Introduction: Why choosing a SIM- card is important for Redmi 4X
Xiaomi Redmi 4X (codename santoni) remains a popular choice among users who value reliability and budget price. However, when buying or replacing SIM- cards, many face confusion: what format supports the device, whether you can use two cards at once, and how to install them correctly so as not to damage the tray. In this article, we will discuss all the nuances of working with SIM- cards in Redmi 4X, including rare problems faced by owners.
The feature of the model is a hybrid slot that allows you to choose between a second SIM- card or a microSD card. This creates additional questions: what is better to choose, how to not lose communication when installing the drive, and which operators work optimally with this smartphone. We will also analyze compatibility with modern communication standards (4G, VoLTE) and give recommendations for setting up the network for maximum Internet speed.
Technical characteristics of the SIM- card slot in Redmi 4X
Xiaomi Redmi 4X is equipped with a single physical tray, but with a hybrid design.
- 📱 Use two Nano-SIM cards (without microSD).
- 📱 Install one Nano-SIM + microSD (up to 256 GB).
- ❌ You cannot use two SIM- cards and a microSD at the same time.
Important: the tray does not support micro-SIM or the standard SIM - only Nano-SIM (4FF). If you have a card of a different format, it will have to be cropped or replaced in the cabin of the operator. Nano-SIM dimensions: 12.3 × 8.8 × 0.67 mm.
The tray is located on the right end of the device. To extract it, you will need a paper clip or a special SIM- key that comes with the kit. Do not use sharp objects (needles, knives) so as not to damage the mechanism!
What type of SIM- card is needed for Redmi 4X: Nano-SIM or another?
The only format supported is Nano-SIM (4FF), which is the smallest standard used in most smartphones today.
- 🔹 Standard SIM (1FF) or mini-SIM (2FF) – it must be trimmed to Nano or replaced at the operator’s office.
- 🔹 Micro-SIM (3FF) -- theoretically, you can trim to Nano, but the risk of contact damage is high.
⚠️ Warning: If you decide to crop the card yourself, use a cropping pattern and act carefully. Damaged contacts can lead to network loss or inability to identify the map.
In rare cases, users encounter a problem when the smartphone does not recognize the new Nano-SIM.
- 🔸 Incorrect installation (card not fully inserted)
- 🔸 Slot contact contamination (dust, oxidation).
- 🔸 Operator incompatibility (e.g., virtual operators such as SberMobile may require additional settings APN).
💡
Before installing the new SIM- card, restart your smartphone, which sometimes helps the system to properly initialize the slot.
Hybrid Slot: How to Choose Between Second SIM and MicroSD
The Redmi 4X's main compromise is that you can't use two SIM- cards and a memory card at the same time, and you have to choose one of the options:
| Option | Pluses | Cons |
|---|---|---|
| Two Nano-SIMs | ✅ Separation of personal/working number✅ Savings on roaming (local SIM on travel) | ❌ No memory expansion ❌ Fast battery discharge when using two networks |
| One Nano-SIM + MicroSD | ✅ Additional 256 GB of storage for photos, videos, applications✅ Less power consumption | ❌ No backup number❌ Data is lost when memory card breaks |
🔹 When to select two SIM- cards:
- 📞 You travel frequently and use local SIM for savings.
- 📞 You have separate numbers for work and personal calls.
- 📞 Operators offer favorable calls/internet rates for card combinations (e.g. Beeline + Tele2).
🔹 When to choose a microSD:
- 📷 You shoot a lot of videos in Full HD or store large files.
- 🎮 Install heavy games (Genshin Impact, Call of Duty Mobile)
- 📂 You need to transfer applications to a memory card (the Adoptable Storage function in Android).
How to migrate applications to microSD in Redmi 4X?
