Xiaomi Cannot Register on Three UK in Glasgow

Xiaomi Cannot Register on Three UK in Glasgow (2026 Fix)

If your Xiaomi, Redmi or POCO phone shows "Not Registered on Network", "Emergency Calls Only", or fails to connect to Three UK while you're in Glasgow, this guide covers the most common fixes. This issue can affect physical SIMs and eSIMs, particularly after system updates or in areas with variable coverage.

Before You Start – Quick Checks

  • Restart your phone – Clears temporary software glitches.
  • Toggle Airplane Mode – Turn on for 30 seconds, then off.
  • Reinsert your SIM card – Power off, remove, clean contacts, and reinsert firmly.
  • Check for Three UK outage – Visit the Three network status page or use the Three app.
  • Check your account status – Ensure your account is active and has credit/payment up to date.

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

Quick Navigation

Why This Happens

  • Automatic network selection fails – Xiaomi devices sometimes struggle to automatically select the correct Three UK network. Manually selecting the network often resolves this.
  • IMS registration failure – IMS (IP Multimedia Subsystem) registration is required for VoLTE and VoWiFi. If IMS shows "Not Registered," your phone may not register fully on Three UK.
  • HyperOS update resets carrier settings – Some network settings may reset after major HyperOS or MIUI updates, causing temporary registration issues.
  • Dual-SIM conflicts – If you have two SIMs, the Three SIM may not register unless it's set as the primary data SIM or the other SIM is disabled.
  • Temporary network conditions – In some areas, local network congestion or maintenance can affect registration. This usually resolves within a few hours.

Check Network Status (Three UK)

Before troubleshooting your device, verify Three UK's network status:

  • Check Three UK's network status page for planned maintenance or outages in the Glasgow area (G postcode).
  • Three UK coverage maps show 5G availability across Glasgow city centre, Southside, East End, and West End.
  • If there is a confirmed outage, registration issues may resolve automatically within 2–4 hours.

Step-by-Step Fixes

Step 1: Select Network Manually

Why this matters: Xiaomi devices can struggle to automatically select Three UK. Manual selection forces the phone to register directly.

  1. Settings → SIM cards & mobile networks
  2. Tap your Three SIM
  3. Tap Network operators or Choose network
  4. Turn off Choose automatically
  5. Wait for the phone to scan for networks
  6. Select Three UK or Three
  7. If the selection fails, try again after 10 seconds

If this doesn't resolve the issue, move to Step 2.

Step 2: Check IMS Registration Status

Why this matters: IMS registration is required for VoLTE and VoWiFi. If IMS shows "Not Registered," your phone may not fully register on Three UK.

  1. Open the Phone app
  2. Dial *#*#4636#*#*
  3. Tap Phone information
  4. Look for IMS Service Status or IMS Registration
  5. If it shows Not Registered, enable VoLTE (Step 3) and restart your phone

If IMS is already registered but the issue persists, move to Step 3.

Step 3: Enable VoLTE (4G Calling)

Why this matters: Three UK uses VoLTE for modern network services. Enabling VoLTE can help with registration and call reliability.

  • Settings → SIM cards & mobile networks
  • Tap your Three SIM
  • Look for "Use VoLTE" or "4G Calling"
  • Ensure it's toggled ON
  • Restart your phone and test

If VoLTE is already enabled or the option is greyed out, move to Step 4.

Step 4: Check Preferred Network Type

Why this matters: If your phone is set to 5G only, it may struggle to register in areas with weaker 5G coverage. Switching to 4G (LTE) preferred often improves stability.

  • Settings → SIM cards & mobile networks
  • Tap your Three SIM
  • Tap Preferred network type
  • Select 4G (LTE) preferred or 5G/LTE/3G/2G Auto
  • Restart your phone and test

If this doesn't help, move to Step 5.

Step 5: Reset APN Settings

Why this matters: Incorrect APN settings can prevent data access. For "Not Registered on Network", APN is rarely the primary cause, but resetting is a quick check.

