> Check your local laws before you start messing with SIM cards, though, altering certain identifiers can be a crime.
Generally the contents of specific important Elementary Files (EF) are protected by requiring you to have an ADM code to read/write.
> I haven't needed to enter APNs in years, there are standards to provision those by SMS if they're missing and most of them are pre-configured in the phone's OS.
You might need to enter an APN if you have a B2B contract with the operator, where they'll route all traffic from your device(s) through a VPN directly to you. Besides that and static addresses, I am not aware of any other prevalent use-case for changing an APN.
Generally the contents of specific important Elementary Files (EF) are protected by requiring you to have an ADM code to read/write.
> I haven't needed to enter APNs in years, there are standards to provision those by SMS if they're missing and most of them are pre-configured in the phone's OS.
You might need to enter an APN if you have a B2B contract with the operator, where they'll route all traffic from your device(s) through a VPN directly to you. Besides that and static addresses, I am not aware of any other prevalent use-case for changing an APN.