Last night I left my iPhone on my bed stand, and noticed a lot less GSM buzz from the clock radio than usual. When I checked in the morning, I found that I had left wifi turned off. Less GSM buzz means that the phone radio may have turned down its transmit power. It would do this if it thought that it had better cell reception, and thus needed less power to contact the nearest cell tower. So has any else noticed whether turning wifi on causes worse reception or more dropped calls? There must be a lot of little antennas crowded together inside an iPhone (4 bands of GSM, 3G, wifi, Bluetooth, & GPS) that could potentially be interfering with one another. Or maybe AT&T stuck a new cell tower in my neighborhood that's not on any of the maps? .