Samsung does not issue unlock codes for its devices, and directs customers seeking these codes to contact their wireless carriers. Samsung phones are locked by individual wireless carriers, not by Samsung.
All four of the major wireless carriers in the U.S. are signatories to the Consumer Code for Wireless Service, and they follow its unlocking policy. This policy requires carriers to unlock postpaid phones upon request once the device is paid off or once the contractual service period is fulfilled. Carriers unlock prepaid devices upon request after one year of reasonable usage. The Consumer Code for Wireless Service does not define a standard of reasonable usage.
The Consumer Code for Wireless Service is a voluntary agreement. Verizon, AT&T, Sprint, T-Mobile and U.S. Cellular are all signatories. Federal law states that unlocking phones is legal, but it does not legally obligate carriers to unlock phones upon request. Smaller carriers that have not signed this agreement are not required to follow its unlocking policies.
Unlocking a device is free of charge to current customers of participating carriers, but carriers are permitted to charge an unlocking fee to non-customers. Third-party unlocking services that circumvent wireless carriers are also permitted to assess fees regardless of the customer's standing with the wireless carrier.