Xiaomi Cannot Enable VoLTE in the UK Fix Guide

Xiaomi VoLTE Not Working or Missing in the UK – Fix

If your Xiaomi, Redmi, or POCO device won't let you enable VoLTE (4G Calling)—the option is greyed out, missing, or doesn't appear to work—this guide explains why and how to fix it for UK networks.

Quick Answer:
VoLTE not working or missing on your Xiaomi is usually caused by your carrier not provisioning VoLTE on your account, incorrect network settings, or the VoLTE option being hidden after a system update. Start by ensuring your preferred network is set to allow 4G, then check your carrier supports VoLTE on your plan. Use the VoLTE carrier check code to verify your device is properly configured.

Before You Continue

Before troubleshooting VoLTE specifically, check these basics first:

  • SIM is inserted correctly.
  • Mobile data is enabled.
  • Airplane mode is off.
  • Your phone is running the latest available software update.

Why VoLTE Is Missing or Not Working

  • Carrier hasn't provisioned VoLTE – Most UK consumer plans support VoLTE, but your account still needs to be correctly provisioned.
  • Network mode not allowing LTE – VoLTE requires LTE when voice calls are carried over the 4G network. On some UK networks with 5G Standalone, calls may instead use VoNR.
  • VoLTE option hidden after HyperOS/MIUI update – Some Xiaomi models hide the VoLTE switch in newer system versions.
  • IMS registration failure – Your phone may not be properly registered for VoLTE services, often due to network issues or outdated firmware.
  • Dual SIM limitations – Some Xiaomi devices support VoLTE on one SIM at a time. Older phones may not support VoLTE on both SIMs simultaneously.

Check Your Carrier Supports VoLTE

Since the UK's nationwide 3G shutdown, most voice calls are carried over VoLTE (4G), with VoNR used on supported 5G Standalone networks.

  • EE – VoLTE supported on all modern plans. Call 150 to check provisioning.
  • O2 – VoLTE supported. Call 202 to confirm your account is provisioned.
  • Vodafone – VoLTE supported. Call 191 to check.
  • Three – VoLTE supported. Call 333 to check.
  • Giffgaff / Lebara / SMARTY – VoLTE supported if your plan includes it. Contact your carrier to confirm.

Find the VoLTE Setting on Your Xiaomi

The VoLTE setting location can vary by Xiaomi model and software version. Try these paths:

Path 1 – Settings → SIM cards & mobile networks:

  1. Settings → SIM cards & mobile networks.
  2. Tap your carrier's SIM.
  3. Look for Use VoLTE or 4G Calling.
  4. Toggle it ON.

Path 2 – Settings → Mobile network (some Xiaomi models):

  1. Settings → Network & Internet → Mobile network.
  2. Tap your SIM.
  3. Look for 4G Calling or VoLTE.

Path 3 – Settings → Connection & sharing → Mobile networks (HyperOS):

  1. Settings → Connection & sharing → Mobile networks.
  2. Tap your SIM.
  3. Enable VoLTE if available.

Toggle Xiaomi's Carrier Compatibility Check for VoLTE

If the VoLTE option is missing or greyed out, use Xiaomi's engineering code to toggle the carrier compatibility check:

  1. Open the Phone dialler.
  2. Enter *#*#86583#*#*.
  3. You should see a message. If it says "VoLTE carrier was disabled", the carrier compatibility check has been disabled. Restart your phone and check whether the VoLTE option becomes available.
  4. If the code returns an unsupported message or nothing changes, your device or carrier may not support this workaround.

Note: This code toggles Xiaomi's carrier compatibility check for VoLTE. It doesn't directly check whether your carrier supports VoLTE—it allows your phone to use VoLTE even if the carrier check would normally block it.

Ensure Preferred Network Allows LTE

VoLTE requires LTE when voice calls are carried over the 4G network. On some UK networks with 5G Standalone, calls may instead use VoNR. Make sure your preferred network mode allows LTE (4G). Avoid using 3G-only mode.

  1. Settings → SIM cards & mobile networks → [Your carrier] SIM.
  2. Tap Preferred network type.
  3. Select 4G (LTE) preferred or 4G (LTE) only.
  4. Go back and check if the VoLTE option is now available.

