Firstly you need to add Wifi and 4G Calling to your account. You may have to do this if you purchased your device before 19th May 2017.

• For personal tariff customers – Sign in to My O2, go to Device Details and tap Wifi and 4G Calling where you can then add the service to your account.
• Business customers – Contact Business customer services, your Digital Advisor or Business Partner.
• Once your new services are added to your account, follow the instructions below to enable Wifi and 4G Calling.

You can turn on Wifi and 4G Calling in your device settings -

1. To enable Wifi Calling, go to Settings > Connections > Wi-Fi calling. Make sure Wi-Fi 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 Wi-Fi 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 set-up process may re-start your device but you can get these instructions by email.

   

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.

If you need more info contact O2 business customer services.

Sony Xperia XZ Premium

Firstly you need to add Wifi and 4G Calling to your account. You may have to do this if you purchased your device before 21st June 2017.

• For personal tariff customers – Sign in to My O2, go to Device Details and tap Wifi and 4G Calling where you can then add the service to your account.
• Business customers – Contact Business customer services, your Digital Advisor or Business Partner.
• Once your new services are added to your account, follow the instructions below to enable Wifi and 4G Calling.

You can turn on Wifi and 4G Calling in your device settings -

1. To enable Wifi Calling, go to Settings > More > Wi-Fi calling. Make sure Wi-Fi calling is set to On. To switch off Wifi Calling, set the toggle to Off.
2. To switch on 4G Calling, go to Settings > More > Mobile networks > Enable VoLTE. Make sure Wi-Fi calling is set to On. To switch off 4G Calling, set the toggle to Off.

To get Wifi and 4G Calling, your device will need to use O2 firmware*. It should do if you bought it direct from us in an O2 shop, online or over the phone. We’re working to make it available on other Premium phones as soon as we can be sure the experience is great. We’ll get in touch when this happens.

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 you need more info contact O2 Business customer services.

Wifi Calling (also called Voice over Wifi or VoWifi), allows you to make calls, receive calls and send and receive text messages* even if you can’t connect to the mobile network. When connected to wifi, you can just dial the number you want to call, or send a text message like normal.

4G Calling (also called Voice over LTE or VoLTE) lets you make calls using our fast 4G network, for a clearer voice call. If 4G Calling is available, you can just dial the number you want to call like normal. You can check 4G Calling coverage using our coverage checker.

They’re two great ways to stay connected with O2. Wifi Calling can help when you can’t get a signal, and both give you great quality calls. In 4G Calling areas, they work together to provide a seamless and uninterrupted experience as you move from one to another, without the call dropping.

*Text messaging over Wifi Calling is only supported on select devices.

All 4G and 5G devices on our business shop now support 4G and Wifi Calling.

To find out if your phone’s running O2 firmware*, check the set-up instructions for Samsung or Sony.

If you need more info contact O2 Business customer services.

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 – clearer calls over 4G and it won’t use your 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.

• Using an iPhone X, iPhone 8 Plus, 8, iPhone 7, 7 Plus, 6s, 6s Plus, SE, Galaxy S7, S7 edge, Sony Xperia XZ1, Xperia XZ1 Compact or Xperia XZ Premium with your sim-only contract? To add Wifi and 4G Calling at no extra charge, either go to My O2 and add it to your account, or contact us.
  Please note, Wifi and 4G Calling is only available on Samsung and Sony devices bought directly from O2 customer services, O2 shops or O2 online.
• Transferring your personal tariff to a sim-only contract and want to add Wifi and 4G Calling? Either go to My O2 to add it to your account at no extra charge, or contact us.
• 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 contact Business customer services to add it to your account at no extra charge.

When you have wifi coverage but can’t connect to the mobile network, your phone will automatically use Wifi Calling.

Apple devices
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’.

Samsung and Sony devices
The indicator bar will display a wifi/phone icon. If you have a strong signal, 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 wifi providers might charge you to connect, like on certain trains and in some hotels.

Yes. 4G Calling when roaming is now live in the USA for customers with a compatible device, tariff and sim. Check if your device will work by clicking here.

You’ll need to have the 4G Calling setting switched on on your phone, for it to work. Follow the steps for your device, at the top of this page.

Calls can be made using apps, such as Whatsapp when roaming. But a standard phone call, over Wifi isn’t available when roaming.

Yes, you can use Wifi and 4G Calling in the UK on most Business tariffs.

4G Calling when roaming is now live in the USA for customers with a compatible device, tariff and sim.

There are two tariffs that aren’t compatible with Wifi and 4G Calling in the UK and when roaming – Mobex and Best for Business.

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’ and follow the instructions to either add or remove Wifi and 4G Calling from your account.
• If you're on a business tariff get in touch with Business customer services, your Digital Advisor or Business Partner 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.

Note: If you need to receive texts, you can switch off Wifi Calling through your device settings

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.