Xiaomi Cannot Enable VoLTE in Leicester (2026 Fix)

If your Xiaomi, Redmi or POCO phone has a greyed out VoLTE toggle, shows "Cannot enable VoLTE", or calls drop to 3G while you're in Leicester, this guide covers the most common fixes. With the UK's 3G shutdown progressing, VoLTE is essential for making calls on modern networks. This issue can affect both physical SIMs and eSIMs across all UK carriers.

Important

A greyed out VoLTE toggle is different from a missing toggle. If the switch exists but cannot be turned on, the issue is usually carrier provisioning, carrier configuration, firmware behaviour, or device compatibility – not a simple device setting problem.

Before You Start – Quick Checks

  • Toggle Airplane Mode – Turn on for 30 seconds, then off to refresh network registration.
  • Restart your phone – Clears temporary software glitches affecting IMS registration.
  • Check you're on 4G/5G – VoLTE requires a 4G or 5G signal. If you're in a 3G-only area, the toggle won't work.
  • Test with another carrier SIM – If VoLTE works with another network, the issue is carrier-specific.
  • Check your data plan – Some pay-as-you-go plans or older contracts may not include VoLTE.

If these quick checks don't work, continue with the step-by-step guide below.

Quick Navigation

Diagnose the Issue First

Before making changes, determine which problem you actually have:

Three Possible Scenarios

  • A. VoLTE toggle is completely missing – The option does not appear in Settings at all. Try the hidden carrier check code (Step 2).
  • B. VoLTE toggle exists but is greyed out – The switch is visible but cannot be turned on. This can point to carrier provisioning, carrier configuration, or how that Xiaomi build exposes VoLTE controls – continue with the steps below.
  • C. VoLTE toggle is on but calls still fall back – The toggle is enabled but calls drop to 3G/2G. Check IMS registration and coverage (Steps 3-4).

Key diagnostic questions:

  • Is the toggle greyed out, missing, or visible but not working?
  • Did the problem start after a system update?
  • Does the same SIM work with VoLTE in another compatible phone?
  • Does another carrier SIM enable VoLTE on this Xiaomi?

Why "Cannot Enable VoLTE" Happens

  • Carrier provisioning failure – Your carrier has not enabled VoLTE on your account or SIM profile. This is one of the most common causes for a greyed out toggle.
  • Carrier configuration or firmware behaviour – A greyed-out VoLTE control can be caused by carrier configuration, how the Xiaomi build exposes VoLTE controls, or device compatibility.
  • HyperOS update reset – Major updates (MIUI → HyperOS or HyperOS 1.0 → 2.1) can hide or grey out VoLTE toggles for certain carriers.
  • Regional firmware mismatch – Some UK Xiaomi models (especially imported units) lack UK carrier VoLTE bundles.
  • Network registration delay – The phone may not register for IMS services quickly enough after boot or network changes.

Check Carrier VoLTE Support

Before troubleshooting your device, verify your carrier's VoLTE support:

UK Carrier VoLTE Support

  • EE – Supports VoLTE on many recent UK Xiaomi models. Text VOLTE to 150 to check provisioning.
  • O2 – Supports VoLTE but may use specific frequency bands (e.g., Band 20, 800MHz for indoor coverage).
  • Vodafone – Supports VoLTE on many recent UK Xiaomi models.
  • Three UK – Supports VoLTE on many recent UK Xiaomi models.
  • MVNOs – Giffgaff, Tesco Mobile, SMARTY, and others may have different provisioning. Check your specific provider's support page.

Carrier support does not guarantee VoLTE compatibility with every Xiaomi model or imported firmware version.

Leicester Network Notes

  • Coverage – All major UK carriers offer 4G and 5G coverage across Leicester city centre and surrounding areas.
  • Location-based diagnosis – If the problem happens only in one part of Leicester, test the same SIM in another location before changing phone settings. A location-specific calling problem is more likely to be related to coverage or local network conditions than a permanently unavailable VoLTE setting.

Step-by-Step Fixes

Step 1: Test Whether VoLTE Already Works

Why this matters: Before troubleshooting the toggle, check if VoLTE is already active. A greyed out toggle does not always mean VoLTE is unavailable.

