I just noticed that every time I enter the Phone App built into the iPhone 3GS, the round, spinning network indicator, which is located next to the 3G icon at the top of the screen, is in use. This indicates that the iPhone is accessing the network even when the phone is not in use. I don't recall this happening on my old 3G. Does anyone else notice this phenomenon? Could this be the culprit in the huge battery drain issues that many face?