SIM locking is very common if subsidized phones are sold with prepaid contracts. It is important to note, however, that the technology associated with the phone must be compatible with the technology being used by the network carrier. A GSM cell phone will only work with a GSM carrier and will not work on a CDMA network provider. Likewise, a CDMA cell phone will only work with a CDMA carrier and will not work on a GSM network provider.[3] Note that newer (2013+) high end mobile phones are capable of supporting both CDMA and GSM technologies, allowing customers to use their mobile devices on any network. Examples of these mobile devices are the Apple iPhone 5c, 6 and newer, Motorola's G4, G5, X Pure, Samsung's Galaxy S6, S7, S8 smart phones, mostly phones based on a Qualcomm Snapdragon chipset or radio.
Most mobile phones can be unlocked to work with any GSM network provider, but the phone may still display the original branding and may not support features of the new carrier. Besides the locking, phones may also have firmware installed on them which is specific to the network provider. For example