This is my second iPhone 4, apple just replaced my first one on Saturday because of proximity sensor and dropped calls.
I just wanted to point out that the reception/bar issue is still apparent even while using the speaker phone with 5 bars. I was on the phone with ATT high speed internet and since this was a long call I had them on speaker phone the entire 1 hour call. While on this call my iPhone dropped the call 3 times within the hour and I had the phone sitting on the table, with 5 bars and a rubber bumper. Luckily ATT had my return number and was able to call me back.
I just wanted to point out that the reception/bar issue is still apparent even while using the speaker phone with 5 bars. I was on the phone with ATT high speed internet and since this was a long call I had them on speaker phone the entire 1 hour call. While on this call my iPhone dropped the call 3 times within the hour and I had the phone sitting on the table, with 5 bars and a rubber bumper. Luckily ATT had my return number and was able to call me back.