When you go abroad your BT Mobile phone will work just like it does at home. But to connect to some networks in certain countries you may have to manually turn off 4G and use 3G instead.
Once you've done that, just pick a network from the list on your phone. If there are no issues with the networks in the country you're visiting, you may need to change your network settings.
The countries and networks where this applies are:
|Mobyland / CenterNet