All Windows Phone come with edge and 3G radios on. Believe it or not but both of these radios suck a lot of battery juice from your phone’s battery. Even when you are using the Internet, your windows phone keeps checking for updates for its operating system and apps in the background. So, when you are not using them, it is better to keep them off, especially the 3G radio. We even recommend using Wi-Fi over 3G as it former sucks less power.
To turn 3G off, go to Settings, then to “Cellular and tap on the 3G Connection to turn it off. To totally turn off the internet, turn the edge off as well. If you are about to board an airplane, you must switch on the airplane mode on your phone. This will turn off the cellular connection along with Wi-Fi and other data radios like edge and 3G.