I keep my cell phone in "airplane mode" almost all the time. I use VoIP on WiFi most of the time. When I do not have WiFI, I will use VoIP on 3G, but that's less than 1% of the time. Of course, this saves me a lot of money because I don't need a voice plan on my cell phone at all. (I do have the option to pay 25 cents/min and make voice calls, but I have never needed to do that so far. Instead, I pay about 1 cent/min for outgoing VoIP and zero for incoming.)
However, I do not do this just to save money. Here's a reason that is at least as important to me, if not more important: radiation exposure from WiFi is a fraction of the level from cellular radios.
Check this out:
He says, in part:
This document is a summary of what I’ve learned during a few weeks of trying to decode