How do you put it in? SIM-map 3S: tray, size, network activation

Introduction: Why the Right Installation SIM-Cards are important for Redmi 3S

Xiaomi Redmi 3S — One of the most popular budget smartphones of 2016, which is still used today because of its reliability, but even such a proven device can have communication problems if you install it incorrectly. SIM-Installation errors often result in a network being missing, permanent reboots or even damage to the slot contacts.

In this article you will find step-by-step instructions with a photo how to insert SIM-map 3S, What tools are needed, how to avoid common errors, and what to do if the smartphone does not see the card, and we will also discuss the features of a hybrid slot that supports either two nano-SIMs or one. SIM + microSD.

If you have just bought a used Redmi 3S or have not used a second slot for a long time, this guide will help you avoid common problems that owners face.

What? SIM-The card is suitable for Xiaomi Redmi 3S: nano-SIM and its dimensions

Redmi 3S supports only nano-SIM (4FF), the smallest SIM format used in modern smartphones, and if you have an old micro-SIM (3FF) or a full-size SIM (2FF), you will have to trim or replace it in the cabin of the operator.

Nano-SIM sizes for Redmi 3S:

📏 Length: 12.3 mm
📏 Width: 8.8 mm
📏 Thickness: 0.67 mm

If you trim the micro-SIM yourself, use the template for nano-SIM (it can be found online) and leave a margin of 0.1-0.2 mm so that the card does not hang around in the slot. In Redmi 3S, the tray does not have locks for micro-SIM - an improperly cropped card can get stuck or damage contacts.

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Before trimming the old SIM, take a photo of it from both sides – this will help to correctly position the chip in the new format.

SIM format	Is it good for Redmi 3S?	What to do if there is a different format
nano-SIM (4FF)	✅ Yes.	Install unchanged
micro-SIM (3FF)	❌ No.	Cut to nano-SIM or replace in the cabin
mini-SIM (2FF)	❌ No.	Replace with nano-SIM in the operator’s cabin
eSIM	❌ No.	Redmi 3S does not support eSIM

If you use two of them SIM-Note that the Redmi cards 3S Supports a hybrid slot: either two nano-SIMs or one nano-SIM + MicroSD: Install two microSDs at the same time. SIM And the memory card's off.

Where is the slot for SIM-maps in Xiaomi Redmi 3S: photo-position

At Redmi. 3S squash SIM-The map is located on the left end of the case, next to the volume buttons, and it is easy to recognize from the small hole for the extraction tool.

The outside of the tray looks like a thin metal plate with a slot for a paper clip.

🔢 SIM 1 - the main slot (supports) 4G)
🔢 SIM 2/microSD – Hybrid slot (only) 2G microSD)

If you can’t find a slot, look at the smartphone case – next to the hole to extract the tray there is usually a small icon. SIM-Some versions of Redmi. 3S (Like Redmi. 3S Prime) slot location identical.

📊 You’ve already used a Xiaomi smartphone before?

Yeah, I had another Redmi.

Yes, but a different model (Mi, POCO)

No, this is my first Xiaomi.

I remember.

Step-by-step instruction: how to insert SIM-map 3S

To establish SIM-map, follow this instruction:

Turn off your smartphone. It's a must-do step -- hot replacement. SIM-The card may cause the communication module to malfunction.
Find a tool to extract the tray. The Redmi 3S comes with a special paper clip, but a regular stationery that is straight-lined will do.
Remove the tray. Put the paper clip in the hole on the left end and press a little until the tray is pushed out. Don't use excessive force - the mechanism is fragile!
Place it. SIM-Make sure the chip looks down and the beveled corner of the card matches the beveled corner of the slot. 3S fitting: 📱 SIM 1 - closer to the edge of the tray (main, 4G) 📱 SIM 2/microSD – further from the edge (secondary, only) 2G memory-card)

Put the tray back in. Carefully insert it into the slot before you click. Make sure the tray sits flat -- if it protrudes, pull it out and try again.

Turn on your smartphone. Check if you have a network in the status bar after you boot, if there's no signal, restart the device or check if the card is installed correctly.

Make sure the smartphone is off |Use the correct size nano-SIM |Combine the bevelled corners of the card and slot |Do not apply force when removing the tray-->

After installation SIM-The card is not determined, try it:

🔄 Reboot your smartphone.
📶 Manually select the operator in the settings (Settings) → SIM-maps and mobile networks → Choice of network).
🔧 Wipe your contacts. SIM-cards with dry cloth (sometimes oxidation interferes with communication).

What to do if the tray is stuck?

If the tray is not removed by a paper clip, do not try to pull it out with pliers - this will damage the mechanism. Instead: 1. Put the smartphone on the soft surface with the screen down. 2. Carefully press the tray on the back side (from the battery side), while simultaneously putting it on paper clip. 3. If it does not help, contact the service center, as you will need to disassemble the case.

Frequent errors in installation SIM-maps 3S and how to avoid them

Even experienced users sometimes make mistakes that lead to communication problems.

⚠️ Attention: If after installation SIM-Redmi card 3S It's constantly rebooting or turning off -- most likely, the card is not tightly sitting in the slot or the contacts are contaminated. Don't ignore this problem: prolonged use with poor contact can disable the communication module.

