I just sent an email to o2 regard poor call quality on my iPhone, and that is what I got in reply (suspiciously quickly). Bloody nonsense.
Their suggestions for ameliorating poor call quality were:
1. Check to see you have enough signal
2. Turn the phone off and on again
3. Remove and replace the sim card (!! How this could help I don’t know. Probably they should have said “Try step 2 again”)
4. Make sure airplane mode is not on (See my note to 3)
They missed out point 5: “Check to see your hands are not stuck in your mouth and that you are not quite as much of a fucking spastic as o2 believe you to be”
Incidentally, I fixed the problem before they responded by simply turning off 3G, in case you are interested or have an iPhone that makes you sound like you are talking with your head stuffed up a thin animal