GSM Unlocked Cell Phones
In the United States, unlocked phones are a relatively new phenomenon. Unlike the rest of the world, Americans are used to purchasing phones directly from the service providers, resulting in inferior technology and restricted phone service.
From the viewpoint of the consumer, an unlocked phone is a phone that can be used on any GSM network without restriction. In the United States, unlocked phones can be used on T-Moblie, AT&T, etc.