Xiaomi WiFi Calling Stops Working After HyperOS Update

Xiaomi WiFi Calling Stops Working After HyperOS Update – UK Fix

This guide helps if your Xiaomi WiFi Calling (VoWiFi) stopped working or disappeared completely after a HyperOS update, even though it worked before the update.

Quick Answer:
If WiFi Calling stopped working after a HyperOS update, first check whether the WiFi Calling toggle is still present in Settings → SIM cards & mobile networks → [Your carrier] SIM → WiFi Calling. If the toggle is missing, try dialling *#*#869434#*#* (VoWiFi carrier check disable) and restarting – this restores the toggle on many Xiaomi devices. If the toggle is greyed out or doesn't work, contact your carrier to check WiFi Calling is still enabled on your account.

Applies to Redmi, POCO and Xiaomi Phones

This guide applies to Xiaomi, Redmi and POCO devices running MIUI or HyperOS on all UK carriers – EE, O2, Vodafone, Three, and their MVNOs.

🔍 Quick Diagnostic – Toggle vs Function

Use this table to quickly identify your issue:

SituationUsually means
Toggle missingCarrier check or region
Toggle greyed outCarrier provisioning
Toggle ON but no WiFi iconIMS registration
WiFi icon appears then disappearsBattery or WiFi stability
Works on one WiFi network onlyRouter configuration

🔍 Quick Start – Find Your Path

SymptomMost Likely CauseGo To
WiFi Calling toggle disappearedCarrier check re-enabledSection 1
Toggle greyed outCarrier provisioning issueSection 2
WiFi Calling doesn't work after updateIMS registration failureSection 3
WiFi Calling keeps disconnectingBattery optimisationSection 4
WiFi Calling option missing entirelyRegion or carrier compatibilitySection 5

Before You Start

Before going through the sections, try this quick sequence:

  • Check the toggle location – Settings → SIM cards & mobile networks → [Your carrier] SIM → WiFi Calling.
  • Toggle Airplane mode – ON for 30 seconds, then OFF. This forces IMS re-registration.
  • Restart your phone – A full reboot can resolve temporary glitches.

If these don't work, continue to the relevant section below.

Before Contacting Your Carrier

Before calling your carrier, try these quick checks:

  • Restart the phone once after enabling WiFi Calling – Some settings only apply after a reboot.
  • Test on another WiFi network – If WiFi Calling works on a different network, the issue may be your router.
  • Disable VPN temporarily – Some VPNs can interfere with WiFi Calling registration.
  • Confirm mobile signal is available before enabling Airplane mode – WiFi Calling requires initial network registration.
  • Ensure the SIM is in the primary SIM slot (if applicable) – Some devices restrict WiFi Calling to the primary SIM slot.

Section 1 – WiFi Calling Toggle Disappeared (Most Common)

When WiFi Calling disappears after a HyperOS update, the most common cause is that the VoWiFi carrier check has been re-enabled. On many Xiaomi devices, HyperOS updates may re-enable the VoWiFi carrier check, causing the WiFi Calling option to disappear.

Try these in order:

  1. Dial the hidden code – Open Phone dialer → dial *#*#869434#*#* → you should see "VoWiFi carrier check was disabled" (if it works on your device). This code doesn't work on all HyperOS versions or all devices.
  2. Restart your phone – After dialling, restart and check if the WiFi Calling toggle has reappeared.
  3. Check the toggle location – Settings → SIM cards & mobile networks → [Your carrier] SIM → WiFi Calling should now appear.
  4. Check whether the toggle remains after another restart – If it disappears again after every reboot, continue to Section 5 because the carrier configuration may not support WiFi Calling on your device.
  5. If nothing happens – Your device doesn't support this code – proceed to Section 2.

Section 2 – Toggle Greyed Out (Carrier Provisioning Issue)

If the WiFi Calling toggle is visible but greyed out, your carrier may not have enabled it on your account after the update.

Try these in order:

  1. Call your carrier – EE (150), O2 (202), Vodafone (191), Three (333).
  2. Ask directly – "WiFi Calling was working before the HyperOS update but is now greyed out – is it still enabled on my account? Please refresh your network provisioning or SIM profile."
  3. Restart your phone – After they confirm, restart and check if the toggle is now active.
  4. Check SIM compatibility – If your SIM is several years old, it may not support WiFi Calling. Request a replacement SIM from your carrier.

Section 3 – WiFi Calling Doesn't Work After Update (IMS Registration Failure)

If WiFi Calling is enabled (toggle is ON) but calls don't route over WiFi, the issue is likely IMS registration failure.

