There is a lot of fluff flying about in india due to the launch of limited mobility. before I go into the details of gsm and cdma, one thing should be clear that both these technologies can be used for long distance communications. the reason as to y cdma was introduced in india under the limited mobility banner is totally regulatory and political. the government in 1994 had already sold licenses to gsm players for hundreds of crores and then later it allowed the operators providing basic services to offer mobile services using cdma. that is when the gsm players started crying foul cause the basic players were not charged extra for mobile services.
now to clear up the technical details:
GSM:
GSM (Global System for Mobile Communications) leads the world as the fastest growing, reliable and advanced digital technology available in the marketplace today. GSM provides integrated voice mail, high-speed data, fax, paging and short message services capabilities. GSM operates on the multiple spectrum frequency bands used around the world - 1900MHZ, which is used in North America and Japan and 900MHz and 1800 MHz for India and Europe. the GSM phone has a SIM card. The SIM (Subscriber Information Module) card - a.k.a. ’’smart card’’ - holds all of a subscriber’s personal information and phone settings. In essence, it is the subscriber’s authorization to use the network. It also holds the phone number, personal security key and other data necessary for the handset to function. The card can be switched from phone to phone, letting the new phone receive all calls to the subscriber’s number.
Can u use different SIM cards on your phone?
All of the cellular phones we rent and sell are unlocked, that is, not ’’locked in’’ with any specific provider or SIM card. Therefore, as long as the frequencies are compatible, you can use any SIM with your phone.
CDMA: ’’code division multiple access’’ was the method developed by the US military in the 1940. it relied on frequency hopping and spread spectrum to disallow the call from being tapped and thus being read. each call is given a separate code and sent over the same spectrum. an analogy will be: if there r 10 ppl in a room; say 2 english speaking, 2 chinese, 2 hindi and so on and everyone starts speaking at the same time then only people of the same language would understand each other and they would reject the languages they cannot understand. similiarly each cdma caller and receiver has a similiar code and an intruder without the same code will get only noise. these codes are dynamically shifted or hopped over different frequencies.
CDMA is supposed to have a number of advantages over gsm like higher capacity of users per cell, more clarity, less call drops etc.
in India reliance has implemented a version aclled CDMA 2001x. MTNL and BSNL have the older american version called IS-95.
world over GSM is more prevalent with whole of Europe majorly onto it. Cdma is there is north america(cause they have to b always differnt) and korea. it also coexists with gsm in china and india.
you cannot however replace the chip on a cdma phone and receive calls from another operator cause that chip is sold to the operator under royalty by a company called Qualcomm. this is the company that developed CDMA to be used in consumer networks. So once u change the operator the phone is kaput.
for further details or queries mail me or go to: https://cdg.org and https://gsmworld.com