Looking for ways to stay connected? With O2, WiFi Calling lets you make calls when you don’t have signal, 4G Calling gives you clearer calls and better indoor coverage, and 5G Calling keeps you connected on our latest network. This guide explains how it works, how to set it up and where you can use it.
What is WiFi, 4G and 5G Calling?
WiFi Calling lets you call and text* as normal using a WiFi connection when you can’t connect to a mobile network. All you need is a WiFi connection and you're able to stay in touch.
4G Calling (also called Voice over LTE or VoLTE) uses our 4G network to deliver clearer, more reliable calls, especially indoors and in busy areas.
5G Calling (also called Voice over New Radio or VoNR) lets you make calls over our very latest 5G+ network, helping keep you connected and delivering even better call quality.
Together, these features work seamlessly — so your call can move between WiFi, 4G and 5G+ without dropping.
*Text messaging over WiFi Calling is supported on selected devices.
Is my device supported?
Most modern smartphones support WiFi and 4G Calling, with 5G Calling available on selected devices and in supported areas.
For the best experience, make sure your device software is up to date, and to check if you can access 5G calling visit our 5G+ page.
How do I enable 4G and WiFi Calling on my device?
First, you'll need to add WiFi and 4G Calling to your account. It's quick and easy to do too.
For personal customers, please sign into My O2 and go to Device Details. From there, tap WiFi and 4G Calling – this is where you'll be able to add these features to your account.
Business customers will need to contact Business customer services, your Digital Advisor or Business Partner.
Once you add WiFi and 4G Calling to your account, you need to configure your device.
To enable WiFi Calling, go to Settings > Phone > WiFi Calling and switch it on
To switch on 4G Calling, go to Settings > Mobile Service > Voice & Data > 4G and switch it on
To switch on 5G Calling, go to Settings > Mobile Service > Voice & Data > 5G and switch it on
If you don't see a WiFi Calling or 4G Calling menu option, you may have to update to the latest iPhone software. If you do not see a 5G Calling menu your device may not be compatible. Check what devices are on our 5G+ page.
https://www.o2.co.uk/5g-plus
Please note: This setup process may restart your device –but you can receive these instructions by email. For more information, please see our iPhone support guides.
Watch how to set up WiFi and 4G Calling on a iPhone on YouTube.
To set up WiFi, 4G and 5G Calling, go to Settings > Connections / Mobile Network > Turn on WiFi Calling > Turn on 4G Calling (VoLTE). If supported, enable 5G or VoNR (5G Calling)
If you don't see a WiFi Calling or 4G Calling menu option, you may have to update to the latest iPhone software. If you do not see a 5G Calling menu your device may not be compatible. Check what devices are on our 5G+ page.
https://www.o2.co.uk/5g-plus
Please note: This setup process may restart your device –but you can receive these instructions by email. For more information, please see our iPhone support guides.
Watch how to set up WiFi and 4G Calling on a iPhone on YouTube.
1. To enable WiFi Calling, go to Settings > Connections > WiFi calling. Make sure WiFi Calling is set to On. To switch off WiFi Calling, set the toggle to Off. If you can’t find the settings here, try going to Phone > tap the 3 dots in the top right corner > Settings > scroll down to find WiFi Calling and toggle On.
2. To switch on 4G Calling, go to Settings > Connections > Mobile networks > 4G Calling. Make sure 4G Calling is set to On. To switch off 4G Calling, set the toggle to Off.
If you don't see a WiFi Calling or 4G Calling menu option, you may have to update to the latest software:
• Go to Settings > Software update > Download updates manually.
• If a new software update is available, select 'Download now'. Once the download completes, your handset will prompt you to install a new version of the software. You can either select 'Install update' or schedule the update overnight.
• When the install process starts, the device will display the Android installation status bar and then restart. Your screen will show the installation has completed. Select 'OK'. You may need to wait for your device to optimise your existing apps for the new software.
Please note: This setup process may restart your device but you can get these instructions by email. Our Samsung help guides contain more information too.
Watch how to set up WiFi and 4G Calling on a Samsung on YouTube.
If you are using a J3 (2017) to get WiFi and 4G Calling, your device will need to use O2 firmware. This is essentially the software that makes your device turn on and run. Sometimes there are different versions of firmware for the same device.
Your device should use O2 firmware if you bought it direct from us in an O2 shop, online or over the phone.
To check if your phone’s running O2 firmware, dial *#1234# and look at the CSC entry. If this line includes ‘TEF’, ‘O2U’ or ‘OTF’ then your device has O2 firmware and you can set up WiFi and 4G Calling.
If the CSC doesn't include one of these codes then WiFi and 4G Calling isn’t supported on your phone right now. Pop into an O2 store to discuss your options.
To enable WiFi Calling, go to Settings > More > WiFi calling. Make sure WiFi calling is set to On. To switch off WiFi Calling, set the toggle to Off.
To switch on 4G Calling, go to Settings > More > Mobile networks > Enable VoLTE. Make sure WiFi calling is set to On. To switch off 4G Calling, set the toggle to Off.
For more help, check out our Sony phone help guides.
If you are using a Sony XZ Premium, XZ1 or XZ1 Compact, to get WiFi and 4G Calling, your device will need to use O2 firmware. This is essentially the software that makes your device turn on and run. Sometimes there are different versions of firmware for the same device. Your device should use O2 firmware if you bought it direct from us in an O2 shop, online or over the phone.