Step-by-step: how to install SIM- card in Redmi 4X
The installation process is simple but requires care, and follow the instructions to avoid damage to the tray or contacts:
Turn off your smartphone (required!)|Find the tray on the right end |Put the paper clip in the hole and remove the tray |Put the Nano-SIM contacts down |Gently insert the tray back before clicking
-->
📌 Detailed instruction:
- Turn off your smartphone. Installing a SIM- card when the device is on can cause contacts to be damaged or the network to malfunction.
- Find a tray on the right side of the case, and next to it there's a small hole to extract.
- Insert a paperclip or SIM- key into the hole and press until you click. The tray will extend a few millimeters - gently pull it out.
- Put the Nano-SIM in the tray with the contacts down. For a second SIM or microSD, use the appropriate slot (see marking on the tray).
- Put the tray back to the end, make sure it's tightly locked, otherwise the smartphone won't recognize the card.
- Turn on the device and wait for the network initialization (can take up to 2 minutes).
⚠️ Warning: If the smartphone does not see the SIM- card after installation:
- 🔹 Reset the device.
- 🔹 Check if the card is inserted correctly (contacts must be clean).
- 🔹 Try inserting the card into another smartphone — if it doesn't work, the problem is SIM, not Redmi 4X.
Compatibility with operators and network configuration
Redmi 4X supports most Russian and foreign carriers, but for stable operation of 4G (LTE) and VoLTE may require additional settings.
📶 Supported communication standards:
- 🔹 2G: GSM 850 / 900 / 1800 / 1900.
- 🔹 3G: HSDPA 850 / 900 / 1900 / 2100.
- 🔹 4G LTE: Band 1(2100), 3(1800), 5(850), 7(2600), 8(900), 38(2600), 39(1900), 40(2300), 41(2500).
🔹 The best operators for Redmi 4X in Russia:
- 📡 MTS is stable 4G, good coverage in the regions.
- 📡 Beeline - favorable rates for the Internet, support for VoLTE.
- 📡 Tele2 is low-cost but low-cost in some areas.
- 📡 MegaFon: High speed 4G, but more expensive than competitors.
⚠️ Warning: If there is no 4G card after installing SIM-, check the settings:
- Go to Settings. → SIM-maps and mobile networks.
- Select your SIM- card and click Network Type.
- Install 4G (recommended) or 3G/4G (auto).
- If VoLTE is available, turn it on for clearer calls.
💡
If the smartphone does not catch the network in the zone of confident coverage, try to manually select the operator in the settings (Settings → Mobile Network → Network Operators).
Frequent problems with SIM- cards in Redmi 4X and their solutions
Even with the correct installation of SIM- cards, Redmi 4X users sometimes encounter errors.
🔧 "SIM-card not found" or "No service":
- 🔸 Reboot your smartphone, which solves 70% of the problems.
- 🔸 Check if the contacts on the card or slot are oxidized (clean with alcohol).
- 🔸 Try inserting SIM into another smartphone — if it doesn't work, contact the operator.
- 🔸 Update your firmware (sometimes software bugs interfere with card recognition).
🔧 "Emergency calls only":
- 🔸 Make sure the SIM- card is activated (new cards require activation via USSD- command or call).
- 🔸 Check balance – with a zero or negative balance, the operator can block outgoing balances.
- 🔸 Manually select the operator in the settings (Settings → Mobile Network → Network Operators).
🔧 The smartphone does not see the second SIM- card:
- 🔸 Make sure the tray is inserted to the point (sometimes the second SIM does not contact due to incomplete fixation).
- 🔸 Check if your firmware supports Dual SIM (some custom firmware may disable support for the second SIM).
- 🔸 Switch priority SIM for data in settings (Settings → SIM-maps and mobile networks → Data transfer).
🔧 The network is permanently lost:
- 🔸 Turn off the power saving mode — it can limit background network activity.
- 🔸 Reset network settings: Settings → System → Reset → Reset settings Wi-Fi, mobile network and Bluetooth.
- 🔸 If the problem persists, try changing carriers — possibly weak coverage in your area.