Earlier today, a leaked slide from a Galaxy S7 and Galaxy S7 edge setup presentation surfaced online revealing that carrier-branded variants of the handsets will lock to the network of the first SIM card that’s inserted. This the first time that Samsung has implemented an automatic carrier-locking mechanism into any of its network-specific Galaxy smartphones. Up until now, all devices sold through operators were unlocked and could be openly used on other networks.
If, for whatever reason, you want to use your handset on a different carrier, you’ll have to contact your current operator or a third-party provider and request a Network Unlock Code (NUC). More often than not, it costs money to generate these codes and unlock your device. However, under certain circumstances, they are free. Many networks in the United Kingdom will unlock a contracted smartphone at the end of a tariff so that customers can sell the devices on and put the money towards a new handset.
It's important to bear in mind that this feature will not affect factory unlocked devices purchased from Samsung or third-party independent retailers, so if you order a device from your local electronic store, you'll be able to switch between carriers without it locking.