Xiaomi Calls Keep Dropping on O2 in London

Quick Answer:
If your Xiaomi drops calls on O2 UK, first enable VoLTE in Settings → SIM cards & mobile networks → O2 SIM → VoLTE. If missing, dial *#*#86583#*#* and restart. Then text "VoLTE" to 2020 to check O2 has enabled it on your account. If still dropping, disable 5G and force 4G only via 4G/3G/2G auto.

How to Stop Xiaomi Calls Dropping on O2 – 5 Quick Steps

  1. Enable VoLTE – Settings → SIM cards & mobile networks → O2 SIM → VoLTE → ON
  2. Force VoLTE toggle – Dial *#*#86583#*#* if missing, then restart
  3. Check O2 provisioning – Text "VoLTE" to 2020, or call 202
  4. Force 4G instead of 5G – Preferred network type → 4G/3G/2G auto
  5. Enable WiFi Calling – Settings → O2 SIM → WiFi Calling → ON (or dial *#*#869434#*#* first)

Why This Happens – O2 Call Drops on Xiaomi

When your Xiaomi drops calls on O2, three technical causes are most common:

  • VoLTE not enabled on your phone – Without VoLTE, calls drop from 4G to 3G. 3G may be weak or unavailable indoors.
  • VoLTE not provisioned on your O2 account – O2 does not automatically enable VoLTE on all plans or older SIMs.
  • Weak indoor signal – Older buildings with thick walls (Victorian flats, council blocks) can block O2's Band 20 (800MHz).
  • Missing Band 20 on imported Xiaomi models – Some China-market Redmi and POCO devices lack Band 20, which O2 uses for indoor coverage.

Most recent UK Xiaomi models (Redmi Note 13 series, POCO F6, Xiaomi 14/15) include Band 20. Imported units often do not – this is a hardware limitation with no software fix.

Check O2 Network Status

Before troubleshooting your phone, verify O2 has no local issues:

  • O2 network status: o2.co.uk/network-status
  • Enter your postcode – look for "Voice" or "4G" issues
  • O2 community forums: community.o2.co.uk – search "call drops"

If O2 reports local mast maintenance or congestion, wait 2-4 hours before troubleshooting.

Fix 1 – Check O2 Band 20 Support (Hardware Check)

If your phone lacks Band 20, O2 indoor calls may drop. This is a hardware limitation.

Find your model number: Settings → About phone → Model number → Search online for "[model number] frequency bands" → Look for "Band 20 (800MHz)".

UK models with Band 20: Redmi Note 13 Pro 5G, Redmi Note 13 5G, POCO F6, POCO X6 Pro, Xiaomi 14, Xiaomi 15. If your imported model lacks Band 20, use WiFi Calling (Fix 6).

Fix 2 – Enable VoLTE on Your Xiaomi (Most Important)

VoLTE keeps calls on 4G instead of dropping to 3G. This is the most important software fix for O2 call drops.

Check VoLTE toggle: Settings → SIM cards & mobile networks → O2 SIM → VoLTE → Turn ON

If missing or greyed out: Dial *#*#86583#*#* once, restart, then check again.

After enabling: Make a test call. If the 4G/5G icon stays visible during the call, VoLTE is working.

Fix 3 – Check O2 Has Provisioned VoLTE on Your Account

O2 must enable VoLTE on their side. Even if your phone shows the toggle, O2 may not have provisioned it.

  • Text message: Send "VoLTE" to 2020 (free). O2 will reply confirming if VoLTE is active.
  • Call O2: Dial 202 → Ask to "Enable VoLTE and 4G Calling on my account".
  • IMS check: Dial *#*#4636#*#* → Phone information → Look for "VoLTE provisioned" – if "false", O2 has not enabled it.

Fix 4 – Disable 5G (Force 4G Only)

In some areas, forcing 4G instead of 5G can improve call stability.

Navigation: Settings → SIM cards & mobile networks → O2 SIM → Preferred network type → Select 4G/3G/2G auto (not 5G/4G/3G auto).

Fix 5 – How to Check Which Band Your Xiaomi Is Using

This helps you see if your phone is on O2's indoor Band 20.

  • Dial *#*#4636#*#* → Phone information → Look for "LTE band"
  • Band 20 (B20) = good indoor coverage. Band 1, 3, or 7 = weaker indoor penetration.

Fix 6 – Enable WiFi Calling (VoWiFi) – Best Indoor Workaround

WiFi Calling routes calls over your broadband, completely bypassing mobile signal issues.

  • Settings → SIM cards & mobile networks → O2 SIM → WiFi Calling → ON
  • If missing, dial *#*#869434#*#*, restart, then check again
  • Text "WIFICALL" to 2020 or call 202 to check O2 has enabled it

Fix 7 – Adjust HyperOS Battery Optimisation

Battery saver can interfere with background VoLTE processes.

  • Settings → Battery → Battery saver → OFF
  • Settings → Apps → Manage apps → Search for "Phone" → Battery saver → "No restrictions"

SIM / Network Reset Actions

  1. Airplane mode – ON for 30 seconds, then OFF
  2. Restart device – full reboot, wait 2 minutes
  3. Reinsert SIM – power off, clean contacts, reinsert firmly
  4. Switch SIM slot – on dual SIM devices, moving SIM to the other slot may help rule out slot-related issues
  5. Manual network selection – Settings → Mobile networks → Network operators → Search → Select O2 UK manually

Reset Network Settings (Last Resort)

Path: Settings → Connection & sharing → Reset Wi-Fi, mobile networks, and Bluetooth

⚠️ Removes saved Wi-Fi passwords and paired Bluetooth devices. Does not delete photos or contacts.

After reset: Restart phone, re-enable VoLTE (*#*#86583#*#* if needed), set preferred network type to 4G/3G/2G auto, re-enable WiFi Calling, then test calls.

Contact O2 – When Required

  • O2 customer service: 202 (free from O2 SIM) or 0344 809 0202
  • O2 technical support: 0800 902 0211 (8am–8pm daily)

Request them to enable "VoLTE" and "WiFi Calling" on your account, or replace your SIM if it's older than 3 years.

Frequently Asked Questions

Why do my calls keep dropping on O2 with my Xiaomi?

Most commonly because VoLTE is not enabled or O2 has not provisioned it on your account. Enable VoLTE in Settings, then text "VoLTE" to 2020 to check O2's side.

Does O2 support VoLTE on Xiaomi phones?

Yes, on most recent UK models (Redmi Note 13 series, POCO F6, Xiaomi 14/15). Enable via *#*#86583#*#* if missing. Text "VoLTE" to 2020 to check provisioning.

Can WiFi Calling fix O2 call drops indoors?

Yes. Enable in Settings → O2 SIM → WiFi Calling. If missing, dial *#*#869434#*#* first. Text "WIFICALL" to 2020 to check O2 has enabled it.

Does disabling 5G stop call drops on O2?

In some areas, forcing 4G instead of 5G can improve call stability. Go to Preferred network type → select 4G/3G/2G auto.

How do I check if my Xiaomi has Band 20 for O2?

Settings → About phone → Model number → search online for "[model number] frequency bands". Look for "Band 20 (800MHz)".

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