SIM card not working in an iPhone XR

[Elisesdad]

I’ve just got an iPhone XR from O2, upgraded from my iPhone 6. The SIM card is the same size so I swapped it over but get this message:

“The SIM card you currently have installed in this iPhone is from a network provider that is not supported under the activation policy currently assigned by the activation server. Please insert another SIM card from a supported network provider or request this iPhone be unlocked by your network provider”.

Both my iPhone 6 and the XR are from O2 and my SIM card is O2. Any help would be appreciated 🙂

[MI5 · Accepted solution]

@Elisesdad 

Your new iPhone is locked to a different network.

You'll need to call customer service.
Numbers here Guide: Coronavirus Community Help and Support 
When it comes to the reason you are calling stay silent for 15 seconds and you will be taken to the keypad options.
Press 2 for Everything Else
Press 5 for More Options
Press 7 for Anything Else which will put you though to someone.
Say "Upgrade", "Lost/Stolen" or "Fraud" if you have to, to get put through to someone.
8.00am is the best time to call if you can.

[Elisesdad]

Thank you, I’ll try that.

[MI5]

You're welcome