on 01-10-2023 18:09
I have put my SIM into a different device which has locked my SIM and I now require a SIM network puk code
on 01-10-2023 18:13
Here Unblock your mobile device | Phones sims and devices | Help | O2
on 01-10-2023 18:14
More likely the phone itself is locked to a different network rather than the SIM
Can you put the SIM back to see if it is OK?
What is the phone and where is it from?
on 01-10-2023 19:47
on 01-10-2023 19:47
Following the advice of @Enlli, you might want to read these pages :-
Mobile unlocking: Unlock phone savings for less - MSE (moneysavingexpert.com)
Mobile companies now banned from selling locked handsets - Ofcom
However, it is fair to say that many handsets purchased before December 2021 were actually unlocked.