To check if your Sony is running O2 firmware:
Open the ‘Chrome’ app and tap the Home icon in the top left corner. If this takes you to www.o2.co.uk then your device has O2 firmware. If it takes you to Google, then WiFi and 4G Calling isn’t supported on your phone right now.
If you have changed the homepage in Chrome since buying your device, tap the three dots in the top right corner of Chrome, tap Settings, tap homepage, tap to edit the homepage and then press ‘Reset’. If it resets to www.o2.co.uk, then your device has O2 firmware. If it resets to Google, then WiFi and 4G Calling isn’t supported on your phone right now.
If that's the case, pop into an O2 store to discuss your options.
Go to Settings > SIM & network > Enhanced communications. Make sure WiFi calling is set to On. To switch off WiFi Calling, set the toggle to Off.
Go to Settings > SIM & network > Enhanced communications. Make sure Enable VoLTE (4G Calling) is set to On. To switch off 4G Calling, set the toggle to Off.
Need more help? Check out our OnePlus device support guides.
Go to Settings > SIM & network > Enhanced communications. Make sure WiFi calling is set to On. To switch off WiFi Calling, set the toggle to Off.
Go to Settings > SIM & network > Enhanced communications. Make sure Enable VoLTE (4G Calling) is set to On. To switch off 4G Calling, set the toggle to Off.
Need more help? Check out our OnePlus device support guides.
Go to Settings > Call > tap on WiFi Calling to turn on. To switch off WiFi Calling, tap to remove the tick.
Go to Settings > Call > tap on 4G Calling to turn on. To switch off 4G Calling, tap to remove the tick.
WiFi and 4G Calling FAQs
Yes — your device will automatically use the best available option: WiFi Calling when there’s no mobile signal 4G or 5G Calling when coverage is available.
iPhone
The carrier message at the top of your screen will change to ‘O2 WiFiCall’. If you have a strong phone signal, your phone will automatically use 4G Calling and your bearer will show as ‘4G’.
Android
The indicator bar will display a WiFi/phone icon. If you're in a 4G Calling area with good coverage, your phone will automatically use 4G Calling and your bearer will show as '4G'.
Calls made over WiFi will only drop if you move out of range and 4G Calling isn't activated or available. If you’re in an area where both WiFi and 4G Calling are available, the call will use 4G first.
You can check 4G Calling coverage using our coverage checker.
You can use WiFi Calling wherever there is WiFi – including wherever O2 WiFi is available. It’s free to connect to O2 WiFi, but remember other providers might charge you to connect – like on certain trains and in some hotels.
It’s no different to making a standard call or sending a standard text message (if you have a supported device that allows for SMS services over WiFi). It will come out of your tariff allowances or be charged at the standard tariff rate if you run out.
No extra charges from O2 – a minute is just a minute no matter how you make the call.
4G calls will not cost you any data.
WiFi calls use very small amounts of data over your WiFi connection.
If the WiFi is unlimited or free (like O2 WiFi) then you won’t be charged anything extra. If your WiFi connection has an allowance, then it will come out of that allowance, and your wiFi provider may charge if you go over.
Multi-Party calls: These are charged as normal but please note that each identical part of a multi-party or conference call will appear on your bill as a separate call entry.
Yes you can. WiFi and 4G Calling is currently available on most O2-compatible devices.
Transferring your personal tariff to a SIM only contract and want to add WiFi and 4G Calling? Add it to your account at no extra charge in My O2.
Have an O2 Business SIM only contract and want to add WiFi and 4G Calling? Get in touch with your Account Manager, Digital advisor, Business Partner or Business customer services to add it to your account at no extra charge.
Yes, WiFi and 4G Calling is available on Pay As You Go.
WiFi Calling is not currently supported outside of the UK. In certain circumstances, however, it may be possible to enable WiFi Calling when abroad. Where used, additional charges will apply.
Mobile calls will use 2G/3G Roaming and you’ll be charged according to your normal tariff.
If you're on a personal tariff, you can use O2 Travel to stay connected when you’re abroad.
If you're on a business tariff, you can use our Rest of the World 24 Hour Pass to stay connected while you’re away.
WiFi and 4G Calling won’t work with some of our other services – including O2 Just Call Me, Mobex, Mobile Recording or Fax and Data. You’ll need to remove WiFi and 4G Calling to use them. This can be done through My O2 or your Business Advisor.
If you're on a personal tariff, sign in to My O2, select ‘Device details’, then ‘WiFi and 4G Calling’. From here, follow the instructions to either add/remove WiFi and 4G Calling from your account.
If you're on a business tariff get in touch with your Digital Advisor, Business Partner, or Business customer services if you need help with WiFi and 4G Calling
Sending voicemails and texts when using WiFi Calling without mobile coverage:
SMS (text messages) can be sent and received over WiFi Calling but only on certain devices where the device firmware allows. Some devices will not be able to send and receive text messages over WiFi Calling.
MMS and Visual Voicemail (VVM) messages need mobile coverage to reach your phone so these won’t work in WiFi-only areas.
iPhone customers – iMessage will continue to work even if you only have WiFi coverage available.
You can still use WiFi Calling to make calls to the emergency services. Please note – if you dial 999 using WiFi Calling where there’s no mobile coverage, the operator will need to ask where you’re calling from. This is because WiFi calls don’t show location information.
You can still use WiFi Calling to make calls to the emergency services. Please note that if you dial 999 using WiFi Calling where there’s no mobile coverage, the operator will need to ask where you’re calling from as WiFi calls don’t show location information.
Last updated: 14/02/2025
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