To be more specific, does the iPhone have an equivalent to slamming the phone on someone? Pressing the End Call button simply doesn't have the same effect - you have to wait until the phone detects that you've moved it away from your face and turns on the screen, and then you have to dismiss the Low Battery notification (if applicable), and only after all that can you actually press the End Call button.
I discovered this on an earlier version of iOS but had completely forgotten about it! It seems that iOS 7 takes longer to turn on the screen after you move the phone away from your face than previous versions of iOS.
Glad you posted this question, as it was something I wondered about too. I'm even "more glad" there is a solution. Thanks to all who replied
Oh, if you slam the phone down it will hang up on the other party. This tends to work only once, though.
Err... am I the only one with an iPhone who preserves the call when I lock the phone... I've never owned an iPhone that hangs up when I use the sleep/wake button it just saves the phonecall in the background.
Never mind, It seems that I've been turning on the speaker to make sure the call is being hung up. This however causes the background feature to kick in, my bad.
Haha I do kind of miss the days of hanging up and the other person being able to hear that "click" sound.
Shoot it with a gun. Smash it repeatedly with a BFH. Drop a wrecking ball on it. Politely inquire as to the caller's location. Go there. Do any of the three aforementioned things while looking sternly in the eyes of the caller to REALLY get your point across. or.. Say "Good day to you, Sir/Ma'am." and calmly end the call knowing that your blood pressure won't spike too high and pop that vein in your forehead.
It will do that if you haven't answered the call yet (I believe one press to silence and one more to send to voice mail), but if you are already on the call (as the OP suggests) then the button will simply end the call.