❌ Micro-SIM installation without cropping.Redmi tray 3S It doesn’t fix larger cards – they’ll hang around, which will cause network loss or damage to contacts.
❌ The wrong orientation of the chip. SIM-The card is up, the smartphone won't see it. Always make sure the gold contacts are pointing down.
❌ Use of damaged SIM-Cracks, scratches or chips on a chip can cause reading errors.
❌ Pressing the tray hard. The extraction mechanism is fragile, so if you push too hard, you can break the spring inside.
❌ Installation of two SIM + microSD. Redmi Hybrid slot 3S It doesn't support that combination. You have to choose between two. SIM-card SIM + memory-card.

After installation SIM-The smartphone says "No service" or "SIM-The card is not supported, try it:

Re-install the map, making sure the orientation is correct.
Wipe your contacts. SIM-cards and slots with alcohol (for removal of oxides).
Checking the card on another phone may be the operator’s side of the problem.
Update the Redmi 3S firmware to the latest version (sometimes bugs are patched in updates).

How to activate the second SIM-map 3S and set the priorities of the network

Redmi 3S Supports the work of two SIM-maps, but with limitations:

📶 SIM 1 - Supports 4G (LTE), 3G, 2G.
📶 SIM 2 – only works on networks 2G (GSM).

To set up the second SIM-map:

Go to Settings. → SIM-maps and mobile networks.
Select SIM 2 and turn it on by moving the slider.
Set priorities: 🔄 Calls: You can choose which one SIM default. 💬 SMS: point out SIM message-board. 🌐 Mobile Internet: Enable data transfer only for SIM 1 (so SIM 2 supportive 3G/4G).

"Notifications of call on SIM 2"

Note that if you use SIM 2 only for calls, turn off mobile internet to avoid unnecessary battery consumption, and check the operator's tariff - some tariffs do not support 2G networks.

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Second second SIM-map 3S only works 2G-If you need the Internet on both of them. SIM, You will have to choose one of them for 4G, a) Use the second only for calls.

What to do if Xiaomi Redmi 3S see SIM-Map: Diagnostics and Solutions

If the smartphone does not recognize SIM-The reasons for this can be software or hardware. Start with simple steps:

Reboot. Sometimes the communication module fails with a normal reboot. Press the power button and select Reboot.
Check the slot, remove the tray and make sure that SIM-The card sits tightly in the slots. Try to install it in another slot (if you use one card).
Clear the contacts. Wipe the gold contacts. SIM-And inside the slot with a dry soft cloth. If there's oxidation, use alcohol.
The test is on another phone. SIM-If it doesn't work, the problem is on the operator's side (maybe the card is blocked).
Network reset. Go to Settings → System → Settings Reset → Network reset. This will remove stored Wi-Fi networks and mobile settings, but often helps with crashes.
Update firmware. Outdated software may contain bugs in the communication module. Check the updates in Settings → About Phone → System Update.

⚠️ Note: If after all the manipulations SIM-The card is still undetectable, and the other phone is working, and the problem may be in the hardware (the slot or communication module is damaged.

If the smartphone is writing "SIM-The card is not supported, this may mean:

🔒 The card is blocked by the operator (for example, due to non-payment).
🛠️ Chip's damaged. SIM-maps (cracks, chips).
📱 Redmi firmware 3S Does not support the map format (relevant to older versions) MIUI).

In the latter case, try flashing your smartphone to the latest version of MIUI via Fastboot or Recovery. Firmware instructions for Redmi 3S can be found on the official Xiaomi forum.

Alternative uses SIM-maps 3S: adapters and eSIMs

Redmi 3S It does not support eSIM, but there are alternative solutions for those who want to use two. SIM-card and memory card simultaneously:

🔄 MicroSD adapter + SIM. There are adapters that allow you to install microSD and nano-SIM in the same slot, but they often cause problems with heating and stability of communication "SIM + microSD in nano-SIM".
📶 Cloud storage, if you need two. SIM-Maps but not enough memory, use Mi Cloud, Google Drive or Yandex Disk to store files.
🔌 USB-OTG + Card reader. You can connect the external drive through OTG-cable, but it is inconvenient for constant use.
📱 Second smartphone, if two are critical. SIM and a memory card, consider buying a second budget phone (e.g. Redmi) 4A microSD-slot).

Important: SIM and microSD adapters often lead to:

⚡ Overheating of the smartphone (due to poor contact).
📵 Network loss or frequent communication breakdowns.
🔋 Fast battery discharge (communication module works with overload).

If you do decide to use an adapter, choose models with metal contacts and good reviews. Before buying, check compatibility with Redmi 3S - some adapters do not fit in thickness.

FAQ: Answers to Frequent Questions about SIM-Maps in Xiaomi Redmi 3S

Can Redmi 3S use micro-SIM without trimming?

No, Redmi 3S only supports nano-SIM. Micro-SIM is not fixed in the slot and can damage the contacts. Cut it to the desired size or replace it in the cabin operator.

Why is the second SIM-card-less 4G?

In Redmi 3S, the second SIM (SIM 2) only works on 2G networks. For 4G, use SIM 1.

How to remove the tray if there is no paper clip?

We can use it: 📎 Folded paper clip. 🔧 Thin needle or pin (carefully not to break). 📌 A toothpick sharpened under a cone, the key is not to use force so as not to damage the machinery.

The smartphone says "No service" after installing SIM.

Try: Reboot the phone. Reinstall it. SIM-map (possibly not seated tightly) Manually select the network in Settings → SIM-maps and mobile networks → Network selection: Check the balance and status of the card operator (possibly blocked).

Can I put two in? SIM-card and memory card simultaneously?

No, Redmi 3S has a hybrid slot: either two nano-SIMs or one nano-SIM+microSD. An adapter will be required to use two SIMs and a memory card at the same time, but it can cause communication problems.