Xiaomi smartphone owners using two SIM cards often face a situation where the message leaves the wrong number, which can lead to misunderstanding with contacts or, in the worst case, to a loss of funds if the rates for sending messages differ. Standard behavior of the MIUI or HyperOS system sometimes ignores the user's expectations, relying on its internal algorithms for choosing a priority card.
The problem of choosing a SIM card for SMS is relevant not only for older models, but also for newer devices, where the logic of the shell can change after updates. Understanding how the Android operating system handles requests for sending media and text messages will help you take control of communication into your own hands. In this article, we will examine all the nuances of the configuration, from basic parameters to hidden functions of the engineering menu.
Sometimes it just forgets your last choice or resets your settings after you reboot. Google Messages and the standard MIUI Messages app work differently, which adds to the confusion. Let's figure out how to make the phone behave predictably and send messages strictly from the right number.
Basic Settings for SIM card selection in the message application
The most obvious, but often ignored, way is to select a SIM card at the time of writing a message. In most versions of the MIUI shell, the interface allows you to switch an active SIM card right in the dialog window. This is usually done by clicking on the SIM card icon next to the input field or send button. However, if you do not change this setting manually, the phone will use the card installed as the default card for voice calls or mobile Internet.
To avoid errors, you need to set up global preferences. Go to Settings → SIM-Maps and mobile networks. You'll see the default section here, or the call and internet settings section, and it's important to note that there may not be a separate "SMS default" item in new versions of Android, as the system tends to select a card automatically based on the last action. However, checking the status of SIM cards is a must: make sure both cards are active and have a signal.
⚠️ Attention: If in the settings SIM-One of them is displayed as “Disabled”, the system will forcibly try to send an SMS via an active card, ignoring your attempts to select in the application.
In some cases, the messaging app can “remember” the choice for a particular contact. If you sent a message to the contact “Mom” from the SIM card 1, then the next dialog the phone will prompt to send again from the SIM card 1. This is a behavioral feature of Android that you need to consider when changing your plans.
Setting Priorities in Google Messages and MIUI Messages
Users are often confused between two main applications: standard. MIUI Messages and Google Messages, they have different logics. In the Google app, which is now the standard for many regions, the SIM card selection is done through the settings menu inside the app itself. Click on the profile avatar in the corner, select Settings. → Communication → SIM-You can rigidly set your preferred map here.
In Xiaomi’s native app (Messages), the algorithm is simpler but less flexible, and it’s a last-action rule that if you want to change priority, you often have to go from the opposite: temporarily disable an unnecessary SIM card in your network settings, send a test message, and then turn the card back on, and this forcefully resets the selection cache for the current session.
The key is to understand the difference between RCS-chatroom SMS/MMS. If you have chat functions enabled (RCS), The message can be sent over the Internet using the SIM card on which the mobile Internet is configured, regardless of the number specified by the sender.
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Use the SIM Selection widget on the home screen if your version of MIUI allows you to add it, which makes it quicker to switch between cards before sending an important message.
Also worth checking is the app permissions, and make sure that the messenger you choose has full rights to control your phone and access your contacts, and without those rights, the app can misread the status of the second SIM card and default to the first one.
Problems with sending confirmation codes and service SMS
A separate category of problems is service messages from banks, social networks and government services, and users often complain that the confirmation code comes to one SIM card, and the phone tries to send a response or balance request with another, which is related to the way Android handles short numbers (Short Codes).
The system can automatically determine which SIM card was used for the last registration on the service, and try to continue the dialogue with it. If you changed the main SIM card for the Internet, the logic can get lost, in such cases, cleaning the data of the message application helps.
☑️ Actions for code problems
If you send a request for a short bank number from the wrong SIM card, the service simply won’t work, even if the balance allows you to send a message.
⚠️ Warning: Never send financial requests through third-party SMS shell applications unless you are sure of their security.
To solve problems with service SMS, you sometimes need to manually write down the message center number (SMSC) in the engineering menu or through hidden SIM card settings, but for most users, it is enough to simply reinstall the SIM card to another slot if one of them has priority in the system.
Use of engineering menus and hidden settings
For advanced users who want to gain full control of the communication module, there is an engineering menu, which is logged in on Xiaomi smartphones via the code set ##4636## in the Phone app, and you can see detailed statistics on each SIM card and force the network type to be changed.
In the Phone Information section (there will be two of them, one for each SIM card), you can see the current registration status on the network. 2G/EDGE, It's the one that might not be sending or receiving SMS, and the system would automatically redirect traffic to the second card. LTE only (only) LTE) This can help stabilize the connection, but remember that this mode may not be used for regular voice calls unless VoLTE is enabled.
Is it dangerous to use an engineering menu?
Also in the engineering menu, you can check the signal level in dBm. If the signal on one SIM card is below -110 dBm, stable SMS operation is impossible, in this case, no software settings will help - the problem is physical (antenna or coverage).
There is another hidden test - # #6484## (CIT). Here's where you can run a test. SIM-This is a great way to diagnose whether the problem is software or physical contact of the SIM card.
Comparison of methods of SIM card selection
To systematize your knowledge, let’s compare the basic methods of SIM management on Xiaomi. Each of them has its advantages and disadvantages depending on your situation.
| Method | Efficiency | Difficulty | Risks. |
|---|---|---|---|
| Choice in the annex | Tall. | Low. | Minimum |
| System settings | Medium | Low. | Absent. |
| Engineering menu | Maximum | Tall. | Medium (setting error) |
| Third-party annexes | Low. | Medium | High (safety) |
As you can see from the table, standard methods (in-app selection and system settings) are the safest and most effective for 95% of users, and only use the engineering menu in case of obvious failures in the communication module, when standard tools are powerless.
The use of third-party SMS management apps on modern Android is limited by Google’s security policies, which often don’t have real access to SIM card selection, but only mimic the interface, so rely on them is not worth relying on.
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Standard MIUI tools provide the best balance between functionality and stability of SIM cards.
Solving typical errors and failures
If none of the methods work and the phone persistently sends text messages from the wrong card, there may have been a failure in the network profile configuration, in which case a full reset of network settings helps. Go to Settings → Connection and Sharing → Reset Wi-Fi, mobile networks and Bluetooth.
This operation will not delete your personal files or contacts, but will return all network settings to factory values. You will have to re-enter Wi-Fi passwords, but this often solves the problem of sticking to the priority of the SIM card. Once reset, the phone will re-register in the operator's network and request the current APN and SMSC settings.
Another common cause is an outdated firmware or bug in a particular MIUI update. Check for system updates. If the problem occurs immediately after the update, it makes sense to search forums for specific bugs of that version. Sometimes cleaning the cache of the Wipe Cache Partition through the Recovery menu helps.
⚠️ Note: Before performing any action in the Recovery menu (Wipe Cache Partition), make sure you do not confuse this item with Wipe Data (Full Reset), which will delete all your data.
Also, remember the physical condition of the SIM card, if the card is many years old, its contacts may have oxidized or it may have been cropped incorrectly, try swapping the SIM cards in slots or erasing the contacts with a wiper, sometimes replacing the old SIM card with a new one from the operator solves all the problems with registering on the network and sending messages.