When Xiaomi suddenly completes an incoming or outgoing call, it can be taken by surprise at the most inopportune moment. Users often experience screen dimming, connection breaking, and device behaving unstable during the conversation, a common problem that can be caused by both software conflicts and physical damage to components.
In most cases, the reason lies in the incorrect operation of the proximity sensor or failures in the settings of the mobile network. MIUI or HyperOS sometimes misinterprets sensor signals, believing the phone is in your pocket, and locks the screen, interrupting the connection. SIM-card that cannot cope with the current of consumption when activating the communication module.
This guide will help you diagnose the source of a malfunction and fix it without going to a service center. We will look at methods from calibrating sensors to deep tuning network protocols to return the smartphone to stability.
Diagnostics of the proximity sensor and screen
The most common reason Redmi or Poco turns off the screen and resets the call is because the proximity sensor is incorrect, and it's located at the top of the case, and it has to respond to the phone being brought to the ear, and if it's contaminated or knocked down, the system blocks the prematurely display.
First, check if the protective film is glued to the area of the speaker, even transparent glass can block the infrared beam, which makes the phone "think" that it is pressed against the cheek, clean the upper frame of the device with soft cloth and make sure that there are no physical obstacles to the sensor.
Next, you need to do a software calibration built into the system's engineering menu, which will reset the sensor's sensitivity to factory values, and enter a special code in the Phone app to access the equipment testing.
☑️ Sensor checks
In the menu that opens, look for the Proximity Sensor. Put your phone on a flat surface without covering the top. Press the Calibrate button or follow the instructions on the screen (usually close the sensor with your hand and then remove it). If the calibration is successful, the system will give a Pass message.
⚠️ Attention: If the test shows Fail several times in a row after calibration, it may be that the sensor is physically defective or that it has detached from the inside of the case.
Mobile network settings and SIM type
Connection instability is often triggered by a conflict of network modes.Modern Xiaomi smartphones support 4G and 5G, But in areas with poor coverage, the device can constantly switch between standards, which causes the call to break. SIM-The cards may not work properly with new modems.
Try to force the phone to switch to mode only 3G or 2G/3G, to see if the problem persists. 3G The calls are stable, so it's about the cover. 4G/LTE In your local area or operator settings, it's also worth checking if it's installed correctly. SIM-card.
To change the type of network, go to the settings menu. The path may vary depending on the version of the shell, but it is usually in the mobile network section. SIM-Change the preferred network type.
Settings → SIM- Maps and Mobile Networks → Select SIM → Network Type → Prefer LTE (or 3G)If you have an old one installed SIM-A card that was issued more than 5 years ago is recommended to be replaced by a carrier, new cards have improved contacts and cope better with modern encryption protocols, which reduces the likelihood of failures when establishing a connection.
Elimination of program conflicts and updates
Software errors in the MIUI or HyperOS shell can cause malfunctions in the system application Phone. Often the problem occurs after the system update, when the old cache files conflict with the new modem algorithms, in which case the cleaning of the application data helps.
Don’t worry, cleaning up your phone data won’t delete your contacts if they’re saved to your Google account or on your phone. SIM-But the call history can be erased, so it's better to rewrite the important numbers in advance.
How to keep contacts before resetting?
To do the cleaning, go to the application management section, find a standard "bell ringer" that usually has a green handset icon, depending on the version of the system, it may be simply called "Phone" or be named from Google.
- 📱 Go to Settings. → Annexes → All applications.
- 🔍 Find the phone app (or Google Phone) in the list).
- 🗑️ Click Clean and select Clean Everything (or Reset Settings").
- 🔄 Restart the device to apply changes.
It’s also worth checking for updates to the system itself. Xiaomi developers regularly release security patches and bug fixes. If you have a beta version of the firmware installed, consider rolling back to a stable version, as test builds often contain bugs.
Comparison of methods of solving the problem
To make it easier for you to navigate the many possible solutions, we have prepared a summary table that will help you quickly determine which method is right for you, based on your symptoms.
| Symptoms. | Probable cause | Method of decision | Difficulty |
|---|---|---|---|
| The screen goes off when I bring my phone. | Approximation sensor | Calibration through the Engineering Menu | Low. |
| The call is reset in 10-20 seconds. | Network or SIM-map | SIM Replacement, Network Type Change | Low. |
| The phone is completely turned off (black screen) | Battery or plume | Contact check, replacement of AKB | Tall. |
| The problem arose after the update. | Software failure (MIUI bug) | Resetting the settings of the "Phone" application | Medium |
As you can see from the table, most problems are solved by software, but if the phone turns off (extinguishes completely, as with a dead battery), rather than just resets the call, this indicates a power problem.
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If the phone is completely turned off when you call, most likely, the battery does not withstand the peak current of the load, or the contacts of the battery have oxidized.
Power and battery problems
The communication module consumes a significant amount of power during a call, especially in areas of uncertain reception when the phone tries to amplify the signal.If the battery is worn out or has a defect, the voltage can fall below a critical level, causing the device to emergency shut down.
Notice the behavior of the phone when the charge is low. If the shutdown only happens when the charge is lower. 20-30%, The problem is that the lithium-ion battery is degraded, and in that case, the only thing that helps is to replace the battery with a new one.
It is also worth checking the battery contacts if it is possible to safely remove the back cover (on models with a removable battery). oxidation of the contacts leads to increased resistance and loss of voltage under load.
⚠️ Warning: Do not use a phone with a ballooning battery. This is life-threatening and can cause fire. If the battery is swelling, immediately stop using and replace it.
Resetting network settings and extreme measures
If none of the above methods worked, you should reset your network settings, which will return all your connection settings (Wi-Fi, Bluetooth, mobile data) to factory values, and your personal files, photos, and contacts will not be affected.
This is especially effective if you have recently changed carriers or moved to another region, and your phone may have conflicting network profiles that interfere with normal operation.
Settings → Connection and Sharing → Reset Wi-Fi, Mobile Network and BluetoothOnce the phone is reset, you'll need to re-enter the Wi-Fi passwords, check the phone for a few hours, and if the problem persists, the motherboard's radio may have malfunctioned, requiring professional repair.
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Before performing a full Hard Reset, make sure to back up all important data to the cloud or computer, as this action will delete all the contents of the memory.