A SIM lock, often pre-installed by carriers, restricts a phone to a specific network or country. As of 2019, the Wireless Smartphone Strategies (WSS) service reported that over 70% of smartphones shipped globally were sold by operator channels, potentially subject to SIM locking.
However, regulations vary, with the EU mandating clear labeling of SIM-locked devices. This lock can be legally removed by the original service provider or through legitimate third-party services, granting users the freedom to switch networks and optimize their mobile experience.
Also called a “simlock” or network lock, a SIM lock is usually meant to ensure that customers who purchase a phone from a particular company continue to use that company’s services. Unless unlocked, a card that is locked will typically work only with the network provided by a particular company or in a certain region. This is done to encourage customers of a mobile service provider to remain loyal to that provider in the long run. Phones that have a SIM lock may also be less expensive than unlocked phones, since they typically ensure that the customer purchasing the phone only uses the network provided by the selling company.
The SIM lock on a phone is typically associated with the SIM card provided with the phone, meaning a customer using a particular mobile provider will be locked on any phone he or she uses with that card. SIM cards allow customers to transfer their information and phone service between different phones. The SIM lock on these cards allows providers to ensure that a customer continues to use their service while under contract.
Most mobile network providers can unlock a SIM lock if asked to do so by a customer. There are typically no statutes requiring that providers do so, however, so it is up to a company to decide whether a SIM card should be unlocked. Even once unlocked, the phone may still retain firmware associated with the service provider, such as menus and operating systems. This is why an unlocked phone may still display the logo for a certain service provider on startup.
A phone with a SIM lock can also typically be unlocked using third-party programs and services. The legality of such services is somewhat questionable, but typically is allowed though such companies may charge a sizable fee. Information provided by a person to have a SIM card unlocked can also potentially be used by someone else to spoof the person’s phone information. This could allow someone else to use his or her service and could lead to legal complications or service cancellation in the long run.