@Rowanlaw
The reason they say not compatible is because they need a 5g sim if you are in a 5g area.
This can be ontained by calling O2 Guide: Coronavirus Community Help and Support or by popping into your local O2 store.
eSim is also an option, again available by the above 2 methods.
However, if you are happy with 4g as now, you just need to use your current O2 sim and it will work fine.
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion. This is not Customer Service so we are unable to help with account specific issues.
Please select the post that helped you best and mark as the solution. This helps other members in resolving their issues faster. Thank you.
