That's a good tip. I usually press the "home" button out of habit and it doesn't hang up just goes to the "home screen"-then I've got to go back to the phone and hang up.
Anyway, I'm out in the boonies and I have no ATT service 'till I get out of the house and it makes it difficult to phone my iPhone. I did manage this today and noticed that the connection does end itself after about 30 seconds or so. I'm on the ATT go-phone plan paying 15 cents per minute so I didn't want to keep an open connection for very long. If I forget to hang up I can live with 7.5 cents penalty
Thanks for the thoughts.