This review is for people who hate technical jargons so ill try and keep it short and simple.
GSM players: Airtel, Hutch, Idea, Aircel, MTNL etc
CDMA players: Reliance, Tata.
Call quality: CDMA players win here. The CDMA technology provides superior voice and data capabilities compared to GSM. So if call quality is important, choose CDMA.
Call costs: Here CDMA players have lower call costs, so if you talk a lot, choose CDMA over GSM.
Surfing speed: If you love to surf the internet on the go, CDMA wins here. CDMA internet speeds are upto 144 kbps while GPRS speeds are merely 30 - 40 kbps. GSM has introduced EDGE which boosts speeds upto 115 kbps, but unfortunately EDGE is available only in a few towns while CDMA provides FULL speed ANYWHERE in India. So if you love to surf, CDMA wins bigtime.
Roaming: If you need to roam, both GSM and CDMA are quite evenly matched, but Reliance is ahead with better coverage in India and roaming is cheaper too with CDMA players. So if you roam, choose CDMA.
International roaming: Here GSM wins big time. CDMA is only available in America and in a few countries in Asia. It is non existent in Europe and South America. So if you roam internationally avoid CDMA.
Handset choice : Here GSM wins bigtime! The choice of handsets is far greater than CDMA
and they are also cheaper. e.g Moto RAZR GSM costs just 8000 while the CDMA versions costs 10500! So if you love to change your handsets, GSM wins big time here.
Choose GSM: If you love handsets and change them more often than you buy new clothes, stay FAR away from CDMA players. Similarly if you need to roam internationally avoid CDMA players.
Choose CDMA: If you want a cheap handset and want to spend less on calls choose CDMA. Also if you love to surf the net but are irritated by slow GPRS speeds switch to CDMA.
Next Generation : The next generation of GSM is 3G which im sure you must have heard about. But dont let that influence your decision. It will be many years before 3G actually comes. Same goes with CDMA, EvDO(next generation CDMA) is available abroad, but since 3G isnt avaialble here, neither Reliance nor Tata seems keen to implement it here.