There are two key networks for cell phone carriers. They are GSM or (Global System for Mobile Communications). Examples are AT&T and T-Mobile. GSM phones have a SIM chip under the battery and cannot be flashed. The second network is called CDMA or Code Division Multiple Access. Examples are Metro, Sprint, Cricket, Boost, Verizon and many others. Cell phones on a CDMA network are not controlled by SIM cards and can be moved or flashed to a new carrier.
How Good Is The Service I Am Moving To?
You can check the quality of almost any carrier by going to Cell Reception. Here you can enter in your zip code and get scores for providers in your area along with comments from others using their service.