequencies for LTE. You can check the supported frequencies in the engineering menu or through special applications, but for the average user it is more important to know that the Pro version is preferable for modern mobile Internet.
Both versions use the same physical map format, Nano-SIM. However, the MIUI software shell can display network status differently. In the Pro version, switching between 3G and 4G is more aggressive and faster, whereas the MediaTek version can think longer when searching for a network after leaving coverage, a software feature, not a defect of the SIM card.
How to determine the version of the processor?
Step-by-step instructions for installing Nano-SIM cards
The process of installing a sim card in Xiaomi Redmi Note 3 requires care, since the tray is quite thin and sensitive to distortion. Before starting the procedure, make sure that the device is turned off, although modern technology supports a “hot” replacement, it is safer for older devices to manipulate when the power is turned off to avoid resetting the network settings.
To perform the operation, you will need a special metal clip that comes with the kit, or its analogue. Do not use needles or pins, as they can bend inside the hole and get stuck, after which it will be extremely difficult to remove them without disassembling the body.
☑️ Pre-installing check SIM
After removing the tray, notice its shape. It usually has cutouts for two Nano-SIM cards. The cards must be positioned so that the cut angle coincides with the shape of the tray, and the golden contacts look upwards (to the screen, if you put the phone up with the screen, but in the tray they usually navigate the contacts down, to the board - follow the icon on the tray itself).
Once the phone is turned on, the system must automatically identify a new SIM card. If this does not happen, check that the installation is correct. Sometimes it takes several seconds to register with the operator's network. PIN-code if you have previously installed protection.
Setup two SIM cards and priorities in MIUI
One of the main features of Xiaomi smartphones is the flexible setting of two SIM cards. → SIM-And you can assign one card to the default voice call, and the other card to the mobile Internet, or you can request a card to choose from every call.
In the settings section, it's important to prioritize things, for example, if you have unlimited Internet on one card and packet minutes on the other, it's logical to assign the first one for data transfer and the second one for calls. MIUI allows you to customize in detail which SIM card will be used for SMS, MMS and voice communication, which is especially convenient for those who share personal and work contacts.
| Parameter | SIM card 1 | SIM card 2 |
|---|---|---|
| Operator. | MTS / Beeline / Megafon | MTS / Beeline / Megafon |
| Type of network | 4G/LTE (Preferred) | 4G / LTE / 3G |
| Voice calls | Always ask / Chosen | Always ask / Chosen |
| Mobile Internet | Included (main) | Off (reserve) |
Also worth noting is the "Flight Mode" feature for a particular SIM card, which means that if you don't need calls from one number temporarily, but you're waiting for an SMS to another, you can programmatically turn off one of the SIM cards in the settings without physically removing it, saving battery power and eliminating unnecessary notifications.
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Use the “Traffic Limitation” function in the settings SIM-cards so that the second SIM card does not consume your main packet of megabytes in the background.
Solving Network and 4G Definition Problems
It is not uncommon for users to experience a situation where, after installing a SIM card, the phone writes "No Network" or does not switch to 4G. The first step should always be to check the correct installation of the card and its integrity. If the card is new and activated by the operator but does not work, try inserting it into another phone to prevent the defect of the plastic card itself.
The second important aspect is the setting of the access point (APN). Often, when you set up the Internet automatically, you may not set the settings correctly, especially for virtual operators or regional tariffs. APN, You can find it on your operator's website. → SIM-maps and mobile networks → (Select a SIM card) → Access points (APN).
⚠️ Attention: When manually adjusted APN Be careful of the letter register and the absence of spaces, and a mistake in one character can lead to the Internet not working, although voice communication will function normally.
If the problem persists, try resetting the network settings. This action will return all network settings to factory values, delete stored Wi-Fi passwords and Bluetooth settings, but often solves the problem with modem "glitches." You can do this in the Settings menu → Advanced Settings → Recover and Reset → Reset Wi-Fi, mobile Internet and Bluetooth settings.
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In 90% of cases, the problem with the lack of 4G is solved by choosing the right APN access point or switching the network mode to the settings menu.
Security and Restoration of Access to the SIM
Security of your SIM card in Redmi Note 3 is ensured PIN and PUK code. PIN-The code is requested when you turn on your phone if this feature is activated in the settings, and it protects your data in the event of a phone theft. PIN-After three failed attempts to enter the code, the card is blocked and you will need to PUK-code.
PUK-The personal unblocking key is usually shown on the plastic card holder you received in the salon when you purchased the SIM card. If the card was reissued or the holder is lost, the code can be found in the operator's personal account or by calling support. PUK-The code also has a limit of attempts (usually 10), after which the SIM card is permanently blocked and requires replacement.
In modern versions MIUI There is also a function of linking the SIM card to the Mi Account for remote management, but the basic protection is carried out through access codes. PUK-If the phone itself is locked with the same code, it is better to write it in a paper notebook or save it in the cloud, accessible from another device.