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.

1. by: Sandeep Kumar Mahto