GSM and CDMA are competing wireless technologies with GSM enjoying about an 82% market share globally. In the U.S., however, CDMA is the more dominant standard. Technically GSM (Global System for Mobile communications, originally from Groupe Spécial Mobile) is a specification of an entire wireless network infrastructure, while CDMA relates only to the air interface — the radio portion of the technology.
Code division multiple access (CDMA) describes a communication channel accessprinciple that employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code). CDMA also refers to digital cellular telephony systems that use this multiple access scheme, as pioneered by QUALCOMM, and W-CDMA by the International Telecommunication Union (ITU), which is used in GSM’s UMTS.