  • Ensure you have a 4G or 5G signal (not 3G)
  • Make a call to any number
  • If your phone remains connected to 4G/LTE during the call, that is a strong indication that VoLTE is being used. On 5G, the status icon alone may not be enough to confirm how the voice call is being handled, so compare the network behaviour during and outside the call or check IMS status if available.
  • If the connection consistently falls back from 4G/5G to 3G or H+ when a call starts, VoLTE is likely not being used for that call.

Note: HyperOS on some models doesn't display the VoLTE icon even when the feature is active. If calls stay on 4G/5G, VoLTE is likely working despite the greyed toggle.

If VoLTE is not working during calls, move to Step 2.

Step 2: Try Xiaomi's VoLTE Carrier Check Code

Why this matters: On some Xiaomi devices, this code can change carrier-check behaviour and make the VoLTE option available. It does not guarantee that your carrier will provision VoLTE.

  1. Open the Phone app
  2. Dial exactly: *#*#86583#*#*
  3. You may see a confirmation message: "VoLTE carrier check was disabled" or similar – this may vary by device and HyperOS version
  4. Restart your phone
  5. Check VoLTE toggle: Settings → SIM cards & mobile networks → Tap your SIM → The toggle may now be enabled

Important: If the code makes the VoLTE option appear but the control remains unavailable, continue with the network and IMS checks. The remaining causes can include carrier provisioning, device compatibility, firmware behaviour, or carrier configuration.

If the toggle is still greyed out, move to Step 3.

Step 3: Verify Preferred Network Type

Why this matters: VoLTE depends on the phone being able to use the carrier's LTE/5G voice and IMS services. If the device is forced to use older network modes, VoLTE may be unavailable.

  • Settings → SIM cards & mobile networks
  • Tap your SIM
  • Tap Preferred network type
  • Select 5G/4G/3G auto or 4G (LTE) preferred
  • If set to 3G only or 2G only, VoLTE cannot work
  • Restart your phone and check if the toggle is now enabled

If network type is correct but the toggle is still greyed out, move to Step 4.

Step 4: Check IMS Registration Status

Why this matters: IMS (IP Multimedia Subsystem) registration is required for VoLTE to work. If IMS shows "Not Registered," VoLTE won't work even if the toggle is on.

  1. Open the Phone app
  2. Dial *#*#4636#*#*
  3. Tap Phone information
  4. Depending on your Xiaomi model and HyperOS version, look for "VoLTE provisioned" – a value of "true" can indicate that VoLTE provisioning is enabled at the device level, but the exact meaning varies
  5. Look for "IMS registered" – if true, your phone is connected to your carrier's VoLTE servers
  6. If both are true but the toggle is greyed out, this may indicate an interface issue – VoLTE may still work

Note: Depending on your Xiaomi model and HyperOS version, some IMS or VoLTE fields may not be available in this menu.

If IMS is not registered, move to Step 5.

Step 5: Check Carrier VoLTE Provisioning and Compatibility

Why this matters: Carriers do not automatically enable VoLTE on all plans or SIMs. A greyed out toggle can point to carrier provisioning, but it can also be caused by device firmware or how that Xiaomi build exposes VoLTE controls.

Contact your carrier to verify VoLTE is enabled on your account:

  • EE – Text VOLTE to 150 (free) or call 150
  • O2 – Call 202 or check the O2 app for "4G Calling" or "VoLTE" settings
  • Vodafone – Call 191 or check the Vodafone app for "4G Calling" or "VoLTE"
  • Three UK – Call 333 or check the Three app for VoLTE settings
  • MVNOs – Contact your specific provider's support channel

If VoLTE is not provisioned, request your carrier to "Enable 4G Calling (VoLTE)" on your account.

SIM age: If your carrier confirms that your SIM is too old for its current 4G Calling service, ask whether your current SIM needs replacing for your carrier's 4G Calling service.

If provisioning is confirmed but the toggle is still greyed out, move to Step 6.

Step 6: Reset Network Settings

Why this matters: This resets Wi-Fi, mobile data, and Bluetooth settings without deleting personal data. It clears corrupted network configurations that may be blocking IMS registration.

  1. Settings → Connection & sharing (HyperOS) or Settings → Additional settings → Backup & reset (MIUI)
  2. Select Reset Wi-Fi, mobile & Bluetooth or Reset network settings
  3. Confirm the reset
  4. Restart your phone
  5. Check VoLTE and test a call on 4G/5G

Note: Resetting network settings will clear saved Wi-Fi passwords and Bluetooth devices, but will not delete photos or personal data.

