3G Mode uses WCDMA, and 3.5G HSPA (if available) instead of
2G also called GSM based communication (which is power efficient but much lower speed when compared to HSDPA) The data couterparts of 2G is GPRS and EDGE 2.5G. As mentioned in an earlier post,
in 2G mode does not usually support data access through cellular network when a cellular voice call is active. Ofcourse one can use WiFi if available.