Code-Division Multiple Access.
CDMA is a digital wireless technology. It is a general type of technology, implemented in many specific technologies. But the term "CDMA" is also commonly used to refer to one specific family of technologies (IS-95 and CDMA2000) used in the US by Sprint and Verizon Wireless. This technology competes with GSM, used by AT&T and T-Mobile.
CDMA is a "spread spectrum" technology, which means that it spreads the information contained in a particular signal of interest over a much greater bandwidth than the original signal.
Unlike many competing technologies, CDMA has no hard limit for the number of users who may share one base station (tower). Instead, with CDMA, additional users can connect until the base station determines that call quality would suffer beyond a set limit.
CDMA (IS-95) systems have been in commercial operation since 1995. CDMA networks operate in the 800 and 1900 MHz frequency bands with primary markets in the Americas and Asia.
IS-95 CDMA technology has also been called cdmaOne and cdma2000. GSM
Global System for Mobile Communication.
GSM is the dominant 2G digital mobile phone standard for most of the world. It determines the way in which mobile phones communicate with the land-based network of towers.
GSM is one of two major mobile phone technologies in the U.S. The other is CDMA. AT&T and T-Mobile use GSM. Sprint and Verizon use CDMA. GSM is more prevalent in most other parts of the world, and especially in Europe.
Although GSM and CDMA provide similar basic features and services to end-users, (such as voice calling, text messaging, and data services,) they operate very differently at many technical levels. This makes GSM phones completely incompatible with CDMA networks, and vice-versa.
The most visible feature of GSM are SIM cards. SIM cards are removable, thumbnail-sized smart cards which identify the user on the network, and can also store information such as phone book entries. SIM cards allows users to switch phones by simply moving their SIM card from one phone to the other. Wilson Amps will work for all of this and others like EDGE, TDMA, etc...