How to Set Your Phone by Default on Xiaomi: SIM and Call Management

Owners of Xiaomi smartphones often face a situation when it is necessary to firmly fix the use of a certain SIM-This is especially true for dual-active SIM devices, where the system can constantly ask which network to call. MIUI The new HyperOS provides flexible tools to control this process, allowing you to avoid unnecessary actions with each dial.

Understanding how priority works can save time and nerves, allowing you to assign a specific SIM to voice, leaving the second only for mobile Internet or receiving messages, not just convenience, but also a way to control costs if operators’ tariff plans differ significantly in the cost of a minute of conversation.

In this article, we will discuss in detail the algorithm of actions necessary to install the phone (SIM-We will cover various scenarios, including settings through the standard menu, using engineer codes and resolving issues with operator selection blocking, and how VoLTE and Wi-Fi Calling settings affect call routing choices.

It is worth noting that the settings interface may vary slightly depending on the firmware version. However, the logic of Xiaomi’s system remains unchanged: the manual selection of the user is given priority if it was explicitly specified. Automode, which is often turned on by default, can behave unpredictable when a bad signal from one of the networks.

Why do we need to fix SIM-call-card

The main reason users want to default is to eliminate the constant SIM card dialog box. Every time you dial or click on tel: in the browser, the system requests confirmation, which is distracting and slows down the communication process, especially in emergency situations when the count is going on for seconds.

Also, fixation SIM-The card helps to avoid accidental calls through an expensive operator. There are cases when Android automatically switches to a second SIM due to a weak signal of the main one, and the user does not notice this until he receives the bill. Forced priority setting ensures that the call will always go through the chosen channel, regardless of the signal level of the second card.

Another important aspect is the stability of messengers and services tied to a phone number. Some applications use the number from which the last activity was performed or which is listed as the main one for calls to verify identity or sign up, and a clear system configuration eliminates login errors in Viber, Telegram or banking applications.

⚠️ Note: If you use the Smart Choice feature SIM" (Smart SIM), The system can ignore your roaming preferences to avoid costs.Make sure this feature is disabled if you want to tightly control routing.

Priority setting also affects the number and call detector, which makes the call log more structured when all the outgoings go through the same line, making it easier to analyze communication and find the right contact in the dial list without requiring operator filtering.

Setting up the selection SIM-maps on Xiaomi menu

The easiest and safest way to install your phone by default is to use the standard settings interface, which does not require root rights or a computer connection and is available on any current version of MIUI. The algorithm is intuitive, but has its own peculiarities depending on the localization of the system.

First, you have to open the main menu of your smartphone settings, and we're interested in the section that connects to the cellular network — SIM-maps and mobile networks. This is where all the levers of voice and data management are concentrated.

Inside this section, you'll see a list of SIM cards installed, and the system offers you to customize their behavior individually, we're interested in Voice or Calls, and if you click on it, you'll be placed in the priority menu, and you can assign Sim 1 or Sim 2 as the primary for all outgoing calls.

Once a particular SIM card is selected, the system may suggest that you enable the Always Ask function. If your goal is to set the default phone, this option must be turned off. Otherwise, the Selection dialog will reappear, negating all previous settings. Make sure the switch is in the off position.

Special attention should be paid to settings for international calls. Some versions of the shell have a separate switch for roaming. If you travel often, it makes sense to leave automatic selection or manually specify a SIM with a favorable tariff, so you don't forget to switch at the right time.

Use of engineering menus and codes

For more advanced users who didn't find the right options in the standard menu or encountered interface bugs, there is access to hidden settings through the engineering menu. It's a powerful tool for diagnosing and configuring the modem, but it requires caution. Changing the wrong settings can lead to loss of communication.

To get into the testing menu, open the Phone app and type ##4636##. On some Xiaomi models with certain versions of Android, this code may not work, so you can try installing the Activity Launcher app from the Play Market and find Testing activity manually.

In the menu that opens, select Phone Information. This shows detailed statistics for each SIM card. Scroll down to find the network type you prefer. Although there is no direct default button, resetting the network settings or selecting a specific mode (such as NR/LTE/GSM) can force you to shift the call priority to a more stable card.

adb shell settings put global prefered_network_mode 13

The above command for ADB (Android Debug Bridge) is an example of how you can change network preferences software, but it is safer for the average user to stay in the GUI. The engineering menu should only be used if the standard methods have failed and you understand what each parameter is responsible for.