  1. Settings → SIM cards & mobile networks
  2. Tap your Three SIM
  3. Tap Access Point Names (APN)
  4. Tap the menu icon (three dots) and select Reset to default
  5. Restart your phone

Three UK APN Settings (if you need to create manually):

SettingValue
APNthree.co.uk
UsernameLeave blank
PasswordLeave blank
APN Typedefault,supl,mms

If APN settings are correct but registration still fails, move to Step 6.

Step 6: Check IMEI Status

Why this matters: If your IMEI is blocked, the phone won't register on any network. This can happen with stolen devices or unpaid bills.

  • Open the Phone app
  • Dial *#06#
  • Check that both IMEI numbers appear correctly
  • If IMEI shows as "Unknown" or "0", the phone has a software or hardware issue
  • If IMEI appears but you suspect it's blocked, contact Three UK to check

If IMEI is valid and shows correctly, move to Step 7.

Step 7: Reset Network Settings (Last Resort)

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

  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. Reconnect to your mobile network

If resetting network settings doesn't work, move to Step 8.

Step 8: Check for HyperOS Updates

Why this matters: Software updates often include bug fixes and improvements for connectivity issues.

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

If you're already on the latest version, move to Step 9.

Step 9: Test SIM in Another Phone

Why this matters: This helps identify if the issue is your phone or your SIM/carrier.

  • Insert your Three SIM into another phone
  • If it works, the issue is with your Xiaomi device
  • If it doesn't work, the issue is with your SIM or carrier

Contact Carrier (When Required)

Contact Three UK if:

  • The SIM works in another phone but not yours
  • You've tried all steps above and still can't register
  • You suspect your IMEI is blocked
  • There's a known network issue in Glasgow
  • You need a SIM replacement
  • Your account is inactive or unpaid

Three UK Support

  • Call 333 from your Three phone or 0333 338 1001 from any phone
  • Three UK Help Centre: three.co.uk/support

Contact Xiaomi UK Support if:

  • You've tried all steps above and still can't register
  • You've tested your SIM in another phone and it works
  • The issue persists across multiple SIM cards
  • You suspect a hardware fault with the cellular antenna or modem
  • IMEI shows as Unknown

Xiaomi UK Support

Final Verdict

If your Xiaomi won't register on Three UK in Glasgow, the most common causes are incorrect network selection, IMS registration failure, or temporary network conditions. Start by manually selecting Three UK in Network operators, then check IMS registration using *#*#4636#*#*. If IMS shows "Not Registered," enable VoLTE and restart your phone. For testing, try switching to 4G preferred and test your SIM in another phone to determine whether the fault lies with your device or Three UK's network. If the issue persists across multiple devices, contact Three UK to check your account and IMEI status.

Frequently Asked Questions

Why does my Xiaomi say "Not Registered on Network" on Three UK?

This usually means the phone can detect the network but cannot register for normal service. Common causes include: incorrect network selection, IMS registration failure, VoLTE disabled, or a blocked IMEI.

How do I manually select Three UK on Xiaomi?

Go to Settings → SIM cards & mobile networks → Tap your SIM → Network operators → Turn off "Choose automatically" → Select Three UK.

What is IMS registration on Xiaomi?

IMS (IP Multimedia Subsystem) registration is required for VoLTE and VoWiFi. Dial *#*#4636#*#* and check IMS Service Status – it should show "Registered" for full functionality.

Does Three UK work on imported Xiaomi phones?

Yes, but you may need to manually configure network selection and APN settings. Imported phones sometimes have different carrier profiles that don't auto-configure for Three UK. A global or EEA ROM is recommended.

Can a factory reset fix "Not Registered on Network"?

Factory reset can help if the issue is caused by corrupted system files or network profiles. It should be used as a last resort. Try the steps in this guide first.

Does replacing the SIM card fix this?

Yes, if the issue is caused by a damaged or faulty SIM card. If you've tried all steps and your SIM works in another phone but not yours, the issue is with your Xiaomi device.

Why does my Xiaomi work on other networks but not Three?

Three uses a different network configuration and device certification process. Manual network selection and VoLTE settings are often the key differences.

Do these fixes work on UK Xiaomi devices?

Yes. This guide applies to Xiaomi, Redmi, and POCO devices sold in the UK. The steps are identical across UK models.

Note: This guide is updated for 2026. Menu names may vary slightly between HyperOS and MIUI versions.

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