Difference Between CDMA and GSM

Parameter	CDMA	GSM
Acronym for	Code Division Multiple Access and also known as IS-95 or CDMAone.	Global System for Mobile Communication.
Technology Used	This Technology is based on spread spectrum technology and does not require dividing the channel by time. It also allows several users to share same frequency in a given band or space. Users are isolated by bipolar sequences and can share same frequency.	In this technology Carrier is divided into number of time slots. These different time slots are assigned to each user and until ongoing call is not finished, no other user can access this assigned slot.
Concurrent User Access	Same frequency is used by several users on the same time and can accommodate more users per MHz of bandwidth than any other technology.	Each user uses separate time slot that can be used by one user at a time.
Network Portability	No such feature is available and hence international roaming is a Problem and very limited support is available.	The availability of Subscriber Identity Modules (SIM) allows users to switch networks.