The last couple of days I've had this problem pop up a couple of times. My phone will show full bars and 3G so no clue as to a problem but if I try to make a call it fails or if I try to send a text it will fail. I have to restart the iphone and then it will work again and I'll have a bunch of missed texts that pop up. This last time happened while it was charging and it showed that it wasn't fully charging then when I restarted it showed a full charge. And I'm not sure if this is connected but the last couple of weeks I'll get off a call at home and notice that it says I'm on an "o" network then it goes to Edge then back to 3G. I've had my iphone for over a year and this has never been a problem before. Any ideas? Is it related to 3.1? 16GB iPhone 3G btw.