⚠️ Note: Do not change the meanings in the "Radio Power" section or"IMEI This may result in the blocking of the communication module or loss of warranty at the software level.

You can also check through the engineering menu whether Dual SIM Dual Standby is active correctly, so if the second SIM is displayed as Disabled or No Service when the first one is active, it may be more than just calling settings, and then resetting the network to factory values helps.

Problems with choosing an operator with two SIMs

It's quite common for a phone to stubbornly refuse to choose the default SIM or reset the choice all the time, often due to a conflict of software priorities, and the system may assume that one card is not ready to work, and automatically redirect calls to the other, ignoring your settings.

The first thing you need to do is check the status of the SIM card, make sure that both cards are active and see the network. If one of the SIM cards periodically loses signal, Android may take this as an excuse to switch, try to extract the problem card, set the priority for the remaining one, and then return the second one to the place.

Another common cause is the cache of the Phone app and system services. Accumulated errors can interfere with the logic of choosing a SIM card. Clearing the data of these applications often solves the problem. → Annexes → All applications, find "Phone" and "Management" SIM-maps, then click "Clear data".

If the problem persists, you should look at third-party calling apps. Many users replace the standard call with Truecaller or analogues. These apps have their own SIM card selection settings that override the system. Check the settings inside the caller app itself.

The Impact of VoLTE and Wi-Fi Calling on SIM Choice

Modern voice technologies such as VoLTE (Voice over LTE) and Wi-Fi Calling make their own adjustments to the dual SIM card, and when these features are activated, voice traffic is transmitted through data channels, which can change the behavior of the phone when choosing a priority SIM.

For example, if VoLTE is on for the first SIM and not for the second, the phone can prioritize the first card even when you set it differently, because the system thinks the LTE connection is better and more stable, and disabling VoLTE on one card can align their priorities in the eyes of the system.

Wi-Fi Calling is also a high priority. If you are in Wi-Fi coverage, the call can go over the Internet using the default Wi-Fi Calling Symbol, ignoring the cellular settings. You can check and change this in the Settings menu. → SIM-maps and mobile networks → Wi-Fi calls.

It is important to understand that support for these features depends not only on the phone, but also on the operator. If your carrier does not support VoLTE, but the phone switch is enabled, routing conflicts may occur, in such cases, it is recommended to switch the network type to 3G/2G mode to check if the problem with selecting the SIM disappears.

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For maximum stability when using two sims, it is recommended to disable VoLTE on the second card, if it is used only for calls, and not for fast Internet, this will reduce the load on the modem.

Reset network settings and eliminate errors

When software failures become critical and none of the above methods work, the radical but effective step is to reset the network settings, which will return all connectivity options, including APN access points, Bluetooth pairs and Wi-Fi passwords, to factory status, but often eliminate deep configuration conflicts.

Resets can be done via Settings → Connection & Sharing → Reset Wi-Fi, mobile networks and Bluetooth. Please note that this step will not delete your personal files, photos or contacts, but you will have to re-enter passwords from wireless networks. Before starting the procedure, make sure you have access to the Internet for quick reconfiguration.

Once it's reset, the phone will reboot. SIM-So, at this point, it's critical to prioritize right away, without waiting for problems to arise, and it's a blank slate where you need to get your settings fixed.

If even a full reset didn't work, it might be because the SIM slot or the card itself is physically malfunctioning. Try swapping the SIM cards. If the problem moved with the card, it's because of it (like an old SIM with cut contacts). If the problem is still in the same slot, it's possible that the reader is damaged.

⚠️ Note: Before resetting your network settings, make sure you remember passwords from important Wi-Fi networks or have the option to view them in cloud storage (if sync has been enabled).

In rare cases, updating firmware to the latest available version helps. Xiaomi engineers are constantly working to improve the modem, and security updates often feature corrections to bugs associated with the Dual SIM. Check for updates in the About Phone menu.

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Network reset is a secure procedure that solves 90% of software problems with choice. SIM-cards without affecting the user's personal data.

Frequently Asked Questions (FAQ)