I was on my second 8GB iPhone when I decided to try a 4GB based on what I heard from an AT&T tech person. This person had a production, off the shelf 4GB but had done a firmware restore even though the firmware version from iTunes had not changed. After the restore his 4GB had no problems. He also said the RF problems were likely to occur when the phone had no direct line of sight to the tower - perhaps not responding correctly to multipath signals.
My first 8GB had the common erratic RF problem - going from 4-5 bars to "No Service" without moving my hand holding the iPhone - as well as the battery not fully charging problem - and lots of dropped calls and/or calls going directly to voicemail. AppleCare had AT&T download an update to the phone and this helped but did not cure the RF or battery problems. On the advice of the AppleCare person I exchanged the first 8GB for another new 8GB. The only difference I could tell between the two phones was the serial number of the second phone was considerably later than the first phone and the LCD display was a different part. RF was slightly better and the battery problem remained. I then did a firmware restore but nothing changed.
The 4GB at first was just as bad as the first 8GB except no battery problem. I then did the firmware restore (again same version number) and afterwards no erratic RF! Still had a drop of a bar or two from time to time but this was also true on my other phones on Cingular. No dropped calls either.
I am not sure what conclusions to draw. It "appears" that with the 4GB a firmware restore can help the RF problem while it makes no difference on the 8GB - at least on the ones I had. I think others have reported that a firmware restore on the 8GBs have made a difference so maybe I got lucky. I just hope the good RF performance continues and if it doesn't I guess I will try another firmware restore. And also return the second 8GB.
What is clear is that Apple has a wide spread problem - probably with the selectivity of the radio front end at non direct line of sight locations and needs to get it fixed as soon as possible. Also this is definitely NOT an AT&T problem - at least at my location - as I have compared 2 "good" 4GBs, a "good" Nokia N95, and a "good" Nokia E61 with 2 "bad" 8GB iPhones. The "goods" all showed a bar or two drop which is normal at my location and in Test Mode showed roughly the same -db signal readings. With the "bads" signal levels would go from -85 to -112, etc., all over the map.
Hope this helps,
Frank
