This read-write enumeration reports and controls whether the CDMA SIM/device's PIN security is locked(2) or unlocked(3). An admin manages this to control physical/logical security of the cellular device, locking it to require a PIN before use, for example in higher-security deployments, or unlocking it for unattended operation. For example, a remotely deployed unattended router would typically need this set to unlocked(3) so the modem can initialize automatically after a power cycle without waiting for manual PIN entry.