Phone manufacturers resort to “locking” the cell phones due to the economics of the wireless industry. A locked phone is pre-programmed to work on a specific carrier’s network only and cannot easily be used with another provider, even with the same technology. Since most new phones bought with service are heavily subsidized by the carrier as a way to attract new customers, the carrier would naturally want to protect the investment it has made on the customer.
The usual way of doing this is by contract while locking the phones is another method. Obviously, a locked phone presents actual physical hindrance to any attempt in violating an agreement which many consumers might be tempted to do with so many service providers coming up with irresistible offers.