Seeing a call fail on your Xiaomi 15 can stop you in your tracks, especially when you're trying to reach someone important. This usually happens because your phone is struggling to connect properly to your carrier's network. Weak signal, a software hiccup in HyperOS, or a simple setting can be the culprit.
Let's run through the most effective fixes, starting with the quickest ones you can try right now.
Toggle Airplane Mode On and Off
The fastest way to reset your cellular connection is with Airplane Mode. This clears out any temporary network glitches that might be blocking your calls. Swipe down from the top of your screen to open the Control Center and tap the airplane icon to turn it on.
Wait about 10 seconds, then tap it again to turn Airplane Mode off. Your phone will reconnect to the network, which often resolves the call failure instantly.
Check Your Signal Strength
Weak signal is the most common reason calls drop or fail to connect. Look at the signal bars in the top-right corner of your screen. If you only have one or two bars, try moving to a different location.
Sometimes, just stepping near a window or going outside can make a big difference. If you're in a building with thick walls, the signal might be struggling to reach you.
Perform a Force Restart
A simple restart can clear out minor software bugs in HyperOS 2 that might be interfering with the phone app. If your phone is responsive, hold the power button and select restart.
If the screen is frozen or unresponsive, use the force restart method. Press and hold the power button for 15 seconds or more until you feel the phone vibrate and see the Xiaomi logo appear on the screen.
Verify Your Focus Mode Settings
HyperOS has various Focus Modes, like Work or Sleep, which can silence calls. Make sure you haven't accidentally enabled a mode that's blocking your calls. Swipe down from the top to open the Control Center and look for a moon or other Focus icon.
If you see one active, tap it to turn it off. You can also check in Settings > Sound & vibration > Focus Modes to see which rules are currently applied.
Check for Blocked Numbers
It's worth a quick check to ensure you haven't accidentally blocked the number you're trying to call. Open your Phone app and tap the three-dot menu in the top right, then go to Settings > Blocked numbers.
Scroll through the list. If you find the number there, tap the remove icon next to it to unblock it. This is a common oversight that's easy to fix.
Ensure Mobile Data and Roaming Are Correct
Double-check that your mobile data is switched on. Go to Settings > SIM cards & mobile networks. Select your active SIM card and make sure the Mobile data toggle is enabled.
If you're traveling, you might need to enable data roaming for calls to work. In the same SIM card settings menu, look for and turn on the Data roaming option. Be aware this might incur extra charges with your carrier.
Update Your Carrier Settings
Occasionally, your carrier pushes small configuration updates to improve network connectivity. These can fix calling issues. Make sure your phone is connected to Wi-Fi first.
Then, go to Settings > About phone > Carrier settings. If an update is available, you'll see a prompt to download and install it. This process only takes a moment.
Switch Between 5G and 4G
Sometimes, the 5G network in your area might be unstable for voice calls. You can try forcing your phone to use 4G LTE, which is often more reliable for calls. Go to Settings > SIM cards & mobile networks and tap your active SIM.
Tap Preferred network type and select "4G/3G/2G (auto)" instead of the 5G option. Test to see if your calls go through. You can always switch it back later.
Inspect and Reinsert Your SIM Card
A loose, dirty, or faulty SIM card is a classic cause of call failures. You'll need the SIM ejector tool that came with your phone. Gently push it into the small hole on the SIM tray to pop it out.
Remove the SIM card, give the gold contacts a gentle wipe with a soft, dry cloth, and then reinsert it firmly. Make sure the tray is fully seated when you push it back into the phone.
Update Your HyperOS Software
Software updates from Xiaomi frequently include bug fixes for network and calling issues. It's a good idea to check for one. Connect to a stable Wi-Fi network and ensure your battery is above 30%.
Go to Settings > About phone > HyperOS version. Tap "Check for updates" and install any available update. I've seen updates resolve persistent calling problems on other Xiaomi models.
Reset Your Network Settings
This is a more thorough step that clears all your saved Wi-Fi networks, Bluetooth pairings, and cellular settings back to default. It won't delete your personal data like photos or messages.
Go to Settings > Additional settings > Backup & reset > Reset phone. Tap Reset network settings and enter your lock screen password to confirm. After the phone reboots, you'll need to reconnect to Wi-Fi and re-pair Bluetooth devices.
Contact Your Mobile Carrier
If you've tried everything here and calls are still failing, the problem might be on your carrier's end. There could be a network outage in your area, a problem with your account, or your SIM card might be damaged.
Give your carrier's customer service a call from another phone. They can check for outages, reprovision your line, or send you a replacement SIM card if needed.
