I'm already on my second iPhone 4 (the first one went back after 3 days as the camera wasn't working) and now the second handset has started behaving strangely. When I answer an incoming call the ringtone continues to play in the earpiece. It's only audible at my end, but does make having a conversation quite difficult. I'm still using the standard apple ring tones and the phone is set to ring and vibrate. I'm loving so much about this phone and have only had it a couple of days and really don't want to send another handset back. Any ideas?