CDMA handsets come without SIM card
And GSM phones need a SIM Card.
GSM standards are the most popular .
And being provided by
BhartiAirtel,Vodafone,Aircel,BSNL and also Reliance and Tata Teleserices since the recent times.
CDMA stands are prominent
from the network operation
Like Reliance,Tata Indicom,etc.
Technically ,the basic difference is between the types of
modulation methods (multiplexation) employed
From the time mobile phones were introduced in country 1997, until the end of 2002, the market was dominated by just ,namely, GSM.
In December 2002, Reliance Communications (then known as Reliance Infocomm) launched CDMA services across 17 circles on country basis.
CDMA has since been growing faster than GSM; although on lower base.