Normal 0 Well, it looks like I've found the answer to my own question. The IPhone does not appear to be a stereo phone without plugging in the earphones or docking. Very high tech 'I don't think'. When you put you phone in your pocket, it is very, very easy to block the only speaker, as it is located at the bottom of the phone. I suppose you could get into the habit of putting your phone into your pocket upside-down or always keeping it in vibrate-mode.
This is a very, very basic omission and a serious design issue (flaw) for me. The bottom lhs rhs is the speaker, bottom lhs is the microphone. The phone is goooooood though.