If resetting network settings doesn't work, move to Step 7.

Step 7: Check for HyperOS Updates

Why this matters: Software updates can include network, modem, or stability improvements that affect VoLTE support.

  1. Settings → About phone → Check for updates
  2. Install any available updates
  3. Restart your phone and test VoLTE

If you're already on the latest version and VoLTE is still unavailable, contact your carrier or Xiaomi support.

Contact Carrier (When Required)

Contact your carrier if:

  • VoLTE provisioning is missing on your account or plan
  • You've tried all steps above and the toggle is still greyed out
  • Your carrier confirms your SIM needs replacement for VoLTE
  • There's a known network issue in Leicester
  • You need to check if your specific Xiaomi model is approved for VoLTE on their network

Carrier Support Contacts

Contact Xiaomi UK Support if:

  • You've tried all steps above and VoLTE is still unavailable
  • VoLTE fails with multiple compatible carrier SIMs on this Xiaomi
  • The device uses UK/Global firmware but does not expose VoLTE correctly
  • The problem started after a specific HyperOS update and persists across networks
  • Another identical compatible Xiaomi device behaves differently with the same SIM
  • You suspect a hardware fault with the cellular antenna or modem

Xiaomi UK Support

Final Verdict – Diagnostic Decision Tree

Use this decision tree to determine the most likely cause and next action:

  • Toggle is completely missing → Try the carrier-check code (*#*#86583#*#*). If still missing, check your device firmware.
  • Toggle is greyed out → Focus on carrier provisioning, carrier configuration, and account status. Contact your carrier to enable VoLTE on your account. Ask whether your current SIM needs replacing for your carrier's 4G Calling service.
  • Toggle is on but IMS shows "Not Registered" → Check network registration, reset network settings, and contact your carrier.
  • IMS is registered and calls stay on 4G/LTE → VoLTE is working despite the greyed toggle. No further action needed.
  • IMS is registered but calls consistently fall back to 3G/2G → Investigate coverage, carrier compatibility, and whether your specific Xiaomi model is approved for VoLTE on your network.
  • Calls behave differently in different parts of Leicester → This points more strongly to coverage or carrier network conditions than to a device fault.

Frequently Asked Questions

Why is my VoLTE toggle greyed out on Xiaomi in Leicester?

A greyed out toggle can point to carrier provisioning or carrier configuration, but it can also be caused by device firmware or how that Xiaomi build exposes VoLTE controls. Contact your carrier to check provisioning.

Does the code *#*#86583#*#* work on all Xiaomi phones?

It works on many but not all devices or HyperOS versions. If nothing happens when you dial the code, your device may not support it. Appearance of the toggle does not guarantee VoLTE will work.

How do I check if my carrier has enabled VoLTE on my account?

Contact your carrier directly. EE users can text VOLTE to 150 to check provisioning. O2, Vodafone, and Three users should call their support numbers or check their carrier apps for "4G Calling" or "VoLTE" settings.

Why did VoLTE become greyed out after a HyperOS update?

HyperOS updates can sometimes re-enable carrier checks or reset network settings. Try dialling the hidden code *#*#86583#*#* and restarting your phone.

How do I know if VoLTE is actually working without the icon?

Make a call while on 4G/5G. If the phone remains on 4G/LTE during the call, VoLTE is likely active. On 5G, the status icon alone may not be enough to confirm how the voice call is being handled.

Does VoLTE work on UK Xiaomi devices?

VoLTE support depends on your exact Xiaomi model, firmware version, and carrier configuration. Many UK-sold Xiaomi devices with Global ROM support VoLTE on EE, O2, Vodafone, and Three.

Why does VoLTE work on one SIM slot but not the other?

Dual-SIM behaviour can vary by Xiaomi model, carrier configuration and software version. If VoLTE works on one SIM but not the other, try disabling the second SIM temporarily and test again.

Why do my calls switch to H+ during calls?

If your phone consistently switches from LTE/5G to H+ or 3G when a call begins, that usually means the call is falling back to the older network rather than using VoLTE. Check IMS registration using *#*#4636#*#* or contact your carrier.

Note: This guide is updated for 2026. Menu names may vary slightly between HyperOS and MIUI versions. With the UK's 3G shutdown progressing, VoLTE is becoming essential for voice calls.

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