How to set up SIM-Default card on Xiaomi Redmi: Instruction 2026

Modern smartphones Xiaomi Redmi support the work with two SIM-cards at the same time, but not all users know how to properly configure the priority card for calls, SMS Or mobile Internet. Without the right settings, you might find yourself in a situation where outgoing calls are coming from the wrong place. SIM, And mobile traffic is consumed from expensive rates instead of profitable ones. SIM-Main card on Redmi Note devices 12/13, Redmi 10/11, POCO X5 and other models with MIUI 12-14.

We will look not only at the basic settings through the phone menu, but also at the hidden duality possibilities. SIM, which the manufacturer does not advertise, such as how to link specific contacts to a specific SIM-map or why settings are sometimes reset after a firmware update. 5G and VoLTE, where the settings SIM It can affect the quality of communication.

Why it's important to set up SIM-default-card

Without the right dual SIM configuration, you risk:

  • 💸 Pay for mobile traffic if the main card is the one where the Internet is more expensive
  • 📞 Skip important calls if incoming calls are inactive SIM
  • 📱 Lose communication when switching between networks of different operators
  • 🔄 Get lost in tariffs when it is not clear which card the funds are written off

The correct setting is especially critical for those who use:

  • 🏢 Working and personal SIM-single-device
  • 🌍 Roaming – not to pay for incoming on the “wrong card”
  • 📶 Different operators for better coverage (e.g. MTS for the city and Tele2 for travel)
📊 Why do you use the second one? SIM-map?
Working/personal calls
Savings on tariffs
Best network coverage
roaming
I don't use it.

Preparation before setting up SIM-map

Before changing your settings, follow a few important steps:

Make sure both of you SIM-The card is active and recognized by the phone|Check the balance on both cards|Write it down. PUK-codes (in case of blocking)|Update the firmware to the latest version MIUI|Turn off the "In the plane" mode"-->

🔹 Recognition check SIM: Go to Settings. → The phone. → General information → Status SIM-This should be the map:

  • Phone numbers (if not hidden by the operator)
  • Network names (Beeline, MegaFon, etc.)
  • Signal level (in dBm)
  • Network type (4G/5G/3G)

⚠️ Attention: If one of the SIM Defined as “Unknown” or “No Network”, the problem may be:

  • Incorrect Nano-SIM trimming (check compatibility with Redmi)
  • Hardware malfunction SIM-The tray (especially after the phone falls)
  • IMEI lock (relevant for phones brought from abroad)
What to do if SIM-map not defined?
1.Reboot the phone with the retrieved SIM 1 minute 2. Check the card in another device 3. Clear the contacts SIM-Liquor tray (carefully!) 4. Update firmware through Settings → System Update 5. If nothing helps, contact the service center (possible problem with the communication module)

Basic selection methods SIM-default-card

V MIUI There are three levels of settings. SIM-map:

Type of setupWhere applicableHow to change
Global (by default)All outgoing calls and SMSSettings → SIM-maps and mobile networks → Choice SIM-default-card
For a specific contactCalls/SMS to a particular subscriberOpen contact → Push"..." → Choose. SIM
For the mobile Internet4G/5G trafficSettings → SIM-map → Mobile Internet
For VoLTE/VoWiFiLTE/Wi-Fi callsSettings → SIM-map → Challenge LTE/Wi-Fi

🔹 Step-by-step instructions for global settings:

  1. Open Settings (cog icon)
  2. Go to section. SIM-maps and mobile networks
  3. Select the option SIM-card by default
  4. Please indicate preferred SIM for: 📞 Calls. 💬 SMS 🌐 Mobile data

Save the changes (some firmware requires a reboot)

💡

If there is no "Selection" option in the settings SIM-Default cards, so your firmware is modified (castomy). Try resetting your network settings through Settings. → System system → Reset → Reset the network settings

Setting up SIM-mobile-internet maps

The configuration of mobile data deserves special attention, since there are several nuances:

🔹 How to choose SIM internet-based:

  1. Go to Settings → SIM-cards and mobile networks → Mobile Internet
  2. Activate the switch at the right place. SIM-map
  3. Make sure that the mobile Internet (top switch) is enabled
  4. For 5G-Networks select Network Mode → 5G/4G/3G/2G (motor-car)

⚠️ Note: Some Redmi models (e.g. Note) 10 Pro) when activating the mobile Internet on the second SIM The first is automatically disconnected from the network. 4G/5G. This is normal behavior – a phone cannot hold a high-speed connection on two cards at the same time.

🔹 Internet trouble? Check it out:

  • 📶 Signal level (in the status bar there should be an indicator) 4G/5G)
  • 🔄 Settings APN (Path: Settings → SIM-map → [choose SIM] → Access points (APN))
  • 🔋 Power saving mode (turn off background restriction for SIM-map)

💡

On models with Dual 4G support (such as the Redmi Note 12 Pro+), you can use 4G on both SIMs at the same time, but the speed on the second card will be limited to 3G.

Linking contacts to specific contacts SIM-map

If you need to make calls to certain subscribers always go with a specific SIM-Maps, use this function:

🔹 Instructions:

  1. Open the Contacts app
  2. Choose the right contact
  3. Press three points (⋮) top-right
  4. Choose. SIM-default-card
  5. Specify the desired SIM (SIM 1 or SIM 2)

🔹 Mass binding: Unfortunately, in the standard MIUI There is no group function SIM - I'm not in contact:

  • Use Google Contacts with Tags and Rules
  • Install third-party applications like Dual SIM Contacts
  • Export contacts, edit CSV-file and import back

⚠️ Note: When resetting the phone to factory settings, linking contacts to SIM Resets. We recommend that you back up before resetting through Settings. → Google → Backup.

Hidden settings SIM-card MIUI

In addition to the standard options, MIUI firmware has hidden features that can be activated through an engineering menu or special codes:

🔹 Diagnostic codes SIM:

  • #4636## - Network and SIM information (Phone Information section)
  • #225## - Balance check (not available for all operators)
  • *#06# - IMEI check (two numbers for Dual SIM should be displayed)

🔹 Engineering menu (MTK): For phones running MediaTek processors (e.g. Redmi) 9A, 10A):

  1. Enter #36446337#
  2. Go to Connectivity → SIM
  3. You can manually change the priority of SIM for voice and data
The dangers of the engineering menu
Don't change the settings unless you understand their meaning! Incorrect settings can lead to: - Network loss on one or both SIMs - Communication quality deterioration - Automatic phone reboots - Resetting needs to be done before factory settings

🔹 Setting up VoLTE: For better call quality:

  1. Go to Settings → SIM-cards and mobile networks
  2. Choose. SIM-map
  3. Activate LTE Call (VoLTE)
  4. Redmi Note 11/12 also has Wi-Fi (VoWiFi)

Frequent problems and their solutions

Even after setting up correctly, Xiaomi Redmi users may face problems:

🔸 Problem 1: Settings SIM reset after resetting

  • 🔹 Reason: Conflict with the optimizer MIUI or third-party applications
  • 🔹 Solution: Turn off Auto-Optimization in Settings → Battery Add Phone app to exceptions Update firmware to latest version

🔸 Problem 2: Mobile Internet is not working on the second SIM

  • 🔹 Reason: There are no settings APN or conflict with the first SIM
  • 🔹 Solution: Check it out APN through settings → SIM-map → [choose SIM] → Access Points Turn off mobile internet on the first SIM Reboot the phone.

🔸 Problem 3: Calls are coming from the wrong person SIM, despite the settings

  • 🔹 Reason: Contact is prioritized to another SIM
  • 🔹 Solution: Open contact and reset settings SIM (see section above)