Hello @Lindsay Wilson
Curry's we're thinking the phone might have been region locked ,which is a feature that Samsung used to apply to help stop grey importing of phone's.
This is the act of buying a phone in one country to then use it in another country permanently.
Depending on where the phone was sourced some maybe locked to a certain network, so as such they need to be unlocked. This can be achieved by using that networks sim card in the phone and then contacting their customer services to get the phone unlocked. Most network's have a support page on this.
That said Ofcom in the UK stopped Networks from supplying locked phone's.
The other option is to approach a Highstreet Store that advertises they unlock phone's, which involves a fee.
A person can check in the phone's settings in regards to roaming to ensure that has been activated.
And also speak with your own mobile network to ensure roaming is activated / allowed on the contract being used.
If i can be of any further help please don't hesitate to ask 😎
Daily Driver > Samsung Galaxy s²⁴ Ultra 512Gb ~ Titanium Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "
