I decided to use an app called "Green Power" (I assume it's like Juice Defender). It can turn off WiFi and/or the mobile network ("APN"). Can someone explain what the APN is and what turning it off does? Does it cut off all calls and texts? If it does, I'm not sure why you would want to turn it off. EDIT: I guess I should also ask... does it really save power to turn off the APN? Thank you!