Why Xiaomi is shutting down the Internet when you call – and how to fix it

Have you noticed that your Xiaomi or Redmi suddenly loses mobile internet when you make an incoming/outgoing call? Pages stop loading, messengers go offline, and after a conversation, communication is restored only after a few seconds (or not at all), a problem that occurs on models from the budget Redmi Note 10 to the flagship Xiaomi 13 Ultra — and it is not always associated with hardware malfunctions.

80 percent of the time, network settings, protocol conflicts, or software bugs are to blame, but there are more serious reasons, from firmware errors to chipset hardware limitations, and in this article, we'll look at all the possible reasons why the Internet shuts down when you call Xiaomi, and give you step-by-step diagnostic and correction instructions, and you'll learn how to tell the difference between a software failure and a hardware problem and when to contact a service center.

1. VoLTE and VoWiFi: Why they're to blame 60% of the time

The main reason for the problem is VoLTE (voice over 4G) and VoWiFi (wi-fi calls), which are supposed to provide stable communication, but in practice often conflict with the mobile Internet.

• 📶 VoLTE prioritizes voice traffic by temporarily shutting down data. MIUI Internet recovery after a call is delayed or does not occur at all.
• 📞 VoWiFi can completely block mobile internet if your phone tries to switch between Wi-Fi and cellular network while you’re talking.
• ⚙️ Setting up the preferred network type in mode 4G/3G/2G (Auto) sometimes causes the modem to "hang" when switching between standards.

How to check if VoLTE is to blame?

1. Go to Settings. → SIM-maps and mobile networks → [yours SIM] → Enable VoLTE.
2. Turn off the option and make a test call.
3. If the Internet doesn't shut down, VoLTE is the problem. If it doesn't, we're looking for another reason.

Important! On some carrier tariffs (e.g. MegaFon All for Communication or MTS Smart), VoLTE is activated automatically and cannot be manually disabled, in which case only a change in tariff or a call for support of the operator will help.

2. Conflict of the two SIM-Why the second one is the second one SIM "stealing

If your Xiaomi supports two of your SIM-The problem with the maps may be network priority settings, and many users find that when they call one at a time, they're not going to be able to do that. SIM-The second one takes the Internet, leaving the first one without communication:

• 🔄 Automatic switching to SIM with a stronger signal (even if it is not used for data).
• 📱 Firmware errors where the system misallocates modem resources between two cards.
• 📡 Different network standards SIM-maps (for example, one of the cards is 4G, second-in 3G).

How to fix it:

1. Go to Settings. → SIM-maps and mobile networks.
2. Choose. SIM-map used for the Internet and set the preferred network type for it: 4G.
3. For the second SIM, install 2G or 3G only (if you only need it for calls).
4. Turn off the option of Automatic Network Selection (if any).

Select the primary SIM for data |

Set it to 4G | priority

Limit the second SIM to 2G/3G|

Turn off automatic network selection |

Reboot your phone after the changes-->

Critical error MIUI 13-14: Some models (e.g. Redmi Note) 11 Pro+) active two SIM-The modem will "hang" after the map 3-5 Calls, and the Internet will only recover after the reboot, in which case only the firmware rollback or update to the latest version will help.

3. firmware errors: When MIUI is to blame

MIUI is known for its bugs, and the problem of shutting down the Internet when you make calls is one of them.

• 🆕 After major updates (e.g., with the MIUI 12 on MIUI 13).
• 🔄 On beta versions of firmware.
• 📱 On models with custom firmware (for example, Xiaomi.eu or Pixel Experience).

How to diagnose:

1. Check the firmware version in Settings → About Phone → MIUI version.
2. Search the Internet for complaints about your model + firmware version (for example, "Redmi 9T MIUI 14 Internet when calling").
3. If the bug is massive, wait for a patch from Xiaomi or roll back to the previous version.

If you are using custom firmware, try:

• 🔧 Fastboot phone with full wipe (fastboot) -w).
• 📥 Establish an official version MIUI via Mi Flash Tool.
• 🔄 Change modem (modem.bXX files for your model).

