QUOTE(sonyclie77 @ Jan 17 2012, 11:45 PM)
Let me answer your question.
On EDGE, you only can have either voice or data at any time. So if you're using data, voice calls cannot come in. You will subsequently get a missed call alert.
So for people whose phone calls are important to them, ie salesperson or businessman, you have to be on 3G all the time. Constant missed calls does not have a good impression on your clients.
Wifi:
Best speed results in both low latency and high bandwidth scenarios
Additional Battery drain
Works while you are on a call
2.75G (EDGE):
Best carrier-connection scores for messages, and IM.
does not work while you are on a call, messages and IMs poll after your call is over.
Draws slightly less power than 3G.
3G:
Best score for rich media, transfers.
Works while you’re on a call.
Marginally slower than 2G for small amounts of data.