Roaming in the USA

Our O2 network will continue to support all types of mobile devices in the UK. But if you’re planning to travel to the USA, some phones won’t be compatible with USA networks. This is because American mobile phone carriers are upgrading their networks and shutting down their 2G and 3G services. It impacts all mobile network operators with roaming agreements with networks in the USA.

So, if you’re going to the USA on business on or after 2 April 2024 and wish to use your phone, you’ll need to ensure the following:

  1. A 4G or 5G phone, which supports 4G calling when roaming (see below) with the latest software installed;
  2. A 4G or 5G enabled sim
  3. A compatible O2 tariff;
  4. 4G calling switched on, on your device

You can make calls, send texts, and use data if you have all the above.

No plans to travel to the USA on business? Then you don’t need to do anything. Your phone will continue to work as usual on our UK network.

Devices that will work in the USA

As device manufacturers release new firmware updates from time to time, please make sure you have the most recent version. Apple devices require iOS 15 or above. Manufacturers using the Android operating system may have enabled it on different versions.

Device compatibility may change from time to time.  Check whether your phone can make 4G calls when roaming or take a look at this list of compatible devices.


Why is this happening?

The mobile operators we partner with in the USA are upgrading their networks. They’re shutting down their older 3G networks to focus on 4G and 5G services over the coming years. This means older smartphones, which don’t support 4G Calling, will no longer work on their networks after they make the switch.

How do I know if I have everything I need?
  • Check the list of devices above that will continue to work in the USA. If your device isn’t on that list, contact us on the number below.
  • If you’re on our Best for Business or Mobile Extension tariff, you won’t be able to use 4G calling when roaming. Please contact our Business Customer Service team to discuss your options, and they’ll tell you what’s right for you.
  • If you’re unsure if your sim card supports 4G or want to clarify anything in more detail before you travel to the USA, call us on 0800 977 7337.

What do I do if my device doesn’t support 4G calling?

Check the list of compatible devices above. If your device isn’t 4G compatible and you intend to travel to the USA, speak to an O2 Business advisor on 0800 977 7337 to upgrade and discuss your options.

What happens if I don’t upgrade my mobile?

If your mobile doesn’t support 4G Calling and you travel to the USA, it won’t work on specific USA operator networks.

My phone isn’t connecting to a network. How do I manually select the network?

There are different ways of doing this, depending on your device. We have step-by-step guides for several manufacturers here. Just select your device manufacturer and follow the instructions.

I’m not likely to travel to the USA. Do I need to do anything?

Not right now. Your device will continue to work as normal in the UK.

Will mobile network operators in other countries be doing the same in the future?

Yes, other foreign mobile network operators will close their 2G and 3G networks in the future. We’ll keep you in the loop.

Can I use Wifi Calling when roaming in the USA?

You can make calls using certain apps when roaming, such as WhatsApp. But a standard phone call over wifi isn’t available when roaming.

How do I know if my sim card is compatible?

Many of our sim cards support 4G. If you see 4G against the network indicator on your phone (like the one below), it’s the correct type of sim card.



I don’t think I have a 4G Sim card. What do I do?

Contact us on 0800 977 7337. We’ll check it out and send you a new one if needed.

Are there any tariffs that are impacted?

Most of our tariffs are compatible with 4G calling already. Yet some aren’t, such as Mobile Extension and Best for Business. If you’re on one of these tariffs and are travelling to the USA, please call your Account Manager or Business Customer Service on 0800 977 7337.

Do I need to leave data roaming switched on?

There are some instances with Apple and Samsung where the settings need to be altered.

To keep costs down while you’re abroad, you can switch off mobile data and data roaming. This prevents automatic app or software updates, which are more expensive when roaming. 

If your phone reboots and 4G calling is lost while you have mobile data or data roaming switched off, don’t worry. You can simply turn it back on and when calling is restored, you can turn it off again.

How do I turn on 4G calling?

Check out our 4G and Wifi calling page here.

What are the terms and conditions for 4G calling?

You can read our terms for using the 4G and Wifi calling service here.

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