Hardware Restrictions: When the Chipset or the Antenna is to Blame

On some Xiaomi models (especially budget ones), the Internet is turned off when calling due to hardware limitations:

• 📡 One modem for two. SIM: Cheap chipsets (e.g. Qualcomm Snapdragon) 4xx MediaTek Helio Gxx cannot physically handle voice calls and data simultaneously.
• 🔋 Energy savings: on weak processors, the system forcibly shuts down the Internet to reduce the load.
• 📶 Weak antennas: with a bad signal, the modem "loses" communication with the tower during switching to the voice channel.

How to check for hardware problems:

1. Install the Network Signal Guru app and check the signal strength (RSSI) before and during the call.
2. If the signal drops below -110 dBm, the problem is in the antenna or SIM card.
3. Try calling in a place with excellent coverage (such as near the operator's tower), if the Internet does not turn off, the weak signal is to blame.

⚠️ Attention! On models with MediaTek Helio chipsets G35/G80 (Like Redmi. 9/9A/9C) The problem with Internet shutdowns when making calls is software-intensive, and that's the iron limit. SIM-Disable mobile internet during conversations.

5. APN settings: why wrong settings are breaking the internet

APNs are the bridge between your phone and the carrier's network, and if the APN settings are not configured correctly, the modem can get confused when switching between voice and data, most often by:

• 🔄 After changing the operator (for example, from MTS to Tele2).
• 📱 After resetting the phone settings.
• 🆕 After updating the firmware (old settings) APN drop off).

How to set up your APN correctly:

1. Go to Settings. → SIM-maps and mobile networks → [yours SIM] → Access points (APN).
2. Click on the current APN profile and check the settings. They should match your carrier's official settings.
3. If there is no profile, create a new one using data from the operator’s website (for example, for MegaFon: Internet in the APN field).
4. Save the settings and restart the phone.

💡

If the APN changes, try manually specifying the authentication type: select PAP or CHAP in the APN settings. On some carriers (e.g. Yota), this solves the problem.

6.Programs and services that block the Internet

Sometimes it's not the phone settings that are to blame, but third-party apps.

• 🔒 Block background traffic (such as Greenify or Battery Saver).
• 📡 Conflict with the modem (e.g, VPN-Clients or Firewall Applications).
• 🔄 Intercept network management (e.g. Dual App or Second Space).

How to find the culprit:

1. Launch your phone in Safe Mode (press the power button → Safe Mode).
2. Make a test call. If the Internet doesn't shut down, the problem is in one of the apps installed.
3. Turn off programs with administrator rights or network access (Settings → Applications → Permissions → Special Rights).

List of apps that most often cause the problem:

• 🔐 VPN-Clients (e.g. OpenVPN, NordVPN).
• 🔋 Battery Optimizers (e.g. AccuBattery, GSam Battery Monitor).
• 📱 Launchers and shells (e.g. Nova Launcher, Microsoft Launcher).
• 📡 Firewall (e.g. NetGuard, AFWall)+).

💡

If the problem occurs after installing a custom core (such as FrancoKernel) or a modified modem, return the stock files. Incorrect kernel settings can cause the modem to "hang" when switching between voice and data.

7. When to contact the service center

If you've tried all of these, but the Internet still shuts down when you make calls, it's probably a hardware problem.

• 📱 The phone fell or was exposed to moisture.
• 🔧 The problem occurred after repair (for example, replacing the display or battery).
• 📡 Network signal is constantly weak, even in places with good coverage.
• ⚡ Phone overheats during calls (may indicate modem malfunction).

What's on the service?

1. Antenna block - for breaks or oxidation of contacts.
2. Modem - for overheating or damage.
3. SIM tray – sometimes the tray contacts become contaminated or bent.
4. Modem firmware - in rare cases, flashing at the level is required QCN-file.

⚠️ Attention, if you're asked to replace the entire mother module because of an Internet problem when making calls, that's a reason to doubt the skill of the master. 99% of the time, it's enough to solder the antenna or clean the contacts.

FAQ: Frequent questions about the problem