Why Xiaomi turns off when you call and how to fix it

When your Xiaomi suddenly goes out on an incoming or outgoing call, it can be taken by surprise at the most inopportune moment. It's not just an annoying error, it's a signal that the power management system or software has experienced a critical failure, most often the problem is a sharp surge in voltage that is necessary to activate the radio module, or a software conflict that blocks the processor.

When the smartphone screen goes out during the connection, it indicates peak battery load, at which point the antenna consumes maximum current, and if the power source is worn out or contacts are oxidized, the device perceives the voltage drop as a discharge and crashes. However, it is not always the physical part that is to blame; sometimes deep system settings or conflicting applications are the cause.

In this article, we will discuss all possible causes, from banal overheating to complex hardware malfunctions of the motherboard, you will learn how to conduct self-diagnosis and what steps to take to return the gadget to stability. Ignoring such symptoms can lead to complete failure of the device in the future.

Problems with battery and contacts

The most common reason Redmi or Poco turn off when you call is because of the battery state. Lithium-ion batteries lose their capacity over time and can't give up the necessary current at peak load moments. When you press the call button, the communication module requires a sharp increase in voltage, and the "tired" battery simply can not cope with this request.

In addition to natural wear, the problem can be oxidation of contact areas. If your smartphone has a removable lid, check whether the battery sits tightly and if the contacts are corrosive or dusty. Even microscopic plaque can create high resistance, which leads to a voltage drop below the critical level necessary for the operation of the RF module.

⚠️ Warning: If the battery is swollen, changed shape or has mechanical damage, immediately stop using it.

You can use the built-in system or third-party utilities to check the battery status. Pay attention to the wear rate: if it exceeds 20-25% and the phone has been running for more than two years, it is likely that you will need to replace the battery. It is also worth checking whether the case at the bottom of the device overheats before turning off, since the cold battery also gives off current worse.

Effects of overheating of the processor and radio module

Modern Xiaomi smartphones are equipped with powerful processors that, when working intensively, emit a significant amount of heat. If the background processes are already loading the system at the time of the call, the additional heat from the antenna can trigger the thermal protection, in which case the device is forced to turn off to prevent the physical destruction of the crystals.

This is especially true for models with metal or glass casings that are less likely to dissipate heat, or for devices used in dense cases. Dust stuffed into the speaker or connectors also impairs heat transfer. If you notice that the phone turns off after long conversations or when using the navigator in parallel with the bell, the reason lies precisely in thermal throtttling.

To reduce the likelihood of overheating, try removing the case during important conversations and avoiding direct sunlight on the case, check the list of applications running and close those not in use. Sometimes overheating is caused by a stuck process in the system that can be eliminated by rebooting.

There is also a software aspect of overheating that involves power management drivers not working properly, in which cases the system can misread the temperature and initiate an emergency shutdown even in normal thermal conditions, a feature that often occurs after failed firmware updates to MIUI or HyperOS.

Energy saving and MIUI optimization

Aggressive energy saving policies embedded in the MIUI shell often cause unstable phone performance. The system may mistakenly define the call process as an energy-intensive task and attempt to limit the power of the processor or radio module, leading to sudden screen quenching and rebooting, especially in "Energy Saving" or "Ultra-Savings" mode.

Check your battery settings and disable the tight restrictions on system applications that handle communication. From the Settings menu → Battery → Energy Saving, select Balanced or Performance mode. Also, go to the settings of specific applications and prevent the system from limiting their background activity, since the phone book and Google Play services can be blocked by the optimizer.

Another important parameter is Autostart, which is that if it's disabled for system services, the phone may not be managing resources properly when the call is in, make sure that all system processes have permission to start and run in the background, which is especially important for older models where performance margins are limited.

Software and firmware conflicts

Operating system instability is the second most common cause of communication problems. If your Xiaomi turns off when you call, it may be that the system has accumulated garbage from remote applications or has a cache failure, especially after upgrading to a new version of Android or shell, when old data conflicts with new algorithms.

Check to see if you have third-party call apps that may conflict with the system dialer. Sometimes call recording, number detectors, or spam blockers cause a critical kernel error that leads to a reboot. Try temporarily removing all of these utilities and checking the regular caller.

⚠️ Warning: Before resetting or flashing, be sure to back up all important data.The system recovery process can lead to complete loss of information if you do not backup in advance.

If the problem occurs after a specific update, it makes sense to reset the settings to factory (Wipe Data), which will return the software to its original state. In more complex cases, when a standard reset does not help, you need to completely flash the device through the computer using the Mi Flash Tool utility and official firmware.

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Use Safe Mode for diagnostics, and if it doesn't turn off when you call, it means that the problem is definitely in a third-party app, not in the system or hardware.

Hardware malfunctions of the motherboard

When software and battery replacement fail, there are serious hardware problems: The smartphone motherboard has power distribution (PMIC) and radio signal components; soldering microcracks that occur after a fall, or a communication chip dump, can cause the phone to shut down when data is started.

There's a common problem with the bottom plume that connects the charging board to the main board, and through that plume, antenna signals and power travel, and if it's damaged or oxidized by moisture, the contact may be lost just when the speaker or microphone vibrates, which is what happens when you call it, and visually inspecting the board under a microscope at the service center will help identify these defects.

• 🔌 Tap. BGA: violation of the contact of the processor or modem with the board due to impact or overheating.
• 💧 Corrosion: oxidation of tracks after moisture has been ingested, causing short circuit.
• 📉 Capacitor degradation: loss of capacity by filter elements in the supply chain.

Self-repair in such cases is not recommended, as specialized equipment and soldering skills are required. BGA-If you suspect a hardware malfunction, the best solution is to contact an authorized service center for accurate diagnostics.

Problems with SIM-map and network operator

Sometimes the reason is not in the phone itself, but in the SIM-map or network parameters. SIM-The card, especially if it has been used for many years and has been cut to the nano-SIM format, may have broken contacts or incorrect electrical characteristics. At the time of registration in the network or setting up a voice call, a surge in current occurs, which the old card "quenches", causing a system error.

You should also consider the impact of communication standards if you have poor coverage in your area. 4G/LTE, The phone can constantly switch between 3G and 4G, This puts a lot of stress on the antenna and the processor. → SIM-maps and mobile networks → Preferred network type: Try to force the "Only" mode. 3G" or "Only." 4G" and check if the problem will persist.

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Replacement SIM-The card for a new in the cabin operator solves the problem in 30% of cases when the phone turns off at the time of the beeps.

Do not forget about the possibility of physical damage to the reader. SIM (SIM-If the card is not tight or the contacts inside the phone are straightened, the contact will be unstable. SIM-cards with an alcohol napkin and install it in the phone again, making sure that the tight fixation.

FAQ: Frequently Asked Questions