Unlocked mobile phones enable you to choose which service provider you use. This Enables you to find the best deal available for phone charges, rather than being stuck with the network that has locked the phone.
An "unlocked phone" is one that can be uses on any wireless carrier network. Usually a wireless carrier (eg AT&T Wireless) locks a phone to ensure that the user stays with the two year contract that...
It is the phone itself.
SIM cards are peculiar to GSM phones. There are other types that do not use a SIM card. The SIM card carries information that is specific to the subscriber.
All phones...