As some of you might know, 2G (GSM) or 2.5G (GSM/Edge) does not support data and calls at the same time. Using the Internet while on 2.5G and lower causes incoming calls be bounced.
3G does support data and calls at the same time by pausing Data while a call is received.
I am an architect, working in and around buildings under construction.
I usually get a low (2G) signal when I enter one and a good (3G) signal when I come out. Together with all the apps I have, the phone finds itself using my Internet connection when on GSM, causing calls to be dropped. I'm effectively unreachable.
I don't want to use 2G internet, only 3G. I would like cellular data to be on only when on 3G. My phone calls take priority over Internet connectivity when on 2G.