Looking for ways to stay connected? With O2, WiFi Calling lets you make calls when you don't have signal. 5G and 4G Calling offer better indoor coverage and clearer calls using our 5G+ and 4G networks. But how do you know if your device is supported? And what do you need to do to enable WiFi, 4G or 5G Calling? Our guide has the answers.
What is WiFi Calling, 4G Calling and 5G Calling?
• WiFi Calling (also called Voice over WiFi or VoWiFi) lets you call and text* as normal when you can't connect to a mobile network. All you need is a WiFi connection
• 4G Calling (also called Voice over LTE or VoLTE) means you can use our 4G network to make clearer voice calls
• 5G Calling (also called VoNR) uses our 5G+ network for much clearer voice quality, faster call connection and smoother, more reliable conversations than 4G Calling – even in busy areas
In 4G and 5G 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 supported on selected devices.
Is my device supported?
All our 4G and 5G devices support 4G and WiFi Calling.
5G Calling is available with the following handsets with the latest software:
Apple iPhone 15, 15 Plus, 15 Pro, 15 Pro Max, 16, 16 Plus, 16 Pro, 16 Pro Max, 16e, 17, Air, 17 Pro Max, 17 Pro and 17e
Samsung Galaxy S26, S26+, S26 Ultra, S25, S25 Edge, S25 Ultra, S25 FE, Z Flip7, Z Flip7 FE and Z Fold7
Google Pixel 9a, 9, 9 Pro Fold, 9 Pro XL, 10, 10a, 10 Pro, 10 Pro XL & 10 Pro Fold
How do I enable 4G, 5G and WiFi Calling on my device?
To use 4G and 5G Calling, make sure you have an R15 SIM and are using a compatible device; once these requirements are met, the settings will be enabled automatically.
For WiFi Calling, if you have a 4G or 5G handset and a good WiFi connection, it should also be enabled automatically. If you experience any issues, you can use the device help guides to find more information on how to set up and use WiFi Calling on your phone.
WiFi Calling 4G Calling and 5G Calling FAQs
If you have good WiFi and your signal is poor, your phone may use WiFi calling to make calls. If your mobile signal is strong, your phone may prefer 4G calling (VoLTE) or 5G Calling (VoNR).
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 and 5G Calling. Your network will show as 4G or 5G depending on the availability of the network.
Android
The indicator bar will display a WiFi/phone icon. If you're in a 4G and 5G Calling area with good coverage, your phone will automatically use 4G Calling and your network will show as 4G or 5G depending on the availability of the network.
Calls made over WiFi will only drop if you move out of range and 4G and 5G Calling aren’t available. If you’re in an area where all WiFi, 4G and 5G Calling are available, the call will use 5G first.
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.
If you’re a Pay Monthly customer, all these services are included in your tariff at no extra cost.
Yes. WiFi and 4G Calling are available on most O2-compatible devices. 5G Calling is available on selected handsets.
Yes, you can use WiFi and 4G Calling, but 5G Calling isn’t available just yet.
Yes, 4G and 5G Calling are available abroad in selected locations. WiFi Calling isn’t currently supported outside of the UK.
Yes. If you dial 999 using WiFi Calling where there’s no mobile coverage, the operator might need to ask where you’re calling from. This is because WiFi calls don’t show location information. If you use 5G Calling, the call will automatically switch to 4G or 2G depending on network availability.
Last updated: 05/06/2026
quality(75))
quality(75))
quality(75))