Update HyperOS / MIUI

Some users on XDA Forums have reported that updating HyperOS restored VoLTE and Wi-Fi Calling functionality.

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

Check IMS Registration Status

IMS registration is required for VoLTE to work. If IMS shows "Not Registered," VoLTE will fail.

  1. Open the Phone dialler and enter *#*#4636#*#*.
  2. Tap Phone information.
  3. Look for IMS Service Status or IMS Registration.
  4. It should show Registered. If it shows Not Registered, your phone cannot use VoLTE. Contact your carrier.

If IMS never registers after restarting and confirming your account supports VoLTE, the problem is usually on the carrier side.

Disable Wi-Fi Calling (Temporary Test)

Only try this if VoLTE stopped working immediately after enabling Wi-Fi Calling. On some Xiaomi devices, Wi-Fi Calling can conflict with VoLTE in rare cases.

  1. Settings → SIM cards & mobile networks → [Your carrier] SIM.
  2. Turn OFF Wi-Fi Calling.
  3. Check if the VoLTE option appears.

Reset Network Settings (Last Resort)

If VoLTE still won't enable, reset network settings. This removes saved WiFi passwords and Bluetooth pairings.

  1. Settings → Additional settings → Backup & reset → Reset phone → Reset network settings.
  2. Confirm the reset.
  3. Restart your phone.
  4. Set Preferred network to 4G and check VoLTE again.

Contact Your Carrier

Contact your carrier if:

  • VoLTE still doesn't work after completing all steps above.
  • Your carrier confirms your plan supports VoLTE but it's not working.
  • IMS Registration shows "Not Registered."

UK carrier contact numbers:

  • EE: 150
  • O2: 202
  • Vodafone: 191
  • Three: 333
  • Giffgaff: 0330 123 0002
  • SMARTY: 0333 202 0033
  • Lebara: 0808 165 0815

Final Verdict

VoLTE not working or missing on your Xiaomi is usually a carrier provisioning issue, an incorrect network setting, or a hidden VoLTE option after a system update. Start by setting your preferred network to allow 4G. If the VoLTE option is missing or greyed out, use the VoLTE carrier check code (*#*#86583#*#*). Check IMS registration status and update your phone. If all fails, contact your carrier to ensure VoLTE is provisioned on your account. Since the UK's 3G shutdown, VoLTE is essential for making calls—so this is worth fixing.

Frequently Asked Questions

Why is my VoLTE setting greyed out on Xiaomi?
Usually because LTE isn't available, the preferred network mode doesn't allow LTE, or your carrier hasn't provisioned VoLTE.

What does * # * # 86583 # * # * do on Xiaomi?
This engineering code toggles Xiaomi's carrier compatibility check for VoLTE. If it says "VoLTE carrier was disabled," the check has been disabled. Restart your phone and check whether the VoLTE option becomes available. If the code returns an unsupported message or nothing changes, your device or carrier may not support this workaround.

Why is VoLTE not showing in settings after HyperOS update?
Xiaomi sometimes hides the VoLTE switch in newer software versions. Use the engineering code to verify carrier support, and check settings paths like Connection & sharing → Mobile networks → SIM settings.

Can I enable VoLTE without root?
Yes. Most Xiaomi devices allow VoLTE through normal settings or Xiaomi's carrier compatibility code. Root access is not required.

Can I use VoLTE on both SIMs at once?
Some Xiaomi devices support VoLTE on one SIM at a time. Check your model's specifications. With the 3G switch-off, phones older than 2018 may not support VoLTE on both SIMs simultaneously.

Why does my Xiaomi say "VoLTE function not supported" with full signal?
This means your carrier hasn't provisioned VoLTE for your account or your location. Contact your carrier to check if VoLTE is enabled on your plan.

Do I need VoLTE to make calls in the UK?
Yes. Since the UK's nationwide 3G shutdown, most voice calls are carried over VoLTE (4G) or VoNR on 5G Standalone. If VoLTE doesn't work, you may not be able to make calls.

Why can I use mobile data but not VoLTE?
Because mobile data and VoLTE use different network services. Your data connection may work normally even if IMS registration or carrier provisioning for VoLTE has failed. This usually indicates an IMS registration or carrier provisioning issue rather than a problem with your mobile data connection.

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