Isn't there a state that's something like "On Call" ? I use something like that to make my media volume low during a call.Sorry... I didn't explain it like I was talking to a noob :/
There seems little point in switching 2g/3g when you connect to WiFi, as these are data modes and the data connection will use neither, since it's connected to WiFi.
Is there any evidence that 2g unused uses less power than 3g unused?
Ok, this may seem like a dumb question, but how did you manage to get your phone to call on wifi? Phone calls still go out over cellular towers regardless of internet connection. Wifi is only used for data, and the cell data connection turns off when wifi connects.