sim card not working in new phones

[jamiem0705]

i've had this sim card for years and have had 2 new phones but the sim card does not work in them. despite being unlocked it says sim 1 not allowed on them both. i've heard that sim cards that are very old may not work in newer phones so wondering if this is the case. both phones are definitely unlocked and able to receive o2 sim cards as a friend's o2 sim card works fine in both of them. how can i get a newer sim card that works in my samsung s10?

[madasaf1sh]

@jamiem0705 

You will have to go into an o2 store with photo ID and one can be provided to you.. Alternatively call o2 and one will be posted to you, but your current sim will be terminated immediately, and you will need to call o2 to have it activated

Guide: How to find help & contact O2