Try these in order:

  1. Check IMS registration – If your device supports the Phone Information menu, dial *#*#4636#*#* → Phone information → look for "IMS registered". If false, the phone isn't registered for WiFi Calling services. This menu is not available on all devices.
  2. Toggle Airplane mode – ON for 30 seconds, then OFF. This forces IMS re-registration.
  3. Check WiFi Calling toggle – Settings → SIM cards & mobile networks → [Your carrier] SIM → WiFi Calling → toggle OFF, wait 10 seconds, then toggle ON.
  4. Disable VPN temporarily – Some VPN services prevent IMS registration on certain networks.
  5. Restart your phone – A full reboot can resolve IMS registration issues.
  6. Test WiFi Calling – Make a call while connected to WiFi with weak or no mobile signal. If the call connects over WiFi, WiFi Calling is working.

Section 4 – WiFi Calling Keeps Disconnecting (Battery Optimisation)

If WiFi Calling works but disconnects frequently after the update, battery optimisation may be interfering.

Try these in order:

  1. Turn off Battery Saver – Settings → Battery → Battery saver → OFF.
  2. Remove battery restrictions for Phone and Carrier Services – Settings → Apps → Manage apps → search for the relevant app → Battery saver → Set to "No restrictions". If an IMS-related app appears on your device, remove restrictions for that as well.
  3. Disable "Clear cache when device is locked" – Settings → Battery → Additional features → Clear cache when device is locked → OFF.
  4. Check WiFi connection stability – If WiFi itself is unstable, WiFi Calling will disconnect. Check your router.
  5. Test with a different WiFi network – If possible, test WiFi Calling on a different network to rule out router issues.

Section 5 – WiFi Calling Option Missing Entirely (Region or Carrier Compatibility)

If WiFi Calling doesn't appear at all after the update, the issue may be region or carrier compatibility.

Try these in order:

  1. Check region setting – Settings → Additional settings → Region → If your region changed after the update, switch it back to United Kingdom. Some regions hide WiFi Calling.
  2. Check carrier compatibility – Confirm your carrier supports WiFi Calling on Xiaomi devices. EE, O2, Vodafone, and Three all support it on most recent models, although support also depends on the exact Xiaomi model and carrier firmware.
  3. Check carrier provisioning – Call your carrier to confirm WiFi Calling is enabled on your account.
  4. Check system app updates – Settings → System app updater → check for updates to carrier-related system apps.
  5. Reset network settings – Settings → Connection & sharing → Reset Wi-Fi, mobile networks, and Bluetooth (last resort – removes saved Wi-Fi passwords).

Why Did WiFi Calling Stop Working After HyperOS Update?

  • VoWiFi carrier check re-enabled (most common) – HyperOS updates can reset the hidden carrier check that hides WiFi Calling for certain carriers. The code *#*#869434#*#* disables this on many devices.
  • Carrier provisioning changed – The update may have triggered a carrier profile refresh that disabled WiFi Calling on your account.
  • IMS registration failure – The phone may not have re-registered for IMS services after the update.
  • Battery optimisation – HyperOS may have re-enabled battery restrictions that affect WiFi Calling.
  • Region setting reset – The update may have changed your region setting, hiding WiFi Calling.
  • Carrier configuration changes introduced alongside the update – May temporarily affect WiFi Calling until the device re-registers.
  • Network registration issue – The phone may need to reconnect to the network to re-establish WiFi Calling.

⚠️ What NOT to Do

  • Don't factory reset your phone – This is rarely needed for WiFi Calling issues.
  • Don't assume the code works on all devices – *#*#869434#*#* works on many but not all Xiaomi models or HyperOS versions.
  • Don't ignore carrier provisioning – If the toggle is greyed out, call your carrier first.

Quick Questions

Why did WiFi Calling disappear after HyperOS update?
Most commonly the VoWiFi carrier check was re-enabled. Dial *#*#869434#*#* and restart to restore it on many devices.

Does the code *#*#869434#*#* work on all Xiaomi phones?
No. It works on many but not all devices or HyperOS versions. If nothing happens, try carrier provisioning instead.

What if WiFi Calling is greyed out after update?
Your carrier may have disabled it on your account. Call them to re-enable and refresh your network provisioning or SIM profile.

Why does WiFi Calling work but disconnect often?
Battery optimisation may be interfering. Turn off Battery Saver and remove restrictions for Phone/IMS services.

Will resetting network settings fix WiFi Calling?
It can help if settings are corrupted, but try the hidden code and carrier provisioning first.

Can a new SIM fix WiFi Calling issues?
Yes. SIMs older than 3-4 years may not support WiFi Calling. Request a replacement from your carrier.

How do I check if WiFi Calling is working?
Make a call while connected to WiFi with mobile signal turned off (Airplane mode + WiFi on) – if your carrier supports WiFi Calling. If the call connects, WiFi Calling is working.

Why does WiFi Calling disappear again after every reboot?
If the option repeatedly disappears after restarting, your carrier configuration or device firmware may be reapplying the carrier check. Contact your carrier and check for newer HyperOS updates.

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