From the carrier’s perspective, the lock is a financial instrument. The Z2335L is often sold at a steep discount (sometimes as low as $20–$40) because the carrier expects to recoup the subsidy through service plan revenue over several months. If the user could simply insert a competitor’s SIM card immediately, the carrier would suffer a net loss. Consequently, the lock is enforced via a cryptographic key pair stored in the phone’s NVRAM (Non-Volatile Random Access Memory), typically requiring an or unlock code to disable.