^^^
GSM 3G in India works on 2100 Mhz. CDMA/EVDO works on 800 Mhz. By the laws of physics, CDMA with shorter wavelength will always have much better reception indoors than GSM 3G. I ahve used GSM 3G in three different metros and my experience is that speed is affected by the number of users in GSM 3G also.